Kenya, Mozambique and Niger have curbed polio outbreaks that erupted in different episodes over the past 24 months, allowing them to regain their polio-free status, World Health Organization (WHO) said on Tuesday.
Transmission of vaccine-derived poliovirus was detected in the three countries in 2018 and early 2019, affecting a total of 14 children.
"Ending outbreaks in the three countries is proof that response activities along with high quality immunization campaigns and vigilant disease surveillance can stop the remaining outbreaks in the region," said Dr Modjirom Ndoutabe, coordinator of WHO-led polio outbreaks Rapid Response Team for the African Region.
"We are strongly encouraged by this achievement and determined in our efforts to see all types of polio eradicated from the continent. It is a demonstration of the commitment by governments, WHO and our partners to ensure that future generations live free of this debilitating virus," added Dr Ndoutabe.
Vaccine-derived polio viruses are rare, but they affect un-immunized and under-immunized populations living in areas with inadequate sanitation and low levels of polio immunization. When children are immunized with the oral polio vaccine, the attenuated vaccine virus replicates in their intestines for a short time to build up the needed immunity and is then excreted in faeces into the environment where it can mutate.
If polio immunization coverage remains low in a community and sanitation remains inadequate, the mutated viruses will be transmitted to susceptible populations, leading to emergence of vaccine-derived polioviruses.