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Dental Optometry Parasitology

Dental Optometry Parasitology. William H. Benjamin, PhD UAB Pathology. Important points for parasites. Life cycle Definitive host Intermediate host Reservoir hosts Vectors How humans are infected Migration pattern and where adults live in humans Diagnostic form in humans

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Dental Optometry Parasitology

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  1. Dental Optometry Parasitology William H. Benjamin, PhD UAB Pathology

  2. Important points for parasites • Life cycle • Definitive host • Intermediate host • Reservoir hosts • Vectors • How humans are infected • Migration pattern and where adults live in humans • Diagnostic form in humans • Geographical distribution

  3. Sedimentation concentration

  4. Floatation concentration

  5. Classification of Parasites • Protozoa - single celled eukaryotes • mastigophora - Giardia lamblia • sarcodina - Entamoeba histolytica • sporozoa - Toxoplasma gondii, Cryptosporidium sp. Plasmodium sp. (malaria) • Helminths - multi-cell eukaryotes (Worms) • nematodes - round worms (Ascaris lumbricoides) • platyhelminths - flat worms • trematodes - (flukes) Schistosoma sp. • Cestodes - (tapeworms) - Taenia sp. (pork tapeworm.)

  6. Entamoeba histolytica

  7. Entamoeba histolytica/dispar • Humans are the only host • world wide distribution • fecal oral or water borne - cysts are the infectious form • diagnostic forms are cysts or trophozoites in stool or serology • Causes amebic dysentery • invade and lyse tissue either in the colon or extraintestinal sites usually liver or lung

  8. Entamoeba histolytica/dispar

  9. Non pathogenic ameba • Entamoeba dispar - morphologically identical to E. histolytica • Entamoeba hartmanni - small race E. histolytica • Entamoeba coli • Iodamoeba butschlii • Endolimax nana

  10. Entamoeba coli cysts

  11. Giardia lamblia • The most commonly diagnosed and important parasite of humans in the US • Transmission is fecal oral or water borne • Daycare centers • Fifty percent asymptomatic - 2 - 15% incidence • Symptoms - frothy fatty diarrhea - malabsorption, osmotic diarrhea • Reservoir hosts - beaver and other animals • Diagnostic forms are cysts and trophozoites in stool - noninvasive

  12. Giardia lamblia

  13. Giardia lamblia

  14. Chilomastix mesnilinon-pathogenic flagellate

  15. Toxoplasma gondii • Cat litter organism • Congenital infections

  16. Montoya, J. G., and O. Liesenfeld. 2004. Toxoplasmosis. Lancet 363:1965.

  17. Congenital Toxoplasmosis 400 – 4000/ year 750 deaths from toxoplasmosis/ year 50% food-borne Rate of Severe sequelae/stillbirth Among infected infants 41% 1st trimester 14% 8% 2nd trimester 29% 0% 59% 3rd trimester Transmission rate

  18. CNS lesions found in immunosuppressed patients

  19. Toxoplasma gondii (cysts)

  20. Cryptosporidium parvum • Zoonosis - first human cases in 1979-1982 Auburn • Worldwide distribution • Cysts are infective - resistant to chlorine • Milwaukee - 1993 370,000 cases • Common in daycare centers • Intracellular in gut epithelium • Self limiting watery diarrhea in adults and children • Severe untreatable disease in AIDS patients

  21. Cryptosporidium parvum

  22. The little blue organisms lined up along the brush border of the small intestinal epithelium are Cryptosporidia. This infection causes diarrhea in immunocompromised hosts. medlib.med.utah.edu

  23. Overview of Malaria Epidemiology • 2.7 million deaths/year mostly children in Africa • 300 to 500 million cases annually • 90 percent of them in sub-Saharan Africa • More than 40 percent of the world's population lives in areas where malaria naturally occurs • 1000 cases/year in the US

  24. Plasmodium (malaria)

  25. Malaria fever

  26. Plasmodium vivax Infected erythrocytes: enlarged up to 2X; deformed; (Schüffner’s dots) Rings Trophozoites: ameboid; deforms the erythrocyte Schizonts: 12-24 merozoites Gametocytes: round-oval

  27. Plasmodium falciparumMalignant malaria

  28. Malaria prevention decreased contact with mosquito • Night biting Anopheles mosquitos are the only intermediate host • Insecticide-treated nets • cheap and, if used correctly, an effective means of preventing malaria. • Indoor house-spraying with residual insecticides (e.g. DDT) • Mosquito resistance • Ecological concerns • wearing of protective clothing and insect repellents at dawn and dusk

  29. US Cases of Cyclospora • Guatemalan spring raspberries • 1995 retrospective cases in New York and Florida • 1996 1465 cases in 14 states and 2 provinces • 1997 90 cases before importation of raspberries stopped • Sweet Basil • Washington DC and Virginia 61 events with at least 1700 cases • Lettuce - specialty baby leaves • 2 events, 1 cruise ship

  30. Cyclospora cayetanensis • First found in Nepal, Peru and Cook County Hospital 1989 - 1990 • Found to be a coccidian and named 1993 • Reservoir unknown • Infects small intestine epithelial cells • Profuse watery diarrhea for 4 - 7 days. Multiple relapses over 3 - 4 months • Treatment trimethoprim - sulfamethoxazole usually more than one course required

  31. Cyclospora cayetanensis

  32. 58,000 specimens from 601 US laboratories

  33. Ascaris lumbricoideslarge roundworm • World wide distribution • Humans are the only definitive host • Embryonated eggs are infective (not food handler) • Eggs hatch in duodenum, larvae penetrate the intestine and migrate through the lungs, swallowed • Large round worm - 20 - 35 cm long • Adults live in small intestine • life span is 6 months to 1 year • Diagnostic form is eggs in stool or passed adult • Erratic adult worms

  34. Ascaris lumbricoides

  35. Ascaris lumbricoidesRoundworm

  36. “Vomit worm”Ascaris lumbricoides

  37. Strongyloides stercoralis • Free living • “life time infection”

  38. Strongyloides stercoralis • Mainly tropical distribution • Can have free living adult forms • Infection is by larvae boring through intact skin • Adult females are small (2 mm long) and live in the mucosa of the small intestine • Autoinfection can lead to hyperinfection syndrome • Infections can be subclinical for decades • Eosinophilia is common • Diagnostic forms are larvae in stool or sputum

  39. Strongyloides stercoralis

  40. Schistosoma sp. (blood flukes) • S. mansoni, S. haematobium and S. japonicum • Geographic distribution - tropics • Adults (1 - 2.5 cm long) reside in conjugal bliss in venules • Infection is by cercaria penetrating intact skin • Snails are the intermediate host - humans acquire infection in snail infested water • Zoonotic - except S. haematobium • Diagnostic form is ova in stool or urine or serology

  41. Schistosoma species Blood flukes

  42. Schistosoma mansoni eggs

  43. Schistosoma mansoni

  44. Taenia soliumpork tape worm • Found where ever people eat uncooked pork and allow pigs to scavenge human waste • Humans can be both definitive host and intermediate host • Infective forms for humans • cysticerci in pork - adult tape worm (10 years) • ova from human stool - cysticerci in humans • Adult tapeworms are 2 - 7 meters long • Diagnostic forms are ova in stool or passed worm segments. CAT/MRI scans for cysticerci

  45. Adult Taenia (tapeworm)

  46. Measly porkSource of Taenia solium(Pork tapeworm)

  47. Other cestodes - tapeworms • Taenia saginata - beef tapeworm • Diphyllobothrium latum - broad fish tapeworm • Hymenolepis nana - dwarf tapeworm • Hymenolepis diminuta - rat tapeworm

  48. Dracunculus medinensisGuinea worm

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