<p>Sewage surveillance for Covid-19 has shown an increase in positive samples and viral load in Bengaluru.</p>.<p>The Tata Institute of Genetics and Society (TIGS) tests samples from 28 sewage treatment plants in the city every week. All samples collected in the previous two weeks — between February 27 and March 4, and between February 20 and 25 — have turned Covid-positive.</p>.<p>This is a drastic change compared to December, when only around half the collected samples were testing positive.</p>.<p>Viral loads seem to have increased as well.</p>.<p>From January to mid-February, the maximum viral load was within 1,250 (SARS-Cov-2 genome copies per ml). Whereas in the week of February 20 to 25, the maximum levels increased to 2,500. And in the week from February 27 to March 4, the maximum level recorded was 6,000 in Nagasandra.</p>.<p>There has been an overall increase in viral load in other parts of the city as well. Eastern areas like Bellandur and Agara have had relatively high viral loads over the past two weeks.</p>.<p>Farah Ishtiaq, principal scientist at TIGS, said the reason for the rise in positivity isn’t clear yet as genomic sequencing for these samples have not been completed.</p>.<p>And while the BBMP has been reporting high weekly test positivity rates (over 8%) recently, the absolute number of identified cases are still low as fewer tests are being done.</p>.<p>The results of sewage surveillance indicate that a large number of cases may be going undiagnosed in the<br />community.</p>
<p>Sewage surveillance for Covid-19 has shown an increase in positive samples and viral load in Bengaluru.</p>.<p>The Tata Institute of Genetics and Society (TIGS) tests samples from 28 sewage treatment plants in the city every week. All samples collected in the previous two weeks — between February 27 and March 4, and between February 20 and 25 — have turned Covid-positive.</p>.<p>This is a drastic change compared to December, when only around half the collected samples were testing positive.</p>.<p>Viral loads seem to have increased as well.</p>.<p>From January to mid-February, the maximum viral load was within 1,250 (SARS-Cov-2 genome copies per ml). Whereas in the week of February 20 to 25, the maximum levels increased to 2,500. And in the week from February 27 to March 4, the maximum level recorded was 6,000 in Nagasandra.</p>.<p>There has been an overall increase in viral load in other parts of the city as well. Eastern areas like Bellandur and Agara have had relatively high viral loads over the past two weeks.</p>.<p>Farah Ishtiaq, principal scientist at TIGS, said the reason for the rise in positivity isn’t clear yet as genomic sequencing for these samples have not been completed.</p>.<p>And while the BBMP has been reporting high weekly test positivity rates (over 8%) recently, the absolute number of identified cases are still low as fewer tests are being done.</p>.<p>The results of sewage surveillance indicate that a large number of cases may be going undiagnosed in the<br />community.</p>