You may be familiar with toxoplasmosis as the reason why pregnant women and HIV-positive people ar exempted from litter box scooping duty.
Toxoplasmosis is also why most cities have banned flushable clumping cat litter, because it is a serious danger to marine mammals like seals and otters. Toxoplasmosis is caused by a protozoan named Toxoplasma gondii, a microscopic parasite which has wide-ranging effects on its host body.
The symptoms of a toxoplasmosis infection are, for most of us, extremely subtle. The acute phase typically presents like a low-grade cold or flu (including fatigue and swollen glands) which lasts about a month. After that, the infection goes into the latent phase, when no normal symptoms are observed.
Up to a third of all people in the world carry the T. gondii parasite. You can get it from contact with infected raw meat, or with infected cat feces. Cats themselves usually pick it up either from their mothers, or by eating infected meat.
The list of other effects of toxoplasmosis is a long and strange list indeed. It includes:
1. Male births.
There is a strong correlation between toxoplasmosis and the probability of having a male baby. This effect is significant: mothers with toxoplasmosis give birth to 260 boys for every 100 girls. Why T. gondii should prefer boys is a complete mystery.
2. Cat love.
Mice and rats which are infected with toxoplasmosis not only lose their fear of cats - they are driven to seek out the smell of cat urine. The benefit to the parasite is obvious: if you have to move from a mouse into a cat as a new host, what better way to accomplish the move than by making the mouse a cat-lover?
But weirdly, this effect has also been observed in people. In one long-range study, people who disliked or were neutral on the topic of cats were surveyed years later. Those who had been infected with toxoplasmosis in the intervening years showed a marked increase in their love for cats, compared to those who didn't have toxoplasmosis.
3. Mental changes.
People infected with toxoplasmosis show a decrease in "novelty seeking behavior," and slower reaction times.
Even weirder? The changes are different for men versus women. Men become more jealous, and pay less heed to rules. Whereas women become more moral, conscientious, and maternal.
It makes sense that a cat would want to infect women with something that makes them more maternal (and therefore more likely to pamper a cat in the manner to which it has become accustomed). But why would cats want men to be more jealous?
4. Car accidents.
People infected with toxoplasmosis are 2.5 times more likely to have a car accident, compared to uninfected people. Could the risky behavior account for this? Perhaps as a side effect of the mechanism that makes mice less wary of cats, people become more likely to run red lights and not wear a seatbelt. It could also be due to the decreased reaction time observed in people with toxoplasmosis.
Photo credit: Flickr/buildscharacter