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Comment by colechristensen | Hacker News Reader

A third of the entire human population is infected with toxoplasmosis, in some places nearly every human.

If you put humans in a sterile bubble you get a different set of diseases, to a considerably greater degree because your immune system evolved in an environment where you actually got infections.

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> A third of the entire human population is infected with toxoplasmosis, in some places nearly every human.

So if it is often harmful to some extent in people who do not show severe symptoms, then it is a terrible disease that causes widespread harm. There is evidence it causes lesser, but possibly significant harm, in far more people than is generally recognised:

https://pmc.ncbi.nlm.nih.gov/articles/PMC2526142/

By that logic, we shouldn't be fighting malaria in Africa either.

Are there any benefits to toxoplasmosis besides some people finding the vector cute? The alternative isn't living in a sterile bubble.

Without infections your immune system gets bored and starts attacking you. You need to have something for your immune system to do on a regular basis. Toxo is to a very large degree asymptomatic. You are full of and covered with organisms. Being paranoid about infection isn't helpful to anyone. Ok you don't like cats, that's fine, but are you as passionate about rare steak which is a much more common vector?

Malaria... is not asymptomatic.

You will have plenty of exposure to microbes simply by existing outside of a sealed sterile chamber, and microbes != pathogens. There's no need to encourage exposure to and infection by pathogens, and this idea often results in increased risk or severity of disease. See: "chickenpox party" intentional exposure of children to varicella, putting them at risk of shingles as adults, with the risk increasing the younger they are at the time of infection.

https://en.wikipedia.org/wiki/Hygiene_hypothesis?useskin=vec...

>There's no need to encourage exposure to and infection by pathogens, and this idea often results in increased risk or severity of disease.

Here's research into intentional infection with a parasite to treat autoimmune diseases

https://pmc.ncbi.nlm.nih.gov/articles/PMC5401880/

https://en.wikipedia.org/wiki/Old_Friends_hypothesis

That's not a great comparison. Malaria is dangerous to almost everyone it infects, while T. gondii is harmless to the vast majority of the human race.

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