Coronavirus Fecal Transmission: Why Flushing the Toilet Might Spread the Virus

Researchers realized months ago that the coronavirus is shed in feces, though few scientists considered it much of a threat. But now there's a new report suggesting that coronavirus fecal transmission is entirely plausible—spread by airborne particles created when we flush.

The review, published in the journal Environmental International, summarizes COVID-19 outbreaks in which aerosol transmission of virus-containing bodily secretions (produced when we cough, sneeze, or poop) may played a role. In one case in China's Guangdong Province, traces of SARS-CoV-2 were detected on the sink, faucet, and shower handle of a long-vacant 16th-floor apartment right above a bathroom used by five people with confirmed COVID-19. Did it waft up through the sewer pipes? Investigators wanted to know, so they set up a simulation to test the possibility of aerosol fecal transmission, and what they found was, well, kind of gross. Viral particles were found on the building's 25th and 27th floors, where two cases of COVID-19 per floor were confirmed.

While it's possible the transmission occurred via a shared elevator, the authors of the review paper note that the event is consistent with a 2003 SARS outbreak in Hong Kong, where clusters of cases were traced to long-range aerosol transmission in a large apartment complex. The new report adds to previous evidence that, yes, America, it appears that the coronavirus spreads through the air, not just via coughs and sneezes, but perhaps flushes too. Another solid reason to close the lid before flushing.

What we know about coronavirus fecal-oral transmission

According to research from the Chinese Center for Disease Control and Prevention (CCDC), those with confirmed cases of the novel coronavirus (aka, COVID-19) have live virus in stool specimens. It means that COVID-19 could be transmitted via a fecal-oral route. Separately, two papers posted online in Gastroenterology on March 3 suggested that the virus sheds into the stool and that fecal-oral transmission is possible.

Essentially, COVID-19 can pass from person to person "if an infected person does not wash their hands properly after using the bathroom," Jeremy Brown, MD, director of the Office of Emergency Care Research at the National Institutes of Health and author of Influenza: The Hundred-Year Hunt to Cure the Deadliest Disease in History, tells Health. He adds that lots of infections—including Hepatitis, cholera, and viruses that cause gastroenteritis—are also transmitted this way.

Another investigation, published February 17, 2020 in the journal Emerging Microbes & Infections found that rectal swabs may be the best method for testing for COVID-19. After testing oral swabs, anal swabs, and blood samples from patients at the Wuhan Pulmonary Hospital in central China, researchers found that anal swabs can detect novel coronavirus even when oral tests come up negative. The virus can also be detected via blood, per researchers.

Some symptoms of COVID-19 come into play here, too. While most agencies have reported coronavirus symptoms to mimic the flu, with fever, cough, and shortness of breath, a February 7, 2020 investigation published in the Journal of the American Medical Association (JAMA) found that, out of 138 patients in a Wuhan hospital, 14 of them experienced symptoms of diarrhea and nausea one or two days prior to development of fever and labored breathing.

Overall, these findings can help explain why COVID-19 seems to be spreading so rapidly—especially in situations where people are in close contact with each other, like cruise ships. "This virus has many routes of transmission, which can partially explain its strong transmission and fast transmission speed," explains the CCDC report.

And from a public health standpoint, the researchers explain that their findings have “important public health significance”—that by practicing proper hygiene, the disease has a better chance of being kept at bay. Those practices include, "strengthening health publicity and education; maintaining environmental health and personal hygiene; drinking boiled water, avoiding raw food consumption, and implementing separate meal systems in epidemic areas; frequently washing hands and disinfecting of surfaces of objects in households, toilets, public places, and transportation vehicles; and disinfecting the excreta and environment of patients in medical facilities to prevent water and food contamination from patients’ stool samples,” according to the CCDC.

Overall, Dr. Brown says the findings underscore the importance of "good hand washing hygiene, as well as careful and hygienic food preparation" in preventing the spread of any disease—apparently now, COVID-19 included.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.