Next spring and summer, health technicians wearing respirators, goggles, surgical gowns and shoe covers will tramp through Utah's junipers and pinyons, scrub oak and grasslands, collecting animals from more than 1,000 live traps.

Their quarry? Mice.Mouse-trapping expeditions are also planned for the same days in Arizona, New Mexico and Colorado, as well as other states. The health experts are hoping to collect hundreds of live mice and other rodents, in a drive to document the spread of the deadly hantavirus that has killed 29 victims so far.

The disease is known to be carried by deer mice.

As of Dec. 20, according to the federal government's Centers of Disease Control in Atlanta, a total of 50 cases of hantavirus had been confirmed in the United States, with 30 deaths. According to reports from Coeur D'Alene, Idaho, one of the most recent was Dyne Phillips, 14, who apparently was infected with the virus near his home in northern Idaho. He died Oct. 14.

No hantavirus illness is confirmed as contracted in Utah, said Tom Skinner, spokesman for the CDC.

State epidemiologist Craig Nichols said many types of terrain will be checked simultaneously in several states during the trapping project.

"We'll be trapping, for example, in some pinyon-juniper forests and also some spruce-fir forests, sagebrush areas and deserts, as well as others," he said.

"We'll all trap about the same time in those same sorts of locations in our various states and then determine the number of deer mice we find, along with other rodents."

Although this might seem like a task for the trappers of the federal Agriculture Department, or the outdoors folk of the state Division of Wildlife Resources, the task will be handled by the Utah Health Department.

"As you trap the mice and then collect the body parts and blood, you have to take special infection-control precautions," he said.

"Everyone who participates in the rodent collection and clinics has to wear a respirator. It has to have an airtight fit."

To make sure that the researcher has enough lung-power to draw in air through the fine filters in the respirator, he must pass a pulmonary function test.

"Then we also wear airtight goggles to prevent the virus from entering the eyes," he said.

After the animals are anesthetized and killed, they will be frozen on dry ice or in liquid nitrogen. Specialists from the CDC will test the samples for the hantavirus.

Nichols said it's possible that 100 traps will be set per night in each of 10 or 12 locations in the state. Rodents will be trapped for two or three nights per location.

"It's a lot of rodents to process if you have good trap success," he said.

Bob Howard, a spokesman for the CDC praised the effort as "an incredible opportunity for us at CDC to study what is essentially a newly recognized virus.

"I'd be safe to say this is a once-in-a-lifetime opportunity."

The hantavirus has been isolated in the laboratory, so researchers can recognize the virus.

"We know the primary carrier of this virus is Peromyscus maniculatus, the deer mouse," he said. Researchers know what the virus looks like and how it is carried.

"Here's an opportunity for us now to really go out and examine and evaluate how this virus is passed in the environment, and in a truly wild, natural setting."

Often this type of virus tends to be carried by one specific species, like the deer mouse in this case, he said. However, in Louisiana, a respiratory hantavirus was discovered that "is substantially different from the one in the Four Corners area."

Because of the difference, Howard said, it was probably carried by another species of animal besides the deer mouse. "We have not identified what that is yet," he said.

CDC will provide support and funding for the new trapping drive. Meanwhile, trapping has been carried out earlier on a smaller scale.

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"Deer mice have a high infection rate," Nichols noted. Of those trapped so far in the Four Corners states, 30 percent to 35 percent of deer mice have hantavirus.

A concern is that "the virus will spill out of the population of deer mice, into other rodents that live in the same terrain," he said.

But Nichols doesn't want to panic anybody. Hantavirus may be a risk for campers and hikers but "a very rare risk," he said. People working and involved in activities outdoors should simply be prudent, he said. That means not letting children dig in rodent borrows or feed rodents, for example.

Although lab tests have not confirmed that anybody became infected with the hantavirus while in Utah, some hantavirus victims from other states have been treated in Utah hospitals, Nichols said.

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