Hyderabad: The World Health Organization (WHO) on Wednesday said the detection of vaccine-derived polio virus (VDPV) in different parts of the country does not change India’s polio-free status, and described it as a “low-level threat”.
VDPV is a rare strain of the polio virus that is the result of a mutation of the one contained in the oral polio vaccine (OPV).
The agency said between January 2015 and May 2016, a total of 14 sewage samples collected from various parts of the country, including Hyderabad, tested positive for VDPV.
“All of these have been responded to urgently and appropriately with polio vaccination campaigns,” said Henk Bekedam, WHO representative in India, in an email to Mint.
“It’s a low level threat,” Bekedam added.
WHO said the sampling and testing of sewage is an ongoing process for identifying polio virus transmission that might occur in the absence of detected paralytic cases medically known as acute flaccid paralysis.
A type 2 VPDV was detected on 7 June in a sewage sample collected on 16 May from an environmental surveillance site at Amberpet Nala, a sewage canal in Hyderabad.
In the wake of the WHO findings, the Telangana government on Tuesday called on for a special polio immunization drive to vaccinate around 300,000 children in Hyderabad and adjoining Ranga Reddy district, in accordance with WHO protocols to mitigate any risk of the virus spreading.
“The risk of further transmission of the Hyderabad VDPV2 from the environmental sample is found to be low as no children have been found to be affected,” WHO said.
Earlier, the Union ministry for health and family welfare issued a statement saying that no children had been found to be affected by the detected VDPV isolate in the nearby areas.
“Strong measures have been put in place in India to mitigate the risk of an importation and spread of polio virus from countries with continued circulation of polio virus,” the government said.
“The country has done two nationwide polio campaigns this year. Polio vaccination is being carried out at international borders and is a must for people travelling to polio-affected countries,” it added.
The government said that the last case of wild polio virus type 2 in the country was reported 17 years ago in 1999.
In the absence of wild polio virus transmission, WHO declared India polio-free in March 2014, a notable public health milestone in a country where polio was endemic just years before.
The polio eradication programme in India continues to protect children from the crippling disease by conducting two nationwide mass polio vaccination campaigns and two to three sub-national campaigns each year.
India continues to maintain a highly sensitive surveillance system for polio. All cases of acute flaccid paralysis in children up to 15 years are picked up by the polio surveillance network.
Each of these cases is followed up and their stool samples tested for polio virus in WHO-accredited laboratories. In addition, sewage samples are collected from over 30 sites across the country and tested for polio virus at regular intervals.