Attaching clinical significance to COVID-19-associated diarrhea

The Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), erupted in 2020 and created severe public health and socioeconomic challenges worldwide. A subset of patients, in addition to presenting with typical features such as fever, cough and dyspnea, was also afflicted with diarrhea. However, the clinical features and prognoses related to COVID-19-associated diarrhea have not attracted sufficient attention. This review of the medical literature examines the incidence, pathogenesis, clinical characteristics, fecal virus changes, prognoses and influencing factors of COVID-19-associated diarrhea. The reported incidence of diarrhea in patients with COVID-19 ranged from 2% to 49.5%. The main cause of diarrhea was found to be invasive by SARS-CoV-2 of ACE-2-expressing epithelial cells of the small intestine, causing local intestinal damage. This cellular invasion may be the key factor for the much longer duration of SARS-CoV-2 positivity observed for feces compared to pharyngeal swabs. The associated diarrhea in these patients upsets the balance of intestinal flora, resulting in more-severe disease intensity and worse prognosis. Clinicians should be vigilant to this kind of COVID-19-associated diarrhea, and design more effective prevention and treatment options for patients with positive fecal nucleic acid tests and intestinal microflora disorders.