Part VI: Parasitology
Regarding Entamoeba histolytica, which one of the following is most accurate?
(A) Entamoeba histolytica causes “flask-shaped” ulcerations in the colon mucosa.
(B) Domestic animals such as dogs and cats are the main reservoir of E. histolytica.
(C) In the microscope, E. histolytica is recognized by having two sets of paired flagella.
(D) Entamoeba histolytica infections are limited to the intestinal mucosa and do not spread to other organs.
(E) The infection is typically acquired by the ingestion of the trophozoite in contaminated food and water.
Regarding Giardia lamblia, which one of the following is most accurate?
(A) The drug of choice for giardiasis is chloroquine.
(B) In giardiasis, ova and parasite (O&P) analysis of the stool reveals sporozoites in the feces.
(C) Giardia lamblia produces an enterotoxin that increases cyclic AMP within the enterocyte, resulting in diarrhea.
(D) Giardia lamblia infection is acquired by ingestion of food or water contaminated with human feces only (i.e., there is no animal reservoir for this organism).
(E) Infection by G. lamblia occurs principally in the small intestine, frequently resulting in the malabsorption of fat and foul-smelling, frothy, fat-containing stools.
Regarding Cryptosporidium hominis, which one of the following is most accurate?
(A) Humans are the only reservoir for C. hominis.
(B) Microscopic examination of the diarrheal stool reveals both red cells and white cells.
(C) Laboratory diagnosis involves seeing cysts of the organism in an acid-fast stain of the stool.
(D) Cryptosporidium hominis is typically acquired by the ingestion of trophozoites in contaminated food or water.
(E) In immunocompromised patients, such as AIDS patients with a very low CD4 count, disseminated disease occurs that typically involves the brain and meninges.
Regarding Trichomonas vaginalis, which one of the following is most accurate?
(A) The drug of choice for trichomoniasis is metronidazole.
(B) Domestic animals, such as dogs and cats, are the principal reservoir of the organism.
(C) Trichomonas vaginalis is typically acquired by contact with the cysts of the organism during sexual intercourse.