- The Washington Times - Tuesday, October 4, 2005

Virus eradicatedgeneration ago

MINNEAPOLIS — How did a baby in central Minnesota contract the virus that causes polio, a crippling disease that essentially was eradicated in the United States a quarter century ago?

That question has mystified state and federal health officials since tests confirmed the polio virus in an unidentified infant last week.

The case is especially puzzling because the baby, who was born in this country, was somehow exposed to a strain of virus found in oral polio vaccines, which haven’t been used in the United States for five years.

“[It] is not a public health concern for the general public,” said Kris Ehresmann, chief of immunization at the Minnesota Health Department. “But it is definitely a situation that is of great scientific interest.”

Investigators now are testing relatives and others who have had close contact with the child to see whether anyone else may have been infected. They suspect that someone contracted the polio virus in another country and unwittingly passed it on.

The baby had no symptoms of polio, Miss Ehresmann said. The virus was discovered during tests while the child was hospitalized for an unrelated immune condition. Officials declined to identify the child’s sex or age, saying only that the child is less than a year old.

The Health Department was asked to run lab tests to find out whether a virus was making the child sick. When no routine viruses showed up, they started looking for obscure ones. And they found the polio virus.

The child hadn’t been vaccinated against polio, apparently because of underlying medical problems.

It has been 50 years since the polio vaccine was developed, during an epidemic that paralyzed as many as 21,000 Americans a year at its peak. By 1979, the disease had been wiped out as a natural threat in the United States.

For the next 20 years, the only cases reported in this country — an average of eight a year — were caused by the oral vaccine, which used a modified live virus. Five years ago, the United States discontinued the oral vaccine.

Since then, federal officials say, no one had contracted polio in the United States.

State officials sent samples of the virus to the U.S. Centers for Disease Control and Prevention (CDC) for more tests. Last week, the agency confirmed it as polio.

“It’s an unusual thing in any country,” said Dr. Jim Alexander, a vaccine specialist at CDC. “There are many more questions so far than we have answers.”

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