Introduction Parasitology

Parasitology DepartmentMedical Faculty of

Universitas Sumatera Utara

ParasiteDefinition:Dependence of one living organism on anotherDependence of one living organism on another

2

CLASSIFICATION (b d h bit t)CLASSIFICATION (based on habitat)Ectoparasite: parasite that lives on the

t f f it h touter surface of its hostex. Pediculus humanus capitisE d it it th t li i id it Endoparasite: parasite that lives inside its

hostex Ascaris lumbricoidesex. Ascaris lumbricoidesParasite facultative: parasite which can be life as parasite or free livingparasite or free livingex. Strongyloides stercoralis

3

ClassificationClassificationParasite obligate: organism that is physiologically dependent on establishing a symbiotic dependent on establ sh ng a symb ot c relationship with anotherEx. Enterobius vermicularis

Accidental parasite (spurious): parasite enter or p ( p ) pattach to the body of a species of host; different from its normal oneex: Toxocara spp

4

ClassificationClassificationPeriodic parasite: parasite that half of its lifecycle as a parasitera parasiter.Ex. HookwormPermanent parasite: parasite that all of its lifecycle Permanent parasite: parasite that all of its lifecycle as a parasiter.Ex. Plasmodium spp.Ex. Plasmodium spp.Monoxen parasite: parasite can life only one host.Ex. Enterebius vermicularisPolyxen parasite: parasite can life more than one host.Ex. Schistosomatidae

5

Terminologi in the Parasitology:g gyHost : organism as a living place for parasiteDefinitive host: host in which a parasite achieves Definitive host: host in which a parasite achieves sexual maturityReservoir host: animal that life same species Reservoir host: animal that life same species parasite with human and can happen lifecycle of the parasite and can be source of infection for humanIntermediate host: host in which a parasite d l b l develops to some extent but not to sexual maturity and transmits agent of disease passively

6

Terminologi in the Parasitology:Terminologi in the Parasitology:Paratenic host: host in which a parasite survives

ith t d i f th d l twithout undergoing further developmentVektor: any agent, such as water, wind, or insect, that transmits a disease organism activelythat transmits a disease organism activelySymbiosis: interactions among organism in which one organisms lives with in or on the body one organisms lives with, in or on the body another

7

Terminologi in the Parasitology:Terminologi in the Parasitology:Commensalisms: kind of symbiosis; can be benefits r nism is n ith r h rm d n r h lp d b ss ci ti norganism is neither harmed nor helped by association

Mutualisms: type of symbiosis in which both host and Mutualisms: type of symbiosis in which both host and symbiotic benefit from the association

8

Binomial NomenclatureBinomial Nomenclature

Scientific system of naming plants and Scientific system of naming plants and animalsGenus: “surname”Genus: “surname”Species: “first name”Strain: “second name”Underlined or italic

Nurfida9

Classification Classification

Ph lPhylum

ClassClass

Order Order Order Order

il il ilFamily Family Family Family Family Family

Genus Genus Genus Genus Genus Genus Genus GenusGenus Genus Genus Genus Genus Genus Genus Genus

10

Species

Helminthic ParasitesHelminthic ParasitesHelminthic ParasitesHelminthic ParasitesTrophoblastic metazoa

M lti ll l•Multicellular•Three germ layers (cuticle, sub-

cuticle, muscular)Helminths of medical importancep

•Phylum Platylhelminthes (flatworms)(flatworms)

•Phylum Nemathelminthes (roundworms)

11

(roundworms)

ClClClassesClassesPlatyhelminthes

Cestoidea (segmented, tapeworms)Trematoda (unsegmented, flukes)

NemathelminthesNe at e t esNematoda (rounded)

12

Comparison of Nematodes Trematodes and CestodesComparison of Nematodes, Trematodes and Cestodes

Nematodes Trematodes Cestodes

Shape Cylindrical, unsegment

Leaf-like, unsegmented

Tape-like, segmentedunsegment unsegmented segmented

Sexes separate not-separate not-separate

Body cavity

present absent absent

Alimentary canal

present present, incomplete

present

Hooklets absent absent Often present

13

Introduction to NematodeIntroduction to NematodeIntroduction to NematodeIntroduction to Nematode

St tStructureLife Cycle

HabitatMode of infection

Egg or larva productionCl ifi tiClassification

14

StructureStructure

Body wallyCuticle, subcuticular layer and muscular layer.

Nervous systemNerve trunk, nerve ring (around oesophagus) and sensory papillae (cuticle)

Digestive systemg yBuccal cavity, +/- teeth/cutting plate, oesophagus, intestine/midgut, rectum & anus

15

Life Cycle (cont )Life Cycle (cont.)Direct type

Infective stage -> adult stage e.g Trichuris trichuria

I di t tIndirect typeSeveral developmental stagese.g Ascaris (ingestion), hookworm (skin penetration) e.g Ascaris (ingestion), hookworm (skin penetration) & filariasis (per cutaneous)

16

Habitat of nematodes in hosts

intestine somatic

L i i Small

subcutaneous

Loa loa

hLarge intestine Small intestine lymphatic

body cavityAscaris

Onchocerca

Dracunculus

conjunctiva

Ascaris

Hookworms

Strongyloides

Enterobius

TrichurisMansonella spp.

17

conjunctivaTrichinella

CapillariaLoa loa

Mode of infectionMode of infection

ingestion Eggs in food, watergg ,

Embryos in intermediate host

Encysted embryos in meatEncysted embryos in meat

Inhalation; ex: Acanthamoeba spp

Insect bite Vectors: Aedes, Anopheles, Culex, Chrysops, Culicoides, Simulium

Skin penetration by filariform larva

18

NEMATODE

Lay eggs(oviparous)

Hatch larvae( i i )(oviparous) (viviparous)

A iLarva

hatch out immediately from egg

AscarisTrichurisHookworms

WuchereriaBrugia

from egg(ovo-viviparous)

Hookworms

EnterobiusDracunculusTrichinella

Strongyloides stercoralis

19

Common conditions / terms related to nematodes

Soil transmitted helminths

hookworms

filarial worms

cutaneous larva migrans

visceral larva migransv sceral larva m grans

20

Reference:Reference:Beaver, P.C., Jung, R.C. 1984. Clinical

l 9th d Ph l d l h L & parasitology. 9th ed. Philadelphia, Lea & Febringer. p.15-17Markel & Vogel Medical parasitology 8th ed Markel & Vogel. Medical parasitology 8th ed. p.269-297Miyazaki I. 1991. An illustrated book of Miyazaki, I. 1991. An illustrated book of helminthic zoonosis. Tokyo : International Medical Foundation of Japan, p. 1-5Schimidt, G.D., Roberts, L.S. 2005. Foundation of parasitology. 7th ed. Mc Graw Hill. p. 411-435

21