Covid patients shed virus through faeces for prolonged period: NIV study
A study conducted by Pune’s National Institute of Virology (NIV) found that many Covid patients continue to shed the virus through faeces, even as their nasal and throat swabs become negative
Mumbai A study conducted by researchers at Pune’s National Institute of Virology (NIV) found that many Covid patients continue to shed the virus through faeces, even as their nasal and throat swabs become negative.
Of the 280 stool samples that were studied, nearly 62% had the presence of the viral RNA. The researchers found that patients with complications or those admitted to the intensive care units (ICUs) during Covid, shed the virus for a longer duration of up to 55 days, while asymptomatic or those with mild symptoms shed the virus in 28 to 40 days.
“This raises the possibility of the faecal-oral route of transmission of SARS-CoV-2 in developing countries, where patients are asymptomatically infected as they stay in crowded places, slums, etc,” said the study published in the Frontiers in Medicine on March 15.
The study found that nearly 15.4% of the patients had gastrointestinal symptoms, however, the presence of viral RNA in the faeces was not related to the presence of such gastrointestinal symptoms or to the severity of the disease.
“Our study reported the presence of RNA of SARS-CoV-2 as well as the whole genome sequence of SARS-CoV-2 from the stool specimens. However, it is difficult to comment on transmission potential unless we isolate the virus (live whole virus) directly from the stool specimen,” said Dr Mallika Lavania, one of the authors of the study.
“The work for isolating the virus from the stool specimen is in progress. It will help in confirming the possibility of faecal-oral route or aerosolization as a possible route of transmission,” she said.
The study highlights that the viral particles within the faeces, if aerosolized, have great involvement in compact environments, such as cruise ships, hospitals, individual households, and densely populated housing, especially in regions with poor sanitation. “There are several potential risk factors and risky practices predisposing human health to risks in developing countries, such as poor wastewater management, poor sanitation and hygiene, high risk of co-infections, and lack of surveillance systems, promoting the SARS-CoV-2 faecal-oral transmission,” it stated.
The viral shedding points to the importance of wastewater surveillance to track the circulation of variants. In this study, Lavania and the co-authors sequenced the viral RNA and they found that the variants detected in the samples were the same as those circulating within the community.
“Wastewater surveillance can be helpful to capture the presence of SARS-CoV-2 virus RNA for the major circulating variants. Data on sequencing from wastewater testing can support human clinical specimen testing,” said Lavania.
Many countries are now tracking wastewater in order to predict the pattern of possible spurts or future variants. Mumbai’s civic body is also in the process of starting wastewater surveillance.
“Wastewater surveillance can be even more beneficial if carried out in areas with vulnerable populations such as old age homes or hospitals,” said Dr Nerges Mistry, director of the Foundation for Medical Research (FMR), a Mumbai-based institution devoted to advanced laboratory research in the field of neurology, immunology and microbiology.