Profile of polio-compatible cases in Nigeria, 2006-2016.

BACKGROUND: The tremendous progress made by Nigeria towards polio eradication has recently suffered a setback with the isolation of circulating vaccine-derived poliovirus (cVDPV) type 2 from environmental samples and confirmation of four wild poliovirus (WPV) cases from acute flaccid paralysis (AFP) cases, with dates of onset of paralysis in July and August 2016. All these viruses were confirmed from the security-challenged northeastern state of Borno. Polio-compatible cases exist in Nigeria, and they indicate surveillance failure. Surveillance, therefore, has to be strengthened for the country to achieve certification. The objective of this paper is to highlight the epidemiological profile and magnitude of polio-compatible cases in Nigeria during the reporting period, as well as immunization and surveillance response activities conducted to close immunity and surveillance gaps. METHODS: We conducted a retrospective review of AFP surveillance performance and polio-compatible cases in Nigeria between 2006 and 2016 from the AFP database at the World Health Organization Country Office. We also reviewed and compared key epidemiological features of polio-compatible cases with those of wild poliovirus cases during the reporting period. RESULTS: The non-polio AFP rate improved from 6.5 in 2006 to 19.5 in 2016. The corresponding figures for stool adequacy rates were 88 and 98%. The total number of polio-compatible cases reported during the reporting period was 888, with the highest number (194) of cases reported in 2006 and the least (24) in 2016. Clusters of polio-compatible cases were reported every year during the reporting period except in 2015. The highest number (65) of polio-compatible cases in clusters was reported in 2006. The key epidemiological features of polio-compatible and wild poliovirus cases were similar. CONCLUSION: AFP surveillance performance has improved significantly during the reporting period. Surveillance gaps still existed as shown by the presence of orphan viruses and polio-compatible cases, and these gaps need to be identified and closed to achieve certification.

Strategies for Improving Polio Surveillance Performance in the Security-Challenged Nigerian States of Adamawa, Borno, and Yobe During 2009-2014.

BACKGROUND: The security-challenged states of Adamawa, Borno, and Yobe bear most of the brunt of the Boko Haram insurgency in Nigeria. The security challenge has led to the killing of health workers, destruction of health facilities, and displacement of huge populations. To identify areas of polio transmission and promptly detect possible cases of importation in these states, polio surveillance must be very sensitive. METHODS: We conducted a retrospective review of acute flaccid paralysis surveillance in the security-compromised states between 2009 and 2014, using the acute flaccid paralysis database at the World Health Organization Nigeria Country Office. We also reviewed the reports of surveillance activities conducted in these security-challenged states, to identify strategies that were implemented to improve polio surveillance. RESULTS: Environmental surveillance was implemented in Borno in 2013 and in Yobe in 2014. All disease surveillance and notification officers in the 3 security-challenged states now receive annual training, and the number of community informants in these states has dramatically increased. Media-based messaging (via radio and television) is now used to sensitize the public to the importance of surveillance, and contact samples have been regularly collected in both states since 2014. CONCLUSIONS: The strategies implemented in the security-challenged states improved the quality of polio surveillance during the review period.