Minnesota health officials are reporting an unusual death linked to a strain of polio once used in vaccines.

The Minnesota Department of Health said yesterday that a man, whom they did not identify, with symptoms of the paralyzing disease died last month. The officials said that he was infected with a strain of polio used in an oral, live-virus polio vaccine that was discontinued in the U.S. in 2000, suggesting that he caught the infection from someone who had received the live vaccine before it was pulled from the market. Polio vaccines used in the U.S. today are injected and contain only inactivated virus, though live-virus vaccines are still used in some developing countries, according to the Centers for Disease Control and Prevention (CDC).

The health department didn’t release any details about the man, including his age, but said he had a weakened immune system and multiple health problems.

Since 1961, there have been only 45 reported cases in the world of so-called vaccine-derived paralytic polio (disease from a mutated version of the vaccine strain) in people with immune deficiencies, according to Minnesota officials. It's transmitted when an unvaccinated person or someone with a weakened immune system comes in contact with the polio shed in the stool of a person who received the oral vaccine. That disease is distinct from vaccine-associated paralytic polio (infection from the strain in the oral vaccine), of which an estimated one case occurs for every 3 million doses of the oral vaccine, said Aaron Devries, an epidemiologist with the Minnesota agency.

The last U.S. case of naturally occurring polio (virus caught in the community, not from a vaccine) was in 1979. The disease is still endemic in India, Pakistan, Afghanistan and Nigeria, where it resurged last year, CDC officials recently reported.

Polio virus coating protein/David S. Goodsell, Scripps Research Institute, U.S. Government via Wikimedia Commons