Traces of polio virus in Kolkata sewage, officials raise vigil
HT Correspondent
KOLKATA: Health officials detected the presence of vaccinederived polio virus from sewage waters in Kolkata, prompting authorities to plan large-scale sampling although experts said the discovery does not represent a significant threat.
A vaccine-derived polio virus (VDPV) is a rare variant that mutates from the strain contained in the oral polio vaccine (OPV). “Sewage monitoring goes on throughout the country. This virus was found in a sample in Kolkata. It has been analysed with the help of World Health Organisation (WHO). Most likely it has come from someone’s gut, who is immune deficient and has since multiplied. It is not a case of human to human polio transfer,” NS Nigam, state health secretary told HT.
According to WHO data, India has not reported a VDPV confirmed case since 2016. Globally, 49 confirmed cases of VDPV cases have been recorded since the beginning of this year, according to WHO’S latest epidemiological report on the disease issued on June 7.
The sample detected in sewage was collected earlier this year from Metiabruz area in south-west Kolkata.
Minutes of a meeting at the state health department stated that frequent measles outbreaks and the detection of the VDPV type 1 virus from the sewage sample indicates the need for better surveillance. To ascertain whether the virus is present in any case of clinically diagnosed primary immune deficient (PID) child, stool samples from such children in and around Kolkata may be initiated, an official said.
“We have done an extensive survey in that area. Genome sequencing has also been done by US health agency Centers for Disease Control and Prevention, and WHO. It is not a case of human polio transfer. We would step up the pulse polio immunisation program in that area. This is a reason for caution but definitely not a worry,” said a senior health department official, asking not to be named.
India reported its last polio case from West Bengal’s Howrah on January 13, 2011. A year later, on February 24, 2012, the WHO removed India from the list of ‘endemic countries with active polio virus transmission’.
“It was also decided in the meeting that medical colleges in and around Kolkata would be soon asked to get baseline information about PID cases. Letters would be sent to the principals, medical superintendents and vice principals of medical colleges soon in this connection,” said the person quoted above.
Attending doctors will be requested to counsel guardians of these patients to give stool samples to ascertain their virological status. “The situation is not alarming. This is just a VDPV and we haven’t come across any child who has been infected with polio after 2011. But at the same time, we have to be alert, because if children are left out of the polio immunization program then they might get infected from these VDPV,” said Dr Sabyasachi Roy, pediatrician.