Question 1

Which of the following parasites is able to cause nosocomial infections if &#34;enteric precautions&#34; are not maintained for patients with severe diarrhea?&#10;A) Cryptosporidium parvum&#10;B) Enterobius vermicularis&#10;C) Giardia lamblia&#10;D) Cystoisospora belli

Accepted Answer

C. parvum öocysts are immediately infective when passed, whereas those of I. belli are not.

Question 2

An AIDS patient suffering with chronic diarrhea was tested for intestinal parasites. Among the testing procedures was an acid-fast stain on a direct fecal smear. The smear revealed red-stained, round structures measuring 4 µm in diameter. The most likely parasite is:

A) Blastocystis hominis
B) Cryptosporidium parvum
C) Cyclospora spp.
D) Microsporidia

Cryptosporidium parvum

Accepted Answer

An acid-fast stain is used to stain C. parvum. This parasite is often characterized by its size. Note: Cyclospora spp. are 8 to 10 µm in size and microsporidia are 1 µm in size.

Question 3

Local city water supplies have been sources of parasitic infections. The most common organisms implicated in these events include:&#10;A) Cryptosporidium parvum and Giardia lamblia&#10;B) Diphyllobothrium fragilis and Entamoeba histolytica&#10;C) Giardia lamblia and Cystoisospora (Isospora) belli&#10;D) Cystoisospora belli and Entamoeba histolytica

Accepted Answer

C. parvum and G. lamblia have caused several waterborne infections.

Question 4

Outbreaks of diarrhea have been caused by a parasite that has been associated with raspberries, strawberries, herbs, and baby lettuces. The most likely parasite is:&#10;A) Cryptosporidium parvum&#10;B) Cyclospora cayetanensis&#10;C) Giardia lamblia&#10;D) Cystoisospora belli

Accepted Answer

Diarrheal outbreaks of Cyclospora cayetanensis have been associated with improperly washed berries and mesclun lettuces.

Question 5

A fecal smear was stained using acid-fast reagents. Examination of the smear revealed round, red forms measuring 8 to 10 &#181;m in diameter. The most likely parasite is:&#10;A) Microsporidium spp.&#10;B) Cystoisospora belli&#10;C) Cyclospora spp.&#10;D) Cryptosporidium parvum

Accepted Answer

Acid-fast stain is used to stain Cyclospora spp., which are 8 to 10 µm in size. Note: C. parvum is 4 µm, I. belli is 30 µm x 12 µm, and microsporidia are 1 µm in size.

Question 6

The malaria parasite species characterized by a single ameboid trophozoite and surrounded by red-stained Sch&#252;ffner's dots is:&#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

Plasmodium vivax infections are characterized by a single ameboid trophozoite that is surrounded by red-stained Schüffner's dots. Other characteristic findings include a schizont containing 12 to 24 merozoites and a round gametocyte.

Question 7

The malaria parasite species characterized by a crescent-shaped gametocyte is:&#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

Plasmodium falciparum infections are characterized by the appearance of a crescent-shaped gametocyte in the RBC. Other characteristic findings include the presence of multiple small-ring trophozoites in a single red cell.

Question 8

The malaria parasite species characterized by a schizont containing 8 to 12 merozoites is:&#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

Plasmodium malariae infections are characterized by the appearance of a schizont containing 8 to 12 merozoites in the RBC. Other characteristic findings include a single- ring trophozoite without Schüffner's dots and an ovoid gametocyte.

Question 9

Massive hemolysis leading to blackwater fever is a characteristic clinical finding for which of the following parasites?&#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

Plasmodium falciparum causes blackwater fever by causing the massive destruction of red blood cells. The elimination of massive amounts of hemoglobin leads to dark-colored (blackwater) urine and renal failure. CNS symptoms occur when RBCs clump and block capillaries in the brain.

Question 10

Plasmodium vivax and Plasmodium ovale are similar for all of the following EXCEPT both:&#10;A) Can cause true relapses&#10;B) Have Sch&#252;ffner's dots&#10;C) Preferentially invade reticulocytes&#10;D) Have only single-ring forms

Accepted Answer

Only P. vivax invades reticulocytes; therefore, using a reticulocyte counterstain may aid identification of this parasite.

Question 11

Babesia spp. infections may be confused with which other parasite?&#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

The answer of Babesia spp. infections may be confused with...

Question 12

Which of the sporozoa is considered to be indigenous to the United States?&#10;A) Babesia microti&#10;B) Plasmodium falciparum&#10;C) Plasmodium malariae&#10;D) Plasmodium vivax

Accepted Answer

The answer of Which of the sporozoa is considered to...

Question 13

The infective stage for Toxoplasma gondii in humans is the:&#10;A) Merozoite&#10;B) &#214;ocyst&#10;C) Sarcocyst&#10;D) Sporozoite

Accepted Answer

The answer of The infective stage for Toxoplasma gondii in...

Question 14

Name the parasite shown in the following image:  &#10;A) Babesia microti&#10;B) Plasmodium falciparum&#10;C) Plasmodium malariae&#10;D) Plasmodium vivax

Accepted Answer

The answer of Name the parasite shown in the following...

Question 15

Name the parasite shown in the following image:  &#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

The answer of Name the parasite shown in the following...

Question 16

Name the parasite shown in the following image:  &#10;A) Plasmodium falciparum&#10;B) Plasmodium malariae&#10;C) Plasmodium ovale&#10;D) Plasmodium vivax

Accepted Answer

The answer of Name the parasite shown in the following...

Deck 6: Protozoa: Sporozoa