The Epidemiological Trend of Poliovirus in Nigeria (2009 – 2013)
Nigeria is a major reservoir of poliovirus in the world and until recently the only country with ongoing transmission of all three serotypes namely: wild poliovirus type 1 (WPV1), wild poliovirus type 3 (WPV3), and circulating vaccine-derived poliovirus type 2 (cVDPV2). Nigeria is one of the three remaining endemic countries. As at 2005, Nigeria was responsible for about half of the global burden of polio. The aim of this study was to examine the trend in polio eradication outcomes and that of different types of poliovirus in Nigeria in the last five years.
METHODS:
Secondary data analyses were conducted on the Global Polio Eradication Initiative data of the three serotypes (2009-2013). The trend in proportion of polio cases in Nigeria over the last five years was examined. Mean - comparison test, paired data analysis was conducted to determine the differences among the serotypes of poliovirus. The analysis was carried using Stata / IC 12.1.
RESULTS:
Nigeria recorded 864 polio cases (18% of the global burden) between 2009 and 2013. In 2009, Nigeria had 542 polio cases ( 30% of the total global burden), 48 (3.4%) in 2010, 120 (42%) in 2012 and 58 (13%) in 2013. Over the years the reduction in new cases has not been consistent. The 2012 data shows sudden surge of about three folds. However, the 2013 data showed reduction to 53 (7%), zero and 3(5%) of WPV1, WPV3 and cVDPV2 respectively.
There was no significant difference in the eradication effort outcome among the serotypes over the years; WPV1 and WPV3 (p = 0.109) and WPV1 and cVDPV2 (p=0.2802)
CONCLUSIONS:
Nigeria on the road towards total elimination of poliovirus with the reduction in new cases in the last two years. However, more effort is needed to sustain this drive in Nigeria and the other endemic countries.