Parasitology Test Questions – Flashcards
Unlock all answers in this set
Unlock answersquestion
| What round worm usually is asymptomatic but with eosinophilia, and can cause abdominal pain and diarrhea? |
answer
| Strongyloides stercoralis |
question
| How does Strongyloides stercoralis maintain chronic infection? |
answer
| Autoinfection |
question
| How does autoinfection occur? |
answer
| Rabditiform larvae in large intestines become filariform larvae, penetrate intestinal mucosa or perianal skin, enter circulation system, transport to lungs, penetrate alveolar space, carried to trachea and swallowed, become adults in intestines, deposit eggs, starts over. |
question
| How do Strongyloides initially infect? |
answer
| penetrate the intact skin |
question
| What happens to an individual who becomes immunocompromised and was previously infected (maybe 40 years earlier) by Strongyloides? |
answer
| Hyperinfection Syndrome Acute abdomen, Respiratory Distress, GNR sepsis Blood eosinophilia my be absent |
question
| When is serology useful for diagnosing Strongyloides stercoralis? |
answer
| Useful for Chronic Form to check for eosinophilia |
question
| How can Strongyloides be diagnosed? |
answer
| Larvae in stool or sputum Serology |
question
| What is the treatment for Strongyloides stercoralis? |
answer
| Ivermectin |
question
| What symptoms are associated with the 3 stages of infection by Strongyloides? |
answer
| Skin Invasion -> purpuric papule Lung Migration -> Loeffler's syndrome Intestinal phase -> GI symptoms |
question
| What species of Hookworm is associated with the Americas, Africa, Southern Asia, and Australia? |
answer
| Necator americanus |
question
| What hookworm is found in the Mediterranean and northern Asia? |
answer
| Ancylostoma duodenale |
question
| How do hook worms stay in the intestines? |
answer
| grasp intestinal villi with teeth or cutting plates Eat tissue |
question
| How can hook worms cause anemia? |
answer
| Eat intestinal tissue, produce anticoagulant, facilitates bleeding |
question
| What can the larva stage of hookworms do? |
answer
| Migratory, can produce inflammation and eosinophilia |
question
| How are hookworms treated? |
answer
| Mevendazole |
question
| What is the life cycle of roundworms from visceral larva migrans? |
answer
| Eggs from dog or cat roundworm ingested -> Larva penetrate mucosa, enter circulation, carried to liver, lungs, eyes -> cause inflammatory necrosis Do Not Replicate |
question
| At what point are Ascaris lumbricoides infectious? |
answer
| When embryos develop in fertilized eggs, under suitable environmental conditions |
question
| What is the life cycle of Ascaris lumbricoides? |
answer
| Infective eggs ingested and hatch in small intestines -> enter venules or lymphatics -> pass through heart and lung to alveoli -> migrate up bronchi -> trachea -> swallowed -> mature to adults in small intestines -> produce eggs -> eggs excreted in feces |
question
| How long do Ascaris Lumbricoids live and how many eggs can they produce? |
answer
| Live 1-2 years Produces 200,000 eggs per day |
question
| How big can Ascaris Lumbricoides get in the intestines? |
answer
| 30 cm |
question
| Why don't you treat Ascaris lumbricoides in the acute infectious stage? |
answer
| If worms are in the lungs and die they will cause inflammation and respiratory distress |
question
| How is Ascaris Lumbricoides prevented and treated? |
answer
| Good Hygiene, proper disposal of sewage Pyrantel pamoate (1 dose) mebendazole (3 doses) |
question
| Why are you likely to see hookworms if a person is infected with Ascaris? |
answer
| infect the same way, improper disposal of sewage |
question
| What worm is associated with the consumption of undercooked pork? |
answer
| Trichinella spiralis |
question
| What is the life cycle of T. spiralis? |
answer
| Ingestion of encysted larva in muscle of undercooked pork -> Larva released in small intestines -> Adults grow in small intestines -> larva deposited in mucosa -> circulation -> form cysts in striated muscle |
question
| What worm initially causes gastroenteritis, followed by fever, muscle tenderness, inflammation and weakness? (increased WBC and eosinophilia) |
answer
| Trichinella spiralis |
question
| After infection with T. spiralis when will a patient show eosinophilia and positive serology? |
answer
| Day 12 |
question
| How is Trichinella spiralis prevented and treated? |
answer
| Supportive therapy for inflammation Mebendazole eliminates adults, not larvae Prevent by eliminateing parsite in hogs, adequately cook meat |
question
| What metazoan parasite is transported to humans by mosquitos? |
answer
| Bancroftian filariasis (Elephantitis) |
question
| How does bancroftian filariasis go from the diagnostic stage (microfilariae) to the infective stage (L3 Larvae)? |
answer
| Mosquito takes blood from infected human, ingests microfilariae -> microfilariae shed sheaths, penetrate mosquito's midgut, migrate to thoracic muscles -> L1 larvae -> L3 larvae -> migrates to mosquito's head and proboscis |
question
| How does Wuchereria bancrofti block lymphatic channels? |
answer
| adults develope and reproduce in lymphatics causing inflammation -> die after about 5 years -> calcify, create more inflammation -> blocks lymphatics -> Fluid accummulates distally |
question
| Why is Wuchereria bancrofti diagnosed by taking blood at night? |
answer
| Microfilaria migration only at night (aggregate in lung capillaries during the day) |
question
| How is Lymphatic filariasis (elephantiasis) treated? |
answer
| Diethylcarbamazine kills adults Steroids Reduce inflammation |
question
| Where do the eggs of the pinworm mature? |
answer
| perianal folds |
question
| Where do female pinworms migrate to at night to lay eggs? |
answer
| perianal region |
question
| Where do pinworms hatch and grow? |
answer
| Small intestines |
question
| What worm is the most common helminth infection in the US? |
answer
| Pinworm infection (Enterobius vermicularis) |
question
| What worm should be suspected with perianal irritation? |
answer
| Pinworm (Enterobius vermicularis) |
question
| What test can be preformed to check for pinworm infections? |
answer
| Scotch Tape Test |
question
| How are Pinworm infections treated? |
answer
| 2 Doses pyrental pamoate, 2 weeks apart Treat whole family Sanitize Bedclothes Cut kids nails short |
question
| What species of Schistosomiasis can cause periportal fibrosis and portal hypertension with hepatosplenomegaly? |
answer
| S. mansoni S. japonicum |
question
| What species of Schistosomiasis can cause bladder granulomas, hematuria, and is associated with bladder cancer? |
answer
| S. hematobium |
question
| Once Schistosomiasis is excreted as the diagnostic stage, how does it develope into the infective stage? |
answer
| Eggs hatch in water releasing miracidia -> penetrate snails -> Sporocysts in snails -> Cercariae released by snail -> free swimming in water -> Penetrate skin of host |
question
| After Cercariae penetrate skin of the host, how does schistosomiasis develop? |
answer
| Cercariae lose tail become schistosomulae (coats self in host proteins) -> circulation -> portal blood in liver and mature into adults -> Paired adults migrate to mesenteric venules of bowel -> lay eggs -> excreted in urine and feces |
question
| How can Schistosomiasis cause acsites? |
answer
| Some eggs don't get excreted and go back into venous system causeing portal hypertension -> ascites |
question
| How is Schistosomiasis (blood fluke) treated? |
answer
| praziquantel snail control proper sewage disposal |
question
| What species of schistosomiasis is found in Africa? |
answer
| S. mansoni S. hematobium |
question
| What species of schistosomiasis is found in Asia? |
answer
| S. japonicum |
question
| What species of schistosomiasis is found in America? |
answer
| S. mansoni But has been irradicated from the snail population. (There is a species that replicates in ducks and can cause pruritic lesions but does not replicate in humans) |
question
| What is the life cycle of the Tape worms? |
answer
| Cattle or Pigs become infected by ingesting vegetation contaminated by eggs -> Onoospheres hatch, penetrate intestinal walls, circulate to musculature -> develope inot cysticorei in muscles -> humans infected by ingesting undercooked meat -> Scolex attaches to intestine -> Adults grow in small intestine, reproduce |
question
| What species of Tapeworm can develop cysticercosis? |
answer
| T. solium |
question
| How is T. saginata and T. solium treated and prevented? |
answer
| Praziquantel Try to find expulsed scolex to be sure Prevention through beef and pork inspection adequate cooking or freezing kill cysticeri |
question
| What worm can cause Neurocysticerosis? |
answer
| T. solium |
question
| What part of the tapeworms break off and are released along with numerous eggs? |
answer
| Terminal proglottids |
question
| What does the tapeworm look like? |
answer
| up to 10 meters long composed of: Scolex - head with sucking parts Proglottids - segments of branched uteri that produce thousands of eggs |
question
| What stage of T. solium can produce cysts in various tissues causeing symptomatic disease? |
answer
| Larval stage |
question
| What Tapeworm is the smallest? |
answer
| Echinococcus granulosus |
question
| What type of worm forms cysts in many tissues that grows slowly over time? |
answer
| Echinococcus granulosus |
question
| What can happen if a cyst formed by Echinococcus ruptures? |
answer
| anaphylaxis, immediate cytokine storm |
question
| Where are animal are adult Echinococcus present? |
answer
| GI tract of dogs (sheep herding dogs) |
question
| How are dogs infected with Echinococcus? |
answer
| by ingesting infected sheep |
question
| What animal is the intermediate host of Echinococcus? Definitive Host? |
answer
| Intermediate - sheep, goats, swine Definitive - Dogs, other carnivores |
question
| What organism multiplies by binary fission in the female genital tract and is transmitted by sexual contact? |
answer
| T. Vaginalis |
question
| What form is T. Vaginalis in vaginal and prostatic secretions and urine? |
answer
| Trophozoite |
question
| At what point is T. Vaginalis in its diagnostic stage? |
answer
| Trophozoite in vaginal and prostatic secretions and urine |
question
| When is is T. Vabinalis in the infective stage? |
answer
| when the Trophozoite is in the vagina or orifice of urethra |
question
| What protozoan is a trophozoite, a single nucleus, undulating membrane, symetrical axostyle, with 4 flagella? |
answer
| Trichomonas vaginalis |
question
| What protozoa produces a pH >4.5 with copious, frothy discharge in women? |
answer
| Trichomonas vaginalis (asymptomatic in men) |
question
| What protozoa causes vaginal epithelium and "strawberry cervix"? |
answer
| Trichomonas vaginalis |
question
| How is Trichomonas vaginalis Diagnosed and treated? |
answer
| Trophozoites in discharge - PCR Metronidazole (Safe Sex Practices-prophylactic) |
question
| What type of protozoa can cause extra-intestinal abscesses containing "anchoby paste" aspirate? |
answer
| Entameba histolytica |
question
| What is the life cycle of E. histolytica? |
answer
| Mature cysts ingested -> Excystation in sm intestine -> trophozoites migrate to Lg intestine -> produce cysts -> pass in feces |
question
| What 3 types of disease can E. histolytica cause? |
answer
| Asymptomatic infection Intestinal Disease Extra-intestinal abscesses |
question
| What protozoa is a trophozoite in its active form that has a single nucleus, often contains ingested RBCs? |
answer
| E. histolytica |
question
| What protozoa is a major cause of amebic dysentary? |
answer
| Entameba histolytica |
question
| What are the signs and symptoms of the acute and chronic infections of Entameba histolytica? |
answer
| Acute - dysentery with abdominal pain Chronic - recurrent episodes with blood and mucus in feces -> can disseminate to liver, lung, brain - form abscesses |
question
| What protozoa causes flask-shaped ulcers in the large intestines? |
answer
| Entameba histolytica |
question
| What is the treatment for E. histolytica symptomatic and asymptomatic? |
answer
| symptomatic - metronidazole asymptomatic & eradication - iodoquinol |
question
| What part of the intestines do E. histolytica preferentially adhere to? |
answer
| elevated interglandular epithelium |
question
| What is the recommended treatment for Primary Amebic Meningoencephalitis? |
answer
| Amphotericin B |
question
| What protozoa can cause PAM? |
answer
| Naegleria fowleri |
question
| How is Naegleria fowleri ingested? |
answer
| through olfactory neuroepithelium |
question
| What forms of Naegleria fowleri are found in the CSF and Tissues? |
answer
| Trophozoites -> CSF and Tissues Flagellated forms -> CSF |
question
| How does Acanthamoeba and Balamuthia mandrillaris enter the body? |
answer
| Lower respiratory tract or ulcerate or broken skin |
question
| What can Acanthamoeba and Balamuthia mandrillaris cause in immune compromised individuals? |
answer
| Granulomatous amebic encephalitis |
question
| How do Acanthamoeba eye infections start? |
answer
| improper lens handling and poor hygiene |
question
| What protazoa should be suspected in chronic keratitis that does not respond to treatment? |
answer
| Acanthamoeba keratitis |
question
| Why is treatment of Acanthamoeba Keratitis difficult to treat? |
answer
| organism's ability to encyst with the use of topical medications |
question
| What is the life cycle of Giardia intestinalis? |
answer
| ingest cysts in contaminated water/food -> Trophozoites multiply by binary fission in small bowel -> Encystation occurs as moves toward colon -> excreted in feces |
question
| What is the most common protozoan intestinal disease in US? |
answer
| Giardia intestinalis |
question
| What protozoa is a Trophozoite with 2 nuclei, bilaterl symmetry of axostyles and suction discs, and flagella? |
answer
| Giardia intestinalis |
question
| What protozoa can cause uncontrolled flatulence, abdominal distension, foul-smelling, bulky diarrhea, but rarely with blood or necrotic tissue? |
answer
| Giardia intestinalis |
question
| What can Giardia do that may lead to malabsorption of nutrients? |
answer
| Trophozoites cover and flatten intestinal epithelium |
question
| What does increased incidence of Giardia infection in immunocompromised suggest? |
answer
| Some Protective Immunity |
question
| What is the Treatment for Giardia? |
answer
| Metronidazole |
question
| What protozoa outbreaks are associated with water parks, swimming pools, and reservoir sources? |
answer
| Cryptosporidium hominis |
question
| What protozoa is ingested as an oocyst, releases sporozoites, differentiate into male or female merozoites, then fuse to form a zygote? |
answer
| Cryptosporidium hominis |
question
| Where do Cryptosporidium hominis sporozoites infect? |
answer
| gastric epithelial cells |
question
| What occurs within the walled zygote of cryptosporidium hominis that results in oocysts containing sporozoites? |
answer
| Reduction division |
question
| What protozoa is associated with community acquired diarrheal disease? |
answer
| Cryptosporidium hominis |
question
| How is community acquired diarrheal disease treated? (Cryptosporidium hominis) |
answer
| Nitazoxanide |
question
| How is community acquired diarrheal disease treated? (Cryptosporidium hominis) |
answer
| Nitazoxanide |
question
| What protozoa infects humans by the Tsetse fly? |
answer
| Trypanosoma brucei (sleeping sickness - African Trypanosomiasis) |
question
| Once the metacyclic trypomastigotes is injected into the blood stream, what is the cycle of T. brucei in the human? |
answer
| transforms into trypomastigotes in blood -> carried to other sites -> multiply by binary fission in body fluids |
question
| How does T. Brucei transmit to others? |
answer
| Tsetse fly takes trypomastigotes from infected persons blood -> transforms into procyclic trypomastigotes in fly's gut -> multiply by binary fission -> leave flys midgut -> transform into epimastigotes -> multiply in fly salivary gland -> transform into metacyclic trypomastigotes -> infects when fly bites |
question
| What type of T. Brucei is in West Africa? East Africa? |
answer
| West -> gambiense East -> rhodesiense |
question
| What are the symptoms of T. brucei? (sleeping sickness) |
answer
| Bite reaction - chancre Parasitemia - Fever CNS - coma and death |
question
| Which form of T brucei progresses more rapidly? |
answer
| East African - rhodesiense |
question
| How is T. brucei treated in the blood and CNS stages? |
answer
| Blood Stage - pentamidine CNS Stage - Melarsoprol |
question
| What protozoa causes Chaga's disease? |
answer
| Trypanosoma cruzi |
question
| What two forms does T. cruzi take morphologically? |
answer
| Blood - trypomastigote Tissue - amastigote |
question
| Where is the primary lesion of Chaga's disease usually found? |
answer
| on Face Ramana's sign |
question
| How does Chaga's disease progress? |
answer
| Acute stage - non-specific - fever, rash, Parasitemia and lymphocytosis Chronic Stage - involves heart, esophagus, and colon |
question
| What can T cruzi cause by directly damaging infected cells? |
answer
| destruction to autonomic nerve ganglia -> cardiomegaly, megaesophagus, megacolon |
question
| How does T cruzi multiply? |
answer
| binary fussion in cells of infeted tissues |
question
| How is T cruzi transmitted? |
answer
| Triatomine Bug Bite |
question
| Where are the Triatomine bug and Chaga's disease found? |
answer
| Central and South America |
question
| What protozoa is associated with the Sandfly? Where is it found? |
answer
| Leishmaniasis Asia, India, Mediterranean, N. and Central Africa, S. and Central America |
question
| How does Leishmaniasis progress in the human once the sandfly injects the promastigote stage into the skin? |
answer
| Phagocytized by macrophages -> transform into amastigotes inside macro -> multiply in cells |
question
| What are the symptoms of Leishmaniasis, Visceral, Mucocutaneous, and Cutaneous? |
answer
| Visceral - organisms multiply in phagocytes of spleen, liver, nodes. Hyperpigmented skin, Superinfection Mucocutaneous - organisms in skin metastasize to mucoid tissue -> severe deformity Cutaneous - ulcer develops at site of lesion |
question
| How is Leishmaniasis treated? |
answer
| Pentostam (antimonial) |
question
| What protozoa are found in Feces of cats? |
answer
| Toxoplasma gondii |
question
| What can infection of toxoplasma gondii cause in a fetus? |
answer
| Hydrocephalus, generalized lymphadenopathy, hepatosplenomegaly |
question
| What is the morphology of Toxoplasmosis in the definitive and intermediate hosts? |
answer
| Difinitive - Cat - Inracellular replication Intermediate - Pseudocysts form |
question
| What are the Human stages of the sporozoites that cause malaria? |
answer
| invade liver -> grow by schizogony -> produce merozoites -> infect RBC -> Trophozoites replicate by schizogony -> produce merozoites -> infect new RBC -> Repeat |
question
| What protozoa are associated with mosquito bites? |
answer
| Plasmodium, vivax & ovale, malariae |
question
| What does release of merozoites do in malaria? |
answer
| overstimulates innate immunity, loss of RBCs |
question
| How is Malaria treated? |
answer
| Quinine derivatives - RBC stage Primaquine - Liver stage |
question
| What are the symptoms of malaria? |
answer
| Parasitemia increases -> headache, pains, chilly sensation, fever Fever and Chills become prominent and cyclic Falciparum modify infected RBC -> become sticky for endothelium -> capillary blockage and cerebral malaria |
question
| When do the paroxysm symptoms occur in the different forms of malaria? |
answer
| 48 hrs - vivax, ovale, falciparum 72 hrs - malariae |
