A new study has uncovered a startling prevalence of hantavirus among rodents in the northwestern United States, suggesting that nearly one in three of these animals may be infected with the deadly pathogen. This discovery comes amid ongoing global monitoring of a hantavirus outbreak on a Dutch cruise ship, which infected 11 people and resulted in three deaths.
Study Findings in the Pacific Northwest
Researchers captured 189 rodents from farms and natural areas in Washington’s Whitman County and Idaho’s Latah and Benewah counties. The animals included deer mice, voles, and chipmunks. Testing revealed that approximately 30% of them carried hantavirus, with 10% actively infected and capable of shedding the virus to humans.
“We were surprised both by how common the virus was locally and by how little data existed for the Pacific Northwest,” said Stephanie Seifert, lead author of the study published in Emerging Infectious Diseases. “We are really just beginning to understand how widespread and complex this virus is in rodent populations here.”
Comparison with Cruise Ship Outbreak
The strain found in the Pacific Northwest differs from the Andes “Sin Nombre” strain responsible for the outbreak on the MV Hondius. The Andes strain, which has shown rare human-to-human transmission in close quarters, is primarily found in South America. The local strain spreads mainly through contact with infected rodents.
Transmission and Risks
Hantavirus infects humans when they inhale airborne particles from contaminated rodent droppings, urine, or nesting materials. Scientists warn that disturbing rodent nests, particularly with equipment like leaf blowers in enclosed spaces, can increase exposure risk.
“People may be exposed more often than we realise, but severe cases are more likely to be tested for hantavirus,” said co-author Pilar Fernande. “Understanding that gap – how exposure translates into disease – is the next big step.”
Prevention and Future Research
To reduce infection risk, researchers advise ventilating spaces and using wet-cleaning methods instead of dry sweeping. Future studies aim to expand understanding of human exposure rates and behavioural factors influencing infection risk.
Global agencies, including the WHO, continue to monitor the hantavirus situation, with authorities in affected regions broadening testing and surveillance of rodent populations to gauge the virus’s prevalence.
