Africa declared free of wild poliovirus

Africa is free of wild poliovirus, after decades of vaccination campaigns, according to news reports.

An independent body called the Africa Regional Certification Commission (ARCC) for Polio Eradication made the announcement today (Aug. 25) during a World Health Organization (WHO) videoconference, Reuters reported. Of the 47 countries within the WHO's Africa region, Nigeria eradicated the virus most recently, and now, four years have passed since the country's most recent wild polio case.

The disease known as polio is caused by three different strains of poliovirus, which sometimes attacks nerve cells in the spinal cord and causes partial or complete paralysis, Live Science previously reported. The majority of people who catch polio don't become paralyzed, but those who do can remain permanently disabled or die from the condition, as the muscles that support breathing can be paralyzed, according to the Centers for Disease Control and Prevention (CDC). 

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People can catch polioviruses through contact with the feces of an infected person, or through contaminated food, water and objects that come in contact with the mouth, according to the CDC. Less commonly, the virus can spread when an infected person sneezes or coughs. While there is no specific treatment for polio, a full course of polio vaccinations is more than 99% effective at preventing the infection, the CDC says. 

To snuff out wild poliovirus in Nigeria, a coalition of national governments and local leaders called the Global Polio Eradication Initiative coordinated a campaign to vaccinate children in Borno State, located in the northeast region of the country, The Guardian reported. 

In addition to administering vaccinations, the coalition improved surveillance systems to monitor for polio outbreaks and worked with polio survivors to raise awareness of the campaign, Dr. Matshidiso Moeti, the World Health Organization (WHO) regional director for Africa, said in a news conference, according to The Guardian. Health care workers also faced threat of attack from the Boko Haram insurgency in northern Nigeria, as well as occasional violence from local communities who opposed the vaccination effort due to concerns about its effects.  

To protect health care workers, the coalition worked with military members and a government-approved militia who acted as their escorts, Dr. Tunji Funsho, a Nigerian anti-polio coordinator for the nonprofit Rotary International, told Reuters. Including polio survivors on eradication teams proved essential to gaining the trust of local communities, Misbahu Lawan Didi, president of the Nigerian Polio Survivors Association, told BBC News. 

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"Many rejected the polio vaccine, but they see how much we struggle to reach them, sometimes crawling large distances, to speak to them," Didi said. "We ask them: 'Don't you think it is important for you to protect your child not to be like us?'" 

Now, thanks to these extensive efforts, Africa has been declared free of wild poliovirus — but the work isn't over yet. Oral polio vaccines, including those used in Africa, contain a weakened poliovirus that can sometimes mutate into a form that behaves like the wild virus and can infect unvaccinated individuals, according to the CDC. In areas with low vaccine coverage, outbreaks of vaccine-derived poliovirus can occur even when wild strains of the virus have been eliminated. 

Nigeria and 15 other African countries are currently experiencing small outbreaks of vaccine-derived poliovirus, Reuters reported, and in total, 177 cases of vaccine-derived poliovirus have been reported in Africa this year, according to BBC News. To avoid vaccine-derived polio, the U.S. stopped administering oral polio vaccines in 2000 and now exclusively uses a so-called inactivated poliovirus vaccine, which is delivered as a shot and contains a dead poliovirus, rather than a weakened one.

"The global eradication of polio requires stopping all [oral polio vaccines] in routine immunization, as soon as possible after the eradication of wild poliovirus transmission," the CDC website notes. With wild poliovirus eliminated in Africa, "we must stay vigilant and keep up vaccination rates to avert a resurgence of the wild poliovirus and address the continued threat of the vaccine-derived polio," Moeti said in the news conference, according to The Guardian. 

Wild poliovirus could reemerge in Africa, given that the virus still circulates in Afghanistan and Pakistan, Michael Galway, a polio expert at the Bill and Melinda Gates Foundation, told Reuters. "Until wild poliovirus is eradicated everywhere, it’s still a risk everywhere," he said.

Originally published on Live Science.