Nigeria, Lake Chad and West Africa

Status: affected by circulating vaccine-derived poliovirus

In Nigeria and the Lake Chad subregion, a cVDPV2 outbreak originating in Jigawa state, Nigeria, continues to spread.  In Cameroon and Ghana, cVDPV2 was detected from environmental samples collected on 20 April 2019 and 11 June 2019, respectively.  The virus was detected in environmental samples only – no associated cases of acute flaccid paralysis (AFP) have been detected.  The same outbreak originating in Jigawa had previously spread to other areas of Nigeria, as well as internationally to the Republic of Niger.  Separately, a second cVDPV2 has been confirmed from Sokoto state, isolated from environmental samples collected from Sokoto North, on 13 March and 27 May.  This virus has been isolated from environmental samples only – no associated paralytic cases have been identified.

WHO risk assessment

WHO assesses the risk of international spread and/or emergence of cVDPV2 across Africa to be high.

WHO advice

It is important that all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for AFP cases in order to rapidly detect any new virus importation and to facilitate a rapid response. Countries, territories and areas should also maintain uniformly high routine immunization coverage at the district level to minimize the consequences of any new virus introduction.

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.

As per the advice of an Emergency Committee convened under the International Health Regulations (2005), efforts to limit the international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC).  Countries affected by poliovirus transmission is subject to Temporary Recommendations.  To comply with the Temporary Recommendations issued under the PHEIC, any country infected by poliovirus should declare the outbreak as a national public health emergency and consider vaccination of all international travellers.