The long and short of tapeworm infection.

When four members of an Orthodox Jewish community in New York City developed an infection with the larval form of the pork tapeworm, epidemiologists were mystified. How did these individuals - who shunned pork for religious reasons - pick up the parasite?

Peter M. Schantz of the Centers for Disease Control in Atlanta and his colleagues took on the medical mystery. To begin with, they noted that none of the patients reported a recent trip to an area in which tapeworm infection is common. Travelers to parts of Asia, Africa, or Latin America can develop such infections, perhaps by eating contaminated food, says epidemiologist Ralph T. Bryan of the Centers for Disease Control, who is familiar with the investigation.

After ruling out travel and pork consumption, the researchers seized upon an important clue: The families of the four patients had employed a series of housekeepers who were recent emigrants from various Latin American countries. Further investigation showed that several of these housekeepers harbored antibodies to the larval pork tapeworm, a sign of infection with the parasite, Bryan says.

Schantz and his colleagues describe their findings in the Sept. 3 NEW ENGLAND JOURNAL OF MEDICINE. In a separate article in the same issue, Mexican researchers compare several methods of treating people infected with the larval pork tapeworm.

All four patients in the Schantz report developed neurocysticercosis, an infection of the central nervous system caused by the larvae of the pork tapeworm, Taenia solium. Epidemiologists suspect that people can contract the illness by transferring the microscopic tapeworm eggs from their hands to their mouths after direct contact with a tapeworm carrier, or by eating food that becomes contaminated when infected cooks don't wash their hands before meal preparation. The larvae make their way from the gastrointestinal tract to the bloodstream, which carries them to the brain. Once in the brain, they cause inflammation and seizures. All four patients in this report were brought to hospital emergency departments after they suffered seizures.

Schantz and his colleagues also looked for signs of parasite infection among the patients' immediate family members and discovered seven others with T. solium antibodies.

In a separate study, Julio Sotelo and Victoria Vazquez of the National Institute of Neurology and Neurosurgery in Mexico City focused on 240 people with seizures caused by infection with larval T. solium. Some participants received the drugs albendazole and/or praziquantel. Others received brain surgery to remove the larvae, while still others received careful monitoring but no drug treatment or surgical intervention.

After monitoring all patients for nearly eight years, the researchers discovered that people who received drug treatments fared better than those in the two other groups. People getting drug treatments showed fewer signs of larval infection in the brain and experienced fewer seizures, the team reports.

Those findings may help settle a controversy over whether or not to treat people for infections with larval T. solium. Some researchers believe it's better to let the infection follow a natural course, relying on the immune system to destroy the larvae. The drugs used to treat the infection can cause side effects such as nausea, headache, and other symptoms arising from the destruction of the larval pork tapeworm. But Sotelo and Vazquez assert that the reduced likelihood of seizures outweighs the potential side effects of drug treatment.

Both new reports underscore the fact that tapeworm infection remains a major threat in Mexico and in Central and South America, comments Dickson D. Despommier of the Columbia University School of Public Health in New York City Despommier wrote an editorial accompanying the research reports. In the United States, the infection most often appears in communities populated by recent immigrants. For example, health officials see tapeworm infections in southern California, where migrant workers from Latin America work for farmers during the growing season, he notes.

Scientists don't know the exact route by which the tapeworm eggs are transmitted from one person to another. However, Schantz and his co-workers say their findings strengthen the theory that infected people can pass the eggs during food preparation. The researchers recommend that people at high risk of the infection undergo screening for T. solium. If infected, such people should be treated, they add. - K.A, Fackelmann