Covid-19: are digestive disorders linked to the gut microbiota?
Although at present there is nothing to confirm a link between infection and gut microbiota, several signs nonetheless point towards an association with the digestive system. Certain precautionary measures are therefore justified.
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Fever, cough and respiratory distress are three symptoms of COVID-19, but they are not the only ones. A first studya has reported that half of patients testing positive for coronavirus also complain of digestive symptoms such as loss of appetite, diarrhea and, to a lesser extent, vomiting or abdominal pain.
Excluding loss of appetite, which is not specific to intestinal disorders, about one in five patients involved this study had strictly digestive symptoms which worsened with the aggravation of COVID 19.a The incidence of diarrhea varied widely between studies (2%-34%)a,b but the genetic material of the virus –or even active virus (i.e. able to spread)– was found in patients’ fecesc-e, suggesting that it may multiply in our digestive system. Another study showed an imbalance of the intestinal flora (dysbiosis) in two patients aged 65 and 78 years who subsequently died from COVID 19f; however, the link between intestinal dysbiosis and COVID-19 seems of little relevance here since it is well known that elderly people typically display gut flora imbalances.g Lastly, a debateh has recently kicked off about the potential role played by Prevotella bacteria in the infection, but to date no scientific evidence has confirmed any such role.
Admittedly, these initial findings are open to criticism, since the studies were carried out in a limited number of patientsf, and some of them were not subject to peer review prior to publication.f Despite this, the findings warrant caution. For example, on March 16, 2020, the (sidenote: ANSM French Agency for the Safety of Medicines and Health Products ) enhanced precautionary measures in the case of fecal microbiota transplants in order to prevent intestinal infections due to the transmission of other pathogens through Clostridium difficile treatment. Enhanced precautions will also apply to patients suffering from inflammatory bowel disease, particularly to those treated with immunosuppressants, who are more susceptible to viral infections, even if specific datab are still lacking. While they are not advised to discontinue immunosuppressive treatment (the risk of flare-up far exceeds other), they must carefully comply with prevention measures.b
a. Lei Pan, Mi Mu, Pengcheng Yang et al. Clinical characteristics of COVID-19 patients with digestive symptoms in Hubei, China: a descriptive, cross-sectional, multicenter study. Am J Gastroenterol. 2020 May;115(5):766-773.