Introduction
Diarrhea, vomiting and fever are common symptoms in children, while the fifth most common clinical findings of COVID-19 disease are gastrointestinal symptoms. On the other hand, the hypothesis that SARS-CoV-2 is much lower in children than in adults has been questioned. And the evidence suggests that prevalence of SARS-CoV-2 in children is not 2%, but 15%. [1] Now, the question arises that, in which patients should we suspect SARS-CoV-2 related gastroenteritis given that diarrhea can have viral, bacterial, parasitic, and non-infectious causes?
Clinical studies have shown that, expression of the Angiotensin-Converting Enzyme 2 (ACE2) is not only high in the lung AT2 cells, but also in GI tract especially upper esophagus, liver, epithelial cells and absorptive enterocytes from ileum and colon [2, 3] and then, gastrointestinal symptoms such as diarrhea will occur. According to studies, intestinal involvement and diarrhea is seen in 2% to 50% of COVID-19 cases, as well as in 20 to 30 % of cases, gastrointestinal findings such as diarrhea are the first presentation of the disease and pulmonary symptoms appear in the following days. So involvement of the gastrointestinal tract and lungs may occur independently of each other.[4]
Usually at this stage of the disease, there is diarrhea without mucus and blood, but if there are complications such as pseudomembranous colitis, intussusception and HUS, there will be exudative diarrhea. Although in COVID-19 disease, diarrhea may be due to drug side effects, but the gastrointestinal tract can be directly involved through ACE2 receptors and indirectly through the gut lung axis. Also in Multi systemic inflammatory syndrome (MIS-C) caused by SARS-CoV-2, diarrhea can be watery or exudative. The average duration of diarrhea in COVID 19 is 4 days and the frequency of defecation varies from 3 to 30 times per day.[4, 5] The number of virus particles in the feces of patients with diarrhea is higher than in patients without diarrhea, and the virus is excreted in the feces for several weeks.
Intestinal involvement in COVID-19 has been reported in up to 50% of studies. The duration of hospitalization, duration of elevated liver enzymes, coagulopathy and high inflammatory markers in patients with diarrhea are higher than patients without diarrhea, and if these conditions are observed, the patient’s prognosis is worse.[4, 6, 7]