Twelve months have passed since the last case of wild poliovirus type 3 (WPV3) was reported anywhere in the world, leading many to ask: is this the end of type 3 polio?

If so, it would be the second polio strain to be eradicated, with just wild poliovirus type 1 (WPV1) remaining. Type 2 was eradicated back in 1999.

“I don’t think it’s gone, but it’s definitely at its lowest ever levels and if we keep up the pressure, it’s on its way out,” says Chris Maher, Senior Scientist for Polio Eradication at the World Health Organization (WHO).

The danger with WPV3 is that it is less virulent than WPV1, Maher explains. It causes cases at a rate of approximately 1 in 2,000 infections, compared with 1 in 200 infections for WPV1.

Causing fewer cases is a good thing, of course, but it also means that the virus can transmit more widely and longer, without being detected. “It’s a sneaky virus, in that sense, so we have to be cautious not to let it surprise us.” says Maher.

---

Read more over at polioeradication.org.