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With COVID-19, you want to place barriers between you and the coronavirus at every possible source. That includes masks, physical distance … and toilet lids? It’s clear that respiratory droplets containing COVID-19 particles can transmit through coughing, sneezing and even talking or singing. It’s possible that gastric secretions – from stool or diarrhea – containing active virus can spread COVID-19, as well.
Fecal-oral spread means coronavirus-infected stool or diarrhea coming into contact with a person’s mouth. It’s being evaluated as a potential risk by researchers. Toilet plumes containing aerosolized coronavirus, released by flushing and lingering in the air or possibly landing on surfaces, may pose another concern.
Scientists are currently investigating these areas for their potential to spread COVID-19 from virus in stool:
- Gastrointestinal shedding or release of active coronavirus through feces.
- Fecal-oral transmission through inadequate hand-washing.
- Aerosolized virus released into the air by toilet plumes.
- Exposure risk from infected stool in hospitalized patients with COVID-19.
- Ventilation systems that might spread aerosolized virus in hospitals, high-rises and building complexes.
- Air hand-dryers propelling virus in public restrooms.
Here’s what experts are learning about coronavirus risk from infected stool.
It’s possible that COVID-19 could also spread by fecal-oral contact or toilet plumes. “We in the GI community have been expressing concern about this for months, since the beginning of the pandemic, but didn’t have objective evidence yet that infectious virus could pass in stool,” says Dr. Brennan Spiegel, director of health services research at Cedars-Sinai Medical Center in Los Angeles. “But now we do have a few lines of evidence that are concerning.”
Active or “live” coronavirus has been identified in stool of patients with severe COVID-19. Diarrhea is a gastric symptom of COVID-19. Among new concerns is a report from China, published by the Centers for Disease Control and Prevention, in which investigators recovered evidence of live virus in stool. “Not just genetic material, but infectious virus,” says Spiegel, who is also the co-editor-in-chief of the American Journal of Gastroenterology and a professor in the David Geffen School of Medicine at UCLA.
Fecal-oral transmission is known to spread viral infections like hepatitis A. “COVID is a new illness from a new virus,” says Dr. Carmen McDermott, an internal medicine physician, hospitalist and a faculty member in the residency program at Providence Sacred Heart Medical Center in Spokane, Washington. She is also a clinical instructor at University of Washington School of Medicine and co-author of a recent evidence review on potential hospital exposure. “But, extrapolating from other experience with closely related viruses, it was worth exploring the question and we proposed that it needed further research to clarify whether it was a concern.”
Flushing the toilet can release a plume of virus-containing aerosols. “If infectious virus can come out of the stool, how can that spread to another person?” Spiegel asks. “One worry is fecal-oral, where, let’s say, a restaurant worker didn’t clean his or her hands and passes it into the food.” However, he says, “It’s not clear to me that fecal-oral transmission, in the traditional sense as with hepatitis A or other fecal-oral bugs, is occurring here.” On the other hand, he adds: “The toilet-plume theory is starting to gain traction.”
Hospital workers and patients face exposure to infected stool. Shared hospital bathrooms, an influx of COVID-19 patients with gastric symptoms like diarrhea, potential exposure through ventilation systems and lack of protective equipment such as masks, glove and gowns may promote fecal virus spread, although it’s uncertain to what extent.
Bathroom surfaces may provide several routes for COVID-19 to spread. Bathrooms are high-traffic areas for viruses to spread. “Any surface in the bathroom could have the potential to have different microbes on it,” McDermott says. “Especially ones that are high-touch surfaces like a soap dispenser. Even the handles of the sinks and doorknobs could have viruses and bacteria on them.”
Practicing good hygiene makes sense in general. In terms of fecal-oral transmission, “The risks are real but being overblown,” says Dr. Joshua Septimus, an associate professor of clinical medicine and medical director of Houston Methodist Primary Care Group Same Day Clinics. “The risks of being infected from a toilet plume are quite low. And the risks of getting COVID-19 from touching contaminated surfaces are fairly low, as well – as long as you wash your hands and don’t touch your face.”
Restroom Prevention Tips
These restroom habits help buffer against nasty infections, possibly including the novel coronavirus.
- Hand-washing is crucial. Take at least 20 seconds to scrub your hands with soap and water. “Since many folks are now carrying hand sanitizer with them, after hand-washing in restrooms, if they have to touch any surfaces while leaving, just apply hand sanitizer right after exiting,” McDermott advises.
- Paper towels are helpful. Dry your hands with paper towels rather than air-dryers, which may spread germs. Also, use a paper towel as a barrier between your hands and high-touch surfaces. “I actually have a practice of grabbing a paper towel and using it the open the door as I exit the bathroom to keep my hands clean,” McDermott says.
- Toilet lids – if available – should be down. Could automatic-flush toilets spew out bio-aerosols with extra force and greater potential risk than regular toilets? In general, lids provide a barrier between toilet contents and the environment. “Certainly, if you have a toilet with a lid, it’s best to close the lid when you flush,” he says. “But the reality is that that public toilets don’t have lids.”
- Masking in restrooms matters. Don’t think “alone at last” and then take off your mask in a gas station or restaurant restroom. “The likelihood of infection when someone flushes the toilet in a public restroom is very low, particularly if you’re wearing a mask,” Septimus says. “Because even if there is some aerosolization of virus in the fecal plume, if you’re wearing a mask that at least reduces your exposure.”
- Avoid restroom crowds. Wait until restrooms are fairly empty before using. Stand a few sinks apart from other users. “Flush and rush” – don’t linger and chat.
Toilet Etiquette at Home
Sharing a bathroom doesn’t mean you want to share germs. Take these simple but sanitary measures to protect yourself and those around you:
- Put the toilet lid down between uses.
- Have separate toilet paper rolls for household members or roommates – particularly if any have confirmed or suspected COVID-19.
- After using toilet paper, putting down the lid and flushing, avoid touching your face until after you’ve washed your hands.
- Have individual towels for drying your hands.
- Use a household disinfectant to clean the toilet bowl, flush handle and seat after each use, if possible.
- Sanitize high-touch areas like sinks, door knobs and light switches.
Research Red Flags
Some research suggests that gastric secretions could be hazardous and calls for increased attention to ventilation systems and restroom sanitation in health care facilities, multi-unit residences, public venues and households.
- High-rise spread. Nine patients infected with COVID-19 were identified among families living in a 29-story high-rise apartment building near Hong Kong. Fecal aerosol transmission via toilet flushing from one apartment to others may have caused the outbreak, according to circumstantial evidence in the Sept. 1 study in the Annals of Internal Medicine.
- Infectious COVID-19 in stool. Infectious coronavirus was isolated from feces of a patient in China with severe COVID-19 who died of the disease, as reported in the August issue of Emerging Infectious Diseases, a CDC journal. Viral particles were also detected in cells from the patient’s gastrointestinal biopsy sample. Several other patients with severe COVID-19 also had infectious coronavirus identified in their feces samples.
- Hospital fecal transmission. “Put a Lid on It,” headlined a new evidence review by McDermott and colleagues. Published in the July issue of the Journal of Hospital Infection, the review looked at COVID-19 transmission risk related to toilet flushing and fecal bio-aerosols, in light of the COVID-19 crisis in the hospital system. “Transmission of virus shed in feces through bio-aerosols may be an under-recognized infection control issue for health care facilities with high numbers of patients shedding virus in stool,” the researchers noted.
- COVID-19 pneumonia and hospital spread. In a single hospital center in Wuhan, China, 138 patients developed COVID-19 pneumonia. Of these cases, 41% were suspected to be caused by hospital-related transmission. Overall, 26% of patients were placed in intensive care and 4.3% died, according to findings published Feb. 7 in JAMA.
- Physics of flushing. Flushing toilets – and urinals – in public restrooms can release virus-infected aerosol particles that could potentially infect people nearby, according to recent findings. In one study, researchers at Yangzhou University in China used fluid dynamics and simulation models to analyze flushing-induced turbulent flow. The study appeared online June 16 in the journal Physics of Fluids.
- Hand-dryers and virus dispersal. Several years before the COVID-19 pandemic, researchers compared potential for dispersing viruses during hand-drying with paper towels versus air dryers. Jet-air dryers, in particular, led to increased amounts and distance of germs being spread from contaminated hands into the air. Warm-air dryers, which use evaporation, spread somewhat more germs than paper towels but less than jet-air dryers in the February 2016 Journal of Applied Microbiology study.
- SARS outbreak in housing complex. Severe acute respiratory syndrome is similar to COVID-19. A SARS outbreak that ultimately affected more than 300 residents of a Hong Kong housing complex was analyzed in the April 22, 2004, New England Journal of Medicine. The outbreak was traced to an initial SARS patient with diarrhea. Using computer models based on airflow dynamics, researchers concluded that the SARS virus was spread by contaminated aerosols generated by flushing. Toilet plumes were released in the air shafts between two housing units and carried by the wind to other buildings in the complex.
Keep fecal transmission risk in perspective. You’re far more likely to become infected with COVID-19 through respiratory droplets than toilet plumes. “There are three big things that are going to help us control COVID – masks, social distancing and hand-washing,” Septimus says. “Those three things haven’t changed.”