McALLEN - Doctors in South Texas say they're seeing more cases of a parasite that burrows into the human brain, sometimes resulting in seizures or even death.

Health officials say the increase is probably due to failure of food handlers to wash their hands after going to the bathroom. They believe increasing immigration from Central and South America, where the tapeworm is more common, may also be a factor.

A condition known as neurocysticercosis occurs when immature larvae of the pork tapeworm travel in the bloodstream and lodge in the brain or central nervous system, sometimes causing seizures and headaches. The disease kills up to 50,000 people worldwide each year, according to a Cambridge University research group, but is uncommon in most of the United States.

"Neurocysticercosis is a major health problem along the United States-Mexico border," according to a 1998 report by the Texas Department of Health, which said the increase corresponds to increased immigration from areas where the disease is more common. It also said doctors are better able to diagnose the disease, using CAT scans.

"It's a tremendous problem in Third World countries and its becoming an increasing problem in the U.S. It definitely has to do with immigration," Dr. Judy Teale, a researcher at the University of Texas Health Science Center, told The Monitor newspaper in McAllen.

Teale is studying the effects of treatment for the disease.