A parasite called Toxoplasma gondii gets into rats, and makes them utterly fearless around cats. This is as disastrous for the rats as might be expected. The parasite can also spread to humans, and while the consequences aren’t nearly as dire, it is still harmful. In fact, the same mechanism that causes infected rats to walk right into the feline jaws of death produces risk-taking behavior in people. The rat risk taking is actually how the disease spreads; the parasite is spread through cat waste. If you have cats, toxo lurks in the litter box; if you don’t, feral cats are probably leaving it in your garden. Unwashed fruits and vegetables that have come into contact with cat feces can also be vectors.
The good news is that the parasite is more common—it’s estimated to infect one in three people—than the actual disease. In people with healthy immune symptoms, it’s largely asymptomatic. At risk are people with compromised immune systems due to diseases such as AIDS or to immune-suppressant medications, children, and pregnant women and fetuses. If a woman becomes infected while pregnant, the parasite can cross the placental barrier. When this happens, the baby is often stillborn, or else can develop cerebral palsy, jaundice, seizure disorders, or developmental or cognitive disabilities.
If people get infected as adults, they too may get seizures, or there may be other symptoms. In some people, toxoplasmosis can look like flu, with achiness, swollen lymph nodes, fever, and fatigue. In people with immune problems, toxoplasmosis can cause vision problems, specifically blurry vision, as well as seizures. The parasite also effects the brain. Most often, it stimulates the production of a neurochemical called gamma aminobutyric acid, which suppresses fear and encourages risky behavior. However, there is some evidence that, in people with a genetic predisposition, toxoplasmosis can lead to schizophrenia.
Treating toxoplasmosis is not always necessary, because usually there are no symptoms. When treatment is needed, anti-malarial medication is administered. Malaria, like toxoplasmosis, is a parasitic illness, so medications that prevents parasite-caused conditions works on it. Recent research has shown indications that statin drugs, used to fight high cholesterol, in combination with osteoporosis medication, can stop the toxoplasma parasite from infecting people without the side effects of the malaria drugs.