Public health officer: three recent hantavirus deaths in Mammoth Lakes; county ramps up testing and outreach

Mono County Public Health Officer Dr. Tom Boo told the Board of Supervisors that three recent Mammoth Lakes residents died of hantavirus infection and that the county is intensifying clinical screening, lab training and public outreach.

"We recently lost three Mammoth Lakes community members to hantavirus," Dr. Boo said. He told the board the cases were confirmed by post-mortem testing and that all three people had illness onset in February. "It is alarming to have three cases in such a short time in a small community and so early in the year," he said.

Nut graf: Hantavirus pulmonary syndrome is a rare but frequently severe respiratory illness carried in deer mice. The county health officer said most infections happen when people inhale aerosolized rodent excreta in poorly ventilated indoor spaces; prevention messages focus on ventilating, wet-disinfecting suspected mouse-infested areas and avoiding sweeping or vacuuming to prevent stirring dust.

Dr. Boo told the board Mammoth Hospital is putting in place a five-point laboratory screening approach developed by experienced clinicians in order to identify suspected hantavirus cases earlier and transfer critically ill patients to centers with ECMO support when needed. He said laboratory staff from Indian Health Service hospitals have offered to provide training to Mammoth Hospital lab personnel to improve screening reliability.

The county's public-information campaign has broadened beyond seasonal spring messages. Dr. Boo said the health department is using press releases, paid newspaper ads, local radio spots and social media; the town of Mammoth Lakes is working with the state health department and local consultants to produce Spanish- and English-language educational videos. The county has also coordinated with chambers and local employers to reach workers.

Board members asked whether typical household cleaning activities could be risky. Dr. Boo answered that infections are often linked to indoor exposures but that routine cleaning of areas with even modest evidence of mouse droppings can create aerosolized particles; he recommended ventilating, disinfecting with an appropriate product and, for heavy infestations or enclosed spaces, use of a well-fitting N95 respirator.

Ending: Dr. Boo said the county remains concerned there could be additional cases and urged residents and property managers to inspect for mouse droppings, ventilate enclosed spaces and follow recommended cleanup procedures. He confirmed free N95 masks are available at the county's Bridgeport and Mammoth Lakes offices.