And now some good news on the polio wars: A second strain of the virus seems to have been eradicated, leaving just one to go. The last sighting of wild poliovirus type 3 occurred in Nigeria in November 2012, where an 11-month-old was paralyzed in the northern state of Yobe. Virologists have been looking hard for a trace of the virus ever since, but can't find it. That means the vaccination strategy is working and will ultimately succeed, say leaders of the Global Polio Eradication Initiative. But experts caution it is not a done deal: There is still a slight chance wild-type 3 is lurking out there undetected. And the remaining virus, wild-type 1, is the toughest to defeat and has sparked a runaway outbreak in Pakistan this year.