PESHAWAR: The testing of environmental water sample positive for poliovirus in Peshawar has triggered investigations to find out the causes of presence of the virus in water that remained free of virus for two consecutive months, according to sources.

The water sample was tested negative twice in the months of May and June in Shaheen Muslim Town, but it tested positive in July.

The health department wants to identify the causes of transportation of the virus and its carriers in the city.

The World Health Organisation has been collecting environmental samples from Shaheen Muslim Town, Larama and Dhando Pul areas from sewerage sites in Peshawar to see presence of poliovirus on monthly basis.

Sample from Shaheen Muslim Town tested negative last month after staying positive since November last year.

`The health department is upset and concerned over presence of poliovirus in the water,` said sources.

The samples from the two other areas have already been tested negative for poliovirus during the past one year.

The emergence of positive water sample alerted the health department to a big threat posed by the results indicating that the virus, which remained non-existent for two consecutive months, was again in circulation.

`The probe, to be completed at the week-end, will identify the mode of transportation of virus and to know as to what went wrong with the campaigns,` said sources.

For this purpose, authorities have been looking into performance of teams deployed for anti-polio vaccination, workload on workers, refusals against oral polio vaccine, missed children, migration of children to the district and issues of social acceptability, monitoring and problems at the union council level to take steps to address the problem.

`Somebody has brought the virus to Peshawar and its presence means unvaccinated children risk infection. There is highly likelihood that more cases will come in future as far as virus stays in the water. The province has cut down polio cases by half this year compared to last year but it is again in limelight,` sources said.

They said that international organisations wanted to scale up vaccination and sustain the success achieved so far in the polio eradication drive.

Peshawar, the capital of Khyber Pakhtunkhwa, has almost half of the country`s 13 polio cases. It can face outbreak and health department is on red alert with plans to carry out vaccination campaigns in high-risk districts, especially Peshawar to protect children from the crippling disease.