The Equinoctial Technological University (UTE) began this Friday a study of wastewater to estimate the number of people infected with coronavirus in the Ecuadorian capital and facilitate health decision-making, now based on an epidemiological traffic light system.
The methodology is necessary given the lack of diagnostic tests for the entire population and due to the failures that a survey system could throw, in which the citizen could lie.
“A LITTLE BLIND”
The SARS-CoV-2 causing COVID-19 disease has been detected molecularly in various human tissues and secretions, and several studies have found its ribonucleic acid (RNA) in the feces of symptomatic and asymptomatic patients.
These clinical observations coincide with the detection of the virus in sewage from several cities around the world, and now Quito joins the analysis with an investigation in which the UTE, the Municipality and the Carlos Andrade Marín Hospital of the Social Security are involved .
Santiago Guerrero, from the UTE’s Center for Genetic and Genomic Research, explained to Efe that with the epidemiological analysis of wastewater, an “indirect calculation” of infected in two phases can be carried out.
Epidemiologists, molecular biologists and wastewater engineers will participate in the first phase, which began today with the taking of a sample.
In it they will seek to detect viral RNA by RT-PCR, and the number of viral particles per milliliter of residual water will be used to determine the number of viral particles per gram of fecal matter.
These data will be extrapolated, taking into account various demographic and environmental parameters, to estimate the number of individuals infected with SARS-CoV-2.
“We’re going a little blind because we don’t know what the city’s wastewater is like at the chemical composition level,” said Guerreo, a doctor in molecular and cellular biology.
The rain converges in the sewers with the sewage and that causes the substances to be diluted and, sometimes, the industries throw chemical compounds into the water, which could cause the genetic material of the virus to degrade and cannot be detected, he commented.
With that uncertainty in between, they hope to have the results of the sample taken this Friday next week.
If the virus is detectable, in a second phase, a larger study will be carried out, with more samples taken at different times and in different areas.
“This is a way that we have sought at an academic level to help control and monitor the number of infected and sectorize the populations most affected in this health crisis,” said Efe Daniel Simancas, director of research at the UTE.
At the moment, official data shows that in Ecuador there are 35,828 infected confirmed by PCR and rapid tests, while the number of deaths from COVID-19 totals 3,056, to which 1,892 probable deaths from the disease are added.
The province of Guayas, the most punished by the coronavirus with 13,516 cases confirmed by PCR, is followed by that of Pichincha, with 3,201, of which 2,999 are in Quito.
The results of the UTE study are key to making health decisions at times in Quito, like the whole country, it is subject to a traffic light system to gradually resume activities.
Quito remains in “red”, but next week the possibility of changing to “yellow” could be analyzed and, from there, the study of wastewater can be decisive in knowing the contagion process.
If new samples determine that cases are increasing or decreasing, authorities will have a scientific tool to determine if the level of restriction turns back to red or goes down to green.