Africa on path toward polio eradication

NAIROBI — Wednesday marked three years since the last case of wild poliovirus was detected in Africa. Now, the World Health Organization’s Africa Regional Certification Commission will evaluate whether the virus is actually eradicated across the continent.

Polio is a highly infectious disease that can lead to paralysis, spread mainly through exposure to feces. There is no cure for polio, but immunization can prevent it.

“The path to eradicating polio in Africa has been a monumental effort of multinational coordination on an unprecedented scale providing vaccinations to hundreds of millions of children and conducting immunization campaigns in some of the most remote locations in the world,” Dr. Matshidiso Moeti, Africa regional director at WHO, said during a press briefing.

The last four cases of wild poliovirus were seen in Borno State, Nigeria in 2016, an area where the terrorist group Boko Haram’s presence has hampered health worker’s ability to immunize children. The country also saw a spike in cases in 2006, when strong community resistance to vaccination fueled a rise in cases.

In response, the Nigerian government and its partners have used innovative ways to reach children in these hard to access areas, said Dr. Pascal Mkanda, coordinator of the WHO Polio Eradication Programme. This included vaccinating children while they were visiting market areas and during lulls in the violence, as well as expanding community surveillance of the virus.

Polio workers from Cameroon, Chad, Niger, and Nigeria also mapped out the islands in Lake Chad in order to reach communities by canoe that had not previously been vaccinated.

In the years since the last reported cases, polio workers have used a three-pronged approach for surveillance of the virus in Nigeria, Mkanda said. This includes inspecting health facilities for cases of children with paralysis of the limbs, sampling sewage systems to see if traces of the poliovirus are present, and training community members to spot polio symptoms and report cases to local clinics.

Moving forward, an independent body of 17 experts from the Africa Regional Certification Commission will work to verify that each of the 47 African nations on the continent have actually eradicated the virus, which includes examining government data and conducting field visits, according to Mkanda. As of June, they have verified 41 countries, with Nigeria, Cameroon, Central African Republic, South Africa, South Sudan, and Equatorial Guinea remaining, he said.  

Four other WHO regions have also eradicated the virus, including the Americas, the Western Pacific, Europe, and Southeast Asia. The Eastern Mediterranean is still working on managing the virus, and wild poliovirus is endemic in Pakistan and Afghanistan.

Wild polio is the strain of the virus that is found naturally in countries, whereas circulating vaccine-derived poliovirus can be transmitted from a child who received the oral polio vaccine, which contains a weakened virus, to others. The virus can spread in severely under-immunized populations until it eventually dies out.

These types of outbreaks continue to occur across Africa. For example, more than 30 cases of circulating vaccine-derived poliovirus have been reported this year in the Democratic Republic of the Congo.

In the coming months, as the wild polio eradication process moves forward, African countries need to intensify their surveillance efforts to ensure there aren’t gaps, Mkanda said.

“This is not the time to relax because we really have to show evidence that indeed we are not missing any transmission of wild poliovirus,” he said.

As was the case in Nigeria, a major challenge across the continent for polio workers is accessing children in areas of conflict, Moeti said. Other challenges include mobile populations, inadequate national vaccination campaigns, and parental refusal of vaccination for their children.