Presence of vaccine-derived polio virus detected in sewage Kolkata waters | Kolkata

Health officials detected the presence of vaccine-derived 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 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 analyzed with the help of the World Health Organization (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 said that frequent measles outbreaks and the detection of the VDPV type 1 virus from the sewage sample indicate 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 the 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 immunization program in that area. This is a reason for caution but definitely not to worry,” said a senior health department official, asking not to be named.

India reported its last polio case from Howrah district in West Bengal on January 13, 2011. A year later on February 24, 2012 the World Health Organization 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 (primary immunodeficiency) 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.

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