Many viral respiratory infections (e.g. Severe Acute Respiratory Syndrome [SARS], Middle East Respiratory Syndrome [MERS], Influenza, Adenovirus) are detectable in faeces as these viruses can cause infection in the gastrointestinal system.  Individuals may also ingest the virus by swallowing their own nasal or respiratory secretions (if infected) or those of an infected individual, or by swallowing material from contaminated environments, such as food or water.  

There is presently inconclusive evidence as to whether infection of the GI system with SARS-CoV-2 occurs. Several studies have shown that infection of the GI system appears to be possible (Study 1, Study 2, Study 3) and one study has detected SARS-CoV-2 genetic material in samples of the oesophagus, stomach, duodenum and rectum of two patients with severe cases of COVID-19. Reports of GI symptoms from COVID-19 patients also suggest the virus may infect the GI system. There is some evidence that SARS-CoV-2 may not survive the harsh conditions of the gastrointestinal tract (specifically the colon), potentially explaining why few studies have detected infectious virus in faeces. More evidence is needed to confirm if and to what extent COVID-19 is transmitted by faecal-oral routes. However, even if faecal-oral transmission is possible, its relative importance as a transmission route is likely to be limited compared with person to person transmission via respiratory droplets and surfaces.

Author: Jackie Knee

Review: Tom Heath, Robert Dreibelbis, Oliver Cumming, Karin Gallandat, Kate Medlicott
Last update: 13.08.2020