In the last month, two twelve-year-old boys have made headlines after being hospitalized with an extremely rare and terrifying infection: the brain-eating amoeba.
Usually found in fresh lakes, rivers and springs, Naegleria fowleri can enter a person’s nose and reach the brain where it begins its job of destroying brain tissue. Thirty-two cases in the United States between 2001 and 2010 have occurred in and around Florida.
Unfortunately Naegleria fowleri is not the only microorganism that, given the chance, will want to invade the human brain.
Taenia solium, common in Africa, Asia, and South America, is a type of Cestoda that can live in the human intestinal tract, producing eggs that are then expelled fecally by their human host. The eggs can then be eaten by pigs while foraging for food. The larvae hatch in the pig’s stomach and find their way into the bloodstream and eventually reach its muscles, where they will most likely be eaten by a human. Once this happens, the parasites travel to the human’s brain and form cysts that cause a disease called neurocysticercosis. This can cause epileptic seizures, headaches, and even lead to death.
Another such parasite is Toxoplasma gondii, a single-celled organism that can only reproduce in conditions provided by a feline’s intestines. When it infects a rat, it causes the rat to lose all fear of cat urine, increasing its chance of being eaten by a cat and returning the parasite to its favorite haunt. Sadly, humans can also be infected by gondii. In the United States, one in four people have been infected with this parasite, but only a small percentage get sick enough to notice. The risk of this parasite is self-mutilation (especially in women). It reaches the brain and causes a kind of psychosis that can lead to the victim’s self-destruction.
Lastly, the Loa-loa is a worm that settles in the eyes. The species, found in western and central Africa, can migrate through human tissues for periods of ten to fifteen years. Infection occurs through a deer bite and by mango flies that live in tropical forests and swamps. Having a worm traveling through your body can cause itching, swelling, nervous system damage, and retinal damage. Paradoxically, using medicine to kill the Loa-loa can be dangerous; When large numbers of their larvae die around the brain, they can block capillaries and cause encephalopathy, a condition that can cause cognitive loss, memory problems, personality changes, and more.
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