Epidemiological alert: risk of poliovirus epidemic, June 10, 2022 – World


Given the risk of importation of wild polioviruses and vaccine-derived polioviruses, or the emergence of vaccine-derived polioviruses in the Region of the Americas, the Pan American Health Organization/World Health Organization (PAHO/WHO ) shares with its Member States a series of considerations related to prevention, surveillance and preparedness

Summary of the situation

Following certification of global eradication of wild poliovirus types 2 and 3, poliomyelitis continues to be endemic for wild poliovirus type 1 (WPV1) in two countries, Afghanistan and Pakistan. In Afghanistan, as of 7 June 2022, one case of WPV1 has been detected and four have been detected in 2021. In Pakistan, 8 cases of WPV1 have been reported in 2022.

Additionally, in February 2022, the isolation of a WPV1 was confirmed from a three-year-old girl with acute flaccid paralysis (AFP) in Malawi. The analysis shows that the virus is genetically related to PVS1 which was detected in Pakistan in October 2019. This is the first case of PVS1 on the African continent in more than five years. In May 2022, a case of WPV1 was identified in stool samples taken from a child with AFP in Mozambique. Sequencing of the virus has confirmed that it is related to a strain from Pakistan, similar to a case of WPV1 reported in Malawi in February.

This detection of WPV1 outside of the two endemic countries, Pakistan and Afghanistan, is of great concern and highlights the importance of prioritizing polio detection and control activities.

In addition, several countries in Africa and Asia have circulation of vaccine-derived poliovirus (cVDPV), variants of poliovirus that can occur in communities with low vaccination coverage. Recently, VDPV outbreaks have been detected in Israel and Ukraine. (Figure 1).

Until poliovirus transmission is interrupted globally, all countries remain at risk of polio importation.

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