Which protozoan parasite is commonly found in soil and water and can cause diarrhea?

Which protozoan parasite is commonly found in soil and water and can cause diarrhea?

• A. Bacillus cereus
• B. Anisakis
• C. Toxoplasma gondii
• D. Giardia lamblia

Answer: (D)

Giardia lamblia is a water- and soil-associated protozoan whose cysts survive in the environment and can contaminate drinking water. When people ingest these cysts, the parasite establishes in the small intestine and disrupts absorption, leading to diarrhea, abdominal cramps, and greasy, foul-smelling stools. This environmental link to untreated water makes giardiasis a classic waterborne diarrheal illness, a frequent concern in campers, hikers, and areas with inadequate water treatment. Bacillus cereus is a bacterium tied to food poisoning, not a protozoan. Anisakis is a parasitic nematode acquired from raw or undercooked seafood. Toxoplasma gondii is another protozoan that can be present in soil or water but is more commonly linked to oocyst exposure from cat feces or undercooked meat and does not typically present as a diarrheal illness the way giardiasis does.

Giardia lamblia is a water- and soil-associated protozoan whose cysts survive in the environment and can contaminate drinking water. When people ingest these cysts, the parasite establishes in the small intestine and disrupts absorption, leading to diarrhea, abdominal cramps, and greasy, foul-smelling stools. This environmental link to untreated water makes giardiasis a classic waterborne diarrheal illness, a frequent concern in campers, hikers, and areas with inadequate water treatment.

Bacillus cereus is a bacterium tied to food poisoning, not a protozoan. Anisakis is a parasitic nematode acquired from raw or undercooked seafood. Toxoplasma gondii is another protozoan that can be present in soil or water but is more commonly linked to oocyst exposure from cat feces or undercooked meat and does not typically present as a diarrheal illness the way giardiasis does.