< Hygiene

Can the SARS-CoV-2 coronavirus be caught by going to the bathroom?

Text updated on 2020-05-03


It is likely that the coronavirus is also caught in the bathroom!

The stool of people infected with the SARS-CoV-2 coronavirus contain numerous viral particles. This appears to be related to the fact that the ACE2 receptor, to which the coronavirus binds to enter cells, is present on the surface of the gastrointestinal tract. As a result, it is possible that the virus can be caught in the toilet: when you flush the toilet, some of the contents of the toilet bowl evaporate as droplets into the air (aerosolization).

In addition, since the beginning of the epidemic, mathematical modelling studies have suggested the existence of an alternative route of transmission of the virus that does not involve direct person-to-person contamination. This alternative route could involve transmission of the virus from stool to the mucous membranes of the face (nose, mouth, eyes).

As a precaution: avoid sitting on the rim of the toilet, clean it regularly, use paper to touch door handles, toilet seat, and toilet flush handles, and close the toilet bowl tightly before flushing. This is important: when you flush the toilet, some of the water from the toilet bowl comes out as droplets. Ventilate the toilet room as often as possible. Caregivers of young children and the elderly should also pay particular attention to handling diapers.


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Sources

DNA from the virus (500-100,000 copies per mL) was found by RT-PCR in the feces of 9 out of 17 infected individuals tested, 0-13 days after the first symptoms. These amounts are less than those observed in respiratory specimens.

Pan, Y., Zhang, D., Yang, P., Poon, L., & Wang, Q. (2020). Viral load of SARS-CoV-2 in clinical samples. The Lancet Infectious Diseases, 20(4), 411-412.

Viral particles were found by RT-PCR in the feces of 8 individuals (including 6 children) among 27 infected people tested. Four weeks after the onset of infection, one adult and two children (2 and 3 years old) still had viral particles in their stool, but no longer had any in their nose and throat swabs.

Ma, X., Su, L., Zhang, Y., Zhang, X., Gai, Z., & Zhang, Z. (2020). Do children need a longer time to shed SARS-CoV-2 in stool than adults?. Journal of Microbiology, Immunology and Infection.

The virus is present in the feces of COVID-19 patients.

Wu, Y., Guo, C., Tang, L., Hong, Z., Zhou, J., Dong, X., ... & Kuang, L. (2020). Prolonged presence of SARS-CoV-2 viral RNA in faecal samples. The Lancet Gastroenterology & Hepatology, 5(5), 434-435.

A meta-analysis of 60 studies, representing a total of 4,243 COVID-19 patients, indicated that 17% of patients had gastrointestinal symptoms and 48% of patients had stool with viral particles during infection. Of these positive cases, 70% of stool samples, collected after observing no sign of the virus in respiratory specimens, still contained the virus.

Cheung, K. S., Hung, I. F., Chan, P. P., Lung, K. C., Tso, E., Liu, R., ... & Yip, C. C. (2020). Gastrointestinal Manifestations of SARS-CoV-2 Infection and Virus Load in Fecal Samples from the Hong Kong Cohort and Systematic Review and Meta-analysis. Gastroenterology.

During the SARS outbreak in 2003, 99 people living in the same building were infected from a single apartment where an infected person had diarrhea. A thorough study shows that flushing triggers resulted in aerosolization of viral particles that were present in the stool. These particles then spread into the bathroom, passed through an exhaust fan and then entered the apartments on the upper floors.

Yu, I. T., Li, Y., Wong, T. W., Tam, W., Chan, A. T., Lee, J. H., ... & Ho, T. (2004). Evidence of airborne transmission of the severe acute respiratory syndrome virus. New England Journal of Medicine, 350(17), 1731-1739.

Even after flushing the toilet several times, some of the viral particles are still present in the water in the toilet bowl. In addition, when you flush the toilet, many droplets containing bacteria and viral particles are formed and can end up more than one meter from the toilet bowl.

Gerba, C. P., Wallis, C., & Melnick, J. L. (1975). Microbiological hazards of household toilets: droplet production and the fate of residual organisms. Appl. approx. Microbiol, 30(2), 229-237.

Discussion on the fecal-oral route of transmission for SARS-CoV-2.

Yeo, C., Kaushal, S., & Yeo, D. (2020). Enteric involvement of coronaviruses: is faecal-oral transmission of SARS-CoV-2 possible? The Lancet Gastroenterology & Hepatology, 5(4), 335-337.

Mathematical modeling that suggests the existence of an alternative route of transmission of the virus that does not involve direct person-to-person contamination.

Ng, T. W., Danchin, A., & Turinici, G. (2020). A new transmission route for the propagation of the SARS-CoV-2 coronavirus. DOI: 10.21203/rs.3.rs-17870/v1 Preprint

In April 2020 in Shanghai, some people testified that in quarantine, back from abroad, before leaving their hotel room, they were asked to decontaminate their bathrooms by adding chlorine tablets in the toilet bowl, waiting 1 hour, and then flushing (Xinyu Jia, personal communication).


Presence of SARS-CoV-2 in wastewater.

Medema, G., Heijnen, L., Elsinga, G., Italiaander, R., & Brouwer, A. (2020). Presence of SARS-Coronavirus-2 in sewage. medRxiv.

ACE2 protein is abundant in the lungs and small intestine.

Hamming, I., Timens, W., Bulthuis, M. L. C., Lely, A. T., Navis, G. J., & van Goor, H. (2004). Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. The Journal of Pathology: A Journal of the Pathological Society of Great Britain and Ireland, 203(2), 631-637.

Indication that the SARS-CoV-2 virus induces lesions in the cells lining the small intestine and could thus lead to gastrointestinal symptoms.

Zhang H, Li HB, Lyu JR, Lei XM, Li W, Wu G, Lyu J, Dai ZM. (2020) Specific ACE2 Expression in Small Intestinal Enterocytes may Cause Gastrointestinal Symptoms and Injury after 2019-nCoV Infection . Int J Infect Dis. 2020 Apr 17. pii: S1201-9712(20)30238-1. doi: 10.1016/j.ijid.2020.04.027.

Further reading

How do you wash your hands?