COVID-19 is primarily known as a respiratory disease, but a new study suggests it can also infect the intestinal tract for weeks or even months after clearing the virus from the lungs. As a reminder, the digestive tract undoubtedly plays an important role in the prolonged symptoms of Covid-19:the High Authority for Health (HAS) considers that about 20% of patients report digestive symptoms during the protracted phase of COVID. These disorders can be chronic diarrhea as the most common symptom (approximately 6 to 10% of patients) or even gastroesophageal reflux. No mechanism has been identified to date, but several hypotheses have been put forward, in particular a consequence of the stress generated by the epidemic, a persistent digestive viral infection, over-inflammation of the body or even anomalies of the intestinal microbiota.
Still, in this study conducted by researchers from Stanford University School of Medicine and published in the journal “Med”, about 1 in 7 COVID patients have continued to clear genetic remnants of the virus in their stool for at least four months after their initial diagnosis, long after they have stopped clearing the virus from their airways. This phenomenon particularly affects people who are infected and who suffer in this context from persistent gastrointestinal symptoms such as nausea, vomiting and abdominal pain. ” The study is the first to assess the presence of viral RNA in fecal samples from individuals with mild to moderate COVID-19 taken at various times after they fell ill. This adds to growing evidence that SARS-CoV-2 (the virus that causes COVID-19) actively infects the gut. », explains the scientific team.
No risk of contamination, but something to watch out for
This is reassuring that this discovery does not mean that there is a transmission of the virus by the fecal route: it has isolated fragmented genetic material rather than intact infectious viral particles. But the results highlight a possible viral reservoir that could partly explain the presence of digestive symptoms that affect a minority of patients for months after their initial infection. ” Nobody really knows what’s causing the long COVID. says Professor Ami Bhatt. “But our study shows that SARS-CoV-2 can hide in the gut for months. Perhaps the long COVID, and the wide variety of symptoms it causes, is due to the immune system’s response to viral proteins in hidden reservoirs throughout the body. »
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For this study, the research team took advantage of an early clinical trial launched in May 2020 at Stanford to test a possible treatment for mild COVID infection. More than 110 patients have been followed to monitor the progress of their symptoms, and regular fecal samples have been taken to track their viral shedding by analyzing the presence of virus DNA. The researchers then found that about half of the patients (49%) excreted viral genetic material in their stool during the first week after their diagnosis. In addition, about 13% of people still excreted viral RNA four months later after clearing the virus from their airways, and about 4% of patients still excreted viral RNA in their stool seven months after their initial diagnosis.
« It is not known why some infected people have gastrointestinal symptoms. But other coronaviruses are known to infect the gut of animals, so the idea isn’t far-fetched. adds Professor Ami Bhatt. The researchers, however, were unable to isolate enough viral RNA to determine which variant had infected the participants. In addition to demonstrating the extent to which COVID-19 causes a wide variety of symptoms, the study also has the merit of showing the interest of monitoring the epidemic via wastewater, which some cities have already chosen to do. to apply. Thereby, ” these findings have implications for public health efforts to predict emerging COVID outbreaks by testing a community’s sewage for evidence of the virus. concludes the scientific team.
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