MOSCOW, April 28. /TASS/. The coronavirus RNA appears in sewage water much earlier than people begin to experience the first disease symptoms, epidemiologists from Spain have discovered. This allows using the sewers as the early warning system for infection outbreaks, they say in an study, published at the medRxiv website.”Our results strongly suggest that the virus was undergoing community transmission earlier than previously believed, and show that wastewater analysis is a sensitive and cost-effective strategy for COVID·19 epidemiological surveillance,” the researchers say.During the first weeks of the coronavirus outbreak in Wuhan, medics and biologists discovered that human biological waste contain large amounts of the virus. Later, scientists connected this feature of the virus to some infection cases in Singapore, blaming improper ventilation systems in some restrooms.Epidemiologists from the University of Valencia and their colleagues from the Institute of Agrochemicals and Food Technologies (Valencia, Spain) attempted to determine, how fast the virus traces appear in city sewers, by studying sewage specimen, collected in Valencia between February and April this year.According to the researchers, Valencia and the surrounding regions were ground zero for the coronavirus outbreak across the entire Iberian Peninsula. The first case was registered in Valencia in late February 2020, but some medics suspect that the virus could have infiltrated into the city much earlier.The study’s authors checked whether this was true, by looking for traces of the virus in the city’s sewage. Unexpectedly, the analysis revealed that fragments of the SARS-CoV-2 genome had already been present in some corners of the city’s sewers by February 24, when medics announced the first infection case in Spain.During the first week of March, fragments of the virus’ RNA were present in large amounts in water specimens, collected at all three of Valencia’s water treatment stations, which points to the start of the local transmission of the virus. In the meantime, medics had registered only 50 infection cases, connecting all of them with travel and business trips to the hotbeds of the epidemic.All this indicates that the city sewers might serve as an early indicator of the virus’s spread to new territories. This could be used to observe the further evolution of COVID-19 and to prevent future outbreaks, the researchers concluded.In mid-April, parallel research was published by scientists from the University of Queensland (Australia) and the Commonwealth Scientific and Industrial Research Organization (CSIRO). They have come to conclusion that the presence of coronavirus traces in sewage might reveal a coronavirus outbreak even before confirmed cases are registered.
