Mono County press release

As the weather warms (finally) and people turn to spring-cleaning and outdoor activities such as camping and hiking, they need to beware of a rare but deadly virus that is spread through mouse droppings and kills up to 40 percent of people who become infected. The severe respiratory illness is known as hantavirus pulmonary syndrome. Most cases are spread by deer mice, which live in woodland areas and deserts and are found throughout North America. People get the disease by breathing in hantavirus when dust from dried rodent urine, saliva and droppings is stirred up in the air, especially while cleaning houses, garages and cabins. Hantavirus is not spread from human to human and there is no specific cure or vaccine for the infection. But if recognized early, and individuals receive medical attention in an intensive care unit, they may have a better chance of recovery.

Here are some highlights from recent publications:

An Emerging Infectious Diseases article looked at potential exposures for 662 laboratory-confirmed cases from 1993 – 2015. (Mono County has more cases than any other county in California, and I believe all of our cases are included in the analysis.) Most were white males (78%), and 35% died (in Mono County, our mortality rate is less than 30% – I believe due to early recognition on the part of the public and healthcare providers). They categorized exposures into three groups: home, occupational, and recreational. They looked at probable occupational exposures, and the highest risks were for agricultural/ranching, construction/landscaping, forestry/parks/outdoor recreation, and cleaning (including janitors and carpet cleaners). Of course, if frequent rodent exposure occurred at the work site, risk was increased. But here is the important message: regardless of occupational category or history of work site related rodent exposure or recreational activity, the most common source of exposure in at least 2/3rds of the cases was the home!! Overall, recreational exposure accounted for 23% of cases, 32% were occupational exposure, and 73% exposure in the home environment.

Here is the citation for the article:

A report on the article and additional information is also available from the Washington Post, 4/12/17:



Here is an additional twist, with the author claiming that the source was droppings in the automobile cabin air system (7% of cases in the EID article were related to cars, trailers, and mobile homes):

Hantavirus, Seattle Washington area, 2 cases, one fatality. My wife was the other case.
My wife collapsed into hantavirus pulmonary syndrome this last Thanksgiving night [24 Nov 2016]. She spent 6 days on the ventilator,10 in ICU, and barely lived.

We have confirmed Sin Nombre virus infection, through 2 sets of IgG and IgM tests from the CDC. We are convinced that she was infected through her automobile cabin air system, which had repeated infestations with deer mice.

I am a scientist and she is an RN, and we have studied our potential exposure sources in some detail. I’ve set up a website at <> to explore the physical chemistry and
epidemiology of hantavirus exposure. I’ve posted 40 or 50 images of auto rodent infestations. This is potentially a way that many people may be contracting hantavirus, without it being diagnosed.

I’ve contacted the brother of the hantavirus [infection] victim, and they think their cars may be the source in their case too. I don’t know their reasoning for that yet.

Mark C Waterbury, PhD (materials scientist)
Perception Development Co
< [email protected]>

And the Editors Comments on

The possibility of transmission of Sin Nombre virus to people through automobile air systems is intriguing. These forced air systems could certainly generate aerosolized particulate mouse excreta that could contain the virus, making the automobile an effective transmission chamber, particularly in colder weather when the blower for the heating system is on and the windows are closed.

Interested readers are encouraged to read Dr Waterbury’s website (URL listed above). It has additional information about his wife’s case, and at the end of the site there are galleries of photos of rodent nests in automobile air systems. It also has nice images of the deer mice reservoir host.

Deer mice commonly move into dwellings, and apparently into automobiles, with the onset of cold weather. Cleaning out deer mouse nests from automobile air systems should be done with
the same precautions as for cleaning out unoccupied cabins. Materials should be wetted down with a bleach solution, materials handled in an open air space, with gloves and a mask worn.

The CDC has recently posted this guidance:

Interim Guidance for Cleaning and Disinfection of Vehicles with Rodent Infestation:


Additional information may be found at:

Occupational Health Toolkit, and Educational Brochures in English and Spanish:

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