Fundamentals Of Medical Helminthology PDF

FUNDAMENTALS OF MEDICAL HELMINTHOLOGY Raymond F Adebiyi Professor Immunology and Medical Microbiology Learning Objectives 1. Given the name of a parasite, state if it is a protozoon or a helminth. 2. Recall the scientific and common names for each parasite. 3. Describe the parasitic form that causes...

FUNDAMENTALS OF MEDICAL HELMINTHOLOGY Raymond F Adebiyi Professor Immunology and Medical Microbiology Learning Objectives 1. Given the name of a parasite, state if it is a protozoon or a helminth. 2. Recall the scientific and common names for each parasite. 3. Describe the parasitic form that causes disease in humans (the infective form). 4. Identify the body site where the parasite is primarily located. 5. Discuss the mode of infection for each parasite. 6. Describe and state the name of the disease caused by each parasite. 7. State the appropriate specimen to be examined and describe the laboratory tests that may be of value for diagnosis. 8. Describe the life cycle of each parasite. 9. Given a case scenario, name the most probable parasite involved and discuss the method(s) for making a diagnosis. 10. Discuss the main features of immunological responses to protozoal and helminthic infections. RFA OFFICE HOURS Please check Canvas calendar https://atge.webex.com/meet/radebiyi email: [email protected] Dr R F Adebiyi Helminthology Platyhelminthes (Flat worms) 1. Trematodes – flukes 2. Cestodes - tapeworms Nemathelminthes (Round worms - Nematodes) 3. Intestinal worms 4. Tissue worms – filarial worms Trematodes (Flukes) Trematodes Hermaphroditic flukes definitive host - mammal mode of infection: ingestion fish crustacean (e.g. crab) vegetable Schistosomes (exception; blood fluke) definitive host - mammal mode of infection: not by ingestion skin penetration - swimming Fundamentals Of Helminthology Schistosomiasis Mode of Infection – direct skin penetration by cercariae (swimmer’s itch) Sites of infection – S mansoni – intestinal blood vessel S japonicum – intestinal blood vessel S haematobium – urinary bladder blood vessel Diagnosis – Eggs in feces S mansoni – huge lateral spine S japonicum – rudimentary lateral spine Eggs in urine S haematobium – terminal spine (associated with squamous cell carcinoma of the bladder) SCHISTOSOMIASIS typical intense eosinophil response Cestodes (Tapeworms) Tapeworm Structure Diphyllobothrium latum Dibothriocephalus latus broad or fish tapeworm very ‘big’ follows ingestion of raw fish intestinal disease complication: megaloblastic anemia Taeniasis Beef tapeworm – T. saginata Pork tapeworm – T. solium ❑intestinal disease (beef, pork) “taeniasis” ❑tissue disease (eggs of T solium) “cysticercosis” Dx – eggs/proglottids in human feces Echinococcus granulosus Echinococcus multilocularis Dog tapeworm Hydatid disease (hydatid cyst) Mode: accidental ingestion of eggs Disease: hydatid cysts in tissues Diagnosis: lesions on x-ray or scan Hydatid Cyst Nemathelminthes Intestinal nematodes 1. Ascaris lumbricoides (round) 2. Strongyloides stercoralis (thread) 3. Ancylostoma duodenale (hook) 4. Enterobius vermicularis (pin) 5. Trichuris trichiura (whip) 6. Trichinella spiralis (pork) 7. Necator americanus (hook) Ascaris Lumbricoides Roundworm – common name One of the most common human infections world-wide Mode – ingestion of eggs (food, raw vegetable) Site – adult in the intestine Diagnosis – large thick-walled eggs in feces Ascaris Lumbricoides Ascaris Lumbricoides Strongyloides stercoralis ❑threadworm (common name) ❑complex life cycle - many larvae produced rapidly especially in immunocompromised persons, leading to very high parasite load - auto-reinfection ❑infective larvae penetrate skin (ground itch) ❑adults in the intestine ❑larvae in stool Enterobius Vermicularis very common in US children most affected - pinworm (common name) Mode – hand to mouth Site – intestine Diagnosis – eggs on anal region (perianal itching) Scotch™ tape technique! Enterobiasis Enterobius Vermicularis (Pinworm) Enterobius Vermicularis (Pinworm) Hookworm Hookworm Necator americanus Ancylostoma duodenale Mode – penetration of bare foot (ground itch) Site – attach to intestine Diagnosis – eggs in feces Trichinella Spiralis Trichinosis no eggs, larvae produced no external phase dead end – transmission by carnivorism Mode – ingestion of infected meat (cysts) Site – adult in intestine Diagnosis – larvae form cysts in muscle muscle pain / muscle biopsy Trichinella Spiralis Tissue Nematodes Filaria adults in tissue eggs not produced microfilariae produced Tissue Nematodes Filaria  Wuchereria bancrofti  Brugia malayi  Brugia timori (mosquito) Loa loa  Onchocerca volvulus (deer fly) (black fly) Dracunculus medinensis (water flea) Elephantiasis Wuchereria Bancrofti / Brugia Malayi Onchocerca Volvulus river blindness/onchocerciasis Mode ✓ Vector bite – Simulium blackfly (breeds in river) Disease ✓ larvae in nodule in subcutaneous tissue ✓ Skin (dermatitis) ✓ Eye (blindness) Diagnosis ✓ Nodulectomy (skin snip) THE END