Which parasite is associated with foul-smelling, fatty diarrhea and is commonly seen in campers and hikers, with a distinct trophozoite shape?

Which parasite is associated with foul-smelling, fatty diarrhea and is commonly seen in campers and hikers, with a distinct trophozoite shape?

• A. Entamoeba histolytica
• B. Giardia lamblia
• C. Cryptosporidium
• D. Trichinella spiralis

Answer: (B)

Giardia lamblia is a flagellated protozoan that causes fatty, foul-smelling diarrhea by inflaming and blunting the absorptive surface of the small intestine, leading to fat malabsorption. It’s classically acquired by drinking untreated water from streams or outdoorsy settings, which is why campers and hikers are often affected. A hallmark feature is the distinct appearance of its trophozoite form. The trophozoite is pear- or teardrop-shaped and has two nuclei, giving a “face-like” look, along with multiple flagella. It attaches to the intestinal mucosa with a ventral adhesive disc, which disrupts normal absorption and leads to greasy stools. Diagnosis is typically via stool antigen testing or finding cysts or trophozoites in stool, and treatment usually involves a nitroimidazole such as metronidazole or tinidazole. Other parasites listed would present differently: for example, Entamoeba histolytica often causes bloody diarrhea and liver abscesses; Cryptosporidium causes watery diarrhea, especially in immunocompromised patients; Trichinella spiralis is acquired from undercooked meat and migrates to muscle.

Giardia lamblia is a flagellated protozoan that causes fatty, foul-smelling diarrhea by inflaming and blunting the absorptive surface of the small intestine, leading to fat malabsorption. It’s classically acquired by drinking untreated water from streams or outdoorsy settings, which is why campers and hikers are often affected.

A hallmark feature is the distinct appearance of its trophozoite form. The trophozoite is pear- or teardrop-shaped and has two nuclei, giving a “face-like” look, along with multiple flagella. It attaches to the intestinal mucosa with a ventral adhesive disc, which disrupts normal absorption and leads to greasy stools.

Diagnosis is typically via stool antigen testing or finding cysts or trophozoites in stool, and treatment usually involves a nitroimidazole such as metronidazole or tinidazole.

Other parasites listed would present differently: for example, Entamoeba histolytica often causes bloody diarrhea and liver abscesses; Cryptosporidium causes watery diarrhea, especially in immunocompromised patients; Trichinella spiralis is acquired from undercooked meat and migrates to muscle.