Everybody has a promiscuous friend, but don’t blame them for their polygamous ways – they may just be harbouring a parasite.
Toxoplasma gondii is a parasite of domestic cats, which is also thought to affect 40% of humans, and is often transmitted by accidental consumption of eggs found in cats’ faeces. It causes the disease toxoplasmosis, which has flu-like symptoms and in severe cases can cause organ damage. These are some of the parasite’s least attractive features, but research indicates that the disease caused by the parasite can have some interesting effects on human behaviour.
Researchers in the Czech Republic have found that female sufferers of the disease can have a variety of behavioural changes, including higher intelligence, increased confidence and higher sexual promiscuity. There is also evidence that women carrying the parasite are considered more attractive by the opposite sex. By contrast, male sufferers show increased jealousy, shorter attention spans, lower IQ scores and tend to be more inclined to take risks. They also appear to be less attractive to women than non-sufferers.
These behavioural traits may seem a little whimsical, but are supported by research in other animals. Mice suffering from toxoplasmosis are also more likely to take risks which could lead to them being eaten by cats; this would be beneficial to the parasite, enabling it to parasitize its main host, the cat. Similarly, a sexually promiscuous woman has an increased chance of pregnancy and therefore transmission of the parasite to the next generation.
Toxoplasmosis has also been linked to the increased occurrence of schizophrenia, and the increased risk of traffic accidents. Research concerning the effects on human behaviour is on-going so we can only await news of more bizarre side effects.