05/04/2020
In early March, a 71-year-old Michigan woman returned from a Nile River cruise with bloody diarrhea, vomiting, and abdominal pain. Initially doctors suspected she had a common stomach bug, such as Salmonella. But after she developed a cough, doctors took a nasal swab and found her positive for the novel coronavirus. A stool sample positive for viral RNA, as well as signs of colon injury seen in an endoscopy, pointed to a gastrointestinal (GI) infection with the coronavirus, according to a paper posted online in The American Journal of Gastroenterology (AJG).
Her case adds to a growing body of evidence suggesting the new coronavirus, like its cousin SARS, can infect the lining of the lower digestive tract, where the crucial ACE2 receptors are abundant. Viral RNA has been found in as many as 53% of sampled patients’ stool samples. And in a paper in press at Gastroenterology, a Chinese team reported finding the virus’ protein shell in gastric, duodenal, and re**al cells in biopsies from a COVID-19 patient. “I think it probably does replicate in the gastrointestinal tract,” says Mary Estes, a virologist at Baylor College of Medicine. Recent reports suggest up to half of patients, averaging about 20% across studies, experience diarrhea, says Brennan Spiegel of Cedars-Sinai Medical Center in Los Angeles, co–editor-in-chief of AJG. GI symptoms aren’t on CDC’s list of COVID-19 symptoms, which could cause some COVID-19 cases to go undetected, Spiegel and others say. “If you mainly have fever and diarrhea, you won’t be tested for COVID,” says Douglas Corley of Kaiser Permanente, Northern California, co-editor of Gastroenterology.
The presence of virus in the GI tract raises the unsettling possibility that it could be passed on through f***s. But it’s not yet clear whether stool contains intact, infectious virus, or only RNA and proteins. To date, “We have no evidence” that f***l transmission is important, says coronavirus expert Stanley Perlman of the University of Iowa. CDC says that based on experiences with SARS and with the virus that causes Middle East respiratory syndrome, another dangerous cousin of the new coronavirus, the risk from f***l transmission is probably low.
The intestines are not the end of the disease’s march through the body. For example, up to one-third of hospitalized patients develop conjunctivitis—pink, watery eyes—although it’s not clear that the virus directly invades the eye. Other reports suggest liver damage: More than half of COVID-19 patients hospitalized in two Chinese centers had elevated levels of enzymes indicating injury to the liver or bile ducts. But several experts told Science that direct viral invasion isn’t likely the culprit. They say other events in a failing body, like drugs or an immune system in overdrive, are more likely driving the liver damage.
