Lecture 1 - Parasitism (1)

8/12/2019 Lecture 1 - Parasitism (1)

1/57

RELATIONSHIPS

BETWEEN ORGANISMS.

PARASITISM

Assoc. prof. Milena Atanasova, PhD

Dept. Biology , MU-Pleven


2/57

I. DEFINITON AND SUBJECTS OF

PARASITOLOGY

Parasitology

a complex biological science

investigates the phenomenon of parasitism.

It studies:

the origin and evolution of the parasites

biological cycle and geographical distribution

host parasite relationships

parasitic diseases

the ways to prevent the humanity from them


3/57

I I. PARASITES, PARASITISM , AND

HOST RELATIONS

Two different ways in which an animal may obtain food at

the expense of other animals.

Predation: Predator attacks another living animalconsuming part or all of its body for nourishment, in the

process frequently but not necessarily killing it. The victim is

the prey.

ScavengingAn animal may derive its nutrition from already

dead animals: such animals are called as Scavengers.


4/57

A. RELATIONSHIPS BETWEEN

ORGANISMS LIVING TOGETHER

Some animals always seek their food by their own effortsor in association with others of their own species. Otheranimals, still in essence predators or scavengers, havebecome so modified, that they are unable to obtain foodexcept in close association, either continuous or at

intervals, with members of another species.

SYMBIOSIS:This association of two species, perhapsprimarily for food getting on the part of one or bothmembers of the group, is known as symbiosis.

Different forms of symbiosis may be distinguished onthe basis of whether or not the associationdetrimental to one of the two partners.


5/57


6/57

C. PARASITISM

Parasitism, like other forms of symbiosis, necessarilliy involves anintimate relationship between the two species, and it is this closeand prolonged contact that differentiates parasitism from thepredatory activities of many nonparasites. A predator must belarger and stronger than its prey, whereas a parasite is small andweak.

Parasite is defined as a living organism which lives upon or inanother organism and derives its nourishment from it thusadapting oneself to live in or on itit is called a host.

The life cycle pattern of a parasite may be:

simple, involving only a single host complex involving two or more intermediate hosts

Parasites employ a variety of ways to effect transmission;ingestion, penetration of skin and mucous membrane,inoculation by arthropod vectors etc.


7/57

D.ORIGIN OF THE PARASITISM

On the basis of logical and historicalconsiderations would be assumed thatparasitism had been arisen after appearance ofthe free-living organisms. In reality to before theparasite exists the host, free-living organism.

Because the size of the parasites are much

smaller then these of their hosts, it may besupposed that they become widespread onlythen the arising of a number organisms withvariety of size.


8/57

D.ORIGIN OF THE PARASITISM

It is supposed that zooparasitesare originated by

three ways:

a) from scavengers(animals living on and feed on

decaying organic substances)

b) from predators(free-living leech)

c) by changing of the relationshipsbetween

symbionts and as a result the one of them turn into a

parasite and the other into a host

d) parasites living within the host may be described as

endoparasites.They originate from predatory

insects and ticks


9/57

D.ORIGIN OF THEPARASITISM

e) Parasites that are found on the surface of the body are calledectoparasites.They originate from former ectoparasites; for ex.some infusoria, specific ectoparasites on the fish gills and fins are

pass to urinary bladder (there is functionally similarity, secretion ofuric acid and ammonia)

Intestinal endoparasites - accidentally get into intestine by food(for ex. Prof. Skryabin, had been found eggs, larvae and adults in

the intestine of miners of two species Rhabditis, usually living insoil)

Blood parasites

i. from intestinal own parasites, somehow get into blood

ii. by intestinal parasites of invertebratesfor ex.Trypanosoma


10/57

III. PARASITES AND HOSTSA. Classification

1) According the place of livingandtheir interactions with hosts

Ectoparasites: a parasite whichlives outside or on the surface ofthe body of host

Endoparasites: a parasite whichlives within the body of the host(cells, tissues, organs)

- Intracellular

- Extracellular


11/57

A. Classification

2) According the number of hostsrequiring to complete their lifecycle

1) Monoxenous(louse , Pediculuscapitis) one host to complete thelife cycle

2) Heteroxenous (taenia,Dyphyllobothrium latum) requiringmore than one host
http://upload.wikimedia.org/wikipedia/commons/f/fe/Pediculus_humanus_capitis_CDC9217.png


12/57

A. Classification

3) According the amount of timespent on the host there are Temporary andStationary parasites

Temporaryvisit host for food (bloodsucking arthropods - mosquito, ticks,flea, louse).

Usually they multiply and develop outside of the hosts body and get in

relationship with the host only to nourish themselves. Preferablyectoparasites.

Stationaryspend a definitive period of development on or in the body ofthe host. According to the amount of time spent with the host stationaryparasites are subclassified as: periodicremain with the host for only a part of their development and then

leave to complete it and continue nonparasitic life. permanentspend their entire existence in hosts except for the times they

occur free while transferring from one host to another (Malarial plasmodia) -they are predominantly endoparasites (all parasitic protozoa, the most of theparasitic nematodes, some of spiderlike and insects), They cannot survivewithout the host.


13/57

A. Classification

4) Facultative and obligate:Parasitism as a way of lifemay be the only possibilityfor a given organism , or itmay be but one alternative.

An organism that cannot survive in any other manner iscalled an obligate parasite. Parasitism for them is aspecies trait (all individuals of the species are parasites)

A facultativeparasite is an organism that may exist in a

free-living stage or as a commensal and that way, ifopportunity presents itself, may become parasitic.Parasitism for them is not obligate, it is not speciesfeature (only some organisms are parasites).


14/57

A. Classification

Commensal: Parasite does not harm the host evenwhen living within or on the host

Occasional or accidentalparasite: Attacks an unusual

hostfor ex. Larvae of domestic ?

Aberrant or wanderingparasite: The parasite arrivesat a place where it cannot survivefor ex. Larva

currents , Visceral larva migrans, produced bynonhuman species, Toxocara canis

Pathogen: A parasite which is able to cause disease


15/57

III. PARASITES AND HOSTSB. Hosts of parasites

a) Definitive Host: A host in which the definitive or thefinal stages of the parasite develop. What this

means????

The host in which the

sexualreproduction of a

parasite takes place.


16/57

B. Hosts of parasites

b) Intermediate Host: A host in which theintermediate stages of the parasite

develop

The host in which

the asexualreproduction of a

parasite takes

place.


17/57


c) Reservoir Host:When the parasite

is maintained in

nature and which

acts as a soursefor individual new

cases


18/57


d) Paratenic Host:Transport or

carrier host in

which the parasite

remains viable butdoes not undergo

further

development
http://www.dpd.cdc.gov/dpdx/HTML/Toxocariasis.htm


19/57

IV. Other Terms used in Parasitology

Habitat: The natural abode of a parasite species

Incubation: The time period between the entrance of a parasiteinto a host and the initiation of the disease

Ecology: The relationship between a population of an organismand the environment; when this is a balanced equation, the hostremains healthy, but break or change in the relationship results indisease outbreak.

Zoonosis: Diseases of animals which are transmissible to men

Opportunistic parasites: Parasites which are not normally

pathogens but become so due to impairment of host resistance

Mutualism: A type of symbiotic process in which both partnerssharing the relationship are benefited


20/57

V. ADAPTATION TO PARASITISM

Some preadaptive changesmight be in the nature of increasedresistanceto enzymatic activities of the host.

Further physiological adaptations to parasitism might involve theloss of enzymes or enzyme systems, which are then supplied by

the host. Such losses may be expected to make a parasitic, or etleast a symbiotic relationship, obligatory.

Sertain groups of parasites exibit profound morphologicadaptationsto their way of life. These modifications are more

striking in those groups that are wholly parasitic than in those thatcontain both free-living and parasitic species.


21/57


Organs not necessary to a parasitic existence are frequently lost. Adigestive tract, moderately complex in the turbellarians, is generallyreducedin the trematodes and is absent in the cestodes.

The reproductive system is very highly developedin the two latter groups;this seems a reflection of the difficulties inherent in transfer of these

organisms to a new hosts.

Specialized attachment organs in the form of suckers and hooks havebeen developed by the parasitic flatworms.

Body size may be greatly affected by the parasitic state. Most free-livingnematodes barely attain naked-eye visibility as adults, but Ascaris canreach 35 cm and some tapeworms as much as 10 m.

On a more basic level, the parasitic mode of existence may result inprofound biochemical changes. The parasite, no longer able to synthesizecertain necessary cellular components, obtains them instead from its host.


22/57


Specialized mechanisms for effecting entranceinto the body ortissues are seen in some parasites: ingestion, penetration ofskin and mucous membrane, inoculation by arthropod vectorsetc.

Immune evasion may involve such factors as location of theparasite in relatively protected sites, changes of the parasitesurface antigenic structure brought about in a variety of ways,and active modification of the host immune response byproducts of parasite metabolism.

The life cycle pattern of a parasite may be simple, involving onlya single host or complex involving 2 or more intermediate hosts.


23/57

VI. EFFECTS OF THE PARASITE

ON THE HOST

Its effects is harmful - produces disease or its effects.Pathogenicity depends on: species, structure and functions,environmental factors etc.

1. Mechanical - it is by nature for parasitic helminthes andarthropods; at invasion, attachment, migration, obstruction ofintestine, injury of mucous membrane and organs. For example:Ascaris, Echinococcus granulosus, Filaria etc.

2. Toxic effect - due to metabolic products of the parasite:secretions, excretions, or other products of the parasite.

Malarial parasites invade and multiply in red blood cells, which aredestroyed in the process and releasing the malarial products intothe blood stream, many of which are also pyrogenic.

Ascaris body fluid is toxic and many sensitizing.


24/57

VI. EFFECTS OF THE PARASITE

ON THE HOST

3. Spoliative effect Some parasites exert their effects by depriving

the host of essential substances.

Hookworms suck blood and bring about anemia.

The broad fish tapeworm, Diphyllobothrium latum,selectively removes vitamin B12 from the alimentarytract, producing megaloblastic anemia in somepersons.

Another parasites feed on blood, lymph, chyle, tissuefluids.

4. Transmission effect

Blood sucking ectoparasites bring about spreadof infections and parasitic diseases among thecommunity. They are known as vectors (flee, louse,mosquito etc).


25/57

VI. EFFCTS OF THE PARASITE ON

THE HOST

5. Sensitization

Majority of parasites have sensitizing effect.

Although that there is a variety of effects of

the parasite on the host the latter remainsalive. System host-parasite keeps up

dynamic balance.

Definition of Sensitization- non-associative learning process

in which repeated administrations of a stimulus results in the

progressive amplification of a response.


26/57

VII. EFFECTS OF THE HOST ON

THE PARASITE

The genetic constitution of the host may profoundlyinfluence the host-parasite relationship. It is now well known thatthere are racial variations in resistance to Plasmodium vivax,which are related to the presence or absence of the Duffy bloodgroup. The sickle cell trait is also associated with increased

resistance to infection with the malarial parasite Plasmodiumfalciparum.

Now we know that every species of animas is naturally resistantto infection by many organisms that parasitize different species.Acquired immunity can be demonstrated in many parasitic

diseases, and it is generally found to be at a lower level thanthat produced by bacteria and viruses.


27/57


THE PARASITE

The host reacts against parasite by two types of reactions:

1) Cellular and tissue reaction

2) Humoral reaction.

The character of these reactions depends on the species of theparasite, age and the nutritional status of the host, environmental

conditions, etc.

1) Cell and tissue reactions

the changes of the cells size; for ex. red blood cells, infected byPlasmodium vivax become enlarged and pale

Red blood cell with multiple

trophozoites of Plasmodium vivax


28/57


THE PARASITE

Eosinophils kill some parasites; Macrophages secrete somecytokines

Inflammatory reaction - multiplying of reticuloendothelial cellsend histiocytes, which pile up and lying down tissue fibers

surrounding parasites, thus isolate it somehow from the host;for ex. Trichinella spiralis, Echinococcus


29/57


THE PARASITE

2) Cells humoral reaction

- it is including phagocytosis

3) Akin to other infectious agents,parasites also elicit immuneresponsesin the host, humoral

as well as cellular butimmunological protection is far lessthan compared to that of bacteriaor virus.

Immune response involvesproduction of specific antibodies byB lymphocyteshumoralimmune response.

- Cell - mediated immune responseinvolves the set of T lymphocytes.


30/57

VIII. DISEASES CAUSED BY

PARASITES

The parasite has to leave the host and gain

entry into other hosts to either complete its

live cycle or to progress its transmission.

Once the parasite overcomes the defenses ofthe host, a certain specific pattern of disease

evolves - parasitic diseases.


31/57


PARASITES

Some parasitic diseases

are belong to the so-

called transmissive

diseases (they aretransmitted by vectors -

some blood-sucking

insects and ticks; for

exp. Malaria - P.malariae - mosquito)


32/57


PARASITES

Transmissive diseases can be two types:

Obligate(they can be transmitted only by specific vectors; exp.Trypanosoma)

Facultative (they can be transmitted by both; vectors and bywater, food, air; for ex. intestinal infection)

There are also nonspecific mechanical vectors (for ex.

cockroaches or beetles). Some vectors may exist as reservoirs.For ex. ticks can keep the infection decades.

Important for these is the transmission of infection by the eggsto their progenytransovarialtransmission.


33/57


PARASITES

The man become infected by sometransmissive diseases if he live in certainarea the so-called seat, focus. They hadbeen by arisen by nature and no matter if

there are human beings or no. The infectionis transmitted from the sick animals intohealth ones by the vectors or predator(Leishmania, Plague, Trichinella spiralis etc.)

The man becomes infected after biting by thespecific vector or when enter into the focus asa hunter, tourist, visitors for a job, etc.


34/57


PARASITES

Depending on the life cycle ofthe parasitic helminths(worms) they are classified asfollow:

Biohelminths (they requirenot only definitive butintermediate host as well;Schistosoma)

Geohelminths(a part of their

life cycle takes place in thesoil; Ascaris, Trichiuris ), thereis no need of intermediatehost


35/57

IX. Parasites names (Nomenclature)

Binomial Nomenclature

Scientific system of naming plants and animals

Genus: surname

Species: first name

Strain: second name

Underlined or i tal ic

To simplify the taxonomy, the major divisions

involved in medical parasitology-specifically,

intestinal and urogenital protozoa, blood and

tissue protozoa, nematodes, trematodes, and

cestodes have been addressed.


36/57

The parasites of humans are classified within the kingdomAnimaliaand are separated into two subkingdoms, Protozoa

and Metazoa.

Parasite classification takes into account the morphology ofintracytoplasmic structures, such as the nucleus, the type of

locomotive organelles, and the mode of reproduction.

The Protozoaare animals whose life functions occur in a

single cell.

The Metazoaare multicellular animals in which life functions

occur in cellular structures organized as tissue and organ systems

IX.Parasite classification and structure

Flagellates


37/57

Parasites

Protozoa

Metazoa

Sarcomastigophora

Amoebae

Flagellates

Ciliophora

Apicomplexa or Sporozoa

Microspora

Helminths

Arthropods

Platyhelminths

Nemathelminths Nematodes

Cestodes

Trematodes

Chilopoda

Pentastomida

Crustacea

Insecta

Arachnida

Subkingdo


38/57

Medically

Important

Parasites

(Kingdom

Animalia)

Subkingdo

m Phylum Organisms

Protozoa Sarcomasti

gophora

Ameba, flagellates

Ciliophora Ciliates

Apicomple

xa

Sporozoa, Coccidia

Microspora Microsporidia

Metazoa Nematoda Roundworms

Platyhelmi

nthes

Flatworms

Trematod

es

Flukes

Cestodes Tapeworms

Arthropoda

Chilopoda Centipedes

Pentastom

ida

Tongue worms

Crustacea Crabs, crayfish, shrimp, copepods

Arachnida Mites, ticks, spiders, scorpions

Insecta Mosquitoes, flies, lice, fleas, wasps, ants,beetles, moths, roaches, true bugs


39/57

Protozoa are simple microorganisms that range in sizefrom 2 to

100 m.

Their protoplasm is enclosed by a cell membrane and contains

numerous organelles, including a membrane-bound nucleus, an

endoplasmic reticulum, food-storage granules, and contractileand digestive vacuoles. The nucleus contains clumped or

dispersed chromatin and a central karyosome.

Organelles of motilityvary from simple cytoplasmic

extrusions or pseudopods to more complex structures, such as

flagella and cilia.

Protozoa

Bi l i M h l i d Ph i l i


40/57

Biologic, Morphologic, and Physiologic

Characteristics of Pathogenic Parasites

Organism Class Morphology Reproduction

Organelles of

Locomotion Respiration Nutrition

Protozoa

Amoeba Unicellular; cyst and

trophozoite forms

Binary fission Pseudopods Facultative anaerobe Assimilation by

pinocytosis or

phagocytosis

Flagellates Unicellular; cyst and

trophozoite forms;

possibly intracellular

Binary fission Flagella Facultative anaerobe Simple diffusion or

ingestion via cytostome,

pinocytosis, or

phagocytosis

Ciliates Unicellular; cysts and

trophozoite

Binary fission or

conjugation

Cilia Facultative anaerobe Ingestion via cytostome,

food vacuole

Coccidia Unicellular, frequently

intracellular; multiple

forms, including

trophozoites, sporozoites,

cysts (oocysts), gametes

Schizogony and

sporogony

None Facultative anaerobe Simple diffusion

Microsporidia Obligate intracellular

forms; small, simple cellsand spores

Binary fission,

schizogony andsporogony

None Facultative anaerobe Simple diffusion


41/57

Biologic Morphologic and Physiologic


42/57

Helminths

Nematodes Multicellular; round,

smooth, spindle shaped,

tubular alimentary tract;

possibility of teeth or

plates for attachment

Separate sexes No single organelle;

active muscular motility

Adults: usually

anaerobic; larvae:

possibly aerobic

Ingestion or absorption of

body fluids, tissue, or

digestive contents

Trematodes Multicellular; leaf shapedwith oral and ventral

suckers; blind alimentary

tract

Hermaphroditic(Schistosoma group has separate

sexes)

No single organelle;muscle-directed motility

Adults: usually anaerobic Ingestion or absorption ofbody fluids, tissue, or

digestive contents

Cestodes Multicellular; head with

segmented body

(proglottids); lack of

alimentary tract; head

equipped with hooks

and/or suckers forattachment

Hermaphroditic No single organelle;

usually, attachment to

mucosa, possible

muscular motility

(proglottids)

Adults: usually anaerobic Absorption of nutrients

from intestine


Organelles of


Biologic, Morphologic, and Physiologic

Characteristics of PathogenicHelminths

Organelles of


43/57

Arthropods

Chilopoda Elongated; many legs;

distinctive head and

trunk; poisoning claws

on first segment

Separate sexes Legs Aerobic Carnivore

Pentastomida Wormlike; cylindrical,

or flattened; two distinct

body regions; digestive

and reproductive organs;

lack of circulatory and

respiratory systems

Separate sexes Muscle-directed motility Aerobic Ingestion of body fluids

and tissue

Crustacea Hard external carapace;

one pair of maxillae;

five pairs of biramous

legs

Separate sexes Legs Aerobic Ingestion of body fluids

and tissue, carnivorous

Arachnida Body divided into

cephalothorax and

abdomen; eight legs and

poisoning fangs

Separate sexes Legs Aerobic Carnivore

Insecta Body: head, thorax, and

abdomen; one pair of

antennae; three pairs of

appendages, up to two

pairs of wings

Separate sexes Legs, wings Aerobic Ingestion of fluids and

tissues


Organelles of



44/57

Additional slides for self reading!


45/57


46/57

2- CILIOPHORA

Phylum Ciliophora consists of the ciliates, which include a variety offree-living and symbiotic species.

Ciliate locomotion involves the coordinated movement of rows of

hairlike structures, or cilia.

Cilia are structurally similar to flagella but are usually shorter and

more numerous. Some ciliates are multinucleate.

The only ciliate parasite of humans, Balantidium coli ,contains two

nuclei: a large macronucleus and a small micronucleus.

Protozoa

P


47/57

3- APICOMPLEXA

Phylum Apicomplexa organisms are often referred to as Sporozoa orCoccidia. These unicellular organisms have a system of organelles at

their apical end that produces substances to help the organism

penetrate host cells and thus become an intracellular parasite.

4- MICROSPORA

The Microspora are small intracellular parasites that differ

significantly in structure from the Apicomplexa organisms.

These parasites are characterized by the structure of their spores,

which have a complex, tubular extrusion mechanism (polar tubule)

used to inject the infective material (sporoplasm) into host cells.

Protozoa

Metazoa


48/57

The protective covering of flatworms is known as a tegument.

Often, helminths possess elaborate attachment structures such ashooks, suckers, teeth, or plates.

These structures are usually located anteriorly and may be useful in

classifying and identifying the organisms.

Helminths typically have primitive nervous and excretory systems.

Some have alimentary tracts; however, none have a circulatory

system.

The helminths are separated into two phyla, the Nematoda and the

Platyhelminthes.

Metazoa

Metazoa


49/57

1-HELMINTHSA- Nematoda

Phylum Nematoda consists of the roundworms, which have

cylindrical bodies.

The sexes of roundworm are separate, and these organisms have a

complete digestive system. The nematodes may be intestinal

parasites or may infect the blood and tissue.

Metazoa

Metazoa


50/57

1-HELMINTHS

B-PlatyhelminthesPhylum Platyhelminthes consists of the flatworms, which have

flattened bodies that are leaflike or resemble ribbon segments.

Platyhelminthes can be further separated into trematodes and

cestodes.

B-1-Trematodes, or flukes, have leaf-shaped bodies.

Most are hermaphroditic, with male and female sex organs in asingle body. Their digestive systems are incomplete and only have

saclike tubes. Their life cycle is complex; snails serve as first

intermediate hosts, and other aquatic animals or plants serve as

second intermediate hosts.

Metazoa

Metazoa


51/57

1-HELMINTHS

B-PlatyhelminthesB-2- Cestodes, or tapeworms, have bodies composed of ribbons of

proglottids, or segments.

All are hermaphroditic, and all lack digestive systems, with nutrition

being absorbed through the body walls.

The life cycles of some cestodes are simple and direct, whereas those

of others are complex and require one or more intermediate hosts.

Metazoa

Metazoa


52/57

In addition, envenomization by biting and stinging arthropods can

result in adverse reactions in humans that range from local allergic

and hypersensitivity reactions to severe anaphylactic shock and

death. There are five major classes of arthropods.

Metazoa

Metazoa


53/57

2-ARTHROPODS

2-A-ChilopodaClass Chilopoda consists of terrestrial forms, such as centipedes.

These organisms are of medical importance because of their

poisoning claws, which may produce a painful "bite."

2-B-Pentastomida

The pentastomids, or tongue worms, are bloodsucking endoparasites

of reptiles, birds, and mammals. Adult pentastomids are white and

cylindrical or flattened parasites that possess two distinct body

regions: an anterior cephalothorax and an abdomen. Humans may

serve as intermediate hosts for these parasites.

Metazoa

2-ARTHROPODS


54/57

2-C-Crustacea

Class Crustacea consists of familiar aquatic forms, such as crabs,

crayfish, shrimp, and copepods.

Several are involved as intermediate hosts in life cycles of various

intestinal or blood and tissue helminths.

2-D-ArachnidaClass Arachnida consists of familiar terrestrial forms, such as mites,

ticks, spiders, and scorpions.

Unlike insects, these animals have no wings or antennae, and adults

have four pairs of legs, as opposed to three pairs for insects.

Of medical importance are those serving as vectors for microbial

diseases (mites and ticks) or as venomous animals that bite (spiders)

or sting (scorpions).

Metazoa


55/57

2-ARTHROPODS

2-E-Insecta

Class Insecta consists of familiar aquatic and terrestrial forms, suchas mosquitoes, flies, midges, fleas, lice, bugs, wasps, and ants.

Wings and antennae are present, and adult forms have three pairs of

legs.

Of medical importance are the many insects that serve as vectors for

microbial diseases (mosquitoes, fleas, flies, lice, and bugs) or as

venomous animals that sting (bees, wasps, and ants).

Metazoa

I t f it


56/57

Medical parasitology is the study of invertebrate animals capable of

causing disease in humans and other animals.

The global impact of parasitic infections and the number of parasite-

associated deaths is staggering and must be of concern to all health

care workers.

Increasingly, tourists, missionaries, Peace Corps volunteers, and

others are visiting and working for extended periods in exotic,

remote parts of the world.

Importance of parasites

I t f it


57/57

Another source of infected patients is the ever-increasing number of

refugees from developing countries.

Finally, the profound immunosuppression problems that accompany

advances in medical therapy (e.g., organ transplantation), as well as

those associated with persons infected with humanimmunodeficiency virus (HIV), place a growing number of

individuals at risk for developing infections caused by certain

parasites.

Given these considerations, clinicians and laboratory workers should

be aware of the possibility of parasitic disease and should be trained

in ordering, performing, and interpreting the appropriate

laboratory tests to aid in the diagnosis and therapy.

Importance of parasites

Documents

Lecture 1 - Parasitism (1)