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WPV1 resurges in Nigeria
The Global Polio Eradication Initiative has reported two cases of acute flaccid paralysis caused by wild poliovirus type 1 among children living in Nigeria, a country previously thought to have interrupted transmission of the neurotropic virus in July 2014.
The resurgence of wild poliovirus (WPV) — which was also isolated from close healthy contacts of the children — nullifies the WHO African region’s chances to be declared polio-free by 2017.
Both cases were found among residents of the country’s Borno state, with genetic sequencing indicating a relationship to virus last detected within the state in 2011. According to the Global Polio Eradication Initiative (GPEI), this finding suggests the strain may have been circulating within Borno undetected for the past 5 years.
Matshidiso Moeti
“We are deeply saddened by the news that two Nigerian children have been paralyzed by polio,” Matshidiso Moeti, MBBS, WHO Regional Director for Africa, said in a WHO press release. “The government has made significant strides to stop this paralyzing disease in recent years. The overriding priority now is to rapidly immunize all children around the affected area and ensure that no other children succumb to this terrible disease.”
Details of an outbreak response plan are currently being finalized, but will consist of three large-scale supplementary immunization activities using bivalent oral polio vaccine, according to the surveillance report. The first will begin within the next 2 weeks, the organization wrote, with subsequent rounds conducted every following 2-3 weeks.
Michel Zaffran
“We are confident that with a swift response and strong collaboration with the Nigerian government, we can soon rid the country of polio once and for all,” Michel Zaffran, MEng, director of polio eradication at WHO and GPEI, said in the press release. “This is an important reminder that the world cannot afford to be complacent as we are on the brink of polio eradication — we will only be done when the entire world has been certified polio-free.”
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While this is an unfortunate setback for all those who have worked tirelessly to end polio, we are confident that in this moment, they will redouble their efforts and stop polio transmission.
Areas such as north-eastern Borno and surrounding areas in other countries in the region that have ongoing dynamic security issues are a challenge to polio surveillance and vaccination efforts. In collaboration with national and international partners, we are actively planning a regional response aimed at strengthening surveillance and immunization activities to overcome this challenge.
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The two cases of polio, caused by wild poliovirus type 1 (WPV1) in northeastern Nigeria’s Borno State, are of concern. No cases of Type 1 polio had been detected in Nigeria since July 2014. The detection of polioviruses after almost 2 years without viruses raises concerns about surveillance quality, because prolonged circulation of virus had not been detected. This prolonged transmission has happened in an area where access has been compromised for a long time and — while acute flaccid paralysis (AFP) and environmental surveillance is ongoing, and mass campaigns known as Supplemental Immunization Activities (SIAs) have been conducted — the security situation in that region has obviously affected the quality and the comprehensiveness of these activities.
Fortunately, Nigerian health authorities with strong support from WHO and other agencies are launching an aggressive response which should terminate transmission, including several mass vaccination campaigns with type 1-containing oral polio vaccine. The campaigns will also likely cover other nearby countries to make sure WPV1 does not circulate.
The cases highlight the need for continued vigilance, continued intense surveillance for polioviruses and rapid vigorous responses to polioviruses when detected. The detection of the new cases reinforces the current requirement for certification of eradication which states that there must be no polio detected for at least 3 years in the presence of high “certification level” surveillance. Continued poliovirus circulation is a threat not only to the populations in which the virus circulates, but our own domestic health security. Hence, it is critical to continue support of the Global Polio Eradication Initiative (GPEI) until success is achieved.