Coronavirus Sewage Study in Hyderabad: Samples were taken from 8 treatment plants and one gated community
A study of sewerage samples by the country's premier research institute in modern biology, the CCMB, suggests that at least 6 lakh people in Hyderabad alone - about 6 per cent of its population - may have contracted the coronavirus. This, when according to the official figures, the overall number of COVID-19 cases in Telangana is under one lakh.
"The numbers do not come as a surprise," CCMB Director Dr Rakesh Mishra told NDTV in an exclusive interview explaining how they harvested sewage samples to check the spread of coronavirus as an infected person not only sheds the virus through the nose and throat, but also faeces for 35 days.
For the study, a collaboration between the CCMB, the Indian Institute of Chemical Technology and the Council of Scientific and Industrial Research, samples were taken from eight water treatment plants and a gated community in the Telangana capital.
"We found at least 2 lakh people could be actively shedding the virus," Dr Mishra said. By extrapolating the data from sewerage covering 80 per cent STPs, but only 40 per cent of all water used in the city, the findings show that over 6 lakh people were symptomatic, asymptomatic or recovered in the last 35 days, he added.
According to the study, a large chuck of the city's COVID-19 patients were asymptomatic, not needing hospitalization.
"Since checking the spread of this pandemic could be a challenge because of absence of symptoms in patients, studying the presence of the virus in sewage could help identify hotspots," Dr Mishra said.
Regular sewage sampling, in collaboration with civic bodies, can help administrations take measures to check spread of coronavirus, he said, adding that the virus was "not infectious" in sewage.
The findings have been posted on medical health sciences preprint server MedRxiv, and is yet to be peer reviewed.
Many countries, including England and Spain, have started monitoring their sewerage for traces of coronavirus to develop wastewater-based COVID-19 surveillance.