Toxoplasmosis is caused by an obligate intracellular protozoan parasite Toxoplasma gondii. This parasite is very common in cat faeces, raw meat, raw vegetables and soil. While the parasite generally replicates in its definitive host, the cat, it is an opportunistic parasite of many other hosts including humans.
Humans infected with T. gondii are generally asymptomatic carriers, but factors such as age and immunocompetence can determine whether an infected host will express disease symptoms. Infection of a pregnant woman can result in abortion or congenital malformation of the foetus, while newborns are also particularly vulnerable. Infection may be acquired through the consumption of undercooked meat, food or water contaminated with cat faeces, or from handling contaminated soil or cat litter trays.