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Mind-altering microbes that play with Mice

Not every cat and mouse game ends with Jerry the mouse winning. And while it is true that a mouse will do everything it can to avoid being eaten by a cat, there exists a microscopic foe that is capable of making mice go against their instincts.

Enter Toxoplasma gondii, a parasite with the ability to infect virtually all warm-blooded animals but capable of sexual reproduction only in organisms belonging to the cat family. It is therefore crucial for this microbe to end up inside a cat and T. gondii has devised a rather remarkable mechanism to ensure this.

T. gondii has been shown to alter the behavior of mice and other rodents in ways that increase their chances of being preyed upon by cats. Studies have revealed that T.gondii infected mice have a decreased aversion to cat urine and therefore do not shy away from areas where cats live. This in turn effects their ability to escape their predators. The parasite is able to accomplish all of this by migrating to a mouse’s brain and altering its natural instinctive behavior through a series of biochemical reactions.

Once inside a cat, T.gondii migrates to its host’s intestine where it undergoes sexual maturity and reproduction, producing millions of cysts. These cysts are shed in the cat’s feces where they may be spread by either water or soil. Here they can remain for several months until they’re ingested by an unsuspecting mouse or any other warm-blooded animal.

T. gondii poses no threat to healthy adults or children, individuals usually recover from infection after showing mild flu-like symptoms. However, the story is different for immune-compromised individuals and pregnant women. In the former, toxoplasmosis can manifest into a serious, potentially life-threatening disease which is associated with seizures and severe loss of muscle coordination while in the latter it is known to cause congenital toxoplasmosis, wherein the parasite is capable of moving across the placenta to infect the fetus causing abortion and fetal death.