Public Urged to Take Precautions to Avoid Hantavirus

With the return of summer, state health officials again are warning Coloradans in rural parts of the state to avoid hantavirus exposure while cleaning cabins, buildings, sheds and barns that may have been closed up for winter.

Hantavirus is a serious respiratory disease carried by deer mice that are common to rural areas throughout the state. The virus can infect humans who inhale dirt and dust contaminated with deer mice urine and feces, when working in or cleaning out rodent-infested structures.

Two more hantavirus pulmonary syndrome cases in the state were confirmed last week, according to John Pape, a Colorado Department of Public Health and Environment epidemiologist who specializes in animal-related diseases. “We are up to four reported cases in 2008, including one fatality,” he said.

The two recent cases occurred in Dolores and Delta counties on the Western Slope. Both patients were hospitalized but are recovering. Local health officials, in coordination with the department, are conducting investigations into how each individual was exposed to the disease. Historically, most hantavirus cases in Colorado are due to people being exposed to the disease in and around their homes.

Two other cases were reported earlier this year, one in Kiowa County in February and the other in Fremont County in early May. The person from Kiowa County did not survive.

Pape urged people to be particularly careful where there are mouse droppings and evidence that mice have been in and around the buildings or nearby wood or junk piles. A large, rapid increase in the number of mice around a home often precedes a human hantavirus case and should be considered a red flag.

“This year’s heavy snowpack has provided moisture for ample vegetation that provides food for rodents, and often results in a large jump in both mouse populations and infection rates,” said Pape. “May, June and July are the months when most of our human cases occur. Before people begin cleaning structures that have been closed up all winter, they need to take precautions if there are accumulations of mouse droppings and other signs of mice.”

PRECAUTIONS

• Rodent proof buildings by plugging holes or other mouse entryways. Conduct year-round rodent control, using traps or poisons, or hire a professional exterminator.
• Make home or work areas uninviting to rodents by keeping indoor areas clean, especially kitchens. Dispose of garbage in sealed containers.
• Eliminate food sources by storing food in rodent-proof containers, including food for pets, livestock and birds.
• Remove rodent hiding places near the home such as wood, junk and brush piles. Store firewood at least 100 feet from the house. Keep vegetation around the house well-trimmed.
• Use special precautions when cleaning rodent infested structures. Open doors or windows to provide good ventilation for 30 to 60 minutes before cleaning out structures. Avoid stirring up dust by watering down areas of mouse infestation with a mixture of bleach and water.

If live mice still are occupying a structure, rodent control should be done before extensive cleaning efforts. The structures should be thoroughly ventilated and any accumulation of dust, dirt and mouse droppings should be sprayed with a mixture of bleach and water before any cleaning begins. “Just vacuuming an area without first wetting it down doesn’t provide the necessary protection,” Pape emphasized.

“If you are living in rural areas and have deer mice around, you can assume there is some risk of exposure to this virus,” said Pape. “The more live mice that are present, the greater the risk. However, some people have been infected by directly handling a single mouse.”

HANTAVIRUS SYMPTOMS

Hantavirus - which is deadly in nearly half of the cases - begins with high fever, severe body aches, headache and vomiting. The onset of these symptoms begins from one week to six weeks after exposure.

Initially, there are no respiratory symptoms present. Symptoms such as a runny nose, sneezing, sinus congestion and a cough that produces phlegm are not associated with hantavirus infection. However, within one to five days, the illness quickly progresses to respiratory distress, including a dry cough and difficulty breathing caused by the lungs filling with fluid.

Because no effective treatment exists for the disease, Pape emphasized prevention as the key to avoiding hantavirus.

“When hantavirus infection is suspected or confirmed, early admission to a hospital where careful monitoring, treatment of symptoms and supportive therapy can be provided is most important,” he said. “If you become ill with these symptoms, it is important to tell your physician about possible exposures to deer mice or rodent-infested environments.”

DEER MOUSE DESCRIPTION

Deer mice are brown on top and white underneath. They have large ears relative to their head size. House mice on the other hand are all gray and have small ears. These small, gray house mice commonly found in urban areas do not carry the disease.

A photograph of a deer mouse can be viewed and downloaded at http://www.cdphe.state.co.us/dc/zoonosis/hanta/index.html  

For more information about hantavirus, call 303-692-2700.