A pilot study of viral load in stools of patients with COVID-19 and diarrhea

It is known that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be detected in the stools of patients with the coronavirus disease 2019 (COVID-19) and that the virus can be transmitted by oral-fecal route. However, there are few reports on the viral load in stools. This pilot study aimed to evaluate the clinical characteristics and viral load of SARS-CoV-2 in the stools of 13 patients with confirmed COVID-19 using as control the pepper mild mottle virus, which was proposed as a potential indicator of human fecal contamination of environmental water. SARS-CoV-2 RNA was detected in stool samples from four patients (31%), among whom three presented diarrhea symptoms. One patient experiencing long-term diarrhea (22 days) had high levels of viral RNA in the stools (8.28 log10 copies/g). However, we could not isolate the SARS-CoV-2 in the stool of any patients, using VeroE6/TMPRESS2 cells for four weeks. Our results suggest that SARS-CoV-2 RNA may be detected in the stools of patients with the diarrhea symptoms. Further studies evaluating the relationship between SARS-CoV-2 viral load in stools and diarrhea symptoms in larger patient cohorts and upon adjusting for other causative factors and virus infectivity are still needed.