‘Earlier signs of coronavirus’ in sewage samples in Brazil
- Brazilian researchers say they found evidence of the pathogen in waste water in November, 91 days before the first case was detected in the country
- The presence of the virus was ‘modest’ until it peaked in March, according to the study
“[The virus] was being shed within the community for several months prior to the first cases being reported by regional, national or Pan-American authorities,” Gislaine Fongaro, from the Federal University of Santa Catarina, said in a non-peer-review paper posted on the preprint server medRxiv.org on Monday.
Fongaro’s study was based on samples collected from the waste water network in Florianopolis, a beach town in southern Brazil.
Previous studies indicated that the coronavirus could bind with cells in the intestines, and the researchers thought sewage could be a useful tool to monitor the rise and fall of the epidemic in the city, with up to 100 million copies of the virus per gram of faecal matter.
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Fongaro and colleagues conducted tests for Sars-CoV-2, the formal name of the coronavirus, on samples dating from October last year to April this year. The tests targeted three different parts of the viral genome to reduce the risk of a false positive, and were carried out on samples that had been stored at a temperature of minus 80 degrees Celsius (minus 112 degrees Fahrenheit).