A Pilot Study on Viral Load in Stool Samples of Patients with COVID-19 Suffering from Diarrhea

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be detected in the stool samples of patients with coronavirus disease 2019 (COVID-19), and this virus can be transmitted via the oral-fecal route. However, there are only few reports on the viral load in the stool samples. In this pilot study, we aimed to evaluate the clinical characteristics and viral load of SARS-CoV-2 in the stool samples of 13 patients with confirmed COVID-19 using pepper mild mottle virus as a control, which has been proposed as a potential marker of human feces contamination in the environmental water bodies. SARS-CoV-2 RNA was detected in the stool samples of four patients (31%), and among them, three exhibited symptoms of diarrhea. One patient who suffered from long-term diarrhea (22 days) exhibited highest level of viral RNA in the stool sample (8.28 log10 copies/g). However, we could not harvest SARS-CoV-2 from the stool sample of any patient, even after culturing with VeroE6/TMPRESS2 cells for four weeks. Our results suggest that SARS-CoV-2 RNA can be detected in the stool samples of patients with COVID-19 suffering from diarrhea. However, further studies elucidating the relationship between SARS-CoV-2 viral load in the stool samples and symptoms of diarrhea in large cohorts and upon adjusting other causative factors and virus infectivity are still warranted.