The first wild poliovirus case in Africa in more than five years has been detected in a young child in Malawi, the World Health Organization said Thursday.
The Malawian health authorities have declared an outbreak of wild poliovirus type 1 after a case was detected in the capital Lilongwe, the WHO said.
Laboratory analysis showed that the detected strain is linked to one that has been circulating in Sindh Province in Pakistan. Polio remains endemic in Pakistan and its neighbour Afghanistan.
"As an imported case from Pakistan, this detection does not affect the African region's wild poliovirus-free certification status," the WHO said.
Africa was declared free of indigenous wild polio in August 2020 after eliminating all forms of wild polio. No polio cases had occurred on the continent for the past four years -- the threshold for eradication.
"Following the detection of wild polio in Malawi, we're taking urgent measures to forestall its potential spread," the WHO's Africa regional director Matshidiso Moeti said in a statement.
"Thanks to a high level of polio surveillance in the continent and the capacity to quickly detect the virus, we can swiftly launch a rapid response and protect children from the debilitating impact of this disease."
The WHO said it was supporting Malawi in conducting a risk assessment and outbreak response, including extra vaccination.
Surveillance of the disease is being stepped up in neighbouring countries.
"The last case of wild poliovirus in Africa was identified in northern Nigeria in 2016 and globally there were only five cases in 2021. Any case of wild poliovirus is a significant event and we will mobilise all resources to support the country's response," said Dr Modjirom Ndoutabe, the WHO Africa region's polio coordinator.
Poliomyelitis -- the medical term for polio -- is an acutely infectious and contagious virus which attacks the spinal cord and causes irreversible paralysis in children.
Poliovirus is typically spread in the faeces of an infected person and is picked up through contaminated water or food. It multiplies in the intestine.
While there is no cure for polio, vaccinating people to prevent them from becoming infected thus breaks the cycle of transmission.
The August 2020 declaration that Africa was free of the virus that causes polio was a landmark in a decades-long campaign to eradicate the notorious disease around the world.
The disease was endemic around the world until a vaccine was found in the 1950s, though this remained out of reach for many poorer countries in Asia and Africa until a major push in recent decades.
In 1996, there were more than 70,000 cases in Africa alone.