1. Enteric Nematodes Ascaris lumbricoides Enterobius vermicularis
Trichuris trichiura
Hookworms
Ancylostoma duodenale
Necator americanus
Strongyloides stercoralis

2. What you should know about the Enteric Nematodes
Name of organism and disease
Transmission (how acquired?)
Location and migration in human
Major clinical manifestations including presence/absence of eosinophilia
Diagnostic tests

3. Organism: Ascaris lumbricoides Disease: Ascariasis
Geographical Distribution:
Worldwide
1.2 billion infected (20%); 20,000 deaths
Transmission:
Ingestion of Ova
Fecal contamination of water, soil and hands

4. Ascaris lumbricoides Location of Parasite Larvae hatch in GI tract,
penetrate GI wall,
migrate via lungs & bronchi back to GI
(Adult stage)

5. Ascaris lumbricoides
Morphology: Adult, cm
Female
Male

6. Ascaris lumbricoides Morphology: Ova Unfertilized Fertilized
Embryonated
Infective

7. Ascaris lumbricoides Clinical:
Larval migration in lungs usually asymptomatic, but may be transient eosinophilia
Intestinal stage may produce abdominal pain, diarrhea & non-specific gastrointestinal complaints
Intestinal obstruction

8. Ascaris lumbricoides
Clinical:

9. Ascaris lumbricoides
Clinical:

10. Ascaris lumbricoides
Clinical:

11. Ascaris lumbricoides
Clinical:

13. Ascaris lumbricoides Diagnosis: O&P Test Control & Treatment:
Mebendazole, albendazole

14. Ascaris lumbricoides

15. Organism: Enterobius vermicularis PINWORM Disease: Enterobiasis
Geographical Distribution:
Worldwide, 20-60% school age children
Transmission:
Ingestion (and inhalation) of eggs
Location of Parasite:
Adults in proximal intestine, cecum & appendix
nocturnal deposition of eggs on perianal area

16. Enterobius vermicularis
Morphology:
Adults are 1 cm
Clinical:
Asymptomatic, vaginal pruritis
No migration, No eosinophilia
Reinfection common

17. Enterobius vermicularis

18. Enterobius vermicularis

19. Enterobius vermicularis

20. Enterobius vermicularis

21. Enterobius vermicularis

22. Enterobius vermicularis

23. Enterobius vermicularis
Diagnosis: “Scotch” Tape test for eggs
Control & Treatment: Mebendazole

24. Enterobius vermicularis

25. Organism: Trichuris trichiura WHIPWORM Disease: Trichuriasis
Geographical Distribution:
Worldwide
Transmission:
Ingestion of eggs
Location of Parasite:
Adult embedded in mucosa of cecum, colon, & rectum

26. Trichuris trichuria Morphology: Adult 3-5 cm
Anterior (digestive) end is thin
Posterior (reproductive) end is thick

27. Trichuris trichuria

28. Trichuris trichuria

29. Trichuris trichuria Clinical: Light infections - asymptomatic
Heavy infections - diarrhea
bloody diarrhea,
rectal prolapse
Diagnosis:
O&P Test
Control & Treatment: Mebendazole & Albendazole

30. Trichuris trichuria

31. Trichuris trichuria

32. Trichuris trichuria

33. Organism: Ancylostoma duodenale & Necator americanus HOOKWORMS
Disease: Hookworm anemia
Geographical Distribution:
Humid areas with poor sanitation
Transmission:
Direct penetration of unbroken skin by larva

34. Ancylostoma duodenale & Necator americanus
Location of Parasite:
Adults attached to mucosa of duodenum and proximal small intestine
Morphology:
Adults are 1 cm

35. Ancylostoma duodenale
& Necator americanus

36. Ancylostoma duodenale
& Necator americanus

37. Ancylostoma duodenale

38. Necator americanus

39. Ancylostoma duodenale
& Necator americanus

40. Ancylostoma duodenale & Necator americanus
Clinical:
Red pruritic lesions at site of larval penetration
Eosinophilia possible
Asymptomatic
Gastric pain & diarrhea
Anemia (due to blood loss)
Diagnosis:
O&P Test
Control & Treatment: Mebendazole & Albendazole

41. Ancylostoma duodenale
& Necator americanus

42. Organism: Strongyloides stercoralis Disease: Strongyloidiasis
Geographical Distribution:
Worldwide
Humid areas with poor sanitation
Transmission:
Direct penetration of unbroken skin by larva
Autoinfection - internal (larva becomes infectious in intestinal tract) & external

43. Strongyloides stercoralis
Location of Parasite:
Larva migrates via blood system to lungs,
penetrates alveoli,
coughed up and swallowed
Adult in mucosa of duodenum & jejunum
Eggs hatch in intestine
Larvae (non-infective) in stool
develops into infective larva in soil
(Free living cycle in soil)

44. Strongyloides stercoralis
Clinical:
Pruritic rash associated with larval entry
Coughing & wheezing, High eosinophilia
Abdominal pain, diarrhea
Hyperinfection - large numbers of larvae
Disseminated strongyloidiasis - in other organs (in immunocompromized patients - but not AIDS)
Control & Treatment: Ivermectin, thiabendazole

45. Strongyloides stercoralis

46. Strongyloides stercoralis
Morphology:
Adult females 2-3 mm

47. Strongyloides stercoralis
Morphology:
Larvae nm

48. Strongyloides stercoralis

49. Strongyloides stercoralis

50. Strongyloides stercoralis

51. Strongyloides stercoralis

52. Strongyloides stercoralis
Diagnosis:
String Test Baermann concentration
Serology & Bacterial agar plate

53. Strongyloides stercoralis

55. Organism:
Disease:
Geographical Distribution:
Transmission:
Location of Parasite:
Morphology:
Clinical:
Diagnosis:
Control & Treatment: