Toxoplasmodi gondii is a parasitic protozoa who's primary host is cats but also infects other mammals, primarily mice and rats but including humans, as part of its life cycle. Infection by Toxoplasmodi gondii is called Toxoplasmosis and may be acute (flu like symptoms) or latent.
Toxoplasmosis is extremely common. Worldwide, about 30% (US 11%; France 88%!) of people about of people have Toxoplasmosis.
It has been found that the parasite has the ability to change the behaviour of its host: infected rats and mice are less fearful of cats—in fact, some of the infected rats seek out cat-urine-marked areas. This effect is advantageous to the parasite, which is able proliferate if a cat eats the infected rat and thereby becomes a carrier.
Observational studies suggest that latent Toxoplasmosis may also cause behavioral changes in humans (source paper). The observed differences between infected people and non-infected people include:
Decreased novelty seeking behavior
Slower reactions
Lower rule-consciousness and greater jealousy (in men)
Greater warmth, conscientiousness and moralistic behavior (in women)
Obviously some or all these may be due to unobserved 3rd causes.
There haven't been any randomized studies yet, as far as I know. It seems like such studies would be easy to conduct rigorously since a high fraction of the population is already infected. For example, by finding people who are already infected and randomly cure some of them. This kind of experiment is even pretty close to how you would expect the information to be used.
I've been around cats a fair amount and the base rate is high in the US, so my chances of having latent Toxoplasmosis seem fairly high. Thus I am curious whether this is worth doing something about. Diagnosis sounds like it is fairly simple (PCR on blood samples). It's easy enough so that it can be done in large scale studies at least. Treatment is done with atovaquone and clindamycin, which appear to be relatively inexpensive.
I'd expect the effects to be net negatives (most random changes are detrimental) and even if the behavioral effects are smallish, the effects over a lifetime will add up. Has anyone else gotten tested and/or treated for latent Toxoplasmosis? Is it worth it?
Might not be so bad after all. (Personal hypothesis : however the trial was only made in New Zealand, so the parasite might not be exactly the same that in other parts of the world . I'm also wondering if the opposite effect on males and females could cancel each other out on a large scale study.)
Before reading this article, I was thinking of an "animal urine blind test" as a prediagnosis. An absence of disgust for cat urine could mean you're likely to be infected (however, in this article, the monkey were the natural prey of Leopard whereas humans in western regions are obviously not cat's preys). What do you think of it ? Any testimonies from people who know whether they are infected or not ? (I realize it's not very useful, because there is no good way to get rid of Latent Toxoplasmis and because it's probably not a very big deal. I wanted to do this mostly out of curiosity and my main interest is to know whether it could be a real instrument of diagnosis)
Toxoplasmodi gondii is a parasitic protozoa who's primary host is cats but also infects other mammals, primarily mice and rats but including humans, as part of its life cycle. Infection by Toxoplasmodi gondii is called Toxoplasmosis and may be acute (flu like symptoms) or latent.
Toxoplasmosis is extremely common. Worldwide, about 30% (US 11%; France 88%!) of people about of people have Toxoplasmosis.
Toxoplasmosis is known to cause behavioral changes in rats:
Observational studies suggest that latent Toxoplasmosis may also cause behavioral changes in humans (source paper). The observed differences between infected people and non-infected people include: