Hantavirus Pulmonary Syndrome (HPS) is a respiratory disease caused by a virus known as Sin Nombre Virus.

The virus is carried by wild rodents, especially deer mice. The virus produces no clinical signs in the deer mice, but can produce a deadly infection in man - over 50% of human cases have been fatal.

Biology

Sin Nombre belongs a family of viruses known as Hantaviruses. Deer mice (genus Peromyscus) and other wild rodents can carry the virus without ill effect and can shed the virus in their urine, feces, and saliva. Sin Nombre virus is not associated with laboratory mice or with ordinary house mice or laboratory mice (genus Mus). Deer mice, in general, inhabit wild areas and rural rather than urban or suburban areas; you won’t find them in your kitchen in a city, but you might in a mountain cabin.

Humans become infected with the hantavirus when they inhale dust which has been contaminated with rodent urine. Most individuals who have become infected have lived or worked in areas that were heavily contaminated with rodent droppings. Campgrounds, abandoned cabins, and other areas that have become infested with high populations of wild rodents should be considered risky. Digging up a rodent nest, trapping wild rodents or performing necropsies on wild rodents would also be considered risky activities.

If a human being becomes infected, signs of illness usually appear about two weeks after exposure, although the time can range from a few days to as long as six weeks. The first signs are fever, headache, and pain in the abdomen, joints, and back. Afterwards the patient’s lungs begin to fill with fluid and breathing becomes extremely difficult. A high proportion of the patients die, but early treatment offers the best chance of survival.

If you develop symptoms that are suspicious of HPS, and you have worked with or been around wild rodents within the last six weeks, report this information to your physician immediately.

Relative Risks

Most individuals who have contracted HPS have acquired the disease by living and sleeping in areas where there are large populations of rodents and copious quantities of dust contaminated with their feces. Confined spaces, such as rodent nests, abandoned cabins, or empty barns or pump houses that have been overrun with deer mice are the greatest potential risks.

In a research setting, there is also risk associated with individuals that work with wild rodents.

Prevention

• Laboratory reared colonies of deer mice on campus must be tested for the virus and shown negative. These animals can be worked with as though they were ordinary mice. These colonies should be re-tested periodically (consult your facility's veterinarian for information).
• Never introduce wild caught deer mice into laboratory reared colonies of deer mice.
• Wild caught deer mice must be contained in isolation facilities until testing establishes their health status. Those caring for these animals must wear fitted HEPA filtered respirators when changing cages.
• Wildlife biologists who work with wild caught deer mice in field conditions must treat all wild deer mice as though they were potentially infected. Individuals who will handle the animals or empty the traps must be fitted with HEPA filtered respirators by EH&S, and the respirators must be worn when handling the animals and cleaning the traps.
• Equipment and surfaces potentially contaminated with Peromyscus urine or feces should be sprayed down with a 10% solution of household bleach before cleaning.
• If you must clean out a rodent infested structure, do the following:
  1. Wear a fitted respirator with a HEPA filter. Contact EH&S (Phone: 2-1493) to arrange to be fitted for a respirator.
  2. Open the building up first and let it air out for a day.
  3. Spray all surfaces to wetness with a 10% solution of household bleach before beginning the cleanup. Wet things down rather than sweeping so that dust is not stirred up.
  4. Wear study rubber sturdy latex gloves when cleaning up, and disinfect them with 10% bleach before taking them off.
  5. Don't sleep in a building or camp in an area that is obviously contaminated with rodent feces.

References

CDC publishes several documents about Hantavirus, including guidelines for working with wild rodents in laboratory situations.