PPT Introduction of Parasitology

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Medical Parasitology Department

Lecture timetable forLecture timetable for

3rd. year Medicine

DR. SAEED ALHARTHIMedical Parasitology DepartmentFaculty of MedicineFaculty of MedicineUmm Al-Qura University

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Aims and Objectives :General Educational Objectives

At the completion of this course students should be ableAt the completion of this course, students should be able to:

1. Understand the importance of: epidemiology, biology, life-cycle, morphology, diagnosis, symptomatology, management and prevention of the common human parasites (helminths and protozoa) that found in tropical and sub-tropical areas.

2. Describe their biology and life-cycle within primary and intermediate hosts.

3 Know the basic principles of laboratory diagnosis and3. Know the basic principles of laboratory diagnosis and treatment of selected parasitic infections.

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Specific Educational Objectives

1. IntroductionStudents should:

1. Understand the concept of parasitism.2. Know how the major phyla and classes of human

helminths are differentiated3. Define a definitive host and intermediate host3. Define a definitive host and intermediate host4. Know the major sources of parasitic infections.5. Be aware of different effects of the parasite on the

host

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Specific Educational Objectives cont.

2. Medical Protozology and Helminthology Students should:2.1. Understand the geographical distribution of the

parasite in the world, as well as in Saudi Arabia.2.2. Understand the epidemiological aspects affecting

transmission of the parasite.2.3. Be able to outline the life cycle of the parasite, and

how to relate the life cycle to :PathogenesisPathogenesisMain clinical manifestations relating to the acute phase of the disease, as well as the chronic phase of the disease.

2.4. Outline the different methods used for parasite diagnosis including:

Direct Method ( Parasitological )Indirect Methods.Supportive Methods.pp

2.5. Understand the different methods used for treatment, mangment, prevention and control of the diseases.

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Specific Educational ObjectivesExample 2.1 : Intestinal Protozoa

Students should be able to:1. Name the protozoa causing diarrhoea and/or dysentery

in humans.2. Know the underline mechanism of diarrhoea and/or

dysentery in humans due to protozoal infectiondysentery in humans due to protozoal infection.3. Discuss the parasitological diagnosis of the intestinal

protozoal infections.4. Know the morphology, life cycle and epidemiology of

Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum.

5. Discuss the modes of transmission of these parasites and how transmission can be prevented.

6. Know what drugs are used to treat these protozoa.*

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Subject

Cestodes

Introduction &Trematodes

Lecture distribution2

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Tissue Nematodes

Intestinal Nematodes

Intestinal Protozoa

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2Amoebiasis + Giardiasis + Cryptosprodiasis

Tissue ProtozoaMalaria +

2

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Toxoplasmosis + LeishmaniasisMedical Entomology 1

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Recommended Textbooks

Medical Parasitology (1999; 8th edition). E. K. Markell; D. T. Jhon & W. A. Krotoski. Publisher. W. B. Saunders Compony.

Basic Clinical Parasitology (1994; 6th edition). Neva and Brown. Publisher. Prentice –Hall International Inc

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SCHEME OF STUDY

N f th it & iName of the parasite: genus & speciesExample: Fasciola hepatica

Name of diseaseGeographical distributionMorphology (Adult + larva)Lif lLife cycleClinical picturePathogenesis & PathologyDiagnosisTreatmentEpidemiologyPrevention & control

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Parasitic infectionsWhat are they and how many people have them??

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What is parasitology??What is parasitology??

Area of biology concerned with the phenomena of dependence of one living organism on another.g

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What is aParasiteParasiteWhat is a ParasiteParasiteparasite is an organism that obtains food and shelter from another organism and derives all gbenefits from this association

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SymbiosisSymbiosisSymbiosisSymbiosis

When a parasite infects a host, symbiosis (living together) relationships results.This relationship may be characterized as:

MutualismCommensalismsParasitism

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Definitions cont.Definitions cont.PARASITISMPARASITISMPARASITISMPARASITISM

OBLIGATE ASSOCIATION BETWEENTWO SPECIES.ONE (the parasite) DEPENDS ON THEONE (the parasite) DEPENDS ON THEOTHER (the host) FOR METABOLISM.THE ABILITY OF THE PARASITE TOKILL THE HOST

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ParasitismAn assortment of definitions

P.W. Price - Evolutionary Biology of Parasites. Princeton Univ. Press. 1980

a parasite is an organism living in or on another living organism, obtaining from it part or all of its organic nutrient,

l hibiti d f d ti t t lcommonly exhibiting some degree of adaptive structural modification, and causing some degree of real damage to its host.

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Parasite-Host RelationshipParasite-Host Relationship

If the parasite lives on the surface of its host it iit is an ectoparasite

(eg. Lice)

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Parasite-Host Relationshipcont.Parasite-Host Relationshipcont.

If internal (living within the body of the host) it is an endoparasite

Ascaris (eg. Worms, protozoan parasites)

Ascaris lumbricoides

Giardia lamblia

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DefinitionsDefinitions cont.cont.

Some parasite are host specificversus non-host specificHost other than the normal host harboring a parasite is accidental/incidental hostObligate versus facultative

itparasites

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The host may be defined as:The host may be defined as:

D fi iti h tDefinitive host– the host in which the parasite is sexually mature

(occasionally defined as the location where sexualreproduction occurs)

Intermediate host– host in which the parasite exists as a larval or

developing stage in its lifecycle OR the host(s)required for the parasite to reach maturity

– it is essential for completion of parasite’s life cycle.

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The host may be defined as:The host may be defined as:The host may be defined as:The host may be defined as:

Host that harbors a parasite that is also parasitic for human, and from which humans may be infected is reservoir host

Host harboring-parasite that no clinical symptoms but is capable of shedding the parasite and infecting others is a carrier

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BRAINTEASERBRAINTEASER

Humans may act as:Definitive host Intermediate hostIntermediate hostDefinitive and intermediate hostReservoir hostCarrier host

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PARASITOLOGICAL PARASITOLOGICAL DEFINITIONSDEFINITIONSPARASITOLOGICAL PARASITOLOGICAL DEFINITIONSDEFINITIONS SUPER INFECTION:

Occurs when a host is re-infected with the same species of parasite.

AUTO INFECTION:Infected host acts as own direct source of re-infection

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PARASITOLOGICAL Def. cont.PARASITOLOGICAL Def. cont.PARASITOLOGICAL Def. cont.PARASITOLOGICAL Def. cont.

VECTOR VECTORAn arthropod that transmits a parasite to another host.

ZOONOSISAn infection which is naturally transmitted from animals to manfrom animals to man

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Name a common vector????

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SOURCES OF PARASITIC SOURCES OF PARASITIC INFECTIONSINFECTIONSSOURCES OF PARASITIC SOURCES OF PARASITIC INFECTIONSINFECTIONS

a)a) SOIL CONTAMINATED WITH SOIL CONTAMINATED WITH ANIMAL OR HUMAN EXCRETAANIMAL OR HUMAN EXCRETA

a)a) SOIL CONTAMINATED WITH SOIL CONTAMINATED WITH ANIMAL OR HUMAN EXCRETAANIMAL OR HUMAN EXCRETA

Egg of Egg of AscariAscarissLarva of Larva of AncylostomaAncylostomaCyst ofCyst of EntamoebaEntamoeba

Egg of Egg of AscariAscarissLarva of Larva of AncylostomaAncylostomaCyst ofCyst of EntamoebaEntamoeba

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SOURCES OF PARASITIC SOURCES OF PARASITIC INFECTIONS cont.INFECTIONS cont.SOURCES OF PARASITIC SOURCES OF PARASITIC INFECTIONS cont.INFECTIONS cont.

b)b) WATER POLLUTED WITH WATER POLLUTED WITH INFECTED EXCRETAINFECTED EXCRETA

b) Egg of Ascarisc) Larva of Schistomomad) Cyst of Entamoeba

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FOODS :a) Raw vegetables or fruits

contaminated with parasites» Egg of Ascaris» Egg of Ascaris» Cyst of Entamoeba

b) Meat & fish (under-cooked)» Tape wormp» H. hetrophis

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c) ANIMALS as hostsMeat

Tape worm

c) ANIMALS as hostsMeat

Tape wormTape wormH. hetrophis

Domestic animalsToxoplasma

Tape wormH. hetrophis

Domestic animalsToxoplasmaToxoplasmaLeishmaniaToxoplasmaLeishmania

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ARTHROPODS (AS vectors)

» Malaria

ARTHROPODS (AS vectors)

» MalariaMalaria» Leishmania» Trypanosoma» Filaria

Malaria» Leishmania» Trypanosoma» Filaria» Filaria» Filaria

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d) CONTACT

e) CONGENITAL

f) SEXUAL INTERCOURSE

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• Name the stage of the parasite that produce infection???produce infection???

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Methods or mode of Methods or mode of infectioninfectionMethods or mode of Methods or mode of infectioninfection

Mouth Skin (Touch, Penetration).Mouth Skin (Touch, Penetration).Inhalation of contaminate dustPlacental.Vaginal or Anal

Inhalation of contaminate dustPlacental.Vaginal or AnalVaginal or Anal.Vaginal or Anal.

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• The most common mode of infection is ????? Wh ???

R S RR S R

-------????? Why???• Do you think that environmental

modification play a role in parasitic diseases increase????diseases increase????

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Effects of the parasite on the host


Mechanical injury

» skin Mechanical injury

» skin » hair» bladder» hair» bladder» intestine» intestine

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Effects of the parasite on the host cont.


Feeds on host cells and tissues

Epith li l lls & R B C»Epithelial cells & R.B.C

Deprive the host essential substances

»Iron

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Toxic effect» nervous system

Toxic effect» nervous system» nervous system

Allergic effect

» rash

» nervous system

Allergic effect

» rash

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Obstruction of vital organs:» portal system

i i l b i» intestinal obstruction

Mechanical pressure on vital organs :

» liver » lungs

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AbortionBlindnessIndirect effects

AbortionBlindnessIndirect effectsIndirect effects

» Mental & physical growth

» Secondary infection

Indirect effects

» Mental & physical growth

» Secondary infectionSecondary nfect on

» Effect on productivity

Secondary nfect on

» Effect on productivity

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• Do you think that the diet or nutritional


• Do you think that the diet or nutritional status of the host play a role in determining the out come of parasitic infection?????

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Parasitic life cycleParasitic life cycleParasitic life cycleParasitic life cycle• Parasitic life cycles range from simple

to complex.• Three common components:

– A mode of transmission– An infective stage– A diagnostic stage

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Parasitic life cycle cont.Parasitic life cycle cont.Parasitic life cycle cont.Parasitic life cycle cont.A iti lif l i t f t• A parasitic life cycle consists of two common phases:– One: the route a parasite follows inside the body

• Clinical symptoms• Pathologyat o ogy• Proper diagnostic technique• Determine the appropriate medication

– Second: the route a parasite follow outside the body:

• EpidemiologyEpidemiology• Prevention• Control

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The life cycle of The life cycle of Fasciola hepaticaFasciola hepatica

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What do we mean by the parasite


What do we mean by the parasite FINAL HABITAT??

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Diagnosis Diagnosis

• Clinically• Laboratory

– Direct methodsDirect methods– Indirect methods

• Intradermal skin test• Serological

R di l t• Radiology etc…

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Indicate the different diagnostic materials that might be used to diagnose parasitic diseases????

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TreatmentTreatmentTreatmentTreatment

• Many anti-parasitic medications are

il blavailable.• Many drugs are toxic• Resistance

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Treatment cont.Treatment cont.

• Factors to be considered:– Accuracy of diagnosis– Potential drug toxicity and side effectg y– Need to monitor therapy

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WHY do you think it is essential

R S RR S R

WHY do you think it is essential to continue research for anti-parasitic medications ???

Documents

PPT Introduction of Parasitology