The World Health Organisation (WHO) has announced that the entire African continent has been free of wild polio cases for the past year, thanks to a dedicated vaccine campaign.

This means that no one has been infected with the virus anywhere in Africa since the last reported case in central Somalia on 11 August 2014, and it suggests that public health officials have successfully treated enough people with the oral vaccine to interrupt the spread of polio in Africa once and for all.

Unfortunately the announcement doesn't mean that Africa is free from polio altogether – there are still people infected, and the virus remains officially endemic in Nigeria. 

But Nigeria hasn't had a new case since 24 July 2015, and in a few more weeks officials are expected to announce that transmission of the virus has been interrupted in the country. If that happens, it means there'll only be two countries left the world where polio is being transmitted – Pakistan and Afghanistan.

"If continued lab results in the coming weeks confirm no new cases in Nigeria, and if the WHO African Region then goes two more years without a case of wild polio in the face of strong surveillance, it could be certified polio-free by the Africa Regional Certification Commission," the World Health Organisation explained in a press release.

Since smallpox was eradicated in 1977, humans have struggled to eliminate any other disease threats from the planet. We were making great strides when it came to controlling measles, until a drop in vaccination rates over the past decade saw new outbreaks pop up around the world.  But thanks to dedicated public health programs, we're now closer than ever to wiping out several diseases, including polio and the parasitic Guinea worm.  

But there's still a lot to be done before we can relax, according to Hamid Jafari, Director of the Global Polio Eradication Initiative at the WHO. "Surveillance for poliovirus has improved considerably. However, in the past we have had year-long periods when we thought the poliovirus had gone from the Horn of Africa and central Africa, only to find out that we were simply missing transmission because our surveillance systems were not strong enough to spot cases," he said. 

And even though results in Kenya and Ethiopia, where polio used to be endemic, and now Nigeria are positive, the WHO admits that its scientists can't rule out whether low-level transmission is occurring undetected in Somalia, as a result of insufficient monitoring. 

"One year with no reported cases of polio is great news, but this progress needs to be treated with caution – a lot of very hard work is needed before we can be fully confident that polio is gone from the Horn of Africa," added Hemant Shukla, who supports polio eradication for the Horn of Africa at the WHO.

So far though, things are looking positive. And while we can't start writing the epitaph for polio just yet, it doesn't hurt to celebrate the small wins when we get them – when it comes to global health threats and vaccines, they definitely don't happen often enough.

H/T: io9