Hantavirus: Rare, but often deadly

SAFETY FIRST When cleaning out areas that could have housed mice,
take precautions such as goggles, a mask and gloves

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In the giddy delight of longer days and warmer temperatures, many landowners will take to cleaning outbuildings and machinery without realizing it could expose them to a rare but often fatal disease.

Hantavirus is contracted by inhaling infected droplets from rodent urine, saliva and feces. There are many hantaviruses, but the one found in Canada is the Sin Nombre Virus (SNV) and its vector is the common deer mouse. The resulting disease is called hantavirus pulmonary syndrome (HPS) and it is fatal in 30-40 per cent of cases. By conducting surveys on deer mice in Alberta, it was learned that as little as one per cent or as much as 35 per cent of the deer mice population carry the virus, depending on region and localized conditions.

Its discovery in North America is relatively recent, and dates back to 1993 to the Four Corners area of the southwest United States, although it has likely existed long before it was found here.

Alberta was home to the first Canadian case in 1989. Since then, there have been approximately 60 cases in Canada, 42 of which have been found in Alberta, and 10 were fatal.

The peak infection time is during April, May and June and 70 per cent of victims are ranchers or farmers. The number of incidents in the spring may be attributed to increased activity in outbuildings that had been left undisturbed all winter, allowing mouse nests, feces and urine to accumulate.

The course of the illness varies, but the incubation period is typically two weeks, though it can be as short as a few days, or as long as six weeks. Initially the patient will experience fever, chills, muscle aches, headaches, nausea and stomach problems. As the disease progresses through the next three to seven days, the symptoms become increasingly severe. The victim may develop a secretion-producing cough and a shortness of breath which mean fluid is accumulating within the lungs. Low blood pressure and reduced heart efficiency may follow and death may follow.

There is no treatment specific for HPS, but early detection and admission into the hospital improves the patient’s prognosis. With supportive medical care such as intubation and oxygen therapy, a victim’s critical systems may be supported enough to avoid mortality. Recovery can take months or even years, and ongoing fatigue is commonly experienced by survivors.

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