MINNEAPOLIS (AP) &045; State and federal health officials are trying to determine how a baby in central Minnesota contracted the virus that causes polio, a quarter century after the disease was essentially wiped out in the United States.

The baby, born in the United States, was exposed to a strain of virus found in oral polio vaccines, which haven’t been used in the United States for five years.

Investigators 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.

&uot;(It) is not a public health concern for the general public,&uot; said Kris Ehresmann, chief of immunization at the Minnesota Health Department. &uot;But it is definitely a situation that is of great scientific interest. It’s a unique situation.&uot;

The baby had no symptoms of polio, 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 gender or age, saying only that he or she 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 found the polio virus.