A polio milestone: One strain left in the crosshairs
Three years ago Tuesday, an 11-month-old child in Yobe, Nigeria, was paralyzed by a polio virus. It was a type 3, one of a trio of strains of the virus that have been the targets of a 27-year long eradication struggle.
The day after the child in Yobe got sick, a type 3 virus was found in a sewage sample collected in Lagos. (Sewage testing is a cornerstone of polio surveillance.)
Since then, there has not been a single detection of a type 3 virus anywhere. In the world of polio, that means type 3 polio is now probably eradicated — although the World Health Organization hasn’t yet officially said so.
“I think we are increasingly confident that it’s gone,” said Dr. Hamid Jafari, director of the WHO’s Global Polio Eradication Initiative.
The polio eradication partners — the WHO, the US Centers for Disease Control and Prevention, UNICEF, Rotary International, and the Bill and Melinda Gates Foundation — aren’t planning to seek a formal declaration at this point. A rigorous review of surveillance data from all of Africa has to be completed in order to decree that type 3 viruses are extinct, and that hasn’t yet been done.
But unofficially, the working assumption is that there is now only one remaining family of polioviruses in the eradication program’s crosshairs, type 1.