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214 Cards in this Set
- Front
- Back
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What is a definitive host?
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A host that harbors the adult (sexual) stage of the parasite.
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What is an intermediate host?
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A host that harbors the larval (asexual) stage of the parasite.
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What is a cestode?
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Tapeworm
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What is a nematode?
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a round worm
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What is a trematode?
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flatworm/fluke
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What is zoonosis?
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disease that is naturally transferable between animals and humans
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What is the route of transmission of entamoeba histolytica?
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Human is ONLY reservoir.
Cysts are infective--> person-to-person transmission (fecal-oral) |
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What is the presentation of entamoeba infection?
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90% are asymptomatic
Intestinal amebiasis: acute rectocolitis (amebic dysentery), can have toxic megacolon, ameboma, acute amebic appendicitis. Extraintestinal amebiasis can have abscesses of entamoeba. |
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What is used to dx entamoeba histolytica infection?
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Examination of stoole for cysts or tropozoites.
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What is the life cycle of entamoeba?
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Cysts & tropozoites are excreted in the feces.
Mature cysts are infective. |
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Describe the epidemiology of giardia infection.
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Cysts survive in water.
Disease is spread fecal-oral. Outbreaks are due to contaminated water supply. |
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What is the reservoirs of giardia?
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humans and beavers
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How does giardiasis manifest?
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Bloating, gas, chronic diarrhea w/epigastric pain and malabsorption of nutrients.
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How is giardiasis diagnosed?
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Stool examination for cysts or tropozoites.
No WBCs or blood in stool |
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What is distinctive about giardia tropozoites?
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Pear shaped w/2 nuclei & sucking disc
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What differentiates giardia infection from entamoebia infection?
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Giardia has NO intestinal invasion.
Entamoeba has intestinal invasion. |
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What are the intestinal protozoans?
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Entamoeba histolytica
Giardiasis |
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What is the important ST protozoan?
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Trichomonas vaginalis
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What are the symptoms of trichomoniasis?
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vaginitis, prostatitis, and urethritis
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What is distincitve of the lifecycle of trichomonas vaginalis?
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Tropozoite stage only.
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How is trichomoniasis diagnosed?
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Detection of motile tropozoites in vaginal discharge or urethral exudate.
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What two groups may the blood & tissue protozoans be classified into?
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Flagellates & Sporozoans
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What are the flagellate blood & tissue protozoans?
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Trypanosoma spp.
Leishmania spp. |
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What are the sporozoan blood & tissue protozoans?
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Plasmodium spp.
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What causes African trypanosomiasis?
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Trypanosoma brucei
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What is vector of African trypanosomiasis?
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tsetse fly
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What causes the clinical manifestation of African trypanosomiasis?
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High parasitemias (almost as high as RBC densities) and diffuse meningoencephalitis
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Describe East African trypanosomiasis.
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Caused by T. b. rhodiense
Acute disease. Abrupt onset of fever, headache, occipital lymphadenompathy (Winterbottom's sign) |
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Describe West African trypanosomiasis.
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Caused by T. b. gambiense.
Subacute, chronic meningoencephalitis. Subtle personality changes--> somnolence-->coma-->death |
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What is nagana?
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Cattle disease caused by T. b. brucei in subsaharan Africa.
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How is African trypanosomiasis diagnosed?
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Identification of trypomastigotes in blood smear.
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What is Chagas disease?
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South American trypanosomiasis.
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What causes Chagas' disease?
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Trypanosoma cruzi
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What is the vector of Chagas' disease?
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reduviid bug (kissing bug)
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What are the clinical manifestations of Chagas' disease with high parasitemia?
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Acute disease.
periorbital edema (Romana's sign), fever, anorexia, hepatomegaly, lymphadenopathy. Can lead to cardiomyopathy & death. |
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What are the clinical manifestations of Chagas' disease w/undetectable parasitemia?
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Cardiomyopathy, megaesophagus, megacolon (autoimmune!!!)
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How is Chagas' disease diagnosed?
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Xenologically or serologically
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What is the vector for leishmaniasis?
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sandfly
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What types of diseases are caused by Leishmania?
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visceral leishmaniasis (kala azar)
cutaneous leishmaniasis mucocutaneous leishmaniasis |
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What species of Leishmania cause visceral leishmaniasis?
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L. donovani
L. donovani chagasi |
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What causes Old World cutaneous leishmaniasis?
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L. major
L. tropica L. ethiopica |
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What causes New World cutaneous leishmaniasis?
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L. mexicana & L. braziliensis
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What causes New World mucocutaneous leishmanaisis?
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L. braliziensis
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Where is kala azar found?
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Africa, India, Brazil
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Where is cutaneous leishmaniasis found?
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Latin America & Middle East
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Where is mucocutaneous leishmaniasis found?
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Latin America
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What is the disease syndrome of kala azar?
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Parasites in macrophages of reticuloendothelial system.
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What is the disease syndrome of cutaneous leishmaniasis?
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chronic, non-healing ulcer w/heaped up margins
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What is the disease syndrome of mucocutaneous leishmaniasis?
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mutialting disease of cartilage
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How is leishmaniasis diagnosed?
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Skin biopsy for presence of intracellular amastigotes or serologic testing.
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What type of cells are infected by T. cruzi?
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All nucleated cells (esp. cardiac & smooth muscle of GI tract)
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What types of cells are infected by T. brucei?
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None. Extracellular parasite.
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What types of cells are infected by Leishmania spp.?
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Macrophages
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What causes malaria?
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Plasmodium spp.
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What is the vector of plasmodium?
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Anopheles mosquito
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What is the reservoir of plasmodium?
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Humans only.
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What are the four species of plasmodium that infect man?
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P. vivax
P. falciparum P. malariae P. ovale |
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What is the erythrocytic cycle time for plasmodium?
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For P. ovale, P, vivax, and P. falciparum: 48 hours
For P. malariae: 72 hours |
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Which specie of Plasmodium is the most severe?
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P. falciparum
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What are complications of infection with Plasmodium in general (all species)?
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Anemia, hypoglycemia, splenomegaly, splenic rupture
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What are the unique complications of P. falciparum infection?
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Cerebral malaria, blackwater fever (massive hemolysis-->hemoglobinuria-->dark urine)
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What causes mortality in malaria?
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P. falciparum: cerebral malaria
P. vivax: splenic rupture P. malariae: immune complex disease + nephrotic syndrome |
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Which types of erythrocytes does P. falciparum invade?
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All erythroid cells.
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What types of erythrocytes does P. malariae invade?
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Mature erythrocytes.
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What types of erythrocytes do P. vivax and P. ovale invade?
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Reticulocytes/immature erythrocytes only.
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What is the importance of a Duffy receptor in malaria infection?
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Needed for entrance of P. vivax into RBCs.
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Which individuals are innately immune to malaria?
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Duffy negative individuals are immune to P. vivax.
Sickle cell individuals have increased resistance to all plasmodium infections. |
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What describes immunity to recurrent disease?
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Individuals who have had it often or have lived in endemic area for 5+ years have decreased severity of infection.
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How is malaria diagnosed?
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Examination of blood smear.
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What are the platyhelminthes?
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Flatworms: trematodes (flukes) and cestodes (tapeworms)
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What are the blood flukes?
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Schistosoma mansoni
Schistosoma japonicum Schistosoma haematobium |
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What are the tissue flukes?
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Clonorchis sinensis
Fasciolopsis buski Paragonimus westermani |
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What are the intestinal tapeworms?
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Diphyllobothrium latum
Taenia saginatia Taenia solium |
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What does Clonorchis invade?
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Liver
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What does Fasciolopsis invade?
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Intestines
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What does Paragonimus invade?
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Lung
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What is an extraintestinal tapeworm?
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Echinococcus granulosus
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What are the characteristics of the trematodes?
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Flukes.
Leaf-shaped flatworms Two anterior suckers & one ventral sucker. Hermaphroditic (except Schistosomes) All trematode life cycles include molluscan hosts. |
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Where is Schistosoma japonicum found?
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Far East
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Where is Schistosoma mansoni found?
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Africa, Middle East, South America, Caribbean
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Where is Schistosoma haematobium found?
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Africa, esp. Nile River valley
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What is the intravascular location of adult schistosomes from S. japonicum?
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Superior mesenteric venules
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What is the intravascular location of adult schistosomes from S. haematobium?
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Venules of bladder
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What is the intravascular location of adult schistosomes from S. mansoni?
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Inferior mesenteric venules
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How do adult schistosomes live?
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Encopula
Female resides in gynecophoral canal of the thicker, shorter male |
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Describe a S. japonicum egg.
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Small round with laterally located appendage
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Describe a S. mansoni egg.
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Spiny appendage with lateral location
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Describe a S. haematobium egg.
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Spiny, terminally located appendage
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How do schistosomes avoid the host immune system?
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They absorb human antigens. but eggs do not
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How can an inflammatory or delayed-type immune response occur with schistosomiasis?
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Eggs that are produced but not released may elicit this type of response b/c eggs do no absorb human antigens as adults do.
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Describe cercarial dermatitis.
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Schistosomal infection where cercariae invade the skin but do not die.
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Describe acute schistosomiasis.
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4-6 weeks after heavy primary infection.
Due to release of egg antigen (antigen-antibody complexes) Serum sickness Lasts weeks w/significant mortality |
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Describe chronic schistosomiasis.
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Due to granulomatous reaction to eggs deposited in various tissues.
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What can cause GI schistosomiasis?
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S. mansoni
S. japonicum |
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What can cause urinary tract schistosomiasis?
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S. haematobium
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What is the progression of GI schistomsomiasis?
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Mild mucohemorrhagic diarrhea
Granulomatous hepatosplenomegaly Periportal fibrosis-->portal hypertension, intractable ascites, esophageal varices, intestinal polyposis-->protein-losing enteropathy |
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What is the progression of urinary tract schistosomiasis?
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Dysuria, terminal hematuria initially. Obstructive uropathy w/pyelonephritis-->renal failure, bladder cancer
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What is used to dx schistosomiasis?
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Detection of eggs in urine (S. haematobium) and feces (S. mansoni & S. japonicum)
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What are the intermediate hosts of Clonorchis?
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snail & freshwater fish
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What are the reservoirs of Clonorchis?
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cat and dog
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What characterizes acute clonorchiasis?
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fever & hepatomegaly
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What characterizes chronic clonorchiasis?
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fever, progressive hepatomegaly, abdominal pain in RUQ
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What are possible complications of clonorchiasis?
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pancreatitis & cholangiocarcinoma
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What is used to dx clonorchiasis?
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eggs in feces
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What is the typical pathway of transmission of clonorchiasis?
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Consumption of undercooked or pickled contaminated freshwater fish.
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What else is clonorchiasis known as?
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Liver fluke infection
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Where is clonorchiasis often found?
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China (far east)
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What is fasciolopsiasis also know as?
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Giant Intestinal fluke infection
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Where is fasciolopsis buski found?
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Far east, SE asia
Where humans raise pigs & consume freshwater plants |
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What are the intermediate hosts of fasciolopsis buski?
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Snails & freshwater plants.
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What are the symptoms of fasciolopsis buski infection?
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Epigastric pain, nausea, diarrhea, intestinal obstruction
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What is the reservoir of fasciolopsis buski?
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Pigs
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How is fasciolopsiasis diagnosed?
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Eggs in feces
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Where is paragonimus westermani found?
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Far East, West Africa, Mexico, Peru
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How is paragonimiasis contracted?
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Eating inadequately cooked contaminated crab or crayfish
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What are the intermediate hosts for paragonimus westermani?
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snails & crustaceans
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What are the reservoirs for paragonimus westermani?
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domestic & wild animals
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What characterizes acute paragonimiasis?
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Eosinophilic inflammatory reaction w/fever, urticaria, cough, dyspnea, abd. pain, blood diarrhea (due to adults in intestine)
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What characterizes chronic paragonimiasis?
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Pneumonia & lung abscess
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What is the lung fluke?
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Paragonimus westermani
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How is paragonimiasis diagnosed?
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Eggs in sputum, pleural fluid, and feces
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What are general characteristics of the cestodes?
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Largest of the intestinal parasites
Long, ribbonlike helminthes w/o body cavity Adult is divided into scolex (head), neck and strobilia (segmented body) |
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What is in the scolex of a cestode?
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Scolex is the head.
Attachment organ w/sucking discs and hooklets |
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What is the strobila of a cestode?
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Composed of proglottids (generated @ neck), each of which is a self-contained, hermaphroditic reproductive unit
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What happens as proglottids mature?
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New proglottids are added at the neck while the older ones proceed posteriorly. More mature male and female proglottids cause fertilize. Gravid proglottid ruptures-->release of eggs
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What is diphyllobothrium latum?
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fish tapeworm.
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Where is diphyllobothrium found?
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temperate, subartic regions (Scandinavia, Russia, Japan, North America, Chile)
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What is the largest human tapeworm?
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Diphyllobothrium
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What characterizes diphyllobothriasis?
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Usually asymptomatic, though megaloblastic anemia may result as the worm uses B12
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What is used to diagnose diphyllobothriasis?
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Detection of eggs in stool
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What is the beef tapeworm?
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Taenia saginata
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What is the distribution of taenia saginata?
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Worldwide
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What are the hosts of taenia saginata?
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Definitive: man only
Intermediate: cow |
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What are the characteristics of the disease caused by taenia saginata?
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dull, colicky abdominal pain (usually mild)
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How is taenia saginata infection diagnosed?
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Detection of eggs and/or proglottids in feces
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How is taenia solium infection diagnosed?
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Detection of eggs and/or proglottids in feces
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Where is Taenia solium found?
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Mexico, Latin America, Africa, Asia
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What is the intermidiate host of Taenia solium?
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Pig
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What is the definitive host of Taenia solium?
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Human
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How is Taenia solium transmitted?
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Consumption of contaminated pork, usually eggs
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What parasite causes cysticercosis?
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Taenia solium
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How does cysticercosis develop?
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Eggs (consumed by human) mature to point that larvae hatch.
Larvae travel to tissue and form cysts (especially in brain & striated muscle) |
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What are the properties of Taenia solium infection?
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Just infection: dull, colicky abdominal pain
Cysticercosis: CNS disease (seizure, focal deficits, hydrocephalus), ocular disease |
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What is hydatid disease?
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Echinococciasis
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What are the definitive hosts of echinococcus spp.?
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Dogs
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What are the intermediate hosts of echinococcus spp.?
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Humans
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What types of infection are caused by echinococcus?
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E. granulosus: cystic hydatid disease
E. multilocularis: alveolar hydatid disease (rare) |
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What are the properties of cystic hydatid diseae?
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Depends on location of cysts (lung & liver are most common)
Rupture of the cyst may result in anaphylactic reaction |
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What is used to diagnose echinococciasis?
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Detection of cysts (chest Xray, abdominal CT scan)
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What are the general properties of nematodes?
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Roundworms.
Elongate, cylindrical worms Usually symmetrical bilaterally NO circulatory system Separate sexes |
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What are the intestinal nematodes?
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Entrobius vermicularis (pinworm)
Trichuris trichiura (whipworm) Ascaris lumbricoides Hookworms (ancylostoma & necator) Strongyloides Trichinella |
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What are the blood, lymphatic & subQ nematodes?
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Wuchereria bancrofti
Brugia malayi Loa loa Onchocerca volvulus |
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What are the nematodes whose larvae causes pathology in human tissues?
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Trichinella spiralis
Toxocara spp. Ancylostoma braziliense |
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What causes pinworm infection?
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Enterobius vermicularis
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What is the morphology of enterobius vermicularis?
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Adult worm female: 8-13mm
Adult worm male: 2-5mm Egg is slightly flattened on one side |
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What is the epidemiology of enterbius vermicularis?
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fecal-oral
Worldwide distribution |
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What are the properties of enterobius vermicularis infection?
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Symptoms of uncommon
Pruritis ani |
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How is enterobius vermicularis infection diagnosed?
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Scotch tape test-->eggs
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What is the morphology of trichuris trichiura?
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Adult: 35-50mm
Egg: barrel-shaped mucoid plug |
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How is trichuris trichiura transmitted?
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fecal-oral
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Where is trichuris trichiura found?
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Asia, Africa, Latin America
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What are the properties of trichuriasis?
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Symptoms are uncommon.
Heavy infection: protein calorie malnutrition, rectal prolapse, inflammatory diarrhea |
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How is trichuriasis diagnosed?
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eggs in feces
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What is the largest intestinal nematode?
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ascaris lumbricoides
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How is ascariasis transmitted?
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Fecal-oral, usually consumption of vegetables if nightsoil used as fertilizer
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Where is ascaris lumbricoides found?
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Tropics, subtropics
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What are the symptoms of ascariasis?
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Usually asymptomatic.
Pulmonary disease: Loeffler's syndrome (transient infiltration of lungs, dyspnea, fever, eosinophilia) Adults may migrate from intestine & cause serious complications Heavy infection-->malnutrition |
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How is ascariasis diagnosed?
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eggs in feces
eosinophilia during tissue phases |
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What is "hookworm"?
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Anclyostoma duodenale (Old world)
Necator americanus (New World) |
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What is the morphology of hookworms?
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rhabditiform (rod-like) larvae which feed on organic debris & grow over five days to become slender, nonfeeding larvae
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Where is hookworm infection found?
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Tropical, subtropical
N. americanus: SE US, S. America, Indonesia, Philippines |
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What is a hookworm infection like, disease-wise?
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Larval penetration--> severe itching (swimmers itch)
Formation of maculopapules & localized erythema Heavy infection=protein calorie malnutrition & anemia |
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How is hookworm infection diagnosed?
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Demonstration of eggs in feces
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What is the morphology of strongyloides?
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Males are not parasitic
Females are thread-like |
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Where is strongyloides found?
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Everywhere
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What is the host of strongyloides?
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Human is only definitive host
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What are the disease properties of strongyloidiasis?
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Larva currens (rash + eosinophilia), migratory pneumonitis, hyperinfection in immunocompromised that may lead to meningitis, pneumonia
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How is strongyloidiasis diagnosed?
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demonstration of larvae in feces
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What causes filiariasis?
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Wuchereria bancrofti
Brugia malayi Loa loa Onchocerca volvulus |
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Where do the adult parasites reside in filariasis?
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Skin or lymphatics
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What are microfilariae?
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Immature larvae in blood or skin that circulate in the blood at certain times of day.
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What is the morphology of filaria?
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Adult worms: 20-70mm
Sheathed microfilariae: .2-.3 mm |
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What is the site of microfilaria in Wuchereria bancrofti?
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blood
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What is the site of microfilaria in Brugia malayi?
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blood
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What is the site of microfilaria in Loa loa?
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blood
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What is the site of microfilaria in Onchocerca volvulus?
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skin
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What disease is caused by Wuchereria bancrofti?
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elephantiasis
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What disease is caused by Brugia malayi?
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elephantiasis
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What disease is caused by Loa loa?
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Calabar swelling
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What disease is caused by Onchocerca volvulus?
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river blindness?
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Which types of filariasis are carred by the mosquito?
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Wuchereria bancrofti
Brugia malayi |
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What types of filariasis are carried by the horsefly?
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Loa loa
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What type of filariasis is carried by the blackfly?
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Onchocerca volvulus?
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What types of filariasis have sheathed microfilariae?
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Wuchereria bancrofti
Brugia malayi Loa loa |
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Where is filariasis found?
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Africa, India, Far East Indochina
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What is the reservoir for filariasis?
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human only
worms do multiply in human host |
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What are the characteristics of Bancroftian filariasis?
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Microfilariae in blood stream have nocturnal/diurnal periodicity
Adults reside in lymphatic vessels & nodes, esp. inguinal, epitrochlear, axillary, testicular, epididymal |
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What are the symptoms of Bancroftian filariasis?
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Acute: filarial fever, filarial adenolympangitis, orchitis (large testicles)
Chronic: lymphatic obstruction-->elephantiasis, tropical pulmonary eosinophilia |
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How does Malayan filariasis differ from Bancroftian filariasis?
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Lymphatic obstruction occurs in extremities more often, genital areas less oftan than Bancroftian
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Describe Loiasis?
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Adults migrate through subQ tissue
symptoms: Calabar swellings, subQ edematous areas, |
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Describe River blindness
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Caused by onchocerca
Found in tropical & subtropical Africa Adults reside in nodules in subQ Microfilariae in skin |
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What are symptoms of River blindness?
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subQ nodules
Dermatitis Regional lymphadema Ocular manifestations (microfilariae trapped in eye) |
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What is the morphology of trichinosis?
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Encysted larvae
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What is the epidemiology of trichonosis?
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widespread in wild mammals PIGS
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What are the disease properities of trichinosis?
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Variable, depend on presence of larvae in striated mm. & organs & on parasite load
Orbital edema, muscle pain, resp. distress, headache, generalized weakness |
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what is toxocariasis?
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visceral larva migrans
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What causes visceral larva migrans?
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Toxocara canis or toxocara cati
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What is the distribution of toxocariasis?
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worldwide
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What are the important reservoirs for toxocariasis?
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cats & dogs
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How is toxocariasis transmitted?
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oral route (eggs)
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Describe toxocariasis disease.
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Results from migration of larvae in viscera (hepatomegaly common); larvae become encapsulated in organs & can persist for many years
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What causes cutaneous larva migrans?
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Ancylostoma braziliense
"creeping eruption" |
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How is cutaneous larva migrans acquired?
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Direct skin penetration
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What is the symptoms of cutaneous larva migrans?
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serpigiouns line of eruption that reflects movement of larva beneath skin
Parasites can persist for weeks to months |
