What gastrointestinal symptoms can covid-19 cause?
Lack of appetite, nausea, vomiting, diarrhoea, and abdominal pain. These may not be the symptoms people expect with covid, but around 50% of people experience them after SARS-CoV-2 infection, and in some people they’re the only symptoms.1 Gastrointestinal (GI) symptoms may be the first sign of infection or may develop later and persist as part of long covid.
Sheena Cruickshank, immunologist at the University of Manchester, tells The BMJ why doctors didn’t initially recognise GI symptoms as part of covid-19. “The frequency of gastric symptoms—anorexia, pain, diarrhoea, vomiting, rectal bleeding—has varied considerably from 12-61% in publications,” she says, explaining that this variance may be due to GI symptoms not being reported as linked to covid. “However, it’s clear that this has the potential to be a major symptom.”
When SARS-CoV-2, the virus that causes covid, enters the lungs it gains entry to epithelial cells by binding to angiotensin converting enzyme 2 (ACE2) receptors. These receptors are found on epithelial cells in many parts of the body and are numerous on those of the small and large intestines.2
Cruickshank says, “One of the reasons for the gut symptoms may be that the ACE2 receptors that the virus uses to enter and hijack cells are found on our gut epithelial cells. We know that viral RNA has been isolated from stool samples, although this may not be infectious.” This evidence was gathered early in the pandemic from studies in China,34 which found SARS-CoV-2 RNA in stool samples from patients in hospital. More recent research5 has confirmed that faecal shedding of viral RNA happens in around half of covid patients and that this is associated with GI symptoms.
Stephen Griffin, virologist at the University of Leeds, explains why we shouldn’t be surprised that so many people experience GI symptoms. He says, “The receptor for SARS-CoV-2, ACE2, is widely expressed within the blood vessels and lining of the gut, and we know that the virus can be detected, recovered from, and sequenced both in stool samples and in wastewater from the environment—which is an excellent, real time way to monitor infections and genetic variability.”