The World Health Organization (WHO) has detected both the P1 and P3 polio virus in sewage at five different locations along the Yamuna River in Delhi, India, as reported in The Hindu on February 15. Findings are the result of the National Polio Surveillance Project (NPSP), a joint WHO and Delhi government project carried out between April and December 2010. The presence of the wild polio virus was found prior to the Commonwealth Games in October 2010.
C. M. Khanijo, MD, an officer in charge of the Delhi government Pulse Polio immunization drive, said that finding the polio virus in the environment is a cause of concern due to the risk of infection in children. The Delhi government is on alert and has increased surveillance and immunization of susceptible children.
“No wild polio case has been detected in Delhi environmental samples since mid-August 2010, providing additional evidence for the remarkable progress towards polio eradication achieved in India,” Khanijo said, adding, “We have written to the health ministry to increase the surveillance sites from five to over a dozen areas so that samples can be collected from upstream areas.”
The national environmental surveillance was started in Mumbai, India, in 2001.The surveillance can promptly detect polio virus circulation in the sampled area and serve as a supplement to the main polio virus detection strategy that involves the testing of stool specimens from acute flaccid paralysis cases.
The surveillance in Delhi can provide information about polio virus transmission in both adjoining Uttar Pradesh and other areas from where migrants come to the capital.
“The environmental surveillance is very strategic…,” Hamid Jafari, WHO-NPSP project manager, said. “Both Delhi and Mumbai, most frequently visited by migrant laborers, are high-risk areas for repeated introductions of [the] polio virus and are therefore covered in all sub-national immunization rounds along with [the] polio-endemic states of Uttar Pradesh and Bihar.”
P1 and P3 are the two types of polio viruses prevalent in India. The transmission of the most dangerous virus, P1, which caused 95 percent of polio cases in India until 2006, fell to a record low in 2010.
India has reported a 94 percent decrease in polio cases between 2009 and 2010, with only 42 cases reported in 2010 as compared to 741 the prior year. Delhi did not report any polio cases last year, while four cases were reported in 2009 and five in 2008.
