Seven cases of extinct poliovirus detected.

Byline: Ikram Junaidi

ISLAMABAD -- Seven cases of the vaccine-derived poliovirus type 2 - a type of the crippling disease for which vaccination in Pakistan were stopped in 2014 - have been detected in the northern areas of the country over the past few months, it has officially been confirmed.

Sources claimed that officials concerned had been reluctant for some time to admit that there was any case of the vaccine-derived poliovirus type 2 in the country.

'It is not a wild poliovirus outbreak. It is an outbreak of Sabin-Like Type 2 Derived (SLT2D). Similar outbreaks have been recently reported in Philippines, China, Indonesia, Nigeria, Democratic Republic of Congo and several other countries in Africa which have completely eradicated the poliovirus,' Special Assistant to the Prime Minister on Health Dr Zafar Mirza told Dawn.

There are three serotypes of wild poliovirus type 1, type 2, and type 3 each with a slightly different capsid protein.

Pakistan has been giving Type 1 and Type 3 viruses in Oral Polio Vaccines (OPVs), but had stopped administering Type 2 vaccine in 2014 and the virus could not be found even in environmental samples since 2016.

An environmental sample is declared positive if virus is found in sewage water.

'However, suddenly cases have been reported from different areas which mean there was some vial left in some laboratory or somewhere else and started spreading due to human error. Just after getting the cases, which cannot be included in the number of wild polio virus, we sent samples to the lab of Centres for Disease Control and Prevention (CDC), Atlanta, and after getting the confirmation, that children were paralysed due to Type 2 polio virus, we...