The Spread Of Polio

Polio Spreads to New Countries and Increases
Where It’s Endemic -- New York Times

Polio infections are increasing and spreading to new countries, according to case counts recently released by the World Health Organization.

Since April, outbreaks have been found in 10 countries beyond the 4 in which polio is considered endemic — Afghanistan, India, Nigeria and Pakistan. And in those four countries, the number of cases is more than double the number found by this time in 2007.

In Africa, cases have been found as far south as Angola and as far west as Ethiopia. Each detected case implies another 200 cases with few or no symptoms, experts say.

There have been outbreaks of both type 1 and type 3 polio, which frustrate W.H.O. plans, begun in 2005, to concentrate on a monovalent vaccine against type 1. Recent studies show that vaccine to be far more effective against type 1 than the old trivalent vaccine was. But it does not protect against type 3, and a new monovalent vaccine against that is being introduced. (Type 2 was eliminated in 1999.)

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