ISLAMABAD: A strain of Type-1 Wild Poliovirus (WPV1) genetically lin­k­­ed to Afghanistan, has been detected in Peshawar dist­r­ict, Pakistan’s National Pol­io Laboratory at the Na­­tio­nal Institute of Health (NIH) confirmed on Tuesday.

The detection of the virus in sewage samples has enhanced the current year’s tally to 11. This is the fifth time that a strain linked to the Afghan gen­o­­me was found in Pakistan, indicating active cross-border transmission.

According to details provided by NIH, the environmental sample was colle­c­ted from the Naray Khuwar collection site, located in the outskirts of Peshawar.

This is the third positive sample from the same collection site, and the fourth positive sample from Pe­­sh­awar this year. A positive strain was observed in Lar­ama collection site in May, an NIH official told Dawn.

The discovered sample is classified as a YB3A cluster, a strain of Type 1 polio that can be deadly if not treated at the first stage. It is 99.11 per cent genetical­ly linked to the environmental sample of Asadabad (Af­­ghanistan) which was collected in September 2022.

The last Wild Poliovirus case from the district was reported in July 2020, the official said, adding that in year 2023, only one case of polio was reported from Bannu.

He explained that collection of sewage samples from different areas of a district is a basic parameter to determine the success of polio campaigns. It also helps in tracking the immunity level of children and calculate the risk of spread of disease.

The Pakistan Polio Programme is already testing for poliovirus at 114 fixed environmental sites in the country every month.

Published in Dawn, July 5th, 2023