At the University of Arizona, the team trying to prevent coronavirus outbreaks had a first victory using an unconventional strategy: analyzing feces.
In addition to performing random covid-19 tests on its thousands of students, making the use of masks and mandatory physical distancing, with the return of students to the dormitories, the strategy of analysis in wastewater.
The plan already avoided an outbreak last week.
“We believe that this is a very valuable tool that helps us stay ahead of the virus,” said the president of the institution, Robert C. Robbins, in a press conference.
With the return to school of more than 30,000 students in the city of Tucson, in the southwestern United States, preventive tests began last week, including monitoring of bedroom sewers of students.
On August 25, the stool analysis detected “an increase in viral load that was coming in the sewage at a particular residence,” Robbins explained.
University labs look for presence of ribonucleic acid (ARN) of SARS-CoV-2, the virus that caused the covid-19 pandemic.
“We did tests 311 individuals from that residence, antigen testing, and we found two positive cases. So we applied contact tracing and those two individuals were put into isolation, “says the president of the university.
The two students with SARS-CoV-2 were asymptomatic, which is a challenge for university authorities trying to avoid outbreaks.
And is that four out of ten carriers of the virus detected on campuses in the past usually do not manifest symptoms, according to Richard Carmona, director of the task force for the return of students to campus.
The analyzes of the wastewater from the student residences on August 27 and August 28 did not detect the presence of the virus. The tests will be carried out several times a week during the rest of the year.
The reopening of activities in Arizona had been canceled on June 30, when that and other US states saw a large increase in covid-19 infections.
Gov. Doug Ducey applied the measure after a record for new confirmed cases in a single day of 3,858 the day before.
But this week the numbers have been reduced to 519 new confirmed infections September 2. The state has accumulated 5,000 deaths since the beginning of the pandemic.
The valuable information of the sewers
The University of Arizona wastewater detection strategy has been tested in other countries.
Due to the great cost of testing the entire population, researchers have turned to the sewers to estimate the number of infections by coronavirus in a certain community.
These conduits carry wastewater, collected from the sanitary parts of our homes.
Several studies supported by the World Health Organization (WHO) have shown that the feces excreted by people with covid-19 contain traces of RNA, that is, the genetic material of the new coronavirus.
As Jean-Marie Mouchel, a professor at the Sorbonne University and an expert in hydrosystems and soils who has done sewage studies in Paris during this pandemic, told BBC World in this type of study the existence of the virus is not measured, but the presence of RNA in the waters with the help of PCR tests, which are able to detect an active infection.
“We estimate that we could detect up to one coronavirus patient in a population of 100,000. This means that we should be able to measure the presence of a very small number of patients and this would allow us to see the progress of the virus in an entire city “, assures the hydrologist.
This information is useful in preventing an outbreak and allows health authorities to quarantine people if necessary, as in the case of the Arizona university campus.
However, one of the shortcomings of the method is that at the moment does not provide an accurate calculation of the number of infected people.
That is why the containment group at the University of Arizona had to test 311 students in the dormitory, who also use an application on their mobile phones to track contacts.
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