PARIS | From Paris to Milan, from the Usa to Australia, researchers are pursuing in the footsteps of the new coronavirus in the wastewater, a means of tracking the evolution of the epidemic and a key to develop an early warning system.
Since the onset of the disease in China, several scientific studies have noted the presence of the virus in the stools of patients.
Of the toilet to the sewer system and to wastewater treatment plants, there is only a step that has been crossed, several research groups who have quickly found elements of the genome of SARS-CoV-2 in the wastewater, to Paris, Amsterdam or Brisbane.
“This discovery (…) poses no risk” to health, has insured Luca Lucentini, director of the department of the quality of the water at the higher Institute of Health in italy (ISS), in a news release announcing several positive samples in Rome and Milan.
No risk actually for tap water in countries where it is subjected to treatment, unscrupulous, ensure the scientific.
But with a virus constantly surprising, the consensus is less about the hypothesis of contamination via wastewater discharged into the environment.
Certainly, the presence of traces in the stool does not necessarily mean that the virus is infectious or that it is transmissible by this route, feel some experts. And it is unable to replicate in the wild outside of a host, insist others.
But even if the spatters seem to be the preferred route of contamination, exposure to SARS-CoV-2 in the wastewater “could pose a health risk”, temper in a text published in The Lancet Willemijn Lodder, and Ana Maria de Roda Husman, of the Centre for infectious disease control in the netherlands.
The Centre had announced at the end of march to have detected the genetic material of the virus especially in the waste water in Amsterdam.
Beyond the issues of health risks, wastewater, could “serve as a source of data to determine if the virus is circulating in the human population”, insist the researchers.
This could even allow you to “follow the evolution of the virus,” says the AFP Vincent Maréchal, virologist at Sorbonne university, who participated in a study conducted by the laboratory of the municipal control Water in Paris.
On the basis of samples collected at regular intervals between 5 march and 7 April, their results published last week (not validated by other scientists) show that the increase of the units of the genome”, in the waste water “follows with precision the increase in the number of the dead”.
– “Mainly in Africa” —
Vincent Maréchal therefore calls for the “creation of a Sentinel network of national surveillance of wastewater, which could allow to anticipate the second wave”.
Given the large number of cases little or no symptomatic, the presence of the virus could be detected before the first clinical cases are confirmed, in areas where the epidemic had subsided, or in those not yet affected.
“We can then put in place measures barriers. It saves time, a major element of this epidemic,” insists the Pr, the Marshal.
Such a system of environmental monitoring has already been used for other viruses. Thus, in a study published in 2018, researchers have shown that the detection of the polio virus in wastewater in Israel in 2013 had helped revive a vaccination campaign, avoiding any cases of children being paralyzed.
For the SARS-CoV-2, studies conducted in several countries are still preliminary. But some scientists are enthusiastic.
The method “can be used as a tool for “early warning” against the pandemic, to ensure the AFP Dr. Warish Ahmed, a researcher at the public health agency australian research CSIRO, which has detected the virus in sewage in Queensland. And also to “assess the effectiveness of measures”, health put in place.
It is preferable to use this system “in addition to other measures, such as tests on the individuals,” he continued. But in a possible program of monitoring to the scale of Australia, these data would be “particularly useful in areas with vulnerable populations where other methods of testing are not feasible,” says the researcher.
“It is a way for a good cost/effectiveness ratio, to track the infection across a community”.
An argument also applicable to countries “that do not have the technical or logistical to test the carriers,” notes the Pr, the Marshal calls on the world Health Organization to address on a global network of monitoring that, beyond the COVID-19, could be used in many other killer diseases related to contaminated water.
“This would be essential in Africa,” insisted the virologist. “To protect the population, it is necessary to ensure the quality of the water”.