Polio virus has been found in 36 members of an Amish community on the borders of St. Mary's and Charles counties in Maryland, according to state and federal health officials.
None of the crippling symptons of polio have been developed by any of the 36 members of the sect, but a 22-year-old Amish woman from Pennsylvania, who visited the community last fall, has been paralyzed by the disease.
While local health officials have said they "are concerned" about the situation, they have stressed that the outbreak does not constitute an epidemic and does not pose a threat to persons who have been vaccinated.
According ot Dr. Marjorie Pollack, an epidemiologist with the federal Center for Disease Control in Atlanta, 20 cases of paralytic polio were reported in the United States last year. Only six of those cases were caused by a so-called "wild virus," or virus found in nature, Pollack said, while the rest were caused by the weakened live virus in the polio vaccine.
Pollack, who is monitoring the Maryland outbreak for the Atlanta center, said yesterday the 36 asymptomatic cases are "to be expected when you're talking about a wild virus.
"It tells us there's virus in the community," she said. Experts say that for every case of paralytic polio, there are a minimum of 49, and a maximum of 999, asymptmatic cases.
Dr. Jonas Salk, developer of the first polio vaccine, said yesterday the Maryland outbreak is one of a number of similar outbreaks worldwide in religious communities whose members -- like the Amish -- shun vaccinations.
There was an outbreak in Holland last spring in an isolated Dutch Reform Church community that resulted in 71 cases of paralytic polio. A similar outbreak in Canada last summer left two persons paralyzed by the disease, which can attack the central nervous system.
"These clusters have been associated with religious groups that are against immunization," said Salk.
"It's very logical, very understand-able andvery interesting.
"It is impossible to eradicate polio virus from the population (as long as such unvaccinated pockets exist), but there's evidence there's resistance to the spread into the general population," said Salk.
There were no cases of polio in either Canada or the Netherlands associated with the two outbreaks, outside the two religious communities. Epidemiologists have discovered links between the Canadian and Dutch communities, and are now investigating the possibility of links between the Canadian and Maryland groups.
According to Salk, "while there may be people in the general population who are not vaccinated, they may be buffered" by the great numbers of persons in the community at large who are protected.
Before the introduction of Salk's vaccine in 1954, polio struck about 21,000 people in this country every year.
According to Dr. William Marek, deputy state health officer for St. Mary's County, 98 to 99 percent of the non-Amish children in the county are vaccinated against polio because a state law requires that children receive the vaccine before attending school.
St. Mary's and Charles County health officials are holding a free polio vaccination clinic tonight for all those living within a five-mile-radius of the Amish community, who are older than six weeks of age, and have not been vaccinated against the disease in the past five years.
Marek said that a separate campaign to vaccinate the Amish community resulted in about 70 percent of the 560 persons taking the vaccine.
Marek said that the Amish agreed to vaccinations after the extent of the threat was explained to them. In Holland, however, health officials met with little success in vaccinating members of the affected Dutch Reform community, according to Salk.
"The Amish have products they sell to the community at large," principally raw milk and butter, Marek said. "We've asked them to voluntarily restrict that, and they have." Marek explained that the virus can be transmitted through milk or butter.
He said health officials are planning to test the stool of a group of children attending schools in St. Mary's and Charles counties within 12 miles of the Amish community in an attempt to determine if the virus is in the community at large.