Introduction to Parasitology

2. Introduction to Parasitology By Sh. Ghaffari September 2012

3. Parasitology: definition • Parasitology: study of parasites • Animals: • Free-living • Symbiotic • Symbiosis Metabolic dependence

4. Parasitism • Parasite (parasitos “para: beside; sitos: grain or food”) • Host Parasitism: a form of symbiosis in which one organism (parasite) benefits at the expense of another organism of different species (host). Must be: • Animals • Different species

5. Medical Parasitology • Life cycle1.Direct life cycle2.Indirect life cycle • Transfer or paratenic host

6. Medical Parasitology • Host specificity • Host: • Reservoir host • Incidental host • Zoonosis • Transmission : • Direct contact • Indirect contact • Vector (carrier): often an arthropod, • Biological V. • Mechanical V.

7. Medical Parasitology Medical Parasites: • Protozoa • Helminthes: • Nematodes(Roundworms) • Trematodes(flukes) • Cestodes(tapeworms) • Arthropoda Platyhelminthes Ectoparasites Endoparasites

8. Classification Kingdom (Animal)Phylum (Platyhelminthes) Class (Trematoda) Order (Digenea) Family (Schistosomidae) Genus (Schistosoma) Species (heamatobium)

9. Binomial nomenclature The scientific naming of species whereby each species receives a Latin or Latinized name of two parts, the first indicating the genus and the second being the species. the genus (capitalized) and species (lowercase) names, both written in italics.For example: Sarcocyctisbovis, Leishmania donovani,

10. Nematodes

11. Parasitic nematodes • Life cycle: • Cylindrical, • Complete digestive system, • Male < Female • Large (parsites) • Long life molting molting molting

12. Ascarislumbricoides Ascariasis

13. Ascarislumbricoides: like Lumbricus • Female: 20-35cm, Male: 10-20

15. Anterior end of Ascaris lumbricoides showing mouth, esophagus, and intestine.

18. Importance • Worldwide • Very common parasitic worm in human: 1/6 of world population • Tropical and subtropical, • poverty

19. worms

20. Need wet warm soil • Resistant to cold weather • Resistant to acids and alkalis as well as other chemicals • Fertilized eggs oval to round , albumin thick outer shell • Unfertilized eggs

22. Small intestine: Ascarislarva emerging from egg

24. Ascariasis • Infection or disease? • Number of worms

25. Ascariasis: Symptoms and signs 1- Migrating larvae: allergic and respiratory symptoms (Loffler syndrome): • Cough • Sever hemorrhagic pneumonia • allergic hypersensitivity reactions(parasite proteins are allergenic): • Asthmatic attacks. • Pulmonary infiltration. • Urticaria . • Edema of the lips. • Eosinophilia

26. Ascariasis: Symptoms and signs 2- Adult parasites in the intestine: • A vague abdominal discomfort. • Nausea. • Colic • Lactose • Malnutrition • Intestinal obstraction

28. Ascariasis: Symptoms and signs • Adult worms outside of the intestine (wandering worms: High infection, Only male / Fever, Drugs) : • carry intestinal bacteria to these sites • Bile duct: jaundice, hepatitis • Appendix and peritonea: appendicitis, peritonitis • Migrate forward through the intestinal tract: vomited up or emerging through the nose.

30. Diagnosis • Stool Examination: appearance of the eggs in feces • Treatment • Albendazole : single dose 400 mg/ 200 mg under 2 years • Mebendazole: 100mg Bid x3 days • Ivermectin • pyrantelpamoate: single dose

32. Biliaryascariasis

33. Transmission • Children 5-9 years old • poor sanitation (sewage disposal) • places where human feces are used as fertilizer • poor personal hygiene • consuming contaminated vegetables or fruits

35. Control • Effective sewage disposal systems. • Wash, peel, or cook all raw vegetables and fruits grown in soil • Periodic treatment

36. EnterobiusvermicularisPinworm, Oxyur Enterobiasis

38. Enterobiusvermicularis • World wide distribution • The most prevalent worm in USA and Western Europe • Incidense: 11.4% among people of all ages in USA • Most in School-age children (30-60%) • Not associated with social class, or culture

39. Enterobiusvermicularis • Female: • about 1 cm • sharply pointed tail • Male: • About 0.5 cm • curved tail

41. Contains developing embryo or a larva • Colorless • Adheres to environmental objects Enterobius eggs

42. Infective in 4-6 h • remain active up to three weeks 11

43. Clinical manifestations • No symptoms in most people • Anal itching in children • Restless sleep • Itching and vaginal discharge in girls • Irritated or infected skin around the anus

44. Diagnosis Treatment • Tape test (Scotch ) • transparent adhesive tape • Done in the morning, before defecation and washing • Adult worms in perianal skin • Mebendazole • Albendazole • pyrantelpamoate • single dose • entire household be treated • repeated after 2 weeks

45. Control • Eggs can be transferred from fingers to clothing, bedding, towels, toilets, and other objects in the environment. • Spread by children to schoolmates or family members. • Dust containing eggs can become airborne • personal hygiene. • laundering of bedding

46. close contact • Finger sucking and nail biting • Autoinfection(infection from the original host to itself): • anus-to-mouth rout • retroinfection,(larvae may hatch on the anal mucosa, and migrate up the bowel)

47. THE END