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Source: https://www.science.org/content/arti...ing-scientists
Poliovirus keeps popping up in European wastewater, perplexing and worrying scientists
Origins and spread of the vaccine-derived viruses remain mysterious
11 Dec 20244:35 PM ETByLeslie Roberts
“Confounding,” “very unorthodox,” and “very concerning.” That’s how Shahin Huseynov, polio lead for the World Health Organization’s (WHO) European region, describes the slew of detections over the past 3 months of poliovirus in wastewater in Spain, Poland, and Germany. On 10 December, the U.K. government reported more positive wastewater samples, as did Finland. So far, no paralytic cases have been found, and the risk of an outbreak in these countries with high vaccination rates is deemed fairly low.
Huseynov is one of dozens of researchers in Europe and the United States trying to figure out where the poliovirus came from and how it is popping up so widely in such a short time. “Genetically, the picture is very, very unusual. It is very fascinating,” Huseynov says. The isolates are descended from a strain circulating in Africa, he says, but the extent of their sequence variation from that strain—and from each other—make it hard to reconstruct where the virus first arrived in Europe, and whether it was imported multiple times or was transmitted locally after a single introduction.
All the newly spotted isolates are vaccine-derived strains, known as circulating vaccine-derived poliovirus type 2, which are spawned by the live, attenuated virus used in the oral polio vaccine (OPV). They are descended from the Zamfara strain, which emerged in Nigeria several years ago and has spread widely across Africa. The closest match is to the strain now circulating in Algeria, Guinea, and Mali, says Robb Butler, director of communicable diseases for the WHO European region....
Poliovirus keeps popping up in European wastewater, perplexing and worrying scientists
Origins and spread of the vaccine-derived viruses remain mysterious
11 Dec 20244:35 PM ETByLeslie Roberts
“Confounding,” “very unorthodox,” and “very concerning.” That’s how Shahin Huseynov, polio lead for the World Health Organization’s (WHO) European region, describes the slew of detections over the past 3 months of poliovirus in wastewater in Spain, Poland, and Germany. On 10 December, the U.K. government reported more positive wastewater samples, as did Finland. So far, no paralytic cases have been found, and the risk of an outbreak in these countries with high vaccination rates is deemed fairly low.
Huseynov is one of dozens of researchers in Europe and the United States trying to figure out where the poliovirus came from and how it is popping up so widely in such a short time. “Genetically, the picture is very, very unusual. It is very fascinating,” Huseynov says. The isolates are descended from a strain circulating in Africa, he says, but the extent of their sequence variation from that strain—and from each other—make it hard to reconstruct where the virus first arrived in Europe, and whether it was imported multiple times or was transmitted locally after a single introduction.
All the newly spotted isolates are vaccine-derived strains, known as circulating vaccine-derived poliovirus type 2, which are spawned by the live, attenuated virus used in the oral polio vaccine (OPV). They are descended from the Zamfara strain, which emerged in Nigeria several years ago and has spread widely across Africa. The closest match is to the strain now circulating in Algeria, Guinea, and Mali, says Robb Butler, director of communicable diseases for the WHO European region....