Poliovirus detected in Karachi, Peshawar sewage samples

Pakistan's fight against polio faces a new challenge as the National Polio Laboratory at the National Institute of Health in Islamabad has confirmed the detection of Type-1 Wild Poliovirus (WPV1) in four environmental (sewage) samples, with one sample from Karachi testing positive.

A sewage sample collected on August 17 from the Muhammad Khan Colony environmental sample collection site in Karachi's Keamari area has tested positive for the wild poliovirus. This marks the second positive sample in Karachi this year.

Read Poliovirus detected in Rawalpindi’s environmental sample

The isolated virus is classified as part of the YB3A cluster and is genetically linked by 99% to the virus detected in an environmental sample in Nangarhar-Batikot, Afghanistan, on March 1, 2023.

This comes after a recent polio vaccination campaign was conducted in the district from August 7 to August 13. Counting this case, the total number of positive environmental (sewage) samples for 2023 in Pakistan now stands at 21.

There have been two reported cases of poliovirus in Pakistan the current year; one on February 20 and another on July 11 in Bannu.

The other three samples were from Peshawar’s Shaheen Muslim Town, Yousafabad and Tajabad and Hayatabad 1 and 2 tributaries. These mark the tenth positive samples recorded in the district this year. All isolated viruses are classified as part of the YB3A cluster and are genetically linked to the virus detected in a polio case in Behsud, Afghanistan, on May 16, 2023.

The recent polio vaccination campaign (fIPV+OPV) in Peshawar was conducted from August 7 to August 13, but the continuous detection of polio in environmental samples raises concerns about the challenges faced by health authorities in the region.