Question 1

Which of the following best describes the difference between the trophozoite and cyst forms of intestinal protozoa?

Accepted Answer

Trophozoites are the feeding and reproducing form within the host; cysts are the infective form that survives in the environment.

Question 2

A patient presents with severe diarrhea, colitis, and ulceration of the intestinal mucosa after traveling to a developing country. Which protozoan is most likely responsible?

Accepted Answer

Entamoeba histolytica

Question 3

Which of the following is the most effective method to prevent Cryptosporidium parvum infection from drinking water?

Accepted Answer

Filtration of drinking water to remove oocysts

Question 4

A laboratory technician is examining a stool sample and identifies ciliated trophozoites. Which organism is most likely present?

Accepted Answer

Balantidium coli

Question 5

Which of the following protozoa is most commonly associated with outbreaks linked to imported raspberries?

Accepted Answer

Cyclospora cayetanensis

Question 6

A patient with AIDS develops severe, chronic diarrhea. Which protozoan infection is most likely and serves as an indicator of AIDS?

Accepted Answer

Cryptosporidium parvum

Question 7

Which of the following is the recommended treatment for symptomatic toxoplasmosis?

Accepted Answer

Pyrimethamine plus sulfadiazine or clindamycin

Question 8

Acanthamoeba and Naegleria are most commonly acquired through which route?

Accepted Answer

Inhalation of contaminated water or dust

Question 9

Which of the following statements about Trichomonas vaginalis is correct?

Accepted Answer

It causes symptomatic infection primarily in women.

Question 10

A pregnant woman is advised to avoid cleaning cat litter boxes to prevent infection by which protozoan?

Accepted Answer

Toxoplasma gondii

Question 11

Which of the following best explains why Balantidium coli infections are rare in healthy adults?

Accepted Answer

The normal microbiota of the digestive tract inhibits colonization by Balantidium coli.

Question 12

Which diagnostic method is most commonly used for detecting Toxoplasma gondii infection?

Accepted Answer

Serology

Question 13

A patient presents with watery diarrhea, myalgia, and fever after eating imported fruit. Which protozoan is most likely responsible?

Accepted Answer

Cyclospora cayetanensis

Question 14

Which of the following protozoa is diagnosed by the presence of trophozoites in vaginal or urethral secretions?

Accepted Answer

Trichomonas vaginalis

Question 15

Which of the following is a common reservoir for Toxoplasma gondii?

Accepted Answer

Cats

Question 16

Which of the following protozoa is most likely to cause keratitis in contact lens wearers exposed to contaminated water?

Accepted Answer

Acanthamoeba

Question 17

Which of the following is the only ciliate known to cause disease in humans?

Accepted Answer

Balantidium coli

Question 18

A patient develops hemorrhage, coma, and dies after swimming in a warm freshwater lake. Which protozoan is most likely responsible?

Accepted Answer

Naegleria

Question 19

Which of the following best describes the transmission route for Giardia intestinalis?

Accepted Answer

Ingestion of cysts in contaminated food, water, or hands

Question 20

Which of the following drugs is used to treat Balantidium coli infections?

Accepted Answer

Tetracycline

Parasitic Protozoa of Humans: Morphology, Life Cycles, and Clinical Significance

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