ISLAMABAD: For the first time in the country’s history, all the environmental samples for polio have tested negative.

A total of 40 samples, collected under the supervision of the World Health Organisation (WHO) in mid-April from 14 cities, were analysed at the National Institute of Health (NIH).

A sample is deemed positive if the polio virus is found in sewerage water, which is the basic parameter to determine if anti-polio campaigns have been successful.

While cases of polio can be reported from any city, due to the frequent movement of people, if the virus is found in sewerage it means the anti-polio campaign in that area did not achieve its target.

Experts say opportunity to eradicate poliovirus during low transmission season must not be missed

The presence of the poliovirus in sewerage also means that the immunity level of children in the area has fallen, and they are at risk of contracting the disease.

The head of the National Emergency Operation Centre (EOC), Dr Rana Safdar, said the negative environmental samples were “great news” for the country.

But he added that while it was a notable achievement, this did not mean the poliovirus had been eradicated.

“Polio cases have been reported in some areas, which means the virus is still present in small pockets. However, an opportunity has been created to eradicate the virus during the current year,” he told Dawn.

A health expert, who is not authorised to speak on the record, said the negative samples are good news, but it is necessary to analyse the trend of the virus.

“The trend of the virus also shows that it can be eradicated. We had two major hubs of the virus: Peshawar and Karachi. In Peshawar initially we used to get three positive samples. Then it declined to two, and then one. Now not a single environmental sample has been found positive. The trend in Karachi is the same,” he said.

“The summer season makes the results more important because the poliovirus becomes active in high temperatures,” he said.

“Negative samples show that the intensity of the virus has decreased. If it remains low until September, the polio programme should run an aggressive campaign during the low transmissions season; that is the only way the virus can be eradicated.”

He said: “We had a similar opportunity in 2005, when 28 polio cases were reported but we missed the train. Now we have an opportunity once again, and we should not let the string slip again. If the intensity of the virus increases it will take many years to reach this stage.”

So far, 11 polio cases have been reported this year, which has decreased from 54 reported last year.

Of the 40 samples, one was collected from Islamabad, Jacobabad and Hyderabad each, two from Rawalpindi, Killa Abdullah and Sukkur each, three from Peshawar, Multan, DG Khan, Faisalabad and Quetta each, four from DI Khan and seven from Karachi.

Last year, 22pc of the environmental samples tested positive, and 9pc of the samples tested positive in the first three months of this year.

A health expert said the samples were collected in the presence of WHO surveillance officers and taken to the NIH.

Dr Safdar said it has been decided that after Ramazan small-scale campaigns will be conducted in focus areas where children’s immunity level is low.

“The low transmission season will start in September, so after that, nationwide campaigns will be held to eradicate the virus for good,” he said.

Published in Dawn, May 28th, 2016