In 1993, a previously unknown disease, hantavirus
pulmonary syndrome (HPS), was identified among residents of the
southwestern United States. HPS was subsequently recognized throughout
the contiguous United States and the Americas. As of May 7, 2003, a total
of 336 cases of HPS have been identified in 31 states, with a case fatality
rate of 38%.
Source and Transmission of the Virus
All hantaviruses known to cause HPS are carried by rats and mice. The
deer mouse, which is common and widespread throughout much of the United
States, is the primary host. Other hosts include the white-footed mouse,
cotton rat, and rice rat. The spread of the hantavirus to humans occurs
most commonly by inhaling airborne dust that has been contaminated with
saliva, urine, or feces from infected mice and rats. One may also become
infected by contacting contaminated material with broken skin or eyes,
a bite from an infected rodent, or possibly from eating contaminated food
or water. To date, no person-to-person transmission has been associated
with any HPS cases in the United States.
It is recommended that you avoid contact with all
wild and commensal mice and rats encountered throughout the United States,
and also the saliva, urine, and feces from those rodents.
Symptoms of HPS
Early symptoms include fatigue, fever, and muscle aches, especially the
large muscle groups-thighs, hips, back, and sometimes the shoulders. About
half of all HPS patients also experience headaches, dizziness, chills,
and/or abdominal problems, such as nausea, vomiting, diarrhea, and abdominal
pain. The first symptoms generally develop between 1 and 5 weeks after
exposure to infected rodents and their droppings. Four to 10 days after
the initial phase of illness, additional symptoms appear, including coughing
and shortness of breath. Earache, sore throat, and rash are very uncommon,
and their occurrence may help in differentiating HPS from common ailments
such as influenza and other respiratory viruses.
Prevention of HPS
Rodent control, good sanitary practices, and safe cleanup of potentially
contaminated materials remain the primary methods of HPS prevention. Eradicating
mice and rats that carry hantaviruses is neither feasible nor desirable
because of their wide distribution and their importance in natural ecosystems.
An Integrated Pest Management Specialist or Public Health Consultant should
be contacted for persistent or severe rodent infestations.
Precautions for Inside the Home
- Keep all food, pet food, trash, and water covered
and stored in rodent-proof containers.
- Wash dishes after use, and remove leftover food;
and clean up all spilled food.
- Frequently dispose of trash and garbage, and
pick up or eliminate clutter.
- Deny rodents all access to moisture. Fix leaks
and insulate pipes to prevent condensation.
- Keep exterior doors and windows closed unless
protected by tight-fitting metal screens.
- Use spring-loaded snap traps in the structures.
Check traps frequently.
- Use of live traps or sticky boards is not recommended.
Their use may increase risk of contact with contaminated material from
- Look for and seal all gaps and holes that are
>¼ -inch in diameter.
- Use rubber gloves during cleanup of contaminated
- Spray dead rodents and contaminated areas with
a disinfectant or chlorine solution (1 ½ cups bleach in 1 gallon
water) and wait 10 minutes before beginning cleanup. A contact time
of 10 minutes is recommended to ensure deactivation of the virus.
- Disinfect gloves after use.
Precautions for Outside the Home
- Place woodpiles and stacks of lumber, bricks,
stones, or other materials >100 feet from the house.
- Store grains and animal feed in metal or other
- Remove from the vicinity of buildings any food
sources that might attract rodents.
- Keep pet food covered and stored in rodent-proof
containers. Allow outdoor pets only enough food for each meal, then
store or discard any remaining food from feeding dishes.
- Avoid using bird feeders near the home.
- Dispose of garbage and trash in rodent-proof
containers with tight-fitting lids.
- Haul away trash, abandoned vehicles, discarded
tires, and other items that might serve as rodent nesting sites.
- Mow grass closely, and cut or remove brush and
dense shrubbery to a distance of at least 100 feet from the home.
- Use concrete foundations in new construction
of sheds, barns, and outbuildings. The top of the foundation should
be at least 6 inches above ground level.
- Place spring-loaded snap traps in outbuildings.
Check frequently and replace bait as needed.
- Look for and seal all gaps and holes outside
the home that are >¼ -inch in diameter.
All About Hantavirus, National Center for Infectious
Disease Control and Prevention, Department of Health and Human Services