Hantavirus Disease at Mountain Home Air Force Base, Idaho

An emerging condition of growing importance, hantavirus pulmonary syndrome (HPS) was first recognized

in the Four Corners region of the southwestern United States in 1993.  In January 2001, a case of HPS was diag 

nosed in a 21 year old active duty male living on Mountain Home Air Force Base in Idaho.  The airman's case

became unusually severe but after a month's coma and the amputation of his hands and feet, he did survive.  The

outcome of this case of HPS is a sobering reminder of the risk HPS poses to military personnel.  This disease is

caused by any one of a number of viruses in the family Bunyaviridae.  Deer mice are the reservoir for Sin Nombre

virus, the cause of this case, and an infection is acquired when a person inhales virus in aerosolized rodent feces or

urine.

A program of education and increased rodent trapping was instituted on base to reduce the risk of additional

infections, and a professional cleanup company was hired to clean one rodent contaminated building.  Realizing

that the rodents and the contamination likely would be a continuing problem, representatives from the US Army

Center for Health Promotion and Preventive Medicine West and the USAF Institute for Environment, Safety

and Occupational Health Risk Analysis were asked to make an on site evaluation of the problem and make

recommendations for short term and long term risk reduction. In early April 2001, a number of environments on

the main base and Saylor Creek Range were examined.  Contamination in those areas ranged from none to

scattered droppings in base housing to the floors of storage vans covered in mouse and rat droppings (Figure).

Large, plastic boxes of deployment equipment kept outdoors were severely infested, and live mice and nests were

observed in the boxes.  In several instances, debris close to buildings provided harborage for mice, and poor

construction (e.g., gaps around doors, poorly fitting siding) allowed mice easy entry into buildings. 

Recommendations for personnel protection and cleanup were tailored for the different situations.  For minor

contamination, which could be easily disinfected without generating aerosols, recommendations included spraying

with a disinfectant, wiping up with a paper towel, and discarding the towel in a sealed bag.  Personal protective

equipment in this situation could be limited to rubber gloves.  Heavily contaminated buildings in which cleanup

would generate dusts or aerosols require extensive use of personal protective gear, such as face mask with P 100

(HEPA) filters, tyvec coveralls, and rubber boots.  Some situations, such as crawl spaces under buildings and

infrequently visited storage facilities, pose particular problems.  In these areas, disinfection is difficult, cleanup

is extremely labor intensive, and reinfestation and recontamination occur rapidly.  If access to these areas is limited,

both in frequency and duration, disinfection and cleanup may be inefficient.  In these situations, the most reasonable

approach is to use a mask with P 100 filters, coveralls, gloves

and boots while in the environment, and decontaminate the

equipment and anything removed from the area.  

The rodent infestation at this Air Force installation is not

unique, and many DoD facilities, particularly those in 

the western United States, are at risk of hantavirus.  The

recommendations made for risk reduction at this particular

base also are appropriate for those installations and are

being included in DoD pest management guidance.

Mouse and rat feces on floor of storage van.

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