The Sin Nombre virus, a hantavirus carried by rodents that can cause a serious lung disease in humans, may be more common in rodents in parts of the Pacific Northwest than scientists once thought, according to a study published in the CDC's Emerging Infectious Diseases journal.
Led by researchers from Washington State University College of Veterinary Medicine, the new study in parts of Washington and Idaho found that nearly 30% of rodents had been infected with the virus at some point. Meanwhile, around 10% were currently infected, signaling that they could still spread it.
The Sin Nombre virus was first discovered during a 1993 outbreak in the Four Corners area of the United States. It mainly lives in deer mice, which are often found near farms, homes, and sheds. Rodents spread the virus to each other through saliva and close contact. Humans usually get infected by breathing in tiny particles from infected rodent droppings, urine, or nests.
Certain activities can raise the risk of infection by stirring virus particles into the air, such as sweeping or using leaf blowers in closed spaces can be especially dangerous. Health experts recommend airing out spaces first and cleaning with wet methods instead of dry sweeping.
For the study, researchers trapped rodents during the summer of 2023 in parts of Washington and Idaho. They collected samples from 189 animals, including deer mice, voles, and chipmunks. In the lab, scientists found both active infections and signs of past infections in deer mice and voles, which suggests that the virus may spread between different rodent species.
The team also created the first complete genetic sequences of Sin Nombre virus strains from the Northwest. They found the virus has a lot of genetic variety and signs of gene mixing. This information could help health officials track how the virus changes over time, find sources of infection, and improve testing and monitoring.
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