Four in 10 Patients With Coronavirus Infection Shed Virus in Stool

By Linda Carroll

June 16, 2020

(Reuters Health) - While just 12% of patients with confirmed SARS-Cov-2 infection experience gastrointestinal symptoms, 40.5% have viral RNA in their stool, a new study suggests.

In a meta-analysis of 29 studies that included more than 4,800 patients, researchers found that gastrointestinal symptoms are common and fecal shedding may present an important transmission risk, according to the report published in JAMA Network Open.

"First, this shows that diarrhea, nausea and vomiting can be symptoms of COVID-19," said the study coauthor, Dr. Sravanthi Parasa, a gastroenterologist at Swedish Medical Center in Seattle. "Second, and this is a more significant public health concern, among those who were tested positive for the virus in their stool by PCR, 40% had viral shedding."

At present it's not known if the virus detected in patients' stool samples is infectious, Parasa said.

But if it is, Parasa said, "a lot of exposure could happen through a fecal oral route through food handling or in public restrooms - if you were to use a restroom after someone who was pre-symptomatic or asymptomatic, you could potentially contract the virus (if it becomes aerosolized)."

To look at how common GI symptoms such as nausea, vomiting, diarrhea were, as well as liver enzyme changes and and fecal shedding, Parasa and her colleagues scoured the recent literature. Ultimately the researchers included 23 published studies and six preprint articles, which contained data on a total of 4,805 patients with a mean age of 52.2 years.

Based on pooled data, the researchers found that 12% of patients showed any GI symptoms, with 7.4% reporting diarrhea and 4.6% reporting nausea or vomiting.

Eight of the studies reported on fecal testing for the virus in a total of 407 patients. Viral RNA was detected in feces in 40.5% of the patients. Under electron microscopy, two stool samples (1.3%) showed live virus.

Overall, viral loads in stool samples were lower than in respiratory samples (range, 550 copies per mL to 1.21 × 105 copies per mL versus 641 copies per mL to 1.34 × 1011 copies per mL).

While it's clear that people can test positive for virus in their stool, it's not known whether the virus particles found in feces can infect anyone, said Dr. Saurabh Mehandru, an associate professor of gastroenterology at the Icahn School of Medicine at Mount Sinai in New York City.

The concern, clearly, is that there could be fecal-oral transmission, Mehandru said. But it's not clear that that is possible, he added.

"And this paper does not address that," Mehandru. "It's a basic science question: is the virus coming out infectious? Will it survive the acidity of the stomach and infect the intestines?"

Unlike the norovirus, say, SARS-CoV-2 has an envelope of lipid covering it, Mehandru said. That lipid layer makes the virus more susceptible to stomach acid, he explained. "It's a pretty hostile environment," he said.

SOURCE: JAMA Network Open, online June 11, 2020.