According to the U.S. Department of Agriculture, in 2022 avian influenza killed millions of chickens and turkeys in the United States due to infection or slaughter. The severity of the situation means that wild populations still need to be tightly controlled today. Other parts of the world have experienced similar situations. Now, researchers have developed a method to detect infectious avian influenza viruses in wetlands frequented by waterfowl.
Wild birds are important hosts of avian influenza viruses. Although some strains of the virus do not cause illness, highly pathogenic avian influenza (HPAI) forms can spread rapidly and are often fatal. It is spread by wild birds, which shed the pathogen through their feces into the environment, including the wetlands where they live. Detecting avian influenza in these waters has proven challenging because the concentrations of infectious virus are often too low to be detected by most methods, hampering our understanding of virus transmission.
To address this problem, Laura Hubbard of the U.S. Geological Survey and her colleagues designed a multi-step process to concentrate and identify infectious viruses in environmental samples.
In a recent study, they tested surface water samples obtained twice in the spring of 2022 from four wetlands and a lake in Iowa, USA. The team found infectious strains of the virus in samples from all four wetlands in April, but not in samples from the lakes. However, the detection rate of viral RNA in water samples using standard diagnostic protocols (11.1%) was significantly lower than the avian influenza detection rate (66.7%) when the same samples were inoculated into eggs for virus isolation and confirmation. The researchers say these results highlight the need to improve RNA detection technology to reduce the risk of false negatives.
Researchers have discovered infectious avian influenza viruses in wetlands frequented by waterfowl. (Photo: Adapted from Environmental Science & Technology Letters 2023, DOI: 10.1021/acs.estlett.3c00668)
Sequencing showed that most virus strains detected in water samples were of low pathogenicity. However, the detection of the HPAI virus in one sample is a milestone because, according to the researchers, this is the first time this strain has been detected in a U.S. waterway. Still, just five weeks later, they didn’t detect the avian flu virus in any samples from the same site, despite previous research showing the virus persisted for months in similar environments. The researchers believe that the apparent absence of the virus may be due to a number of environmental factors, such as reduced waterfowl numbers in May and significantly higher water temperatures that affect the survival of the virus.
While more research is needed to better understand the persistence and potential spread of avian influenza in wetlands, researchers say the detection of highly pathogenic avian influenza viruses and other strains highlights the need for wild and domestic poultry, other Potential risks to animals and even humans since these waterways are used for human activities. Entertainment purposes. They also suggested that regular surveillance and early detection could help mitigate the spread of the virus and the costs of rising egg and poultry prices.
The study is titled “Environmental surveillance and detection of infectious highly pathogenic avian influenza viruses in Iowa wetlands.” And published in the academic journal “Environmental Science & Technology Letters”. (Source: American Chemical Society)