Coronavirus disease 2019 (COVID-19) is known to result in gastrointestinal symptoms and liver damage. Consideration needs to be given to COVID-19 as a potential cause of new-onset gastrointestinal symptoms. Awareness of special issues affecting patients with chronic gastrointestinal and liver diseases in a pandemic is important.
Respiratory symptoms are the classic symptoms of coronavirus disease 2019 (COVID-19), but some people with COVID-19 can experience gastrointestinal symptoms such as diarrhoea, nausea and vomiting without any respiratory symptoms.1 Faecal swab and intestinal biopsy specimens from patients with COVID-19 have tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid, confirming active viral replication in the gastrointestinal tract.2 SARS-CoV-2 has been isolated from the stool samples of patients with COVID-19, indicating the possibility of faecal-oral transmission.3
The liver can be affected in COVID-19. It is recognised that abnormal liver enzyme levels are common in patients with COVID-19 and correlate with the severity of illness.4
The Gastroenterological Society of Australia (GESA) COVID-19 guidelines on inflammatory bowel disease (IBD), liver diseases and endoscopy were published in 2020 and made appropriate recommendations for management during the pandemic.5-7 This review of COVID-19 in the gut and liver emphasises issues relevant to primary care.
Mechanism of SARS-COV-2 infection and the gut
SARS-CoV-2, the virus that causes COVID-19, enters cells by latching onto protein receptors called angiotensin converting enzyme 2 (ACE2) receptors (Figure 1). These receptors are found in respiratory cells but are also highly expressed in the cells lining the oesophagus and the enterocytes of the ileum and colon.8 Two other proteins found in the membranes of cells, transmembrane serine proteases 2 and 4 (TMPRSS2 and TMPRSS4), help to promote SARS-CoV-2 infection of enterocytes.9 The mechanism by which SARS-CoV-2 does damage to the gastrointestinal tract is not fully understood.
Gastrointestinal implications of COVID-19
What is clear is that COVID-19 can result in gastrointestinal symptoms. One in six people hospitalised with COVID-19 may show only gastrointestinal symptoms at presentation.10 Gastrointestinal symptoms appear to be common, with one review of more than 25,000 patients with COVID-19 finding that about 18% had gastrointestinal symptoms before or at the same time as onset of respiratory symptoms.11 The most common symptom was diarrhoea, the next nausea, and vomiting was the third most common. Abdominal pain is considered rare. In some studies, diarrhoea affected one in three people hospitalised with COVID-19.12,13
Critically ill patients with COVID-19 have a higher rate of gastrointestinal symptoms than critically ill patients without COVID-19, but it does not appear that there is an increased mortality from COVID-19 for patients with gastrointestinal symptoms.14-16