Wastewater test for early detection of COVID-19

Wastewater-based epidemiology (WBE) is a technique by which scientists can find out specific human exposure to contaminants and pathogens by testing the faeces and urine from their wastewater systems. WBE acts as an essential tool to provide information about the following things: 

• Use of drugs (both legal and illegal)
• Pesticides
• Persistent Organic Pollutants (POP)
• Pathogens such as Escherichia coli and Clostridium perfringens.
• Personal care products (shampoos, soaps)
• Traces of some diseases like diabetes, allergies, oxidative stress and even cancer.
• Doping substances like anabolic steroids, human growth hormone and diuretics.
• Products used for the treatment of erectile dysfunction

In the case of COVID-19 - where asymptomatic patients can also transmit the disease - this test may even help to identify hotspots: or areas from which there are high chances of transmission.

Read more: How COVID-19 spreads

Wastewater tests have shown tremendous results in finding various infectious diseases in past such as malaria, rotavirus A, Zika virus and even HIV. These paper-based kits have already been successfully used to conduct the tests for rapid veterinary diagnosis in India and for the detection of malaria among rural populations in Uganda.

This time the scientists at the Cranfield Water Science Institute have used this technique to find the places which have been affected with COVID-19. The scientists believe that if they would be able to monitor COVID-19 in a community at an early stage with the help of WBE, a powerful intervention can be done as soon as possible to restrain the movements of the people living in that area to minimise the spread of the infection in the public.

Wastewater test can be done with the help of a simple paper testing device which is folded and unfolded in steps to filter the nucleic acids (DNA or RNA) of pathogens derived from the wastewater samples. The testing paper has preloaded reagents which cause a biochemical reaction that detects whether the sample has the nucleic acid of SARS-CoV-2 (COVID-19 virus) or not. 

The results of the test are very clear as a green circle on the paper indicates positive whereas a blue circle indicates negative. 

The scientists have already developed and tested a specific paper device to test the genetic material of the COVID-19 virus from wastewater. 

The reasons why wastewater tests are more effective than other tests are:

• This test would help in preventing the spread of the disease from a particular region as it tests COVID-19 even before patients start showing symptoms.
• This test requires very little equipment and resources. It is done with the help of a paper device.
• These test kits are easy to stack, store and transport. This would enable the test kits to reach markets across continents relatively quickly.
• The device used for this test is cheap and costs less than £1 which is equivalent to Rs. 93 in India.