Polio Eradication

Nigeria is the only country in Africa yet to be certified free of Wild Polio Virus (WPV). The country consists of 36 States and a Federal Capital Territory. Gombe is one of the 19 Polio high risk States in the North-eastern geo-political zone of the country. The last case of WPV isolated in Gombe State was in 2013. One of the strategies for Polio eradication is a sensitive Acute Flaccid Paralysis (AFP) surveillance system in which any AFP is promptly detected and timely investigated. The focus of the investigation is to analyze two faecal samples of the patient, and/or sometimes those from contacts for any possible isolation of Polio Virus (PV). AFP surveillance is meant to be applicable to any human population at any time; however, there are situations in which there are good reasons to suspect that negative results of AFP surveillance are not reliable. Supplementary information is required in such situations and one approach for that is Environmental Surveillance (ES), in which a search for PV is made in environmental specimens contaminated by human feaces. ES in the African region started in Nigeria in July 2011. Since the introduction of this strategy, it has achieved its objective of complimenting the AFP surveillance system. There has been a gradual increase in the number of ES sites in Nigeria from 2011 to date. The increase is largely due to the successes recorded in terms of the PV isolation from the sites, PV epidemiology, the large population size and mobility. The last cases of WPV1 and WPV3 from environmental samples had dates of collection in May 2014 (Kaduna) and July 2012 (Kano) respectively. ES was initiated in Gombe State in December 2016. Four ES sites were identified and sample collection began soon after training of personnel responsible for collection of the sewage sample. The four identified ES sites are Baba Roba Valley, Unguwauku Railway Bridge, Gadan Bayan Moonshine and Dan Gusau Bridge. Since inception of ES in Gombe State, ambiguous Vaccine Derived Poliovirus type 2 (aVDPV2) were confirmed from sewage samples collected from Baba Roba Valley site on the 30th January 2017 and from Dan Gusau Bridge site on the 6th March 2017. In 2018, a circulating Vaccine Derived Poliovirus type 2 (cVDPV2) was also detected from sewage samples collected on the 9th April 2018 from Baba Roba Valley site. We reviewed the laboratory results from the 2 surveillance methods so as to evaluate the VDPV2 isolation rate.

Objective: To evaluate Vaccine Derived Polio Virus 2 isolation rate from Environmental Surveillance and its contribution to Polio Eradication Initiative (PEI).