Malawi has declared a wild polio outbreak after a case was identified in a three-year-old girl – the first of its kind in Africa for more than five years.
The continent was declared free of all forms of wild polio in 2020.
The Malawian authorities are now working to contain any possible spread including by boosting immunisation.
Wild polio remains endemic in only two countries in the world – Afghanistan and Pakistan.
The strain that was identified in Malawi was linked to one found in Pakistan, but it is not clear how or when it arrived in the southern African country.
The case was confirmed after tests were carried out on samples from the infected child who was suffering from paralysis, according to the Global Polio Eradication Initiative.
Polio usually affects children under five, sometimes leading to irreversible paralysis. Death can occur when breathing muscles are affected.
Twenty-five years ago thousands of children in Africa were paralysed by the virus. But following a mass vaccination campaign across the continent 95% of the population has been immunised.
There is no cure but the polio vaccine protects children for life.
As the case came from Pakistan, it does not affect the continent’s wild poliovirus-free status, the World Health Organization (WHO) says.
Wild polio is caught from the environment, but there is another type of polio linked to the oral vaccine (which contains live, weakened virus) that is equally worrying.
It can linger in the gut, mutate and spread in areas where few people are vaccinated. There have been outbreaks of this form of polio in more than 20 African countries in recent years.
But an injectable form of the vaccine is now used, containing dead virus, which does not lead to polio cases.