key: cord-262735-xj9md751 authors: Li, Lian Yong; Wu, Wei; Chen, Sheng; Gu, Jian Wen; Li, Xin Lou; Song, Hai Jing; Du, Feng; Wang, Gang; Zhong, Chang Qing; Wang, Xiao Ying; Chen, Yan; Shah, Rushikesh; Yang, He Ming; Cai, Qiang title: Digestive system involvement of novel coronavirus infection: Prevention and control infection from a gastroenterology perspective date: 2020-05-12 journal: J Dig Dis DOI: 10.1111/1751-2980.12862 sha: doc_id: 262735 cord_uid: xj9md751 An epidemic of an acute respiratory syndrome caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in Wuhan, China, now known as coronavirus disease 2019 (COVID‐19), beginning in December 2019, has attracted an intense amount of attention worldwide. As the natural history and variety of clinical presentations of this disease unfolds, extrapulmonary symptoms of COVID‐19 have emerged, especially in the digestive system. While the respiratory mode of transmission is well known and is probably the principal mode of transmission of this disease, a possibility of the fecal‐oral route of transmission has also emerged in various case series and clinical scenarios. In this review article, we summarize four different aspects in published studies to date: (a) gastrointestinal manifestations of COVID‐19; (b) microbiological and virological investigations; (c) the role of fecal‐oral transmission; and (d) prevention and control of SARS‐CoV‐2 infection in the digestive endoscopy room. A timely understanding of the relationship between the disease and the digestive system and implementing effective preventive measures are of great importance for a favorable outcome of the disease and can help climnicians to mitigate further transmission by taking appropriate measures. Currently, available data show that gastrointestinal involvement in COVID-19 is relatively infrequent compared with MERS and SARS. Among the 1602 patients enrolled in the 10 case series reported, 55 had diarrhea (average 5.6%, range 2%-33.98%), and 72 had nausea or vomiting symptoms (average 4.49%, range 1%-10%) ( Table 1) . 1, [4] [5] [6] [7] [8] [9] [10] [11] [12] A recent study found that almost half of 99 patients with COVID-19 showed liver involvement to some degree, with variable degrees of elevated alanine aminotransferase and aspartate aminotransferase. Although the exact cause remains obscure, it may be related to direct liver damage caused by COVID-19 or antiviral drugs. 6 The involvement of the digestive system in COVID-19 may be underestimated as most patients initially develop respiratory symptoms. Gastrointestinal symptoms were not recognized or were neglected at the early stage of this epidemic outbreak until the first case was reported in the USA, when coronavirus RNA was identified in the patient's stool sample. 8 Moreover, it is necessary to find ways to prevent transmission through the sewage system. Gastrointestinal manifestation in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection above, by adopting single-cell RNA-sequencing technology from two cohort samples, a recent study has shown that ACE2 is highly expressed in cholangiocytes rather than the hepatocytes or other interstitial cells. Therefore, during the diagnosis and treatment of patients with SARS-CoV-2, clinicians should pay special attention to their liver function. 17 However, another study pointed out that ACE2 also participated in the prevention of inflammation of the intestine by regulating innate immunity, cellular cytotoxicity, and energy metabolism ( Figure 1 ). Nevertheless, it is necessary for clinicians to note that the digestive system may be invaded by SARS-CoV-2 and evolve into an alternative source of infection. Although there been no solid evidence to confirm that SARS-CoV-2 can be transmitted through the fecal-oral route, this possibility exists as the virus has been successfully isolated in a stool or anal swab of patients with COVID-19, which is almost as accurate as a pharyngeal swab. 18, 19 Moreover, SARS-CoV-2 was also detected in the stool sample of patients in rehabilitation, which stays positive longer than in the swab. 20 Table 2 and Figure 3 . SARS-CoV-2 is a serious threat to human health worldwide due to its strong ability for human-to-human transmission. In the early days of the disease outbreak, medical staff focused on screening for respiratory symptoms. However, as the disease progresses and understanding unfolds, digestive symptoms related to COVID-19 have also been identified. A literature review has shown that the SARS-CoV-2 and the SARS that broke out in 2003 belong to the same β-coronavirus family and possess highly similar genomes. 24 In addition, the receptors for both SARS and SARS-CoV-2 is ACE2. 25 Therefore, it is not difficult to understand why SARS-CoV-2 may give rise to digestive system symptoms similar to those induced by SARS-CoV. A recent case series in China has confirmed that SARS-CoV-2 nucleic acid which is negative in throat swabs can still be detected in the feces of three COVID-19 patients, two of whom manifested diarrhea before treatment. 26 Nevertheless, as it remains unknown whether the virus in the digestive system is derived from cellular fragments from the respiratory system or consists of replicates in the digestive tract, it is sensible to take early steps to prevent fecal-oral transmission both in the hospital and in the community. Additional clinical case reports and laboratory studies are needed to confirm the existence of this transmission route. More importantly, efforts should be made to formulate the clinical protocols and develop antiviral drugs targeting the digestive system in the future. All authors have no conflicts of interest or financial ties to disclose. None. 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