ISLAMABAD: Wild poliovirus type 1 (WPV1) has been detected in four more sewage samples taken from previously infected districts, taking the tally of current year’s environmental samples to 112.

The confirmation was made by the Regional Refer­ence Laboratory for Polio Eradication at the National Institute of Health which said that three samples collected from different districts of Karachi and one sample collected from Pishin have been found positive.

The samples were genetically linked to the imported YB3A cluster of WPV1.

According to a lab official, the virus was found in sewage samples of 33 districts this year so far.

“All positive samples and the two human cases reported this year contain YB3A cluster, which disappeared from the country in 2021, remained in circulation in Afghanistan and was reintroduced through cross-border transmission last year,” he said.

“Samples of sewage water from the area are a basic parameter to determine the success of polio campaigns. Moreover, the presence of virus in sewage also shows that the immunity level of children in the area has fallen and they are at risk of catching the disease,” he said

Published in Dawn, May 8th, 2024