New evidence supports the possibility of gastrointestinal infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as a possible feco-oral route of transmission, according to results of a study published in Gastroenterology.
Currently, SARS-CoV-2 infection causes primarily a respiratory-based constellation of symptoms. Due to the respiratory nature of symptoms, it has been hypothesized that the virus infects respiratory epithelial cells, and is transmitted via respiratory droplets from human to human. However, viral target cells and organs have not been explicitly identified, creating a significant gap in the current understanding of the pathogenesis of SARS-CoV-2 and its transmission routes. Moreover, a recent case report detected SARS-CoV-2 viral RNA in stool samples, thus challenging these hypotheses.
Therefore, researchers examined stool samples obtained between February 1 and February 14, 2020 from 73 patients hospitalized as a result of SARS-CoV-2 infection for viral RNA. Results demonstrated that 53.42% of these patients had positive samples for SARS-CoV-2 RNA. The samples remained positive for a range of 1 to 12 days; of note, 23.29% of patients had positive stool samples after respiratory samples were negative for viral RNA.
One patient also provided esophageal, gastric, duodenal and rectal tissues. This patient, a man aged 78 years, was admitted to a hospital in the Guangdong Province, China on January 17, 2020. Real-time reverse transcriptase polymerase chain reaction testing (rRT-PCR) was positive for SARS-CoV-2, and the patient experienced 10 days of a respiratory illness with the hallmarks of COVID-19. On day 10, however, he presented with coffee-ground gastric contents in his gastric drainage tube. Fecal occult blood testing indicated an upper gastrointestinal bleed; subsequent endoscopy found mucosal damage to the esophagus, and esophageal, gastric, duodenal, and colonic samples were taken for testing. Hematoxylin and eosin staining showed no significant damage, but numerous infiltrating plasma cells and lymphocytes as well as interstitial edema were seen in the lamina propria of the stomach, duodenum and rectum.
Most significantly, results demonstrated positive angiotensin converting enzyme 2 (ACE2) protein staining, mainly in the cytoplasm of gastrointestinal epithelial cells. It has been previously shown that SARS-CoV-2 uses this protein as a viral receptor for its entry process. Immunofluorescence testing showed that ACE2 was abundantly expressed in the glandular cells of gastric, duodenal and rectal epithelia of the above mentioned patient, as well as other patients. These data demonstrated that infectious virions are being secreted from gastrointestinal cells of people with SARS-CoV-2 infection, and thus support a potential for feco-oral transmission of the virus.
Because >20% of the study cohort demonstrated positive viral RNA in stool samples after negativity in respiratory samples, researchers “strongly recommend that rRT-PCR testing for SARS-CoV-2 from feces should be performed routinely in SARS-CoV-2 patients.” Further, they concluded that prevention of feco-oral transmission should be considered in infection control strategies.
Xiao F, Tang M, Zheng X, Liu Y, Li X, Shan H, Evidence for gastrointestinal infection of SARS-CoV-2 [published online March 3, 2020]. Gastroenterology. doi:10.1053/j.gastro.2020.02.055