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32 Cards in this Set
- Front
- Back
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Parasites in the US
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Trichomonas, (vaginitis)
Giardia Cryptosporidium (MCC water related) Toxoplasma (congenital, conjunctivitis) |
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parasites causing human Dz
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Protozoa, Helminths and Ectoparasites
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hosts
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Definitive host: Where a parasite undergoes sexual reproduction or reaches sexual maturity
Intermediate host: Where asexual stage develops Reservoir host: The animal which harbors a parasite harmful for other animals Incidental host: An animal that is accidentally infected and is not required for the parasite survival |
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zoonoses
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Zoonoses: Infection in which man is an incidental host for a parasite normally found in other animal
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fecal oral
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hardy, dormant form either a cyst (Giardia, Amebas), an oocyst (Cryptosporidium, Isospora, Toxoplasma), or a spore (Microsporidia). Helminths spread by the fecal-oral route are spread as eggs or as larvae.
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food-borne
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Either due to ingestion of a tissue form in the tissues (e.g., Trichinella and pork) or associated with the contaminated external surface of the food
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Skin penetration-
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hookworm, strongyloides, schistosomiasis
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arthropod vectors
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Malaria, Chagas
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4 groups of protzoa
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Sarcodina – the ameba, e.g., Entamoeba
Mastigophora – the flagellates, e.g., Giardia, Leishmania Ciliophora – the ciliates, e.g., Balantidium Sporozoa – adult stage is not motile e.g., Plasmodium, Cryptosporidium |
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Sarcodina –
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the ameba, e.g., Entamoeba
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Mastigophora –
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the flagellates, e.g., Giardia, Leishmania
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Ciliophora –
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the ciliates, e.g., Balantidium
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Sporozoa –
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Sporozoa – adult stage is not motile e.g., Plasmodium, Cryptosporidium
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intestinal protozoa infections
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Amebiasis
Giardiasis Cryptosporidiosis Microsporidiosis Cyclosporiasis Isosporiasis Blastocystis homninis Balantidiasis |
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blood or tissue protozoa
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Babesiosis
Malaria African sleeping sickness african trypanosomiasis leishmaniasis (Kala-alzar) Naegleria, Acanthamoeba Toxoplasmosis |
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Flatworms–
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including the trematodes (flukes) and cestodes (tapeworms).
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Thorny-headed worms–
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Thorny-headed worms– the adult resides in the GI tract. Thought to be intermediate between the cestodes and nematodes
not too much in humans |
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Roundworms (nematodes) –
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the adult nematode can reside in the GI tract, blood, lymphatic system or subcutaneous tissues. Larval stages cause disease through their infection of various body tissues
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trematodes
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flatworm: flukes
Bilharzia (Schistosomiasis) Cercarial Dermatitis (Swimmer's itch) Clonorchiasis (Clonorchis) Fascioliasis (Fasciola) Faschiolopsiasis (Fasciolopsis) Heterophyiasis (Heterophyes) Paragonimiasis (Paragonimus) |
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cestodes
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flatworm: tapeworms
Cysticercosis (Neurocystistercosis) Diphyllobothriasis (Diphyllobothrium) Dipylidium caninum infection (dog or cat tapeworm) Echinococcosis (alveolar echinococcosis, hydatid disease) Hymenolepiasis (Hymenolepis) Opisthorchiasis (Opisthorchis infection ) Tapeworm infection (Taeniasis, Taenia) Toxocariasis (Toxicara, Ocular Larva Migrans, Visceral Larva Migrans) |
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Nematodes
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Ancylosomiasis (hookworm, cutaneous larva migrans)
Ascariasis (Ascaris, Intestinal roundworms) Angiostrongylus (rat lung worm) Anisakiasis (marine mammals) Baylisascariasis (Baylisiascaris, racoon roundworm) capillariasis (Capillaria) Dracunculiasis (guinea worm Dz) Elephantiasis (filariasis, Lymphatic filariasis) Enterobiasis (Pinworm) Filariasis (Lymphatic filaiasis, elephantiasis) gnathosomiasis (gnathostoma) loaiasis (Loa loa) onchocerciasis (river blindness) strongyloidiasis(strongyloides) trichinosis (trichinellosis) trichuriasis (whipworm, trichuris) |
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MCC death by parasite
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malaria
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MCC infection but not death by parasite
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#1 Ascaris
#2 - Hookworm |
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compare protozoa and helminth
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Protozoans
- single celled - microscopic - multiply within host (usually asexual reproduction) - usually not associated with eosinophilia Helminths - multicellular - visible to the eye at some stage - usually do not reproduce within the host - associated with eosinophilia |
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2 classic GI sx with protozoa
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Bloody diarrhea (dysentery)
Entamoeba histolytica Balantidium coli Trichuris trichiura Shistosoma spp Stronglyloides Watery diarrhea (malabsorption) Giardia lamblia Cryptosporidium parvum Cyclospora cayetanensis Isospora belli Microsporidium spp |
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Amebiasis
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Several Entamoeba species infect humans, but not all of them cause disease.
Entamoeba histolytica is a pathogenic ameba, associated with intestinal and extraintestinal infections. Other species may be confused with E. histolytica in diagnostic investigations. Worldwide, with higher incidence of amebiasis in developing countries. Industrialized countries: male homosexuals, travelers and recent immigrants, and institutionalized populations. Infection by Entamoeba histolytica occurs by ingestion of mature cysts in fecally contaminated food, water, or hands. Cysts can survive days to weeks in the external environment. Transmission can also occur through exposure to fecal matter during sexual contact (in which case not only cysts, but also trophozoites could prove infective Asymptomatic carriers: trophozoites confined to the intestinal lumen (noninvasive infection), passing cysts in their stool - E. dispar or histolytica 2) Intestinal disease: trophozoites invade the intestinal mucosa - E. histolytica 3) Extraintestinal disease: trophozoites invade through the bloodstream to liver, brain, and lungs - E. histolytica Entamoeba histolytica must be differentiated from nonpathogenic amebas (E. coli, E. hartmanni, E. gingivalis, Endolimax nana, and Iodamoeba buetschlii) and Dientamoeba fragilis (flagellate not an ameba) Differentiation based on morphologic characteristics of the cysts and trophozoites may be difficult. |
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Acanthamoeba spp
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Acanthamoeba spp can cause severe keratitis in healthy individuals, especially contact lens users
Acanthamoeba spp and Balamuthia mandrillaris: opportunistic amebae that can cause granulomatous amebic encephalitis (GAE) in immunocompromised individuals |
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trichomonas males
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Frequently asymptomatic
Occasionally, urethritis, epididymitis, and prostatitis. dx Wet mount of vaginal or urethral discharge - detecting motile organisms - practical and rapid - relatively insensitive Direct immunofluorescent antibody staining - more sensitive Culture – most sensitive but requires 3 – 7 days Metronidazole 2g po once or 500mg BID x 7 days Tinidazole 2g po once |
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GET on the Metro
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G Giardia
E Entamoeba T Trichomonas on the Metro Metronidazole |
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What parasites associated with gastroenteritis are acid-fast?
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Cryptosporidium parvum and Cryptosporidium hominis: most prevalent species causing human disease
Cyclospora isospora so you should know the sizes! crypto - 4-6ym cyclospora 8-10ym isospora 25-30ym football shaped |
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>400,000 cases in Milwaukee 1993
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also Nosocomial/daycare cases 1983
cryptosporidiosis Low infectious dose (30 cysts or more) The oocysts are infectious when shed The oocysts are hardy (resist chlorine) Some species have animal reservoirs Immunity can prevent infection |
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________ highly resistant to purification by chlorination
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Cryptosporidium and Giardia are highly resistant to purification by chlorination
oocyst is what causes the transmission and contamination Immunocompetent: self-limited Nitazoxanide 500mg po BID x 3 days approved for immunocompetent Effectiveness of nitazoxanide in immunosuppressed unclear AIDS – HAART - Nitazoxanide, paromomycin, paromomycin/azithromycin |
