Which organism causes Toxoplasmosis?

• A. Toxoplasma gondii
• B. Entamoeba histolytica
• C. Giardia lamblia
• D. Candida albicans

Answer: (A)

Toxoplasma gondii is the organism that causes toxoplasmosis. It is an intracellular protozoan parasite (an apicomplexan) with a life cycle that often involves cats as the definitive host and many warm-blooded animals, including humans, as intermediate hosts. Humans typically acquire infection by eating undercooked meat containing tissue cysts or by ingesting oocysts from cat feces, and it can be transmitted from mother to fetus during pregnancy. In healthy individuals the infection is often asymptomatic, but it can cause ocular disease when reactivated in the eye, leading to focal retinochoroiditis and potential vision loss. In immunocompromised people, reactivation can cause severe brain inflammation (toxoplasmic encephalitis). The other organisms listed cause different infections: Entamoeba histolytica causes amebic dysentery, Giardia lamblia causes giardiasis, and Candida albicans causes candidiasis.