Status: Circulating vaccine-derived poliovirus type 2 (cVDPV2) detected in an environmental sample

In Cameroon, a circulating vaccine-derived poliovirus type 2 (cVDPV2) was detected from an environmental sample collected on 20 April 2019 in Extreme Nord.  The virus was detected in an environmental sample only – no associated cases of paralysis have been detected.

The affected province borders Borno, Nigeria, and genetic sequencing confirms it is related to cVDPV2 circulating in neighbouring Nigeria.  This outbreak originated in Jigawa state and had previously spread to other areas of Nigeria, as well as internationally to the Republic of Niger. Cameroon had already been participating in outbreak response to the Nigeria cVDPV2 across the Lake Chad subregion.

Polio this week in Lake Chad Basin

  • No circulating vaccine-derived poliovirus type 2 (cVDPV2) was reported in the past week.
  • In the Lake Chad region, cVDPV2 linked to the outbreak originating in Nigeria has been detected in Niger (one case in 2019 and ten cases in 2018), and Cameroon (one positive environmental sample, collected on 20 April 2019 in Extreme Nord.
  • The risk of further cVDPV2 spread across the Lake Chad subregion remains high.

International Health Regulations

Countries affected by poliovirus transmission are subject to International Health Regulations Temporary Recommendations that request them to declare a case of polio as a national public health emergency and consideration vaccination of all international travellers, as per temporary recommendations issued as of  May 2019

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Key at-risk: no longer poliovirus-infected, but at high risk of outbreaks
Outbreak: has stopped indigenous WPV circulation but affected by outbreak of imported WPV or circulating vaccine-derived poliovirus
Endemic: has never stopped indigenous wild poliovirus (WPV) circulation

Travel Advice

WHO’s International Travel and Health recommends that all travellers to polio-affected areas be fully vaccinated against polio. Residents (and visitors for more than 4 weeks) from infected areas should receive an additional dose of OPV or inactivated polio vaccine (IPV) within 4 weeks to 12 months of travel.