In the month of July alone, two cases of the serious respiratory illness Hantavirus Pulmonary Syndrome (HPS) have been connected to Park County, according to the Colorado Department of Public Health (CDPH). One resulted in death this week. Two weeks ago, the first Park County case was diagnosed. The first patient survived the illness after a prolonged hospitalization.

This brings the number of hantavirus cases in Colorado in 2007 to six, with four deaths. Two cases reported in May occurred in Weld and Alamosa counties; the patient from Alamosa died. In the past five days, Custer and Costilla Counties each reported one hantavirus death.

HPS is a serious respiratory disease carried by certain wild rodents, mainly deer mice, and is passed to humans through contact with a rodent's infected urine, droppings or saliva. Breathing in contaminated mist or dust is the most common form of transmission. Deer mice are brown on top and white underneath, with a very distinct separation of these colors. They have large ears relative to their head size. House mice on the other hand are all gray and have small ears. The small, gray house mice commonly found in urban areas do not carry the disease.

The case fatality rate is high, according to CDPH. The incubation period varies widely, but ranges from 1 to 6 weeks, with an average of 2-3 weeks. The early symptoms include fever, headache, and muscle pain, severe abdominal, joint and lower back pain, nausea and vomiting. A cough and shortness of breath usually develops 1 to 5 days after the onset of symptoms. The primary symptom of HPS is difficulty in breathing due to fluid build-up in the lungs. This can quickly progress to respiratory failure. The CDPH urges early hospitalization for supportive therapy.

With the confirmation of four cases within the past two weeks, state health officials are warning Coloradans in the rural part of the state to be cautious and avoid exposure to hantavirus when working in and around cabins, buildings, sheds and barns where deer mouse populations have left droppings. John Pape, a Colorado Department of Public Health and Environment epidemiologist who specializes in animal-related diseases, said, "The virus can infect humans when they inhale dirt and dust contaminated with deer mice urine and feces, which occurs when people have contact with infected mice or stir up dust while working in or cleaning out rodent-infested structures."

If live mice are occupying a structure, rodent control should be done before extensive cleaning efforts. The structures should be ventilated thoroughly 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.