Microbiology Quiz: Parasitology Overview

A patient is diagnosed with taeniasis after a segment of a tapeworm is found in their stool. The physician is concerned about the potential for neurocysticercosis. Which laboratory finding would most strongly support that the patient or their close contacts are at risk for this complication?

A pregnant woman is counseled on preventing toxoplasmosis. Her obstetrician explains that the parasite, Toxoplasma gondii, can be acquired from undercooked meat or contact with cat feces containing oocysts. In the context of the parasite's life cycle, what is the biological role of the domestic cat?

A patient from a filariasis-endemic region presents with chronic, progressive lymphedema of the lower extremities, consistent with elephantiasis. This condition is a late sequela of infection with Wuchereria bancrofti. The diagnostic stage for this parasite is typically identified by which method?

A patient who frequently consumes raw freshwater fish as part of their diet presents with right upper quadrant pain, jaundice, and fever. An endoscopic retrograde cholangiopancreatography (ERCP) reveals the presence of adult flukes within the biliary ducts. This clinical scenario is most consistent with an infection by which of the following trematodes?

Autoinfection can lead to a massive increase in parasite burden without re-exposure to an external infective source, resulting in a hyperinfection syndrome that can be fatal in immunocompromised individuals. Which of the following parasites is most clinically significant for this capability?

Both Trypanosoma brucei (causing African sleeping sickness) and Trypanosoma cruzi (causing Chagas disease) are hemoflagellates that cause significant human disease. A key difference in their life cycles that profoundly impacts their pathogenesis and diagnosis is that:

A child in a rural, resource-poor community presents with chronic fatigue, pallor, and poor cognitive development. A complete blood count reveals microcytic, hypochromic anemia. Given this clinical picture, the parasite most likely responsible has a life cycle that involves which of the following steps?

A mother brings her 5-year-old child to the pediatrician due to several nights of restlessness and intense perianal itching. The physician suspects an infection with Enterobius vermicularis. Which diagnostic approach has the highest yield for confirming this infection?

A stool sample from a patient with bloody diarrhea is examined, and amoebic trophozoites are identified using a Trichrome stain. To confirm a diagnosis of invasive amebiasis caused by Entamoeba histolytica and rule out colonization by the non-pathogenic commensal Entamoeba dispar, which morphological feature is the most definitive?

A veterinarian presents with a prolonged history of fever, hepatomegaly, and a complete blood count showing marked eosinophilia. The patient reports no international travel but has frequent contact with puppies at their clinic. This condition, known as visceral larva migrans, is most likely the result of accidentally ingesting the eggs of which parasite?

A soldier returning from deployment in the Middle East presents with a large, chronic, non-healing ulcer with raised borders on his forearm. A biopsy is taken from the margin of the lesion. Microscopic examination of a Giemsa-stained smear of the tissue is performed. Which finding would confirm the diagnosis of cutaneous leishmaniasis?

An immunocompromised patient with AIDS presents with severe, chronic, watery diarrhea. A standard stool ova and parasite (O&P) examination using trichrome stain is negative. Given the high clinical suspicion for cryptosporidiosis, which diagnostic technique should be performed next for confirmation?

A 24-year-old female presents with a malodorous, frothy yellow-green vaginal discharge and vulvar irritation. A saline wet mount preparation of the vaginal fluid is examined. Which finding is most consistent with a diagnosis of trichomoniasis?

A pregnant woman is counseled on preventing toxoplasmosis. Her obstetrician explains that the parasite, Toxoplasma gondii, can be acquired from undercooked meat or contact with cat feces containing oocysts. In the context of the parasite's life cycle, what is the biological role of the domestic cat?

A patient is diagnosed with taeniasis after a segment of a tapeworm is found in their stool. The physician is concerned about the potential for neurocysticercosis. Which laboratory finding would most strongly support that the patient or their close contacts are at risk for this complication?

A stool sample from a patient with bloody diarrhea is examined, and amoebic trophozoites are identified using a Trichrome stain. To confirm a diagnosis of invasive amebiasis caused by Entamoeba histolytica and rule out colonization by the non-pathogenic commensal Entamoeba dispar, which morphological feature is the most definitive?

Autoinfection can lead to a massive increase in parasite burden without re-exposure to an external infective source, resulting in a hyperinfection syndrome that can be fatal in immunocompromised individuals. Which of the following parasites is most clinically significant for this capability?

A veterinarian presents with a prolonged history of fever, hepatomegaly, and a complete blood count showing marked eosinophilia. The patient reports no international travel but has frequent contact with puppies at their clinic. This condition, known as visceral larva migrans, is most likely the result of accidentally ingesting the eggs of which parasite?

A mother brings her 5-year-old child to the pediatrician due to several nights of restlessness and intense perianal itching. The physician suspects an infection with Enterobius vermicularis. Which diagnostic approach has the highest yield for confirming this infection?

A microbiology course is reviewing the major groups of eukaryotic pathogens. A student is asked to correctly classify several organisms. Which of the following is correctly classified as a helminth?