Parasitology

1. Parasitology

2. Introduction • Relationship between two living organisms Commensalism Mutualism Parasitism

3. Definitions:-Parasitology: It is the branch that studies the parasites which live on the expense of man. They obtain food and shelter from him without compensation, but causing injury.

4. Primary host or definitive host : is a host in which the parasite reaches maturity and, if applicable, reproduces sexually. • A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which (usually) some developmental stage is completed.

5. A reservoir can harbor a pathogen indefinitely with no ill effects. A single reservoir host may be reinfected several times. • A dead-end host is an intermediate host that does generally not allow transmission to the definite host, thereby preventing the parasite from completing its development.

6. Classification: Parasitology Protozology Helminthology Entomology

7. Continue Helminthology Platyhelminthes (Flat worms) Nematohelminthes(Round worms) Trematoda(Flukes) Nematoda Ceastoda (Tape worms)

8. Phylum Platyhelminthes (Flat Worms) General Characters:- • Dorsoventeraly flattened. • Solid body (segmented or non segmented). • No respiratory system & no vascular system. • Bilaterally symmetric excretory system. • Generally hermaphrodite (except Schistosoma)

9. Trematoda (Flukes) Characters:- • Leaf – like worms (except Schistosoma female). • With 2 or 3 suckers (oral, sexual and ventral suckers). • Generally with two intermediate hosts ( a snail and an animal). • Non segmented. • Blind ended digestive tract.

10. Trematodes of medical importance in our course Heterophyes heterophyes Fasciola hepatica & Fasciola gigantica Schistosoma haematobium & Schistosoma mansoni

11. Heterophyes heterophyes

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15. Heterophiasis • Presence of the flukes in human intestine initiate intestinal mucosa inflammation, most of patients are asymptomatic, if symptoms appear, abdominal pain & non bloody diarrhoea occurs.

16. Adult worm • Heterophyes heterophyes adult worm is the smallest trematodes in size (2 mm in length).

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18. Diagnostic Stage • Egg. • Found in stool of heterophiasis patient. • Yellowish oval egg with conical operculum, thick shell and mature miracidium.

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20. First intermediate host Snail (Prienella conica)

21. Fasciola hepatica & Fasciola gigantica

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23. Fasciola hepatica

24. Fasciola gigantica

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27. Fascioliasis (Liver rot) • Presence of worm in biliary duct cause inflammations, right upper quadrant pain and fever. • Thickening of biliary walls cause fibrosis, hepatomegaly and liver cirrhosis. • Fascioliasis is mostly asymptomatic. • Obstruction of biliary duct can occur in months or years leading to obstruction jaundice. • Sometimes the adult worm gets into blood circulation causing abscesses & general toxemia.

28. Continue • Halzoun: * Disease caused by the adult worm in raw sheep liver. Which adheres to posterior pharyngeal walls and larynx, and causes painful pharyngitis, asphyxiation. Removed Surgically.

29. Adult worm

30. Continue It is leaf shape with a cone-shaped projection at the anterior end.  Living specimens are a grayish-brown in color

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32. Diagnostic Stage • Egg • The largest egg in trematodes. • Operculated containing immature miracidium. • Eggs hatches in fresh water after 2-3 weeks.

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34. First intermediate host Fasciola hepatica Snail(Lymnaeatrunculata )

38. publichealth3rd@yahoo.com

39. Continue • Praziquantel is very safe, taken as a single or divided dose according to the worm type. • Dose is calculated according to the patient weight. • Praziquantel is swallowed, not chewed; as it is very bitter in taste.