Coronavirus (SARS-CoV-2) in gastroenterology and its current epidemiological situation: An updated review until January 2021

Coronaviruses are positive-sense single-strand RNA viruses that infect amphibians, birds, and mammals. Coronavirus Disease 2019 (COVID-19) has become a major health problem caused by one of the coronaviruses called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has spread fast throughout the globe since its first identification in Wuhan, China, in December 2019. Although COVID-19 is principally defined by its respiratory symptoms, it is now clear that the virus can also affect the digestive system causing gastrointestinal (GI) symptoms like diarrhea, loss of appetite, nausea/vomiting, and abdominal pain as a major complaint. GI symptoms could be the initial signs of preceding respiratory signs, carrying a potential for slowed investigation and raised disease transmission opportunities. Various studies recognized the COVID-19 RNA in stool specimens of infected patients, and its viral receptor angiotensin-converting enzyme-2 (ACE-2) is highly expressed in GI epithelial cells. Many cases were reported negative using nasopharyngeal/oropharyngeal swabs and finally, SARS‐CoV‐2 RNA was detected in their anal/rectal swabs and stool specimens. These suggest that COVID-19 can actively infect and replicate in the GI tract. In this review, we elaborate on the close relationship between SARS-CoV-2 and the digestive system, focusing on the current status in the field of COVID-19 in gastroenterology, liver injury, endoscopy, inflammatory bowel disease, imaging, and the potential underlying mechanisms with illustrating the current epidemiological status regarding this pandemic.