Mutated Polio Virus Breached Vaccine Protection During Congo Outbreak

Vaccinations can virtually eradicate diseases. In fact, effective vaccination has nearly eliminated polio worldwide; only a few hundred people are stricken globally each year. Now, though, scientists are reporting that a mutated virus that was able to resist vaccination protection was behind an outbreak in the Congo in 2010.

The polio epidemic in the Congo in 2010 infected 445 people, mostly young adults. The disease was fatal for 209 of the patients, which was surprising considering that many of those affected had apparently been vaccinated. That's why researchers investigated this incident a bit further.

"We isolated polio-viruses from the deceased and examined the viruses more closely," said Jan Felix Drexler, one of the researchers, in a news release. "The pathogen carries a mutation that changes its form at a decisive point." In other words, the new, mutated virus can resist the vaccination.

The researchers also tested blood samples from 34 medical students of the University of Bronn who had all been vaccinated during childhood. While scientists found the antibodies in the blood samples had no problem combating the normal polio viruses, it was another matter entirely when it came to the mutated virus. In fact, the researchers estimated that about one in five of the subjects could have been infected by the new polio virus.

Fortunately, the polio epidemic in the Congo was stopped with a massive vaccination program and hygiene measures. Yet the new pathogen serves as, perhaps, a warning.

"We can't afford to sit back and do nothing," warn the scientists. "We need to further increase the vaccination rate and develop new, more potent vaccines. Only in this way do we have a chance of permanently vanquishing polio."

The findings are published in the journal Proceedings of the National Academy of Sciences.