Toxoplasma Gondii

Toxoplasma gondii is a single-celled parasite found worldwide that can infect nearly all warm-blooded animals, though cats are the only host in which it can reproduce sexually, making cats central to its life cycle. In rodents the parasite is known to alter behavior in ways that increase the chance of being caught by a cat, such as reducing a rat's normal avoidance of the smell of cat urine, changes thought to be an evolutionary adaptation that helps the parasite complete its life cycle. Human infection, causing the disease toxoplasmosis, is usually symptomless in healthy adults beyond mild flu-like symptoms, but it poses serious risks to infants and people with weakened immune systems; researchers estimate that as much as half the world population may carry a chronic infection, with rates varying widely by country.