Abstract:

Background: Environmental Surveillance (ES) for polio is assuming a greater relevance as we move closer to a polio-free world. ES involves testing sewage, wastewater or other environmental samples for the presence of poliovirus. Environmental surveillance has been shown to confirm wild and vaccine derived polioviruses even in the absence of human case of paralysis. The resurgence of wild poliovirus (WPV) in Borno state of Nigeria in 2016 was related to insecurity; and Borno bore the most of the brunt of the Boko Haram insurgency in Nigeria. It has now been more than one and a half year since the last WPV was isolated in Borno and the pertinent question is whether poliovirus has been eliminated from Nigeria. Here, we piloted ES sweep, a one-time collection of sewage samples from ES collection sites in partially accessible and inaccessible areas in Borno state from the 15th of March to the 10th of April 2017 to determine whether poliovirus transmission is still ongoing in these areas. Objectives: The main objective of the environmental surveillance sweep is to ascertain whether poliovirus transmission is still ongoing in security compromised areas of Borno state. Methods: Using grab method, one litre of sewage sample was collected per site from 17 of the 27 Local Government Areas (LGAs) in Borno state by four sanitary technicians from the state Ministry of Environment from the 15th of March to the 10th of April 2017. Collected samples were transported in reverse cold chain to Ibadan National Polio laboratory where they were analyzed as per WHO standard operating procedure for environmental surveillance samples. A total of 47 samples were collected over the four weeks’ period. Results: A total of 47 environmental sewage samples were collected from 47 sites in partially accessible and inaccessible areas distributed in 17 LGAs over a period of one month. A total of 35(74.5%) of the samples were negative, 6(12.8%) had Non Polio Enterovirus (NPENT) isolated and 4(8.5%) were Sabin3. We also noted that there was 1(2.1%) Non Enterovirus (NEV) and 1(2.1%) NPENT+ Sabin 3 isolates. Neither WPV nor cVDPV was isolated from the samples.