… the toilet plume — an airborne dispersal of microscopic particles created by the flush of a toilet — is a real phenomenon and, in some cases, a valid public health concern. Flushing a toilet produces both aerosol droplets that mix with the air in the room and larger droplets that land on and contaminate surrounding surfaces.
Scientists have long been interested in the possibility of toilet plumes as a vector for infectious diseases. Epidemiologic studies have found evidence implicating toilet plumes in disease outbreaks on cruise ships, in restaurants, on airplanes, and within apartment complexes. Virtually all of these cases involved pathogens that are both highly concentrated in feces or vomit and able to survive on surfaces for a relatively long time — like the norovirus, which is not only copiously excreted in feces and vomit but also able to survive for weeks on hard surfaces and resistant to some common cleaning agents.
Fortunately, when it comes to these characteristics, norovirus and SARS-CoV-2, the virus that causes the COVID-19 illness, appear to have very little in common. We know that SARS-CoV-2 can be killed by common disinfectants. We also know it has a comparatively short half-life on hard surfaces — 5.6 hours on stainless steel, 6.8 hours on plastic.
But is infectious SARS-CoV-2 virus found in feces? The answer to that question is a bit more equivocal.
We’ve known for some time that viral RNA from SARS-CoV-2 is found in feces. In fact, based on one estimate that a person infected with COVID-19 sheds between 56.6 million and 11.3 billion viral genomes per day, projects are now underway in Tempe, Arizona, and elsewhere to track community spread of the virus through wastewater analysis. But viral RNA is just a calling card of sorts. It indicates that the person who made the feces has been infected with SARS-CoV-2, but it doesn’t necessarily indicate the presence of infectious viral particles.
In fact, a detailed virological analysis of COVID-19 in nine patients, published in April, revealed no evidence of infectious virus in feces. While researchers found very high levels of infectious virus in samples from patients’ throats and lungs during the course of their illnesses, particularly during the first week, they were unable to isolate infectious viral particles in stool samples, despite finding very high concentrations of viral RNA.
However, a more recent report in the CDC journal Emerging Infectious Diseases describes finding live, infectious SARS-CoV-2 in the stool sample of a 78-year-old patient in China. The patient was severely sick with COVID-19 and later died. Researchers concluded that the finding “affirms the potential for fecal–oral or fecal–respiratory transmission and warrants further study.”
