The novel coronavirus (Covid-19) pandemic highlights the urgent need for careful evaluation of its transmission. Though the World Health Organization (WHO) has stated that the virus transmission is mostly through droplets and aerosols emerging from the infected person and anyone close (<1m) to the person is in risk of getting infected, there are other ways of possible infection and human transmission.
Recent information from countries like Australia, France and UK has revealed that the Covid-19 virus may be present in the drainage and sewage water of cities. One of these reports (by Australia’s national science agency) says that the virus was detected in their sewage treatment system. In the greater Paris area in France, a sharp increase in Covid-19 concentration was detected before an outbreak.
Though the number of such reports are few, it is a concern for developing countries like India, where there is no proper sewage-treatment systems.
Adding to the problem is the open water drainage system in most Indian cities, which leads to flooding and transmission of the virus to other places. The presence of this virus in sewage water and its increased viability is well documented for the SARS-Covid virus, which caused Severe Acute Respiratory Syndrome (SARS) in 2003, and the coronavirus, belonging to the same category, increases the risk.
Though the survival of coronavirus in waste water depends on a number of factors including temperature (increasing temperature may kill the virus), light exposure (solar or Ultra Violet radiation), organic matter (viruses can adsorb onto particles of organic matter, affecting settling behavior) and the presence of antagonistic microorganism (increasing the extent of inactivation), its surveillance in waste water is almost none, which can easily help in its transmission.
Odisha is one such state, where the small towns and cities get easily flooded by torrential rains. Just an hour of rain floods the roads of the Smart City, Bhubaneswar and Cuttack. In such a scenario, it becomes worrisome as the novel coronavirus can spread to new areas without containment and can infect more people.
Drainage systems in the cities are connected some way or the other, like Bhubaneswar and Cuttack hospital areas, and their waste do not have a special treatment. Without the sewage being treated, these wastes are released into the common drainage system — which contain feces, urine and cough — helping the Covid-19 virus survive for longer periods of time.
However, during these periods of torrential rain, there is a lack of factors like increasing temperature and humidity that inactivates the virus. Therefore, in Bhubaneswar and Cuttack, lack of proper sewage treatment combined with torrential rains and the possibility of cyclone can increase the level of transmission of the virus and related infections to areas that were not totally shut down.
Though it is summer time, the torrential rains ensure a drop in average temperature. Lack of proper sewage treatment and uncovered drainage systems can wreak havoc and increase the number of infections.
Additionally, with people walking much more than travelling by car during the lockdown period, chances are all the more of them getting infected. Though Cuttack and Bhubaneswar are called Smart cities, they do not have either a smart sewage systems or a sewage treatment plant. This can overturn the tide towards more infection and spreading of the virus to hitherto non-contaminated areas, thus leading to a sharp spike in positive cases.
A collective effort is needed to overcome the crisis we are facing now. But the fact is that we need to invest more in science and technology, and more importantly, in creating better sewage management plants.
(The writer is a scientist in Ecosystem Health and Conservation at Bombay Natural History Society, Mumbai)