Pork tapeworms can infest the human brain. They are the most common cause of adult onset epilepsy (see also here). Another type of brain worm can be contracted from eating fish. Approximately 1 in 6 US lambs is infected with toxoplasma brain parasites; about 10% of Americans are infected with this brain parasite. There also is a rare condition called delusional parasitosis, where the patient believes they are infected with parasites even though they are not (though it can be caused by pork tapeworms in the brain!).
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