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Wastewater, a new weapon in the fight against the pandemic

2022-01-26T22:40:00.938Z


Thanks to wastewater tests, it is possible to monitor the early behavior of the virus that causes covid-19 and take measures against the pandemic


In Guayaquil, Ecuador, the presence of SARS-CoV-2 in wastewater is already being investigated Courtesy ESPOL - EP EMAPAG

In Yellowknife, a community with 20,000 inhabitants in northern Canada, there were still no confirmed cases of covid-19 in December 2020, but local authorities already had information about the presence of the virus in their territory.

How did they know if no one had taken a clinical test?

The data came from the least expected place: the waste water from the houses.

When infected people go to the bathroom, they expel fragments of SARS-CoV-2, the virus that causes the covid-19 disease, through their feces, and the genetic material of the microorganism travels through the wastewater. There, the samples are collected and then analyzed in a laboratory with a PCR test (RT-qPCR) to confirm the viral load. The tests are so sensitive that the virus can be detected even when faeces are diluted with river water or industrial effluents. Watch this video to learn more about how it works:

Thanks to this early warning, those responsible for the health area of ​​the Canadian town were able to make a quick assessment of the situation and had enough time to react.

They contacted the 1,500 people who had traveled to the site in the days before the discovery and invited them to undergo a clinical test.

They also did it with all those who presented symptoms.

Five cases were identified, the days of isolation for those infected were increased and their contacts were quarantined.

Thus, the sustained spread of the virus was prevented.

A lens for Latin America and the Caribbean

Like Canada, 58 countries are using sewage-based epidemiology to fight the spread of COVID-19.

While there are more than 3,000 testing sites around the world, the majority of these sites (85%) are in wealthier countries, primarily in Europe.

Only eight lower-middle-income countries are using this method and the list does not include any low-income countries, even though these are the ones that could benefit the most.

Developing national plans for early surveillance using wastewater would help tackle the pandemic in Latin America and the Caribbean, a region with more than a quarter of the cases of covid-19 in the world and in which the list of deaths adds up to more of 1.5 million people.

Some countries in the region, such as Brazil, Argentina, Peru, Uruguay and Mexico, have already taken steps to use this epidemiological approach.

The World Bank is supporting a wastewater surveillance program in Guayaquil, Ecuador, one of the first cities in the region to be hit by COVID-19.

In partnership with the municipal water and sanitation authority (EP-EMAPAG) and the Universidad Superior Politécnica del Litoral, samples are being taken at 12 points in the city.

The information is sent to the Cantonal Emergency Operations Committee so that measures can be taken according to the situation.

Joint work between different actors is one of the main challenges to promote this surveillance approach.

"Implementing this technology requires the participation of various sectors that usually do not work together, such as the water sector and the health sector, as well as the executive," highlights Dr. Mariana Matus, executive director of Biobots Analitycs, which leads water monitoring waste in the United States.

Matus also emphasizes the importance of private sector involvement in accelerating the creation of these programs around the world.

Inequity in the detection and monitoring of covid-19

Since its inception, covid-19 has been difficult to detect, since many patients are asymptomatic, and to diagnose, since individual diagnoses are expensive and maintaining a diagnostic infrastructure becomes more difficult as cases increase.

It has also been difficult to control, as the variants are becoming more transmissible.

In addition, the disease has not been monitored equitably: there has been inequity in case detection, control and treatment, especially in informal settlements and for groups that do not have easy access to health services, especially in developing countries. low and middle income.

According to a new World Bank report, wastewater testing is key for regions like Latin America and the Caribbean because:

· They generate an early warning and offer a broad view of the presence of the virus, whose trail can be followed before people show symptoms or even if they are asymptomatic.

· They include all members of a community, from a building, to a neighborhood or an entire city.

Specific studies can be designed in more vulnerable areas, where the risk of COVID-19 is greater or where people do not have greater access to clinical tests.

Samples can be taken anywhere wastewater flows, for example in large cities with sewage systems and treatment plants or in areas where only individual sanitation solutions and open ditches exist.

· Support control through rapid identification of outbreaks and waves, which is very important when new variants emerge.

· Enable sustainable surveillance as a complement to clinical trials: wastewater testing requires fewer supplies and human resources than clinical trials;

therefore, they are economically more accessible.

In addition, the total cost of clinical testing increases considerably during peaks and surges, while the cost of testing in wastewater generally remains constant.

Introducing the report, Douglas Manuel, a professor at the University of Ottawa, noted that sewage is hardly being seen as a surveillance approach.

“There are more than 40 biological infections that can be identified in wastewater.

All over the world, work is being done quickly with the influenza virus or RSV (respiratory syncytial virus), knowing that these are also going to be important challenges,” said Manuel.

"These tests open a window to the health of the community, not only of humans, but of animals and the environment," he added.

Thus, beyond covid-19, the analysis of wastewater, which has been used before to detect polio and antimicrobial resistance, can make a difference when facing future threats to public health.

In this also lies the value of taking note when the waters that run under our feet speak.

Marjorie Delgado

is a Communications Consultant for the World Bank.

Source: elparis

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