It was a mystery: How could Orthodox Jews who keep kosher in New York City catch tapeworms that usually afflict people who eat pork in Central America?
Forget the patient's medical history. In every case, the common denominator was a baby sitter or housekeeper.The affair came to light last summer when a 6-year-old Brooklyn boy was stricken with a seizure while his family drove to the New Jersey shore. They turned around and took him to New York University Medical Center, where doctors feared he had a brain tumor.
The youngster was scheduled for neurosurgery when Dr. Jose L. Munoz, a pediatrician who specializes in infectious diseases, found the real cause. A CT scan showed two cysts in the boy's brain. They were the larval stage of laenia solium, the pork tapeworm.
The tapeworm is common in parts of Mexico and elsewhere in Central America, where people get it from eating poorly cooked infected pigs. But pork sold in the United States almost never carries the parasite, and this boy's family followed Jewish dietary rules. They never touched pork.
Americans also sometimes get the worm when they go to places where it is common. However, this patient and his family had not traveled.
Dr. Deborah Persaud, a physician in training, questioned the boy's mother about possible sources of the infection and discovered the family had used 16 different baby sitters from Central America.
"We were initially very confused," Munoz said. "But by the end of the first day, there was no doubt that was what had to be going on."
Munoz called Dr. Peter M. Schantz, an authority on parasitic diseases at the U.S. Centers for Disease Control. During that summer, Schantz heard of two other cases of the tapeworm from Orthodox Jewish families in the same part of Brooklyn, and he learned of another case there that had been treated a year earlier.
Schantz and two CDC colleagues conducted a formal investigation. Starting with the four initial victims, they checked 17 immediate family members and found that seven from two families also had been exposed to the tapeworm.
In every case, the common denominator was a baby sitter or housekeeper from Central America.
Schantz, Munoz and other doctors involved wrote up their findings in the New England Journal of Medicine. They believe the infection spreads this way:
The housekeepers came from places where pigs roam freely in the streets. The pigs' flesh is infected with larvae of the tapeworms, and the adult tapeworms live in their intestines.
When people eat the infected pigs, the pea-size larvae enter their intestines and grow into tapeworms, often reaching lengths of 30 to 50 feet.
Both humans and pigs who carry the adult worms shed tapeworm eggs in their excrement. When people inadvertently eat food tainted with egg-laced excrement, the eggs hatch and enter their blood stream. They can become lodged in any organ of the body, including the brain, where they form cysts and live for up to 10 years.
The doctors believe that in each New York case, housekeepers unknowingly carried tapeworms in their intestines and contaminated the family's food with worm eggs. People's skin, clothing and dirt under their fingernails can harbor the eggs.
In the section of Brooklyn where the outbreak occurred, most of the 6,000 or so families employ housekeepers, and about 90 percent of them are from Latin American countries where the tapeworm is common.