Fecal–Oral Transmission of SARS-COV-2: Practical Implications

Dear Editors:

We read with great interest the study by Xiao et al¹ on evidence for gastrointestinal infection of coronavirus disease-19 (COVID-19). Testing for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA in stool specimens of 73 hospitalized patients resulted in virus detection in 53.4% of patients, both with and without gastrointestinal manifestations (ie, diarrhea, nausea, vomiting, gastrointestinal bleeding). In addition, COVID-19 nucleic acid was positive in feces of 23.3% of patients in which respiratory samples had already turned negative. Stool positivity after respiratory sample switched negative had already been reported by Tang et al.² As the authors stated, these findings support a possible role of fecal–oral transmission and suggest the need of enhanced control measures, especially during the convalescence period of infected patients.

However, the reported data have also other potential consequences that deserve further investigations. First, stool sampling could be a complementary, noninvasive test for initial diagnosis. Currently, real-time reverse transcriptase polymerase chain reaction test for COVID-19 nucleic acid in nasopharyngeal swabs is the recommended modality for etiological diagnosis.³ However, false-negative results are documented and can be responsible of misdiagnoses or missed isolation of sources of infection.^{4 , 5} Even if the study by Xiao et al¹ evaluated only patients with positive throat swabs, stool sampling could be effective for detecting viral load even in patients with negative nasopharyngeal swabs. Large-scale studies would be useful to determine accuracy of this noninvasive test.

Furthermore, with the growing spread of COVID-19 infection, concerns should raise on how to guarantee safety for Endoscopy operators. Undetected cases (asymptomatic patients or during the latency period) could undergo endoscopy for many indications. Currently, local authorities from a high-incidence area in Italy recommend the use of extraordinary personal protective equipment only for microaerosol-generating procedures, including esophagogastroduodenoscopy. However, unrecognized exposure to potentially infectious biologic samples during endoscopy is well-documented;^{5 , 6} thus, the presence of SARS-CoV-2 RNA in stools, as found in the present study, could lead to a not negligible risk of transmission also for colonoscopy in endemic areas, especially in absence of additional protection measures. Dedicated personal protective equipment should be provided to all clinical staff.

In conclusion, evidence on fecal–oral contagion by SARS-COV-2 is growing. Stepping up infection control measures both among the general population to avoid fecal–oral transmission, and the health care workers operating in the endoscopy room, would be highly desirable.