CURRENT EPIDEMIOLOGY OF POLIO IN PAKISTAN
As of 21st January, a total of fifty eight wild poliovirus (WPV) cases (55 type-1, 2 type-3 and 1 mixed typo-1 & type-3) have been reported during the year 2012 from twenty eight districts/ tribal agencies. Fifteen circulating Sabin-2 Derived poliovirus cases have also been reported for 2012 so far. Moreover WPV-1 has also been isolated from 87 out of 236 environmental samples (of the available results) collected during 2012 from large urban populations in the four major provinces.
This compares with 198 wild poliovirus cases in 2011 indicating 70% decrease in the number of reported polio cases in 2012. Likewise there is 53% decrease in the number of districts with polio cases (60 in 2011 compared to 28 in 2012). The proportion of the WPV positive environmental samples nationally indicates 29% decrease in 2012 (37% WPV positive samples out of the total 231 samples) as compared to 2011 (66% WPV positive samples out of the total 205 samples). It is of note that environmental surveillance was expanded to 3 more large cities in 2012, bringing the total number of cities with environmental surveillance to 11. Type-3 wild poliovirus was isolated in 2012 only from Bare Shall of Khyber Agency; last type-3 case had onset of paralysis on 18th April. WPV-3 was not isolated in environmental samples collected in 2012.