20% To 30% Of Covid-19 Cases Have Diarrhoea — Dr Tan Poh Tin

An estimated 20 per cent of Covid-19 patients are likely to experience diarrhoea soon after contracting the disease.

A young working adult recently saw his general practitioner for diarrhoea of two days’ duration. He had no vomiting or nausea. He was treated for food poisoning.

Later that night, he had fever, shivering and flu-like symptoms. He self-tested negative with a Covid Ag test.

On the following day, he had a cough, a sore throat and lost his sense of smell first, and then his sense of taste. A repeat Antigen test (different brand from the first) was positive. His PCR test confirmed he had Covid-19.

This patient has kindly allowed me to share his story so we can all learn about less well-known Covid symptoms to minimise delays in diagnosis and the inadvertent spread to close contacts. 

An estimated 20 per cent of Covid-19 patients are likely to experience diarrhoea soon after contracting the disease. People whose immune systems are compromised are at greatest risk of getting diarrhoea, which can include vomiting and nausea.

Researchers from the Faculty of Medicine, Chinese University of Hong Kong (CuMed) investigated the stool samples of 15 Covid-19 patients in Hong Kong between February and April 2020. 

Active gut viral infection was found in seven patients in the absence of gastrointestinal symptoms. Three patients continued to display active viral infection up to six days after clearance of the virus from their respiratory samples (nasal swabs negative). 

From March 29 to August 31, 2020, they offered free stool tests for asymptomatic arrivals at Hong Kong Airport, especially children and those who needed it.

Of the 2,128 stool samples collected, the Covid-19 detection rate was 0.28 per cent. Six asymptomatic children were confirmed to be Covid-19 positive.

“Viral load in the stool of infants and children is many times higher than that in adults, and could be equivalent to that of adult respiratory samples. The viral infection and replication also persist longer in their guts,” said Prof Paul Chan, chairman of the Department of Microbiology and associate director of the Centre for Gut Microbiota Research.

“This makes the stool test a better option for Covid-19 screening in babies, young children and those whose respiratory samples are difficult to collect,” he added.

Gut microbiota of patients with high Covid-19 infectivity is also characterised by the enrichment of pathogens and loss of ‘good’ bacteria, hence the CUMed recommendation for the use of probiotics and micronutrients for confirmed cases.

A paper, Evidence for Gastrointestinal Infection of SARS-CoV-2, was later published by the Department of Infectious Diseases, Sun Yat-sen University, Guangdong, China, in March 2020.

53.4 per cent of 73 hospitalised Covid-19 patients from February 1 to 14, 2020 tested positive for SARS-CoV-2 RNA in their stool.

The age of patients with positive results ranged from 10 months to 78 years old.

The duration for positive stool results ranged from one to 12 days. Seventeen (23.3 per cent) patients continued to have positive results in their stool after showing negative results in respiratory samples.

A few cities in China (Beijing, Shanghai and Qingdao) require Covid-19 anal swab tests, in addition to nasal or throat swab tests, for some international arrivals.

According to the Chinese Centre for Disease Control, the anal test is performed with a sterile cotton swab (like a very long ear bud), that is inserted 3 cm to 5 cm (1.2 inches to 2 inches) into the anus before being gently rotated out.

There are three points to be noted:

  1. Diarrhoea (for a duration of 4.1 ± 2.5 days) can be an initial symptom of Covid-19. This was observed before and after diagnosis.
  2. Once you have a fever from Covid-19, you have already been infected, and have likely been contagious for several days.
  3. A new loss of sense of smell or the inability to taste food is strongly suggestive of Covid-19. You can test by regularly smelling strongly scented items e.g. coffee grounds, vinegar, scented candles, or flowers.

Dr Tan Poh Tin is a consultant paediatrician and public health specialist.

  • This is the personal opinion of the writer or publication and does not necessarily represent the views of CodeBlue.

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