Top doctors give lowdown on tricky virus

A Chinese University study found that Covid-19 remains in patients' stool even after it is cleared from the respiratory tract.

Researchers said the results showed that stool tests could provide a way to detect early cases involving patients that do not show any respiratory symptoms.

A team analyzed more than 339 stool samples from 14 confirmed patients, with the virus being detected in all their feces regardless of their degree of illness.

"All of our patients studied saw coronavirus detected in their stool, which should lead us to be very careful about the possibility of transmission through contamination of environments such as toilets," said Paul Chan Kay-sheung, head of microbiology.

The study aimed to understand the distribution of the virus within the body by collecting respiratory, blood, urine and fecal samples.

Researchers said three out of 14 patients tested still had the virus in their feces for one to two days despite the virus no longer being present in their sputum and saliva.

Aside from feces, the virus is also present in all sputum samples.

The results show that sputum contains the highest coronavirus concentration - containing more than 300 times the quantity found in deep-throat saliva and more than 200 times the amount found in feces.

The experts added that testing sputum was the "best choice" for virus detection.

The team is currently working with the government to perform stool and saliva tests on 100 asymptomatic persons who have had close contact with Covid-19 patients, said Francis Chan Ka-leung, dean of medicine and director of the Centre for Gut Microbiota Research.

According to the Hospital Authority, stool samples are only collected if patients suspected to be infected report they have diarrhea.

"[People] must be extra vigilant of hand hygiene because if carriers have this virus residing in their stool then there's always a risk of transmitting the virus through contamination of the environment," Chan said.