Public Health

Hantavirus pulmonary syndrome (HPS) is an acute illness caused by a group of viruses generally known as hantaviruses, which are carried by rodents. Infected rodents shed these viruses in saliva, urine, and feces.
The deer mouse (Peromyscus maniculatus) is the
host for Sin Nombre virus (SNV), the primary causative agent of HPS in the United States, and is common and widespread in rural areas throughout much of the United
States, including Wyoming. A few other species of rodents may carry hantaviruses, mostly in other parts of the country.
Human infection occurs most commonly through the inhalation of infectious saliva or excreta, or materials contaminated by rodent saliva or excreta. Infection can also be
acquired when the virus (from rodent saliva, urine, feces, or materials contaminated by such) is directly introduced into broken skin or mucous membranes, or possibly, when
ingested. Persons have also acquired HPS after being bitten by rodents.
HPS begins anytime from a few days to 6 weeks after exposure (most often around 2 weeks) usually with a constellation of non-specific symptoms which may include fever, muscle aches, headache, back pain, chills, dizziness, cough, nausea, vomiting, diarrhea,
and shortness of breath. After a few days of these symptoms (approximately 3-7 days)more severe illness usually develops characterized by worsening lung function (difficulty breathing, increased shortness of breath, cough) and low blood pressure. Once this more
severe illness develops, the disease progresses rapidly usually necessitating hospitalization. HPS is fatal in approximately 30-40% of the cases.
The best currently available approach for disease control and prevention is risk reduction through practices that deter rodents from colonizing the home and work environment in the first place, as well as safe cleanup of rodent waste and nesting materials. This document focuses on the safe clean-up of rodent contaminated areas; in addition these
precautions should be taken for any activity that is likely to put someone in contact with rodent waste or nesting materials either directly or through aerosolization. For more information on methods to prevent rodents from entering places where human exposure could occur contact your local health department, or the Wyoming Department of Health, or a reliable pest control company.
These recommendations emphasize the prevention of HPS associated with sigmodontine rodents (the group that includes deer mice) in the Americas, however it is recommended that persons avoid contact with all wild and peridomestic rats and mice. The precautions described in this report are broadly applicable to all groups of rats and mice.
Hantavirus infections are associated with activities and situations that bring humans into contact with infected rodents, such as occupying or cleaning buildings that are actively infested with rodents, and disturbing rodent excreta or nests. This document focuses primarily on the safe clean-up of rodent contaminated areas, however precautions should be taken to limit exposure to rodents and their materials in all situations, even if not
actively involved in clean-up.
The control and prevention recommendations in this report represent general measures to minimize the likelihood of human exposure to hantavirus-infected rodents and their
waste, however following these recommendations may not prevent hantavirus exposure in all instances. These recommendations might be supplemented or modified in the
future. For more information call the Wyoming Department of Health, Preventive Health and Safety Division,
at 307-777-7172.
Precautions for Cleanup of Rodent-Contaminated Areas and Dead Rodents Areas with evidence of rodent activity (e.g., dead rodents and rodent excreta) should be
thoroughly cleaned to reduce the likelihood of exposure to hantavirus-infected materials.
Cleanup procedures must be performed in a manner that limits the potential for dirt or dust from contaminated surfaces to become airborne.
Cleanup of Rodent Urine and Droppings and Contaminated Surfaces
• During cleaning, wear rubber, latex, vinyl, or nitrile gloves.
• Spray rodent urine and droppings with a disinfectant or bleach solution until
thoroughly soaked (see Disinfecting Solutions below).
• To avoid generating potentially infectious aerosols, do not vacuum or sweep
rodent urine, droppings, nesting materials, or contaminated surfaces until they
have been disinfected.
• Use a paper towel (while wearing gloves) to pick up the urine and droppings.
Place the paper towel in the garbage.
• After the rodent droppings and urine have been removed, disinfect items that
might have been contaminated by rodents or their urine and droppings:
--- Mop floors with a disinfectant or bleach solution.
--- Disinfect countertops, cabinets, drawers, and other durable surfaces with a
disinfectant or bleach solution.
--- Spray dirt floors with a disinfectant or bleach solution.
--- Disinfect carpets with a disinfectant or with a commercial-grade steam
cleaner or shampoo.
--- Steam-clean or shampoo rugs and upholstered furniture.
--- Launder potentially contaminated bedding and clothing with hot water and
detergent. Use rubber, latex, vinyl, or nitrile gloves when handling
contaminated laundry. Machine-dry laundry on a high setting or hang it to air
dry in the sun.
--- Leave books, papers, and other items that cannot be cleaned with a liquid
disinfectant or thrown away, outdoors in the sunlight for several hours, or in an
indoor area free of rodents for approximately 1 week before cleanup. After that
time, the virus should no longer be infectious. Wear rubber, latex, vinyl, or
nitrile gloves and wipe the items with a cloth moistened with disinfectant.
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--- Disinfect gloves before removing them with disinfectant or soap and water.
After removing the gloves, thoroughly wash bare hands with soap and warm
water.
In substantially dirty or dusty environments, additional protective clothing or equipment
should be worn (see Special Precautions for Homes of Persons with Confirmed
Hantavirus Infection or Buildings with Heavy Rodent Infestations).
Cleanup of Dead Rodents and Rodent Nests
• Wear rubber, latex, vinyl, or nitrile gloves.
• In the western United States, use insect repellent (containing DEET) on clothing,
shoes, and hands to reduce the risk of flea-bites that might transmit plague.
• Spray dead rodents and rodent nests with a disinfectant or a bleach solution,
soaking them thoroughly (see Disinfecting Solutions below).
• Place the dead rodent or nest in a plastic bag or remove the dead rodent from the
trap and place it in a plastic bag. When cleanup is complete (or when the bag is
full), seal the bag, place it into a second plastic bag, and seal the second bag.
Dispose of the material in the double bag by 1) burying it in a 2- to 3-foot-deep
hole or 2) burning it or 3) discarding it in a covered trash can that is regularly
emptied.
• Clean up the surrounding area as described in Cleanup of Rodent Urine and
Droppings and Contaminated Surfaces.
Disinfecting Solutions
Two types of disinfecting solutions are recommended to clean up rodent materials:
1. General-Purpose Household Disinfectant --- Prepare according to the label. Almost
any agent commercially available in the United States is sufficient as long as the label
states that it is a disinfectant. Effective agents include those based on phenols, quaternary
ammonium compounds, and hypochlorite.
2. Hypochlorite (Bleach) Solution --- A chlorine solution, freshly prepared by mixing 1½
cups of household bleach in 1 gallon of water (or a 1:10 solution) can be used in place of
a commercial disinfectant. Bleach solutions should be prepared fresh daily.
Cleaning Sheds and Other Outbuildings
Before cleaning closed sheds and other outbuildings, ventilate the building by opening
doors and windows for at least 30 minutes. Use cross ventilation if possible. Leave the
area during the airing-out period. In substantially dirty or dusty environments, additional
protective clothing or equipment should be worn (see Special Precautions for Homes of
Persons with Confirmed Hantavirus Infection or Buildings with Heavy Rodent
Infestations).
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Special Precautions for Homes of Persons with Confirmed Hantavirus Infection or
Buildings with Heavy Rodent Infestations
Special precautions are indicated for cleaning homes or buildings with heavy rodent
infestations. A rodent infestation is considered heavy if piles of feces or numerous nests
or dead rodents are observed.
• If the building has been closed and unoccupied for a long period (weeks or
months), ventilate the building by opening doors and windows for at least 30
minutes before beginning any work. Use cross ventilation if possible. Leave the
area during the airing-out period.
• Persons involved in the cleanup should wear coveralls (disposable if possible);
rubber boots or disposable shoe covers; rubber, latex, vinyl, or nitrile gloves;
protective goggles; and appropriate respiratory protection. Proper respiratory
protection includes masks that cover the nose and mouth designated as N-95 or N-
100, or a positive pressure powered air-purifying respirator equipped with N-95 or
N-100 filters (N-100 masks or filters should be used in situations where there has
been a confirmed hantavirus case). Persons with respiratory or cardiac conditions
should consult with their physician before wearing masks or respirators.
• Personal protective gear should be decontaminated or safely disposed of upon
removal at the end of the day. If the coveralls are not disposable, they should be
laundered on-site. If no laundry facilities are available, the coveralls should be
immersed in liquid disinfectant until they can be washed.
Persons involved in clean-up who develop a febrile or respiratory illness within
45 days of the last potential exposure should immediately seek medical attention
and inform the physician of the potential risk of hantavirus infection.
For more information call the Wyoming Department of Health, Preventive
Health and Safety Division, at 307-777-7172.