Can the coronavirus disease spread through sewage?

Wastewater Filtration Sedimentation System

After scientists confirmed that coronavirus is indeed present in the stool of infected patients, the big question now is whether it can spread through sewage. Superficially, it seems that such a mode of transmission is possible. But further analysis of the matter reveals some intricate dynamics of virus transmission that again makes it seem impossible. Needless to say, advanced research on COVID-19 is still ongoing. So far, there has been no concrete evidence of the transmission of the SARS-CoV-2 virus through human feces.

The main transmission method is through the exchange of respiratory droplets. The infected person coughs, sneezes, or spits while talking. The droplets float in the air and an uninfected person inhales them through the mouth, nose, or even eyes. Once inhaled, the virus multiplies first within the respiratory tract and then spreads to other parts of the body. 

One certain part it spreads to is the gastro-intestinal tract. Given that this is the route for excreting human waste, coronavirus finds its way to human feces. 

How long does the COVID-19 virus survive in sewage?

The journey from the respiratory tract to expulsion from the body takes about 3 days. It should not be noted that what has been detected in human waste is the RNA of the SARS-CoV-2 virus. This presents two possibilities:

i) the COVID-19 virus may still be alive

ii) the COVID-19 virus may be destroyed.

The genetic material of the virus lingers on even after the virus has been destroyed. Take the example of how the DNA of people buried long ago can be obtained. 

In case the virus is still alive, any person coming into contact with the sewage or ingesting it through contaminated food or water can get COVID-19. Another dimension to this is the amount of time the virus can stay active once removed from the human body as through stool. On plastic and metal, the virus can survive up to 3 days. On clothes, it can survive up to 2 days. On copper, it can survive up to 4 hours. On cardboard, it can survive up to 24 hours.  

What about sewage? Let’s dig deeper.

Can coronavirus escape unscathed from the human body?

Understand that the COVID-19 virus is a non-enveloped type of virus. That means it doesn’t have the usual protective covering that other viruses have. As such, the duration of its survival in the environment is significantly reduced.  

For instance, it is hard for the SARS-CoV-2 virus to survive in treated drinking water as chlorine rapidly inactivates it. Now, compare treated drinking water and the fluids in the GI tract. Which is harsher?

Scientists are on record claiming that the gastrointestinal tract is very harsh – to such a point that it is more likely for coronavirus to be destroyed as it travels down the gut than to escape unscathed. And if it happens to escape alive, the conditions in wastewater cause it to die off rapidly. The usually high temperatures of sewage and the presence of other harsh substances see to it that the virus does not survive beyond 2-4 days.

The positive implication of this is that the spread can be adequately reduced. Contamination of food and water by human feces has in the past led to outbreaks of diseases such as cholera. If the transmission of COVID-19 through sewage was highly likely, the number of cases would most possibly be higher than the current figures. Millions of people live in not-so-sanitary conditions, especially in slums and rural areas.

Another positive aspect of the presence of coronavirus in sewage is that it can be used to map out breakouts of the virus in good time. As earlier mentioned, traces of the virus can be detected in feces about 3 days before the infected individual starts showing symptoms of the disease. As such, wastewater analysis for Covid-19 helps authorities to enforce the necessary containment measures before the entire community gets sick and the health system gets overwhelmed. 

Disclaimer

Scientists are working round the clock to verify whether coronavirus can spread through sewage. The fact that there is still no evidence of such transmission does not mean we lower the bars. Stay on guard always. You never know about tomorrow. Perhaps you might be the first case. 

To avoid such, constantly improve your standards of cleanliness. Discharge toilet wastes in the right manner, ensuring that there is zero likelihood of contaminating your food and water. And last but not least, wash your hands after every visit to the loo.