Which infection poses a high risk to seronegative pregnant women and immunocompromised individuals, with cats as definitive hosts?

• A. Toxoplasmosis
• B. Toxocariasis
• C. Feline Leukemia Virus
• D. Sarcocystis neurona

Answer: (A)

Exposure to Toxoplasma gondii through cats as the definitive hosts creates a risk profile that fits seronegative pregnant women and immunocompromised individuals. Cats shed oocysts in their feces, which can contaminate soil, water, or litter. People typically become infected by handling contaminated material or eating undercooked meat containing tissue cysts. For a pregnant woman who has not been exposed before, a primary infection can cross the placenta and cause congenital toxoplasmosis, potentially harming the fetus with brain or eye involvement. In immunocompromised individuals, latent infection can reactivate or a new infection can cause severe disease, such as encephalitis. Other listed infections involve different hosts or do not pose the same pregnancy- and immunity-related risks: Toxocariasis involves roundworms with dogs or cats but humans are incidental hosts and it’s not a major pregnancy risk; Feline Leukemia Virus is a cat-specific virus with no human health risk; Sarcocystis neurona life cycle and human relevance are not centered on cats as definitive hosts or on pregnancy/immunity concerns.