Role Of Fecal Excretion In Spread Of SARS-CoV-2 'Cannot Be Ignored'

The novel coronavirus (SARS-CoV-2) stays significantly longer in stool than in the lungs and serum, suggesting that the management of stool samples is important for controlling the virus, clinicians in China report.

Dr. Tingbo Liang and colleagues of First Affiliated Hospital in Hangzhou estimated the viral load from 3497 respiratory, stool, serum, and urine samples from 96 patients with SARS-CoV-2 infection.

Infection was confirmed in all patients via sputum and saliva samples, they report in a fast-track report in The BMJ. In addition, viral RNA was detected in the stool of 55 (59%) patients, in the serum of 39 (41%) patients, and the urine of only one patient.

The average lifespan of the virus was 22 days (range 17-31 days) in stool compared to 18 days (range 13-29 days) in respiratory tissue and 16 days (range 11-21 days) in serum, the researchers report.

Based on this finding, they say the role of fecal excretion in the spread of SARS-CoV-2 "cannot be ignored; however, the importance of high detection in stool samples in the prevention and control of the SARS-CoV-2 epidemic requires comprehensive and careful evaluation."

They also found that the virus persists for a longer period and peaks later in respiratory tissue in people with severe disease. The average duration of virus in respiratory samples of patients with severe disease was 21 days (range 14-30 days) compared with 14 days (range 10-21 days) in those with mild disease.

In those with mild disease, the viral loads peaked in respiratory samples in the second week after disease onset, whereas viral load continued to be high during the third week in those with severe disease.

"These findings suggest that reducing viral loads through clinical means and strengthening management during each stage of severe disease should help to prevent the spread of the virus," the authors write.

They also observed that the virus lasts longer in men than women and in patients over age 60 years, which may partly explain the high rate of severe illness in older patients.

By way of limitations, they note that this was a single center cohort study, and the sample size was inadequate to compare the effects of antiviral therapy in different subgroups, "which could lead to an unbalanced distribution of confounders when evaluating viral shedding and viral load. Secondly, viral load is influenced by many factors. The quality of collected samples directly affects the viral load, so the study of viral load only partly reflects the amount of virus in the body."

Dr. Liang did not respond to a request for comment by press time.

—Reuters Staff

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