News Release
Hanta Virus Question/Answer
5/27/2003
Ken Pekoc
406-444-2596
kpekoc@state.mt.us
(Adapted from www.cdc.gov and Montana Department of Public Health and Human Services, epidemiology section)
How does hantavirus spread?
The short story is that some rodents are infected with a type of hantavirus that causes hantavirus pulmonary syndrome (HPS). In the United States, deer mice (plus cotton rats and rice rats in the southeastern states and the white-footed mouse in the Northeast) are the rodents carrying hantaviruses that cause hantavirus pulmonary syndrome.
These rodents shed the virus in their urine, droppings and saliva. The virus is mainly transmitted to people when they breathe in air contaminated with the virus.
This happens when fresh rodent urine, droppings or nesting materials are stirred up. When tiny droplets containing the virus get into the air, this process is known as "aerosolization."
(http://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/aerosol.htm)
There are several other ways rodents may spread hantavirus to people:
· If a rodent with the virus bites someone, the virus may be spread to that person—but this is very rare.
· Researchers believe that you may be able to get the virus if you touch something that has been contaminated with rodent urine, droppings or saliva, and then touch your nose or mouth.
· Researchers also suspect that if virus-infected rodent urine, droppings or saliva contaminates food that you eat, you could also become sick.
These possibilities demonstrate why disinfecting rodent-infested areas is so important in preventing transmission of the virus.
Therefore, the most sensible way to avoid exposure is to prevent rodents from infesting the places where you live and work, and to follow safety precautions if you do stumble into a rodent-infested area.
Prevention aspects:
Mainly … eliminate or minimize contact with rodents.
Make your home, workplace, vacation home or campsite unattractive to them.
Indoors:
Keep a clean home, especially kitchen (wash dishes, clean counters and floor, keep food covered in rodent-proof containers).
· Keep a tight-fitting lid on garbage; discard uneaten pet food each day.
· Set and keep spring-loaded rodent traps. Set traps near baseboards because rodents tend to run along walls and in tight spaces rather than in the open.
· Set Environmental Protection Agency-approved rodenticide with bait under plywood or plastic shelter along baseboards. These are sometimes known as "covered bait stations."
· Remember to follow product use instructions carefully, since rodenticides are poisonous to pets and people, too.
· Seal all entry holes 1/4 inch wide or wider with lath screen or lath metal, cement, wire screening or other patching materials, inside and out.
Outdoors:
· Clear brush, grass and junk from around house foundations to eliminate a source of nesting materials.
· Use metal flashing around the base of wooden, earthen or adobe homes to provide a strong metal barrier. Install so that the flashing reaches 12 inches above the ground and six inches down into the ground.
· Elevate hay, woodpiles and garbage cans to eliminate possible nesting sites. If possible, locate them 100 feet or more from your house.
· Trap rodents outside. Poisons or rodenticides may be used as well, but be sure to keep them out of the reach of children or pets.
· Encourage the presence of natural predators, such as non-poisonous snakes, owls and hawks.
· Remember, getting rid of all rodents isn't feasible, but with ongoing effort you can keep the population very low.
What are the symptoms?
Early symptoms include fatigue, fever and muscle aches, especially in large muscle groups -- thighs, hips, back, sometimes shoulders. These symptoms are universal.
There may also be headaches, dizziness, chills and/or abdominal problems, such as nausea, vomiting, diarrhea and abdominal pain. About half of all HPS patients experience these symptoms. On the basis of limited information, it appears that symptoms may develop between 1 and 5 weeks after exposure to potentially infected rodents and their droppings.
Four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These include coughing and shortness of breath, with the sensation of, as one survivor put it, a "tight band around my chest and a pillow over my face" as the lungs fill with fluid. Earache, sore throat and rash are very uncommon.
Summing Up: These Are the Symptoms of HPS
· Early (universal): fever, fatigue, muscle aches
· Early (about half): headaches, dizziness, chills, abdominal problems
· Late (universal): coughing, shortness of breath.
What questions should ill people ask themselves / tell doctors?
People with above symptoms should assess their risk or history of exposure to rodents or rodent infested materials and may wish to seek health care. If shortness of breath occurs and a history of recent exposure is present immediate medical attention is essential.
What questions should doctors be asking patients?
Providers seeing patients with unexplained respiratory symptoms should routinely assess for exposures of interest (i.e. rodent contact, travel to areas of concern for other conditions like SARS, etc.).
Why do we have an apparent cluster of cases now?
Based on prior experience, this is an usual event for MT. These are our first cases in some time and to have them occurring at the same time in several different areas is unusual. We are not sure if this is just an anomaly or a reflection of some other factor like more mice or an increase in the number infected. We hope that by getting information out on prevention we can help prevent additional cases and your assistance is appreciated.
What does this tell us, having 3 cases in a matter of days?
We need to remind people of how to protect themselves by preventing exposures to rodents and to seek care if illness develops. In addition, we need to remind clinicians to assess for exposures and take advantage of diagnostic testing.
What circumstances in people lead to different outcomes?
Aside from preventing exposure as discussed elsewhere, it is essential to seek care early and indicate possible rodent exposures so that a medical assessment can be performed.
Do other rodents carry hantavirus?
In the western US, the deer mouse is the primary vector of hantavirus. Other rodents in our area occasionally test positive but it is unclear the role they may play in transmission and some are less likely to come into contact with humans.
Are cats an effective prevention tool?
Yes, they can help and do not appear to be at risk for infection.
