Lectures Cpcb

8/2/2019 Lectures Cpcb

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LECTURE

MICROBIOLOGY OF WATER AND WASTE WATER

Dr. Reeta Goel

Professor& Head

Department of MicrobiologyCollege of Basic Sciences and Humanities

G.B. Pant Uni. of Agri. & Technology, Pantnagar

In urban areas, the household consumption of water is about 150 liters per

day per person. Water is used for bathing, washing utensils, washing clothes etc.

This domestic water consumption may vary with the lifestyle of community and

the availability of water. Most of the water taken into the house may be returned

as wastewater through drainage system. Moreover, industries also consume large

quantities of water and contribute to the discharged effluent.

WATER AND HEALTH

Water which is fit for human consumption is called drinking water or

potable water. Sometimes the term safe water is applied to potable water of a

lower quality threshold (i.e., it is used effectively for nutrition in humans that have

weak access to water cleaning processes, and does more good thanharm).Sometimes microorganisms that cause health problems can be found in

drinking water. However, as drinking water is thoroughly disinfected today,

disease caused by microorganisms is rarely caused by drinking water. There are

various bacteria and protozoa that can cause disease when they are present in

surface water(Table 1).

Water Purity Tests

Explain how water is tested for bacteriological qualityHistorically, most of our concern about water purity has been related to the

transmission of diseases. Therefore, tests have been developed to determine the

safety of water; many of these tests are also applicable to foods.

It is not practical, however, to look only for pathogens in water supplies.

Because, if we were to find the pathogen causing typhoid or cholera in the water

system, the discovery would already be too late to prevent an outbreak of the

disease. Moreover, such pathogens would probably be present only in small num-

bers and might not be included in tested samples.

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Table 1. various bacteria that can be found in surface water, and the

diseases caused by them .

Bacteria Disease/ infection SymptomsAeromonas Enteritis Very thin, blood- andmucus-containingdiarrhoea

Campylobacter jejuni Campilobacteriose Flue, diarrhoea, head-and stomachaches, fever,cramps and nausea

Escherichia coli Urinary tract infections,neonatal meningitis,intestinal disease

Watery diarrhoea,headaches, fever,homiletic uraemia, kidneydamage

Plesiomonas shigelloides Plesiomonas-infection Nausea, stomachachesand watery diarrhoea,sometimes fevers,headaches and vomiting

Salmonella Typhoid fever Fevers

Salmonellosis Sickness, intestinalcramps, vomiting,diarrhoea and sometimeslight fevers

Streptococcus (Gastro) intestinal disease Stomachaches, diarrhoeaand fevers, sometimes

vomitingVibrio El Tor (freshwater) (Light form of) Cholera Heavy diarrhoea

The tests for water purity in use today are aimed for detection particular

indicator organisms. There are several criteria for an indicator organism, the

most important being that the microbe is consistently present in human feces in

substantial numbers so that its detection is a good indication that human wastes

are entering the water. The indicator organisms should also survive in the water at

least as well as the pathogens would. The indicator organisms must also be

detectable by simple tests that can be carried out by people with relatively little

training in microbiology.

Coliforms are defined as aerobic or facultatively anaerobic, gram-negative,

non-endospore-forming, rod-shaped bacteria that ferment lactose to form gas

within 48 hours of being placed in lactose broth at 35C. Because some coliforms

are not solely enteric bacteria but are more commonly found in plant and soil

samples, many standards for food and water specify the identification of fecal

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coliforms. The predominant fecal coliform is E. coli, which constitutes a large

proportion of the human intestinal population. There are specialized tests to

distinguish between fecal coliforms and nonfecal coliforms. Further, coliforms arenot themselves pathogenic under normal conditions, although certain strains can

cause diarrhea and opportunistic urinary tract infections.

The common methods for determining the presence of coliforms in water are

largely based on the lactose-fermenting ability of coliform bacteria. The multiple-

tube method can be used to estimate coliform numbers by the most probable

number (MPN) method. The membrane filtration method is a more direct method

of determining the presence and numbers of coliforms.

A more convenient method of detecting coliforms, specifically the coliform E.

coli, makes use of media containing the two substrates o-nitrophenyl--D-

galactopyranoside (ONPG) and 4-methylumbelliferyl--D-glucuronide (MUG).

Coliforms produce the enzyme -galactosidase, which acts on ONPG and forms a

yellow color, indicating their presence in the sample. E. coli is unique among

coliforms in almost always producing the enzyme -glucurom'dase, which acts on

MUG to form a fluorescent compound that glows blue when illuminated by long-

wave ultraviolet light. These simple tests, or variants of them, can detect the

presence or absence of coliforms or E. coli and can be combined with the

multiple-tube method to enumerate them. It can also be applied to solid media,

such as in the membrane filtration method. The colonies fluoresce under UV light.

Coliforms have been very useful as indicator organisms in water sanitation, but

they have limitations. One problem is the growth of coliform bacteria embedded in

layers of biological slime (or biofilms, discussed in detail shortly) on the inner

surfaces of water pipes. These coliforms do not, then, represent external fecal

contamination of the water, and they are not considered a threat to public health.

Wastewater

Wastewater is liquid effluent derived from domestic sewage of industrial

sources that cannot be discarded in untreated form into lakes or streams due to

public health, economic and aesthetic considerations. Sewage is liquid effluent

contaminated with human or animal fecal materials. For technical purpose can be

divided into urban and industrial wastewater. The composition of the former

usually conforms to a general typology.

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Most industrial processes emit wastewater during one or more stages of

production. The composition of this type of water can vary dramatically as it is

determined both by the products themselves and processes of production. Allthese waste waters contain organic and inorganic wastes as suspended or

dissolved matter. In addition they may also contain microorganisms, including

those of faecal origin and pathogenic nature.

The solids content of an urban wastewater may be physically classified

approximately as shown in fig. 1 (Metcalf and Eddy, 1987)

ds

Fig.1 Classification of solids found in urban wastewater (Metcalf andEddy, 1987)

In a typical urban wastewater, about 75 percent of the suspended soli

and more than 50 percent of the filterable solids are organic in nature. These

solids are derived from both the animal and plant kingdoms and the activities of

these as related to the synthesis of organic compounds. The principal groups of

organic substances found in wastewater are proteins (40 to 60 %), carbohydrates

(25 to 50 %), fats and oils(10 % (Metcalf and Eddy, 1987). Beyond these

substances, wastewater contains small quantities of a large number of different

synthetic organic molecules. Surfactants, phenols and pesticides are typical

compounds.

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Various forms of nitrogen in urban wastewater (Ekama et al., 1984)Industrial waste generally has a strong odour. The substances responsible

for causing odour and taste are phenol compounds, sulphur compounds, iron,

manganese, sodium chloride, calcium chloride, magnesium salts, acids,

hydrocarbons, often present in wastes from gas and wood industries, refineries

and various chemical industries (Mendia, 1962).

Microbiological Characteristics of Sewage

The sewage composition varies depending upon the source of wastewater.

This also causes variation in the microbial flora of sewage. Almost all groups of

microorganisms, algae, fungi, protozoa, bacteria and viruses are present. The

bacterial group comprises mainly the soil borne organisms, Bacillus subtilis, B.

megaterium, B. mycoides, Pseudomonas fluorescens, Achromobacter spp. and

Micrococcus spp. Bacteria of intestinal origin also occur in sewage in large

numbers. Mostly these are pathogens. Examples of this type are Escherichia coli,

and other coliforms, Proteus and Serratia species. Potential pathogens include

enterococci (Streptococcus faecalis) and Clostridium perfringens. Pathogenic

bacteria which cause serious illness like Vibrio cholerae, Salmonella typhi, S.

paratyphiand Shigella dysenteriae may also occur in sewage. Viruses (released

in the faeces from infected host) are also occasionally found in sewage, for

example, poliomyelitis virus, infectious hepatitis virus and Coxsackies virus.

Bacteriophages also occur in comparatively large numbers. During treatment

process the microbial flora may be dominated by the corresponding physiological

groups.

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WASTEWATER AND SEWAGE TREATMENT

Wastewater treatment refers to the process of removing pollutants from water

previously employed for industrial, agricultural, or municipal uses. The main

objectives of the sewage treatment are:

To convert waste and wastewater into a readily reusable resource.

To prevent pollution of any water body to which treated or reused water

enters.

To reduce the BOD (biochemical oxygen demand) of sewage from 30 mg/l

to about 20 mg/l in the final effluent.

To destroy the causative agents of waterborne diseases

Wastewater and sewage treatment involves a large-scale use of

microorganisms and can be considered a type of industrial-scale bioconversion.

Wastewater enters a treatment plant and, following treatment, the effluent water is

suitable for release into rivers and streams or to drinking water purification

facilities. The techniques used to remove the pollutants present in wastewater can

be broken into biological, chemical, physical, and energetic. These different

techniques are applied through the many stages of wastewater treatment.

Systems commonly used for treatment of urban wastewater are constituted of

primary treatment by settling, a biological second stage, and a tertiary treatment

by disinfection, in some cases following a filtration process.

Primary sedimentation is most efficient in removing coarse solids.

Biological processes are used to convert the finely dissolved organic matter in

wastewater into flocculant settleable solids that can be removed in sedimentation

tanks. These processes are employed in conjuction with physical and chemical

processes and they are most efficient in removing organic sub-stances that are

either soluble or in the colloidal size range. Disinfection is generally operated by

chlorination with Cl2 or NaOCl.

The main systems for removal of solids, organic matter and pathogens are

the activated sludge process, trickling filters, aerated lagoons, high-rate oxidation

ponds, stabilization ponds. Stabilization ponds or aerated lagoons are most often

used for small installations. The activated sludge process, or one of its many

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modifications, is most often used for larger installations. In some cases trickling

filters are applied.

Several processes have been used for activated sludge. The mostimportant are (Metcalf and Eddy, 1987): tapered aeration process; modified

aeration process; continuous-flow stirred tank; step aeration process; contact

stabilization process; extended aeration process; oxidation ditch; carrousel

system; high-rate aeration process.

Wastewater treatment and biochemical oxygen demand

The goal of a wastewater treatment facility is to reduce organic and

inorganic materials in wastewater to a level that no longer supports microbial

growth and to eliminate other potentially toxic materials. The efficiency of

treatment is expressed in terms of a reduction in the biochemical oxygen demand

(BOD), the relative amount of dissolved oxygen consumed by microorganisms to

completely oxidize all organic and inorganic matter in a water sample. Higher

levels of utilizable organic and inorganic materials in the wastewater result in a

higher BOD. Typical values for domestic wastewater, including sewage are

approximately 200 BOD units. For industrial wastewater for example from sources

such as dairy plants, the values can be as high as 1500 BOD units. An efficient

wastewater treatment facility reduces levels to less than 5 BOD units in the water

released from the treatment plant.

A typical wastewater facility must treat both sewage and industrial wastes.

Treatment is a multistep operation employing a number of independent physical

and biological process. Primary, secondary(Fig.3) and sometimes tertiary

treatments are employed to reduce fecal and chemical contamination in the

incoming water. Each level of treatment employs more complex and more

expensive technologies.

Primary treatment

Primary treatment usually includes the removal of large solids from the

wastewater via physical settling or filtration. The first step in primary treatment is

screening. Wastewater entering the treatment plant is passed through a series of

grates and screens that remove large objects. The effluent is left to settle down for

a number of hours to allow suspended solids to sediment. Municipalities that

provide only primary treatment suffer from extremely polluted water when the

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effluent is discharged into adjacent waterways because high levels of organic

matter and other nutrients remain in water following primary treatment. Therefore,

most treatment plants employ secondary treatment to reduce the organic contentof the wastewater before release to natural waterways. Secondary treatment is

intimately tied to microbiological processes.

Secondary Treatment

Secondary treatment typically removes the smaller solids and particles remaining

in the wastewater through fine filtration aided by the use of membranes or through

the use of microbes, which utilize organics as an energy source. Energetic

techniques may also be employed in tandem with biological techniques in the

secondary phase to break up the size of particles thus increasing their surface

area and rate of consumption by the microbes present. A common first step in the

secondary treatment process is to send the waste to an aeration tank.

Anoxic secondary wastewater treatment

Anoxic wastewater treatment involves a series of digestive and fermentative

reactions carried out by a number of bacterial species and is usually employed to

treat materials that have large amounts of insoluble organic matter (and hence

very high BOD), such as fiber and cellulose waste from food-and dairy processing

plants. The anoxic degradation process itself is carried out in large enclosed tanks

called sludge digesters or bioreactors and requires the collective activities of

many different types of microorganisms.Through the action of the resident anoxic

microorganisms, the macromoleculare waste components are first digested by

polysaccharases, proteases and lipases into soluble components. These soluble

components are then fermented to yield a mixture of fatty acids, H2 and CO2 and

the fatty acids are further fermented to acetate, CO2 and H2. These products are

then used as substrates by methanogenic bacteria, which are capable of carrying

out the reactions CH3COOH CH4+CO2 and 4H2O + CO2 CH4 + 2H2O. Thus

major products of anoxic sewage treatment are CH4 (methane) and CO2. The

methane can be collected and either burned off or used as fuel to heat and power

the treatment plant.

Aerobic secondary treatment

In general, nonindustrial wastewater can be treated efficiently using only aerobic

secondary treatment. Several kinds of aerobic decomposition processes are used

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for wastewater treatment, but the trickling filter and activated sludge methods

(Fig.2) are the most common. A trickling filter is a bed of crushed rocks, about 2 m

thick, on tip of which the wastewater is sprayed. The liquid slowly passes throughthe bed, the organic matter adsorbs to the rocks and microbial growth occurs on

the rocks. The complete mineralization of organic matter to carbon dioxide,

ammonia, nitrate, sulfate and phosphate takes place in the microbial biofilms on

the rocks. The most common aerobic treatment systems is the activated sludge

process. Here, the wastewater to be treated is mixed and aerated in a large tank.

Slime-forming bacteria, including Zooglea ramigera, among others, grow and form

flocs (large, aggregated masses) and these flocs form the substratum to which

protozoa and small animals attach. Occasionally, filamentous bacteria and fungi is

pumped into a holding tank or clarifier where the flocs settle. Some of the floc

material (called activated sludge) is then returned to the aerator to serve as

inoculum and the rest is sent to the anoxic sludge digestor or is removed, dried

and burned or used for fertilizer.

Fig.2; Simple Activated Sludge with Trickling filter

Wastewater normally stays in an activated sludge tank for 5 to 10h, a time

too short for complete oxidation of all organic matter. However, during this time

much of the soluble organic matter is adsorbed to the floc and is incorporated into

microbial cells. The BOD of the liquid effluent is considerably reduced (by up to

95%) by this process, with most of the BOD now contained in the settled flocs and

the goal of BOD reduction in the water is achieved. Nearly complete BOD

reduction can occur if the flocs are then transferred to the anoxic sludge digestor.

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Most treatment plants now chlorinate the effluent (to further reduce the possibility

of biological contamination) and discharge the treated water to streams or lakes. A

few plants, however, process wastewater through a tertiary stage.Tertiary treatment

Tertiary treatment is the most complete method of treating sewage but has not

been widely adopted because it is very expensive. Tertiary treatment is a

physicochemical process employing precipitation, filtration and chlorination

procedures similar to those employed for drinking water purification to sharply

reduce the levels of inorganic nutrients, especially phosphate and nitrate, from the

final effluent.

Fig.3: Primary and secondary treatment of raw water

Physiochemical purification

A typical drinking water treatment installation for a small city is shown in

figure 4. Raw water is first pumped from the source, in this case a lake, to a

sedimentation basin where anionic polymers, alum (aluminum sulfate), and

chlorine are added. Sand, gravel and other large particles settle out. This

pretreated water is then pumped to a clarifier or coagulation basin, a large holding

tank where coagulation takes place. The alum and anionic polymers form larger

suspended particles from the much smaller suspended colloidal particles. After

mixing, the particles continue to interact, forming large, aggregated masses, a

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process known as flocculation. The large, aggregated particles, called floc, settle

out by gravity, trapping any remaining microorganisms and absorbing organic

matter and sediment. After coagulation and flocculation, the clarified waterundergoes filtration. The water is passed through a series of filters designed to

remove the remaining suspended particles and microorganisms. The filters

usually consist of thick layers of sand and ionic filtration media. When combined

with previous purification steps, the filtered water is free of all particulate matter,

most organic and inorganic chemicals, and all microorganisms.

Disinfection

Clarified, filtered water must then be disinfected before it is released to the supply

system as pure, potable finished water. Chlorination is the most common method

of disinfection. In sufficient doses, chlorine kills microorganism within 30 minutes

(certain pathogenic protozoa such as Cryptosporidium are not easily killed by

chlorine treatment and thus can be important waterborne pathogens. In addition to

killing microorganisms, chlorine reacts with organic compounds, oxidizing and

effectively neutralizing them. Therefore, since most taste and odor-producing

compounds are organic in nature, chlorine treatment also improves water taste

and smell. Chlorine is added to water either from a concentrated solution of

sodium or calcium hypochlorite or as a gas from pressurized tanks. The latter

method is used most commonly in large water treatment plants because it is most

amenable to automatic control.

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Fig. 4: Water treatment system

Further Reading

Ekama G.A., G.v.R. Marais and I.P. Siebritz., (1984). Biological Excess

Phosphorus Removal. In Theory, Design and Operation of Nutrient

Removal Activated Sludge Processes, information document prepared for

the Water Research Commission by the University of Cape Town, City of

Council of Johannesburg and the National Institute for Water Research of

the CSIR, Pretoria.

Mendia L., (1962). Aspetti tecnici del problema degli scarichi industriali.

Ingegneria Sanitaria, N. 1.

Metcalf and Eddy, Inc., (1987). Wastewater Engineering: Treatment, Disposal,

Reuse. Tata McGraw-Hill Publishing Company Ltd., New Delhi, second

edition, 6th reprint.

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*Basic Terminology of Microbiology

Autoclave : A sterilizer that destroys microorganisms by hightemperature using steam under pressure

Bacteria : All prokaryotes that are not members of thedomain Archaea

Biofilms ; Microbial colonies encased in an adhesive,usually polysaccharide material, and attached toa surface

Bioremediation : Use of microorganisms to remove or detoxifytoxic of unwanted chemicals in an environment

Biotechnology : The use of living organisms to carry out definedchemical processes for industrial application

Coccus : a spherical bacterium

Coliforms : Gram-negative, nonsporing, facultative rods thatferment lactose with gas formation within 48 hr at35o C

Colonization : Multiplication of a microorganism after it hasattached to host tissues or other surfaces

Colony : A macroscopically visible population of cellsgrowing on host tissues or other surfaces

Complex media : Culture media whose precise chemicalcomposition is unknown. Also called underfinedmedia

Consortium : A two-(or more) membered bacterial culture (or

natural assemblage) in which each organismbenefits from the others

Culture : A particular strain or kind of organism growing ina laboratory medium

Culture medium : An aqueous solution of various nutrients suitablefor the growth of microorganisms

Disease : Injury to the host that impairs host function

Eukarya : The Phylogenetic domain containing alleukaryotic organism

Extremophile : An organism that grows optimally under one ormore chemical or physical extremes, such as

high or low temperature or pHFungi : Nonphototrophic eukaryotic microorganisms that

contain rigid cell walls

Gene : A unit of heredity; a segment of DNA specifying aparticular protein or polypeptide chain, a tRNA oran rRNA

Gram-negative cell : A prokaryotic cell whose cell wall containsrelatively little petidoglycan but has an outermembrane composed of lipopolysaccharides,lipoprotein and other complex macromolecules

Gram-positive cell : A prokaryotic cell whose cell wall containsrelatively little peptidoglycan and lacks the outermembrane or gram-negative cells

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Growth : In microbiology, an increase in cell number

Growth rate : The rate at which growth occurs, usuallyexpressed as the generation time

Guild : A group of metabolically related organismsMicroorganisms : A microscopic organism consisting of a single cellor cell cluster, also including the viruses

Nutrient : A substance taken by a cell from its environmentand used in catabolic or anabolic reactions

Parasite : An organism able to live on and cause damage toanother organism

Pasteurization : Destruction, usually by heat treatment, of alldiseases-producing, microorganisms along with areduction in the number of spoilagemicroorganism

Pathogen : An organism able to inflict damage on a host itinfects

Pure culture : A culture containing a single kind ofmicroorganism

Stationary phase : The period during the growth cycle of a microbialpopulation in which growth ceases

Sterilization : The killing or removal of all living organism andtheir viruses from a growth medium

Strain : A population of cell of a single species alldescended from a single cell; a clone

Virus : A genetic element containing either DNA or RNAthat replicates in cells but is characterized byhaing an extracellular state

Water activity (aw) : An expression of the relative availability of waterin a substance. Pure water has an aw of 1.000

Xenobiotic : A completely synthetic chemical compound notnaturally occurring on Earth

Yeasts : Unicellular fungi

* Source: Brock Biology of Microorganism 2003, 10th Edition

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Water Purification and Public Health

S.P. Singh

Prof. & HeadDepartment of Veterinary Public Health

College of Veterinary and Animal Sciences,G. B. Pant University of Agri. & Tech., Pantnagar-263145

Water and Health

The worlds population is expected to increase every year by 74.8 million.

To meet requirement of water for such a huge population, sincere efforts are

being made at international level. The United Nations have declared 2005-2015

as the International Decade for Water for life and World agenda has been set

focusing the water related issues. This issue is of great consequence since

approximately 1.8 million people die every year from diarrhoeal diseases

(including cholera); mostly in developing countries where 88% of diarrhoeal

disease is attributed to unsafe water supply, inadequate sanitation and hygiene.

Improvements in drinking-water quality through household water treatment, such

as chlorination at point of use can lead to a significant reduction of diarrheal

episodes. There is a need to undertake an integrated water resources

management so as to provide safe and clean water to all.

Waterborne diseases occur not only as an endemic but also often appear

as an epidemic. In the context of zoonoses, the waterborne diseases have

significance in both developed as well as developing countries alike. The

associated pathogens are transmitted predominantly by faecal-oral andoccasionally by faecal-droplet routes.

Consequent to the dynamics in the population as well as its resultant effect

on the environment, many pathogens are taking newer and virulent forms

resulting in the emergence and re-emergence of the waterborne disease. Such

changes are not free from the adverse consequences on the public health and

these include (i) changing patterns of water use (ii) population

growth/migration/variation (iii) increased population of the immunocompromised(consequent to the malnourishment as well as immunodeficiency diseases such

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as AIDS and its deadly combinations with tuberculosis/toxoplasmosis etc) (iv)

increased use of water due to the changed lifestyle and access to recreational

activities (v) water scarcity, climate changes, disasters, & the emergencies (vi)war and bioterrorism (vii) increased population in the urban and periurban areas

(viii) use of non-conventional alternatives to meet the never ending human

demands (ix) increased use of agro-chemicals, antibiotics, growth promoters, and

other veterinary drugs for the production and protection of plants, animals and

human (x) altered ecological rhythm and (xi) the global trade, its regulations and

their related consequences.

Zoonotic pathogens have been encountered in water as a cause of gastro-

enteric infections with the symptoms of diarrhea in many countries. But, still there

exist many diseases that just escape the diagnosis process. Leptospirosis, E. coli

O157:H7, Cryptosporidiosis, Campylobacter, Toxoplasmosis and Giardiasis, occur

regularly in some countries. It is also important to mention more than 75% of all

the emerging pathogens are zoonotic on nature. Further, animals and other lower

vertebrate or non-vertebrates play an equal role as that of human in the

maintenance or transmission of such infections that ultimately threaten the human

life by the way of vehicles, particularly water.

A variety of bacteria, parasites, fungi, viruses can be acquired by the way

of water. The transmission routes involve drinking, contact, water use (food

preparation, agriculture) exposure to wastewater, faeces, urine, and abattoir

waste.

The viruses / prion particles possess considerable host specificity yet can

infect the related species. There are 1.5 million cases of clinical hepatitis reported

every year.Many of the bacterial pathogens are well established water borne

pathogens such as Salmonella, E. coli O157:H7, Campylobacter, Yersinia,

Mycobacterium avium (ssp. paratuberculosis) and Leptospira. They can be

transmitted by improperly purified water and can put the end users of water at risk.

The waterborne zoonotic bacteria are principally those shed in faeces by warm-

blooded animals (birds and mammals), although some are also harbored by

reptiles.

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Although fungi are transmitted directly by contact but at times, water can

act an agent of transmission and the infections such as Trichophyton spp.,

Cryptococcus, and Coccid odes may enter by such route.Protozoan pathogens originating from animal and human waste have been

recorded from water sources throughout the world. A number of well documented

waterborne zoonotic protozoa exist, including Giardia intestinalis,

Cryptosporidium, Toxoplasma gondii, and Entamoeba histolytica. There are other

potential candidates including Cyclospora, where waterborne transmission has

been demonstrated but a zoonotic route remains to be established. Protozoan

pathogens, including microsporidia, amoebae, ciliates, flagellates, and

apicomplexans, originating in human or animal faeces have been found in surface

waters worldwide The zoonotic protozoa that are emerging or are of renewed

interest consequent to their spread associated with water include several species

of microsporidia, the amoeba Entamoeba histolytica, Giardia duodenalis (G.

lamblia), Toxoplasma gondii, and Cryptosporidium spp. Although Cyclospora

cayetanensis is known to be a waterborne threat and has been detected in

washings from vegetables contaminated with irrigation water, humans are the only

confirmed hosts for this species.

Major helminthic zoonoses include nematodes such as ascarids, pinworms,

hookworms, strongylids, angiostrongylids, capillarids, and guinea worms, flukes

such as schistosomes and liver flukes, and tapeworms such as the beef, pork,

and fish tapeworms, as well as cystic and alveolar hydatid tapeworms. Poor

sanitation and poor water quality facilitate transmission among animals and

humans.

Water purification

The ultimate purpose of water purification is inactivation and removal of

pathogens such as bacteria, viruses, parasites, microbial toxins and other

miscellaneous pathogens, as well as elimination of contaminants that arise into it

by the way of its pollution at various levels of the distribution system. Hence

routine analysis of water is a mandate to assess the number of pathogens in the

water, to select a suitable treatment facility to assure the consumers about

wholesomeness of the water. Since decades, a composite system known as

multiple barrier concept have been in use for the purification of water, which

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holds good till today. This includes protection of the source of water, coagulation,

flocculation, sedimentation, filtration, disinfection, and finally protection of the

water distribution systems. But the recent epidemiological data indicate lacunae insuch traditional systems and there is a need to modify them by adding multistage

filtration and disinfection especially to remove the pathogens and still stringent

treatment so to remove the environmental pollutants, contaminants and other

miscellaneous substances that have health implications. There is a need to

implement HACCP in the water related industries so as to keep the contaminants

at the lowest possible limits. Water safety plan has also to set and followed strictly

as per the recommendations of the competent authorities. Frameworks need to be

strengthened to so as to maintain minimum residual concentrations of the

disinfectants in the distribution systems even taking care health implications

arising from such chemicals.

Keeping in view the public health significance of water, it must pass

through the various stages of water purification system. The various water

purification processes include are described as follows:

Boiling for one minute can kill harmful organisms and thus can be

considered as a reliable method. Various halogens such as iodine and chlorine

preparations can also serve the function. Iodination is a very effective and

convenient method for water purification as it destroys bacteria, viruses and

protozoan cysts in concentration temperature and duration dependent destruction

of such pathogens (8 mg/liter at 20 0C for 10 minutes). Preparations of iodine such

as tincture of iodine (4 drops in a 1 litre of water or one drop for a glass), iodine

crystals and tablets can be used for the purpose; but all the halogens are not

effective against Cryptosporidium. While using iodine preparations for water

purification, proper care must be taken for pregnant women, very young

individuals and the persons suffering from thyroid disease or iodine allergy. After

the iodine application, the taste due to remaining iodine residues can be

eliminated by the use of vit-C tablets, lime or lemon juice.

The various processes employed for removal of microbes from the water

include (i) pre-treatment by using any process that modifies microbial water quality

before, or at the entry to, a treatment plant; (ii) coagulation, flocculation and

sedimentation by which small particles interact to form larger particles and settle

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out by gravity; (iii) ion exchange used for the removal of calcium, magnesium and

some radionuclide; (iv) Granular filtration, in which water passes through a bed of

granular materials after coagulation pretreatment; (v) slow sand filtration, in whichwater is passed slowly through a sand filter by gravity, without the use of

coagulation pretreatment.

Pre-treatment

Pre-treatment of water (roughing filters, microstrainers, off-stream storage

and bank infiltration), help in the removal of algae, turbidity, viruses and protozoan

cysts. During pretreatment a variety of treatment s are undertaken that vary in

their complexity and may vary from disinfection to membrane filtration.

Roughing employed for pretreatment are filters derived from rock or gravel

that are used prior to filtration (slow sand) process to reduce turbidity (up to 60-

90%), coliform count (93-99.5%), algal cell (37%), total chlorophyll (53%). Further;

color, organic carbon, and the turbidity can still be reduced by the use of alum

coagulant.

Micro strainers are made of fabric meshes woven of stainless steel or

polyester wires and many large sized protozoa such as Balantidium coli, but

smaller pathogens such as bacteria or viruses can not be removed and these also

reduce turbidity (520%) which can even be enhanced by the use of coagulants

(alum).

The quality of water in the off-stream storage reservoirs that feed the

potable water source directly or indirectly feeds a potable water intake is

determined by the physical, biological and chemical processes taking place in it.

The algal growth, influx of nitrogen, phosphorous and other contaminants and the

faecal contamination at or near surroundings should be limited even attempts

should be made to reduce birds. If properly stored at off-storage reservoirs there

can be significant reduction in the counts ofCryptosporidium, E.coli, Giardia, and

entero-viruses. Further, storage of water in divided reservoirs is better compared

to single large reservoir.

A process of surface water seeping from the bank or bed of a river or lake

to the reduction wells of a water treatment plant is known as Bank infiltration

which is used in some of the European countries. This process reduces Giardia,

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Cryptosporidium, Clostridia, bacteriophase and certain viruses such as Entero and

Reoviruses.

Coagulation, flocculation and sedimentationCoagulation, flocculation and sedimentation are used in conjunction with

subsequent filtration. Coagulation promotes the interaction of small particles to

form larger particles. In practice, the term refers to coagulant addition (i.e. addition

of a substance that will form the hydrolysis products that cause coagulation),

particle destabilization and inter-particle collisions. Flocculation is the physical

process of producing inter-particle contacts that lead to the formation of large

particles. Sedimentation is a solidliquid separation process, in which particles

settle under the force of gravity. Most bacteria and protozoa can be considered as

particles, and most viruses as colloidal organic particles that are eliminated by

such processes.

Conventionally, clarification refers to chemical addition, rapid mixing,

flocculation and sedimentation. Here the chemical coagulation is critical for

effective removal of microbial pathogens, in the absence of a chemical coagulant;

removal of microbes is low because sedimentation velocities are low. When

properly performed, coagulation, flocculation and sedimentation can result

inconsiderable removals of bacteria, viruses and protozoa. However,

Cryptosporidium and Giardia are found at very low levels, and methods for their

detection have limitations use of coagulants further helps in the reduction of

turbidity. Removal of bacteria (E. colivegetative cells and Clostridium perfringens

spores) and protozoa (Giardia cysts and Cryptosporidium oocysts) is possible but

this can be achieved by the use of iron-based coagulants which are slightly more

efficient than alum (aluminum hydroxide) or poly-aluminum chloride (PACl);

however, coagulation conditions (i.e. dose, pH, temperature, alkalinity, turbidity

and the level and type of natural organic matter) affect the efficiency of removal.

High-rate clarification involves using smaller basins and higher surface

loading rates than conventional clarifiers, and is therefore referred to as high rate

clarification. Processes include floc-blanket sedimentation (also known as solids-

contact clarification), ballasted-floc sedimentation, and adsorption or contact

clarification. In floc-blanket sedimentation, a fluidized blanket increases the

particle concentration, thus increasing the rate of flocculation and sedimentation.

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Ballasted-floc systems combine coagulation with sand, clay, magnetite or carbon

to increase the particle sedimentation rate. Adsorption or contact clarification

involves passing coagulated water through a bed where particles attach topreviously adsorbed material. Such processes help in the removal of algae,

Cryptosporidium and Giardia.

In dissolved air flotation (DAF), bubbles are produced by reducing

pressure in a water stream saturated with air. The rising bubbles attach to floc-

particles, causing the agglomerate to float to the surface, where the material is

skimmed off DAF can be particularly effective for removal of algal cells and

Cryptosporidium oocysts.

Precipitative lime softening is a process in which the pH of the water is

increased (usually through the addition of lime or soda ash) to precipitate high

concentrations of calcium and magnesium. Removal and reduction in the viability

of disinfection efficiency ofGiardia, viruses and coliform bacteria is achieved.

In-line coagulation can be used with high-quality source waters (e.g. those

where turbidity and other contaminant levels are low). The coagulants are added

directly to the raw water pipeline before direct filtration.

Ion exchange is a treatment process in which a solid phase pre-saturant

ion is exchanged for an unwanted ion in the untreated water. The process is used

for water softening (removal of calcium and magnesium), removal of some radio-

nuclides (e.g. radium and barium) and removal of various other contaminants (e.g.

nitrate, arsenate, chromate, selenate and dissolved organic carbon). The

effectiveness of the process depends on the background water quality, and the

levels of other competing ions and total dissolved solids.

Filtration using a wide variety of filters removes sand, clay and other matter

as well as organisms by means of small pore size membranes, adsorption,

exchange resins and osmosis. They effectively remove bacteria and parasites but

not viruses. Good filters are effective against Cryptosporidia and Giardia. Due to

the inability to remove viruses, filtered water must also be chemically treated or

boiled and hence many a times filtration is combined with other chemical

sterililants such as iodine (or chlorine) hence, modern filters incorporate chemical

disinfection, which is usually achieved by passing water through iodine exchange

resins. When negatively charged contaminants contact the iodine resin, iodine is

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instantly released so killing the microorganisms without large quantities of iodine

being in solution.

Various filtration processes (diatomaceous earth; micro-filtration; nano-filtration; reverse osmosis; ultra-filtration) are used in drinking-water treatment.

Filtration can act as a consistent and effective barrier for microbial pathogens.

Granular high rate media filtration is the most widely used filtration process in

drinking water treatment. Under optimal conditions, a combination of coagulation,

flocculation, sedimentation and granular media filtration can result better removal

of protozoan pathogens with chlorine-resistant cysts.

The use of slow sand filtration to protect drinking-water consumers from

microbial risk was well established more than 100 years ago. Numerous disease

outbreaks due to chlorine-resistant protozoan pathogens in the past two decades

have increased interest in slow sand filtration because of its ability to remove

parasites. It can provide some degree of protection against microbial pathogens

reducing bacteria, protozoa (Cryptosporidium, Giardia) and turbidity.

Pre-coat filtration was developed by the US Army during World War II as a

portable unit for the removal of Entamoeba histolytica (a protozoan parasite

prevalent in the Pacific war zone) from drinking-water. The process involves

forcing water under pressure or by vacuum through a uniformly thin layer of

filtering material pre-coated onto a permeable, rigid, supporting structure (referred

to as a septum). Diatomite grades used for drinking-water treatment have a mean

pore diameter of 17 m. Pre-coat filtration can remove protozoan parasites such

Giardia very effectively and the removal ofCryptosporidium can be significant, but

because organism is smaller than Giardia, it is more difficult to remove.

In membrane filtration, a thin semi-permeable film (membrane) is used as a

selective barrier to remove contaminants from water. There are very few

contaminants that cannot be removed by membrane processes. For the past two

decades, the use of membrane filtration in drinking-water treatment (including

pathogen removal) has been growing, due to increasingly stringent drinking-water

regulations and decreasing costs of purchasing and operating membrane filters.

The membrane processes most commonly used to remove microbes from

drinking-water are micro-filtration (pore size 0.1 m or more), ultra-filtration ((pore

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size 0.01 m or more), nano-filtration (NF) and reverse osmosis (RO). Membrane

filtration eliminates most of bacteria, virus, protozoa and algae.

Bag, cartridge and fibrous filters are widely used in the recent past. A bagfilter is one that has a non-rigid fabric medium for the filter. Water flow is usually

pressure-driven from the inside of the filter bag to the outside. A cartridge filter is

one that has a rigid fabric medium or membrane for the filter. In this type of filter,

water flow is usually pressure-driven from the outside of the filter to the inside.

Bag and cartridge filters are often developed for small systems and for point-of-

use filtration applications. They are also sometimes applied as a pretreatment

process for membrane filtration. Bag filters and cartridge filters remove

microorganisms by physical straining. The removal efficiency thus depends

primarily on the pore size of the filter medium and on the size of the microbes. A

typical pore size range is from 0.2 to 10 m. The pore size of the filter medium is

usually designed to be small enough to remove protozoa such as Cryptosporidium

and Giardia. Submicron particles, including viruses and most bacteria, can pass

through the filters. As water passes through a bag or cartridge filter, pressure drop

increases to a level impractical for operation. The bag or cartridge is then replaced

by a clean one. Since the removal mechanism is physical straining, chemical

pretreatment is usually not required for bag filters and cartridge filters. Straining of

large compressible particles can blind the filters and reduce filter life. High turbidity

and algae can also clog these filters. These processes are therefore only

appropriate for high-quality waters. A pre-filtration process may be employed to

remove large particles.

Disinfection of water and public health

Various disinfectants are used in the treatment of water used for drinking

purposes. Water treatment to inactivate pathogenic microbes: The disinfection

processes have strong bearing on the final quality of the water used for the

drinking purpose viz., (i) pre-treatment oxidation (wherein oxidants are added to

water early in the treatment process) (ii) primary disinfection which is a common

component of primary treatment of drinking-water, and important because

granular filter media do not remove all microbial pathogens from water and (iii)

secondary disinfection which is employed to maintain the water quality achieved

at the treatment plant throughout the distribution system up to the tap.

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The factors like disinfectant concentration, contact time, temperature and

pH influence disinfection efficiency. Further, disinfection kinetics and CT of the

disinfectant (CT = concentration x contact time) have practical implications.Increased resistance to disinfection may result from attachment or association of

microorganisms to various particulate surfaces, including, (i) macro-invertebrates

(Crustacea, Nematoda and Platyhelminthes); (ii) particles that cause turbidity; (iii)

algae; (iv) carbon fines and other miscellaneous substances.

Primary disinfection

A disinfection barrier is a common component of primary treatment of water

and is typically a chemical oxidation process, although ultraviolet (UV) irradiation

and membrane treatment are gaining increased attention. Different types of

disinfectant such as chlorine, monochlorine, chlorine dioxide, ozone, UV light and

mixed oxidants can be used various pathogenic microorganisms.

Chlorine and silver based preparations destroy most the bacteria (e.g.

V.cholerae), but are less effective against viruses (hepatitis A) and cysts (Giardia,

amoebic cysts, and Cryptosporidia). Chlorine alone is readily inactivated by

organic matter and its action varies with pH. However if used in combination with

Phosphoric acid it is more effective and this combination will destroy both Giardia

and Cryptosporidia.

Chlorine gas and water react to form HOCl and hydrochloric acid (HCl),

further HOCl dissociates into the hypochlorite ion (OCl) and the hydrogen ion

(H+) which act as a germicide by destroying microorganisms by combining with

proteins to form N-chloro compounds and has effects on sulfhydryl groups and

convert them to several alpha amino acids by oxidation into a mixture of

corresponding nitriles and aldehydes. For nearly 100 years of chlorination of

drinking-water has demonstrated the effectiveness of this process for inactivation

of microbial pathogens, with the notable exception of Cryptosporidium. Even

certain bacteria show a high level of resistance to free chlorine. Spore forming

bacteria such as Bacillus orClostridium are highly resistant when disseminated as

spores. Acid-fast and partially acid-fast bacteria such as Mycobacterium and

Nocardia can also be highly resistant to chlorine disinfection. Since Gram-positive

bacteria have thicker walls than Gram-negative ones the pathogenic group that

survives chlorination are gram positive as well as acid fast pathogens. Also,

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enteric viruses are generally more resistant to free chlorine than enteric bacteria

due to the protective nature of the particle surface (Coxsackie A2). Protozoan

cysts such as Entamoeba histolytica and Giardia lamblia are highly resistant tochlorine disinfection and may require prolonged contact times at high chlorine

residuals (23 mg/l) to achieve 99.9% acceptable inactivation and chlorine-based

disinfectants are generally not effective at inactivation ofCryptosporidium.

Monochloramine interact with nucleic acids or free purine and pyrimidine

bases by inducing single and double stranded breaks by transforming activity of

DNA and enhanced the sensitivity of DNA to endonuclease cleavage, it also

reacts to lesser extent with amino acids. Monochloramine is not recommended as

a primary disinfectant because of its weak disinfecting power also it is not effective

for inactivation ofCryptosporidium and hence in systems using monochloramine,

free chlorine is usually applied for a short time before addition of ammonia, or an

alternative primary disinfectant is used (e.g. ozone, chlorine dioxide). Treatment to

produce a monochloramine residual poses the risk of nitrite formation in the

distribution system, especially in low-flow stagnant areas, because bacteria on

surfaces and in deposits may nitrify any slight excess of ammonia.

Chlorine dioxide is a strong oxidant that can be used to control iron,

manganese and taste and odour causing compounds. It is highly soluble in water

(particularly at low temperatures), and is effective over a range of pH values (pH

510). Chlorine dioxide is thought to inactivate microorganisms through direct

oxidation of tyrosine, methionyl, or cysteine containing proteins, which interferes

with important structural regions of metabolic enzymes or membrane proteins. In

water treatment, chlorine dioxide has the advantage of being a strong disinfectant,

but not forming THMs or oxidizing bromide to bromate. Chlorine dioxide is roughly

comparable to free chlorine for inactivation of bacteria and viruses at neutral pH

but is more effective than free chlorine at pH 8.5. Chlorine dioxide is an effective

disinfectant for control of Giardia lamblia and Cryptosporidium. Chlorine dioxide

forms undesirable inorganic by-products (chlorite and chlorate ions) upon its

reaction with constituents of water such as dissolved organic carbon, microbes

and inorganic ions. Therefore, a water utility may need to provide additional

treatment depending on the level of these inorganic by-products and their specific

regulatory requirements.

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Water can also be purified by the use of Ozone, which is very effective in

purifying water. Ozone use in water applications for treatment is now easier, more

efficient and much less costly. Ozone systems can be applied safely to any homeor business in water applications or effective air purification disinfectant. Ozone

has been used for more than a century for water treatment, mostly in Europe,

although its use is now spreading to okther countries. Ozone in aqueous solution

may react with microbes either by direct reaction with molecular ozone or by

indirect reaction with the radical species formed when ozone decomposes. Ozone

is known to attack unsaturated bonds, forming aldehydes, ketones or carbonyl

compounds. Additionally, ozone can participate in electrophilic reactions,

particularly with aromatic compounds, and in nucleophilic reactions with many of

the components of the microbial cell. Of the vegetative bacteria, Escherichia coli

are one of the most sensitive, while Gram-positive cocci (Staphylococcus and

Streptococcus), Gram-positive bacilli (Bacillus) and mycobacteria are the most

resistant. Mycobacterium avium can be effectively controlled by low doses of

ozone (CT=99.9 of 0.10.2 mg/min l1), whereas the organism is highly resistant

to free chlorine (CT=99.9 of 5511552 mg/min l1 for water-grown isolates).

Viruses are generally more resistant to ozone than vegetative bacteria, although

phages appear to be more sensitive than human viruses. For the protozoa Giardia

lamblia and Naegleria gruberi, ozone inactivation did not follow linear kinetics, due

to an initial latent phase. Ozone is effective for removal of Cryptosporidium.

Ozonation is an effective process for destruction of both intracellular and

extracellular algal toxins. Essentially complete destruction of microcystins,

nodularin and anatoxin-a can be achieved if the ozone demand of the water is

satisfied.

UV light can be categorized as UV-A, UV-B, UV-C or vacuum-UV, with

wavelengths ranging from about 40 to 400 nm. The UV light in the UV-B and UV-

C ranges of the spectrum (200310 nm) is effective for inactivating

microorganisms with maximum effectiveness at around 265 nm. Thymine bases

on DNA and ribonucleic acid (RNA) are particularly reactive to UV light and form

dimers (thyminethymine double bonds) that inhibit transcription and replication of

nucleic acids, thus rendering the organism sterile. Thymine dimmers can be

repaired in a process termed photo-reactivation in the presence of light, or dark

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repair in the absence of light. As a result, the strategy in UV disinfection has been

to provide a sufficiently high dosage to ensure that nucleic acid is damaged

beyond repair. Adenoviruses are double-stranded DNA viruses and are veryresistant to UV inactivation. Typical doses used for drinking-water disinfection

would not be effective for treatment of adenoviruses. Similarly, protozoa are also

sensitive to UV rays.

The use of mixtures of oxidants for microbial inactivation has gained

attention as a way to maximize the efficiency of current disinfectants. The

chemistry of mixed oxidant production is complex, resulting in a solution of free

chlorine, chlorine dioxide, ozone and various oxidation states of chlorine.

Secondary Disinfection

Secondary disinfection strategy is employed to maintain water quality in

distribution systems. The purpose of a secondary disinfectant is to maintain the

water quality achieved at the treatment plant throughout the distribution system up

to the tap. Secondary disinfection provides a final partial barrier against microbial

contamination and serves to control bacterial growth. The practice of residual

disinfection has become controversial, with some opponents arguing that if

biological stability is achieved and the system is well maintained, the disinfectant

is unnecessary.

Occasionally, corrosion of iron pipes can influence the effectiveness of

chlorine-based disinfectants for inactivation of biofilm bacteria. Microbial quality of

drinking-water cannot depend only on maintenance of a residual disinfectant. The

extensive nature of the distribution system, with many kilometres of pipe, storage

tanks, interconnections with industrial users and the potential for tampering and

vandalism, provides opportunities for contamination. Cross-connections are a

major risk to water quality. Although the risk can be reduced by vigilant control

programs, complete control is difficult to achieve and water utilities worldwide face

challenges in maintaining an effective cross-connection control program.

Backflow devices to prevent the entry of contaminated water are important as a

distribution system barrier. Because of high costs, backflow devices are installed

mainly on service lines for facilities that use potentially hazardous substances

(e.g. hospitals, mortuaries, dry cleaners and industrial users). Recent research is

focusing on transient pressure waves that can result in hydraulic surges in the

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distribution system. These waves have both positive and negative amplitude,

meaning that they can create transient negative pressures (lasting only a few

seconds) in a distribution system, which may be missed by conventional pressuremonitoring. Because these waves travel through the distribution system, any point

where water is leaking out of the system is a potential entry point for microbes

during the brief period of negative pressure.

Conclusions

The water used for drinking purpose should not only be visibly clean but

also be wholesome and free from microbial as well as non-microbial

contaminants. The water purification is never an accident, stringent exercises

need to be undertaken so as to keep it away from these contaminants. Various

processes used for the purification of water suffer from one or the other lacunae,

thus, there is a need to use a composite system which can enhance safety. In the

industries, where water is used directly or indirectly for the preparation of food,

HACCP system needs to be implemented in order to reduce contamination of

water. The source of water should be kept clean and suitable primary purification

system should be employed as per the recommendations of the competent

authority. In situations, where the secondary disinfection is required, a strategy

needs to be first defined and then implemented to keep the pathogens away from

the water distribution system. Assurance for the supply of safe water to the

consumers should be the prime objective of public health administration in order

to safeguard the health of the public from the water associated problems.

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WATER BORNE MICROBIAL DISEASES

V. D. P. RAO

Department of Veterinary MicrobiologyCollege of Veterinary and Animal Sciences

G.B. Pant University of Agriculture & Technology,Pantnagar 263145

Water-borne diseases are infectious diseases spread primarily through

contaminated water. Many classes of pathogens excreted in the feces are able to

initiate waterborne infections. These are bacterial pathogens, including enteric

and aquatic bacteria, enteric viruses, and enteric protozoa. Though these

diseases are spread either directly or through flies or filth, water is the chief

medium for spread and hence they are termed as water-borne diseases.

Water borne microbial diseases are one of the major health hazards mainly

in the developing countries. Worldwide, in1995 contaminated water and food

caused death of more than three million persons of which more than 80% were

among children of 5 years of age (Mary and Ross, 1996). In India, more than 70%

of the epidemic emergencies are either water borne or water related.

Most intestinal (enteric) diseases are infectious and are transmitted through

faecal waste. Pathogens which include virus, bacteria, protozoa, and parasitic

worms are disease-producing agents found in the faeces of infected persons.

These diseases are more prevalent in areas with poor sanitary conditions. These

pathogens travel through water sources and interfuses directly through persons

handling food and water. Since these diseases are highly infectious, peoplelooking after an infected patient should maintain extreme care and hygiene.

Hepatitis, cholera, dysentery, and typhoid are the more common water-borne

diseases that affect large populations in the tropical regions.

Water borne bacterial diseases:

Clostridium: The bacteria are found in soil, fresh water or marine sediments. The

Genus Clostridium is having many species that are pathogenic in animals and

human beings that can be classified into neurotoxic, histotoxic,enteropathogenic and enterotoxemia producing Clostridia.

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Neurotoxic clostridia include C. tetaniand C. botulinum. C. tetanicauses tetanus

in animals and humans and leads to synaptic inhibition and muscular spasms. C.

botulinum inhibits neuromuscular transmission and leads to flaccid paralysis.Histotoxic group of clostridia includes many species of genus Clostridium

causing variety of diseases in animals. C. chauvoie causes black leg in cattle and

sheep. C. septicum causes malignant oedema in cattle, pig and sheep and

abomasitis in sheep. C. novyitype A causes big head disease in young ram and

type B causes infectious necrotic hepatitis (black disease) in sheep and

occasionally in cattle. C. haemolyticum causes bacillary haemoglobiniuria in cattle

and sheep. C. perfringens type A causes necrotic enteritis in chicken and

necrotizing enterocolitis in pigs.

Enteropathogenic and enterotoxemia producing Clostridia: This group

includes type A to type E. Clostridium perfringens type A causes disease

conditions viz., necrotic enteritis in chicken, necrotizing enterocolitis in pigs and

canine haemorrhagic gastroenteritis. Type B causes lamb dysentery and

haemorrhagic enteritis in calves and foals. Type C causes struck in adult sheep,

necrotic enteritis in chickens and haemorrhagic enteritis in neonatal piglets. Type

D causes pulpy kidney in sheep, enterotoxaemia in calves, adult goats and kids.

Type E is responsible for haemorrhagic enteritis in calves and enteritis in rabbits

(Quinn et al. 2002).

Listeria: This bacterium can replicate in the environment and can be recovered

from herbage, faeces of animals, sewage effluents and bodies of fresh water. L

monocytogenes causes encephalitis, abortion, septicaemia or encephalomyelitis

mainly in case of sheep, goat and cattle but some times dog, cat, horse and pigs

may also get affected.

Mycobacteria: Lipid rich wall of mycobacteria is hydrophobic and resistant to

adverse environmental influences. The bacteria are found in soil, vegetation and

water and are obligate pathogens, shed by infected animal, can survive in

environment for long periods. The bacteria cause tuberculosis and J.D. in various

species of animals and also in human beings. Legionella and Mycobacterium

avium complex (MAC) are environmental pathogens and found have ecological

micro in drinking and hot water supplies.

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Leptospira: It can survive in ponds, river surface water, and moist soil and in mud

when environment temperature is warm. The bacteria causes abortion, still birth,

agalactia, influenza like illness, nephritis in pups, chronic renal disease in dogs,septicaemia in calves, piglets and lambs. In dog and human it causes jaundice

and hepatitis.

Vibrio spp: Mostly found in brackish and salt water.The emergence in early 1992

of serotype O139 of Vibrio cholerae with epidemic potential in Southern Asia

suggests that other than V. cholerae 01 could also getting on epidemic. Along with

important human pathogen Vibrio cholerae, there are five more species, which

cause enteric infections. Vibrio cholerae is the major pathogen of human beings

causing cholera. Vibrio metschnikoviicauses enteric disease in chickens. Vibrio

anguillarum and some Vibrio spp are pathogens of fish.

Escherichia coli: The bacteria have a worldwide distribution, inhabit the intestinal

tract of human and animals and contaminate vegetation, soil and water. Such

water becomes the most frequent source of infection. Colonization of the intestinal

tract by E. coli from environmental sources occurs shortly after birth. These

organisms persist as important members in the intestine as normal microflora

throughout life. Most strains of E. coli are of low virulence but may cause

opportunistic infection in extra intestinal locations such as the mammary gland

and urinary tract. Pathogenic strains of E. coli possess virulence factors, which

allow them to colonize mucosal surfaces and subsequently produce disease.

The main categories of pathogenic strains ofE. coliand their clinical effects are as

follows-

Enteric disease

Enterotoxigenic E. coli(ETEC): It produces heat labile (LT) and heat stable (ST)

enterotoxins. LT induces hypersecretion in gut and ST reduces absorption leading

to diarrhoea in neonatal piglets, calves and lambs; also causes post- weaning

diarrhoea in pigs.

Enteropathogenic E. coli(EPEC): Although nature of toxins of these organisms

are uncertain but they are found to cause destruction of microvilli, atrophy and

shedding of enterocytes leading to maldigestion, malabsorption and diarrhoea in

piglets, lamb and pups.

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Vreotoxigenic E. coli(VTEC): It binds to enterocytes and produces verotoxins

viz: VT1, VT2, VT2e leading to damage to vasculature in intestine and in other

locations and causes oedema disease in pigs, haemorrhagic enterocolitis incalves, post- weaning diarrhoea in pigs and heamorrhagic colitis-haemolytic

uraemic syndrome in man.

Necrotoxigenic strains ofE. coli: These organisms binds to enterocytes and

produces cytotoxic necrotizing factors CNF1 and CNF2 leading to damage to

enterocytes and blood vessels and ultimately causes haemorrhagic colitis in

cattle, enteritis in piglets and calves, diarrhoea in rabbits and dysentery in horses.

Septicaemia: Septicaemic strains of E. coli invade blood stream and causescolisepticaemia in calves, piglets, pups and chickens and watery mouth in lambs

and arthritis and meningitis in many species.

Non enteric localized disease caused by E. coli:

Uropathogenic strains of E. coli: For these bacteria adhesion is required for

colonization. Local reaction attributed to endotoxin and exotoxin and causes

cystitis in many bitches.

Invasion by opportunistic E. coli: They can cause coliform mastitis in cattle andsows, pyometra in bitches and omphelitis in calves, lambs and chicks if they get

entry inside the organ.

Salmonella: The serotypes occur worldwide and infect many mammals, birds,

and reptiles and mainly excreted in faeces. Ingestion is the main route of infection.

The organism may be present in water, soil, and raw meat, offal and in vegetable

material. Source of environmental contamination is invariably faeces.

Salmonellosis is of common occurrence in animals and human and theconsequences of infection range from sub-clinical carrier state to acute fatal

septicaemia. Salmonella serotypes of clinical importance are as follows:

Serotype Species affected Disease/ syndrome

SalmonellaTyphimurium

Humans

Animals

Food poisoning

Enterocolitis and septicaemia

Salmonella Dublin Cattle

Sheep, horses anddogs

Septicaemia, abortion, joint ill,osteomylitis and dry gangrene

Enterocolitis and septicaemia

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SalmonellaCholeraesuis

Pigs Enterocolitis and septicaemia

Salmonella Pullorum Chicks Bacillary white diarrhoea

SalmonellaGallinarum

Adult birds Fowl typhoid

Salmonella Arizonae Turkeys Paracolon infection

Salmonella Enteritidis Poultry

Mammals

Humans

Sub-clinical infection

Clinical infection

Food poisioning

SalmonellaBrandenburg

Sheep Abortion

Corynebacterium: It is a gram-positive pleomorphic bacterium that can survive

for months in the environment. C. pseudotuberculosis causes caseous

lymphadenitis in sheep and goat and ulcerative lymphadenitis in horse and cattle.

It is prevalent in Australia, New Zealand, Middle East, Asia, Africa and North and

South America.

Erysipelothrix rhusiopathiae: Soil and surface water become contaminated with

the organism mainly with pig faeces. Bacteria are often present in the slime layer

of fish, a potential source of human and animal infection. In sheep the bacteria

causes polyarthitis, post-dipping lameness, pneumonia and valvular endocarditis.

In case of human beings the organism affects mainly workers of fish and poultry

industry or agriculture based occupation. The organism enters through minor cuts

and aberration in the skin and leads to local cellulitis known as erysipeloid. In rare

cases disease extends to blood leading to joint and heart involvement.

Bacillus: The bacteria are sporulated and thus persist in soil and water for a long

time. B. anthracis causes anthrax in cattle, sheep, horse and pigs. In human

beings the bacteria causes cutaneous, pulmonary and intestinal form of anthrax.

Another species, B. cereus causes mastitis in cattle and food poisoning and eye

infection in human. The significance of Aeromonas species in the drinking water to

the occurrence of acute gastroenteritis need to be evaluated by further

epidemiological studies.

Shigella: The organism essentially S.sonnei causes bacillary dysentery; stool

containing blood and mucus along with heavy inflammation of colonic mucosa, in

human, chimpanzees and monkeys. The organism is transmitted by oral-faecal

route. Shigella can be found in surface water and drinking water and is highly

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significant mode of transmission in developing countries. Within clean water the

organism may survive from 14 days to several weeks (Percival et al. 2004).

In addition Giardia, Cryptosporidium, some species of genera Cyclospora,Isospora and of family Microsporidia are emerging as opportunistic pathogens and

may have waterborne routes of transmission.

Water borne viral diseases : A relatively small group of viruses have been

incriminated as cause of acute gastroenteritis in humans and fewer have proven

to be true etiologic agents, including rotavirus, calcivirus, astrovirus, and some

adenoviruses. More than 15 different groups of viruses, encompassing more than

140 distinct types can be found in the human get.Avian Influenza viruses:

Avian Influenza virus has caught attention of the whole world in recent

times. These viruses belong to family Orthomyxoviridae and infect domestic birds,

wild waterfowls, humans, sea mammals, horses, felines and pigs (Webster, 1997).

Wild waterfowls are the known carriers, which carry these viruses in their gut

across the continents. They are usually asymptomatic carriers but mortality has

been observed in recent outbreaks among these birds also. This virus replicatesin gut, which is in contrast to human influenza viruses (Gupta, 2005). The virus is

excreted in large quantity from nasal and oral secretions and cloaca of affected

birds. Infected waterfowl may be able to excrete up to 3 109 EID50 of virus per

gram of faeces.

Infection to domestic birds occurs by mixing of these wild birds with local

population or droppings of these birds may contaminate the water sources. Avian

influenza viruses do not affect human population directly. Infection to humans is

spread only after gene assortment with human influenza viruses in swine

(Webster, 1997). But in recent outbreaks with H5N1 subtype direct transmission to

human beings has been recorded. Therefore, it is possible that humans may get

this infection directly from contaminated water bodies. Virus is also excreted in the

faeces of affected human beings.

Picornaviruses:

These viruses belong to Picornaviridae family (Murphy et al. 1999 e).

Following Genera of this family are transmitted through water:

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1. Apthovirus:

Foot and mouth disease virus (FMD) affects cloven-hoofed animals. Besides

other routes of transmission, it is also transmitted by contaminated waters(Schijven et al., 2005).

Equine rhinovirus I causes disease similar to FMD virus in equines.

2. Enterovirus:

Human poliomyelitis: Polio is a highly contagious disease. Poliovirus can survive

in the body, and in raw sewage or freshwater systems; polio is frequently found in

areas where raw sewage directly enters a water source without treatment.

Transmission of the virus occurs either by direct person-to-person contact, or byindirect contact with infectious saliva or faeces, or with contaminated sewage or

water (Cliver, 1997; Thapliyal, 1999).

Porcine polioencephalomyelitis: causative agent is porcine enterovirus I.

Avian encephalomyelitis causes high morbidity and mortality in affected flock.

Mode of transmission is by faecal-oral route (Murphy et al. 1999 e).

VIRAL GASTROENTERITIS:

Rotaviruses:

Rotaviruses belong to RNA virus family Reoviridae (Murphy et al. 1999a).

Infection has been reported all over the world. These are classified into seven

groups; from A to G. Transmission is through faecal-oral route. Virus is excreted in

the faeces of infected animals in high titers. Virus can survive in the faeces for

several months. Therefore, contaminated water and poor sanitary conditions are

responsible for its transmission. Group A viruses affect multiple species of

mammals and birds. Group B viruses show species specificity. They may infect

cattle, sheep, swine and man. Group C viruses are present in swine and man,

group E viruses in swine whereas group D, E and F affect chickens (Thapliyal,

1999; Hill-king, 2005). The virus affects villi of proximal part of small intestine

resulting in malabsorption and severe diarrhoea.

In animals, disease is referred as white scours or milky scours and mainly

affects young ones. Faeces of affected animals are voluminous soft or liquid.

Young animals may die as a result of dehydration or secondary bacterial infection

(Murphy et al., 1999 a).

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In human beings it accounts for significant proportion of diarrhoea cases in

children. It affects children during Ist

four weeks of life. Death may occur due to

dehydration (Hill-king, 2005).Caliciviruses:

Water borne caliciviruses have been incriminated in the cases of diarrhoea

in adults and older children. These RNA viruses are the members of the family

Caliciviridae (Murphy et al. 1999 b). Calciviruses and some protozoan agents

such as Cryptosporidium, are the best candidates to reach the highest levels of

endemic transmission, because they are ubiquitous in water intended for drinking,

being highly resistant to chemical disinfecting procedures.Norovirus: These were earlier known as Norwalk virus and Norwalk like viruses

and are recognized as major causes of water-borne illnesses world-wide. Main

feature of these infections is severe vomiting. Aerosol infection may also occur

(Hederberg and Osterholm, 1993).

Sappovirus: Main feature of infection is persistent watery diarrhoea. It can infect

young children also. Virus is excreted in the faeces of affected persons. Mortality

is usually less.Adenoviruses:

These are the members of family Adenoviridae (Murphy et al., 1999c).

Enteric adenoviruses of human beings are second most common cause of viral

diarrhoea. These enteric viruses are usually non- cultivable and cause severe

watery diarrhoea in children of one to two years of age. Infection is usually faeco-

oral but nosocomial infection may also occur through contaminated fomites. Virus

is excreted in faeces and urine (Hill-king, 2005).In animals and birds these are associated with respiratory and gastro-

intestinal tract infections (Murphy et al., 1999c).

Infectious canine hepatitis: Fever, vomiting, diarrhoea, petechial haemorrhages

and jaundice in pups mark canine adenovirus-1 infection. Virus is excreted in high

concentration in faeces.

Fowl adenoviral infections: fowl adenoviruses have been categorized in three

serogroups.

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Group I adenoviruses are associated with fowl, geese, ducks and turkeys.

In fowls, 12 serotypes of this virus are associated with inclusion body hepatitis-

hydropericardium syndrome. Virus has natural tropism for liver of poultry. Thedisease is characterized by hydropericardium, severe hepatitis, anaemia and

sometimes-yellowish diarrhoea. Mortality is usually high in broiler birds.

Group II adenoviruses are associated with haemorrhagic enteritis of

turkeys and marble spleen disease of pheasants. The disease is usually acute

and there is sudden onset of bloody diarrhoea.

Group III adenoviruses are associated with egg-drop syndrome in poultry.

Virus infects the pouch shell gland of oviduct resulting in decreased thickness ofeggs.

Equine adenoviruses: sometimes cause mild diarrhoea in horses.

Astroviruses:

These RNA viruses are the members ofAstroviridae family. These have

wide host range and are present in gastrointestinal tract of young ones of almost

every mammalian species and young ducklings. Affected animal may develop

mild diarrhoea which is not life threatening. But in ducklings of less than 6 week ofage it may cause severe hepatitis (Murphy et al., 1999d). In human beings, it

usually infects children and diarrhoea is of mild nature (Hill-King, 2005).

VIRAL HEPATITIS:

Hepatitis A, Hepatitis E and Hepatitis F viruses are transmitted by

contaminated water (Cliver, 1997). Hepatitis A virus (HAV) and Hepatitis E virus

(HEV) known to cause illness unrelated to the get epitheliums. Numerous large

outbreaks have been documented in the U.S. between 1950 and 1970, andincidence rate has strongly declined in the developing countries since the 1970s.

Hepatitis E is mostly confined to tropical and subtropical areas, but recent reports

indicate that it can occur at a low level in Europe. These cause mild form of

hepatitis in adult humans. Hepatitis E virus may sometimes cause fatal disease in

pregnant ladies. Infection in children is usually asymptomatic. Virus is excreted in

the faeces.

Water-borne epidemics and health hazards in the aquatic environment aremainly due to improper management of water resources. Proper management of

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water resources has become the need of the hour as this would ultimately lead to

a cleaner and healthier environment (Mara and Huran, 2003). In order to prevent

the spread of water-borne diseases, people should take adequate precautions.The city water supply should be properly checked and necessary steps be taken

to disinfect it. Water pipes should be regularly checked for leaks and cracks. At

home, the water should be boiled; filtered or other necessary steps should be

taken to ensure that it is free from infectious agents (Environmental protection

agency 1975).

References:

Cliver, D.A. (1997). Viral transmission via food. Food tech. 51(4): 71-78.

Gupta, S. and Arvind Nath (2005). Human disease due to an avian influenzavirus: The influenza (H5N1) virus. ICMR bulletin34(2-3): 13-18.

Environmental Protection Agency. 40 CFR Part 141. Water programs: nationalinterim primary drinking water regulations. Federal Register1975;40:5956674.

Hederberg, C.W. and Osterholm, M.T. (1993). Outbreak of food-borne and water

borne viral gastroenteritis. Clinic. Microbial. Rev. 6(3). 199-210.

Hill-king, L. (2005). Viral diarrhea. The biomedical scientist5: 462-466.

Leclerc, H. Schwartzbrod, L. and Dei-Cas, E. (2002). Microbial agentsassociated with Waterborne diseases. Crit Rev Microbial. 28(4): 371-409

Mary, A and Ross, M.A. (1996) Microbiological water pollution. Health effectreview1(7). Pp 1-2

Mara D. and Huran N. (2003). Faecal indicator organism. In: Handbook of waterand water born disease. Academic press. Pp193-208

Murphy, F.A.; Gibbs, E.P.J.; Horzinek, M.C. and Studdert, M.J. (1999a).Reoviridae. In: Veterinary Virology. 3rd edn. Academic press. Pp 391-404.

Murphy, F.A.; Gibbs, E.P.J.; Horzinek, M.C. and Studdert, M.J. (1999b).Caliciviridae. In: Veterinary Virology. 3rd edn. Academic press. Pp 533-542.

Murphy, F.A.; Gibbs, E.P.J.; Horzinek, M.C. and Studdert, M.J. (1999c).

Adenoviridae. In: Veterinary Virology. 3rd edn. Academic press. Pp 327-334.

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Murphy, F.A.; Gibbs, E.P.J.; Horzinek, M.C. and Studdert, M.J. (1999d).Astroviridae. In: Veterinary Virology. 3

rdedn. Academic press. Pp 543-545.

Murphy, F.A.; Gibbs, E.P.J.; Horzinek, M.C. and Studdert, M.J. (1999e).Picornaviridae. In: Veterinary Virology. 3

rdedn. Academic press. Pp 391-

404.

Percival S.L., Chalmers R.M., Embrey M. Hunter P.R., Sellwood and Wyn-Jones P. (2004). Shigella species. In: Microbiology of water born disease.Academic press. Pp 185-196

Pontius F.W., Roberson J.A. (1994) The current regulatory agenda: an update.Journal of the American Water Works Association.86:54-63.

Quinn P.J., Markey B.K., Carter M.E., Donnelly W.J.C. and Leonard

F.C..(2002) Clostridium species. In: Veterinary Microbiology and MicrobialDisease.Pp63-106

Schijven, J., Rijs, G. B. J.and De Roda Husman A. M. (2005). Quantitative RiskAssessment of FMD virus transmission via water. Risk analysis 25 (1). 13-21.

Thapliyal, D.C. (1999). Diseases caused by viruses. In: diseases of animalstransmissible to man. 1

stedn. International book distributing company,

Lucknow. Pp. 57-71.

Webster, R.G. (1997). Influenza virus: transmission between species andrelevance to emergence of the next human pandemic. Arch. virol. suppl.13. 105-113.

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Microbiological Analysis of Narmada River: A Case Study

Anjana Sharma

Bacteriology Lab, Department of Biosciences,R.D. University, Jabalpur (M.P.) India

River Narmada (21o23

ito 24

o46

iN latitude, 72

o32

ito 81

o46

iE Longitude) is the

largest west flowing and the fifth largest river in Peninsula. The total length of the

river from the head to its outfall into the sea is 1312 km. The first 1077 km is in

M.P, the next 35 km forms boundary between the states of Madhya Pradesh and

Maharashtra further 39 km from the boundary between Maharashtra and Gujarat

and the rest of the 161 km lies in Gujarat. The basin had an elongated shape

almost like a thin ribbon with a maximum length of 953 km east to west and a

maximum width of 234 km north to south.

River was divided into 11 different stations for the complete study from its

origin to end viz. Amarkantak, Dindori , Mandala, Jabalpur, Narsinghpur,

Hoshangabad , Omkareshwar, Koral, Neelkantheshwar, Ankleshwar and Dahez

was investigated for its Physicochemical and Bacteriological status.

We screened the river for seven very important genera of pathogenic

potential belonging to the f

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