By Elizabeth Merab

More by this Author

Africa has been declared wild polio-free after a three-decade campaign against the disease that once paralysed about 75,000 children on the continent every year.

The highly contagious disease is the second to be eradicated since smallpox 40 years ago, the World Health Organisation (WHO) Africa director Matshidiso Moeti said on Tuesday. However, a minor strain still infects hundreds.

Polio, also known as poliomyelitis, is an infectious disease caused by a virus that attacks the nervous system causing paralysis in children. It is transmitted from person-to-person mainly through faecal matter entering the mouth with children under five years being more likely to contract the disease than any other group. 

One in 200 infections leads to irreversible paralysis. Among those paralysed, World Health Organisation (WHO) estimates that five to 10 percent die when their breathing muscles become immobilised.

“Now future generations of African children can live free of wild polio,” said Dr Moeti.

The achievement is a major step towards ridding the globe of the virus that causes the disabling — and sometimes deadly — disease. Only Afghanistan and Pakistan are still reporting cases, said the African Regional Certification Commission for Polio eradication (ARCC).

“Today is a historic day for Africa. The ARCC is pleased to announce that the region has successfully met the certification criteria for wild polio eradication, with no cases of the wild poliovirus reported in the region for four years,” said Prof Rose Gana Fomban Leke, ARCC chairperson. 

The certification comes four years after Nigeria – the last polio-endemic country in Africa – recorded its last case of wild polio. It also means that five of the six WHO regions, representing over 90 percent of the world’s population, have eliminated wild polio. 

Nigeria was a major sticking point on the African continent after its northern Muslim-majority region boycotted use the vaccine in 2003 following rumours about its safety with Islamist extremists claiming it would sterilise young Muslims. As a result, an outbreak emerged and spread to 20 countries in five years. 

In 2016, four new cases of wild polio were reported in northern Borno state, the epicentre of the Boko Haram jihadists’ violence, compelling the global health infrastructure to pool resources to contain the situation, using satellite imagery, data analysis, and daring methods of getting to seemingly impossible-to-reach children.

Polio strain 

When smallpox was certified eradicated in Africa in 1988, the World Health Assembly adopted a resolution for the worldwide eradication of polio which marked the launch of the Global Polio Eradication Initiative (GPEI), spearheaded by national governments, WHO, Rotary International, the US Centers for Disease Control and Prevention (CDC), UNICEF, and later joined by additional key partners including the Bill & Melinda Gates Foundation and Gavi, the Vaccine Alliance.

Despite this accomplishment, challenges remain. Dr Moeti warned that people must remain vigilant and countries must keep up vaccination rates to avert a resurgence. 

Every year, hundreds of people across Africa are still being infected with a polio strain known as circulating vaccine-derived poliovirus (cVDPV), which can infect people in areas where there is only partial vaccination. There are still pockets of children have no access to the polio vaccine, leading to outbreaks of the cVDPV. In 2018, experts from the Kenya Medical Research Institute (Kemri) and Centres for Disease Control and Prevention (CDC) reported finding traces of vaccine-derived poliovirus in environmental samples from Eastleigh, Nairobi.

“Since then we are yet to detect any other incidence but we are remaining vigilant especially because Kenya remains vulnerable due to its porous borders,” explained Dr Peter Borus, who heads the Kemri polio laboratory, and a  WHO lab scientist.

When a vaccine-derived poliovirus is detected, a country cannot be certified polio-free as the WHO only considers a country to be polio-free if it goes 12 months without a case – or a positive environmental sample.

“Africa has demonstrated that despite weak health systems, significant logistical and operational challenges across the continent, African countries have collaborated very effectively in eradicating wild poliovirus,” said Dr Pascal Mkanda, Coordinator of WHO Polio Eradication Programme in the African Region.

African cases of the vaccine-derived strain, which results in the same symptoms as the wild kind, increased to 320 last year from 68 in 2018 and could rise again in 2020 because many vaccination campaigns were paused during coronavirus lockdowns.

The 16 countries in Africa currently affected by circulating vaccine-derived polioviruses outbreaks are Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d'Ivoire, the Democratic Republic of the Congo, Ethiopia, Guinea, Ghana, Mali, Niger, Nigeria, Togo, and Zambia.

In 1998, WHO appointed the 16-member Africa Regional Certification Commission for Polio Eradication with the mandate to oversee the certification process and act as the only body to certify the African Region to have eradicated the wild poliovirus.

To address the growing challenge of circulating vaccine-derived polioviruses, the GPEI’s new ‘Strategy for the Response to Type 2 Circulating Vaccine-Derived Poliovirus 2020-2021’ is focused on working with affected and at-risk countries to control outbreaks across the continent.