Hantavirus: Tiny mouse can pose deadly threat to humans

Sometimes Sara Shields-Priddy went into the dusty storage area of her mother's old barn. Other times she went into unused portions of the 85-year-old farmhouse near Lynden.

Or she fetched gardening supplies from her own pump house a half-mile away.

No one knows for sure where the 44-year-old mother of two may have inhaled the dust with the deadly hantavirus.

But there is no doubt that the virus came from the droppings, dried urine or saliva of tiny deer mice that live in rural areas and often get into buildings. And probably about three weeks after she inhaled the virus-laced dust, she was dead of the rare viral infection.

"All of us — her family, everyone — have been just so shocked that she died. ... She felt tired on a Saturday and she died on Wednesday morning," said her mother Elerine Shields, who lives outside of Lynden, in Whatcom County.

What to watch for

Since January, hantavirus infections across the nation have been higher than usual, according to the Centers for Disease Control and Prevention.

Twenty-two cases have been reported nationally, three in Washington state. Ten of the patients died, including two in this state. Four cases are being investigated in other states.

Infectious-disease experts suspect the increase resulted from an unusually wet winter and spring. More rainfall increases vegetation, which is more food for deer mice.

"Reproduction is more effective because there is more food out there. The mice interact with each other and spread the virus," said Dr. Mira Leslie, State Department of Health veterinarian, who helped investigate the first known outbreak of the disease in the United States. The outbreak, which began in 1993, was concentrated in the "Four Corners" area of Arizona, New Mexico, Colorado and Utah.

Symptoms of hantavirus illness begin one to five weeks after infection — usually about two — and start out like the flu: fatigue, fever and muscle aches, especially in the thighs, hips and back. About half of patients may also have headaches, dizziness, nausea, diarrhea and stomach cramps.

Four to 10 days later, the virus causes the lungs to swell and fill with fluid, causing coughing and shortness of breath. The CDC quoted one survivor saying the sensation was like a "tight band around my chest and a pillow over my face."

"It is a real severe infection. It's very uncommon and it takes an astute doctor to pick up [the early signs]," said Dr. Jeff Duchin, chief of communicable disease control for Public Health-Seattle & King County, who also investigated the initial hantavirus outbreak in the Southwest.

A sudden onset

Sara Shields-Priddy began feeling bad just four days before she died, her mother said.

On Saturday morning, March 18, she did chores around her home, including trimming the goats' hooves. Early that afternoon, she felt tired, but helped her husband, Kirk Priddy, clear some fallen trees and spoke later of how she enjoyed that. In late afternoon, she took a nap while her husband prepared dinner.

Sunday her fatigue increased, and on Monday, she asked her husband to take their son to preschool because she was too tired. On Tuesday morning, she drove herself to her Bellingham doctor, who thought she might have caught the flu from one of her children. But on Tuesday night as her breathing was increasingly labored, she went to the emergency room at St. Joseph's Hospital in Bellingham, and was quickly put on a ventilator. There is no medication or vaccine for hantavirus. Shields-Priddy died about 4:30 a.m., Wednesday, March 22.

Sara Shields-Priddy earned a master's degree in divinity, served on the National Council of Churches, worked with her husband in organizations to help troubled youth, was active in the Mennonite church and took great joy in her family, her mother said.

"She died about five minutes before I got to the hospital," said Shields. "I thought, as I looked at her, about all she had done with her life."

Such a rapid course of the disease is "very typical," said Leslie, of the State Department of Health.

Since hantavirus was identified in the U.S., nearly 450 cases have been reported nationwide. Thirty two have been in Washington state, 11 of them fatal. Washington has the fifth highest number in the nation, but no one knows why.

After Shields-Priddy died, a Yakima County man in his 60s survived a bout with the disease in May. In June, a woman in her 20s died in Okanogan County. Both were probably infected in their homes, health officials said. For privacy reasons, the state Department of Health would provide no other details.

How it transmits

Hantavirus, also called Sin nombre virus, does not pass from human to human. It is transmitted among deer mice in the West, where most hantavirus infections occur, and among certain other mouse species in the Southeast and Northeast.

The mice do not become ill. Experts estimate an average of about 10 percent are infected, but that can increase dramatically with favorable climactic conditions and population increases. Deer mice, which are 5 to 8 inches long including the tail, have white bellies and throats.

Deer mice can live in every habitat type — from desert to alpine tundra, including rural suburbs. One Washington state woman was even infected, investigators suspected, when food she had in her tent while camping in the North Cascades attracted the animals.

A few people have been bitten by mice and contracted the virus. And researchers also believe people may be infected if they touch something that is contaminated, then touch their nose or mouth, or if they eat something that is contaminated.

But human infection almost always occurs in a building or shelter when someone inhales dust contaminated from the mouse droppings, urine or saliva, Leslie and Duchin said. That's why it's important to wet down the area with bleach water before cleaning any area with rodent droppings, they said.

"You can't tell if they're deer-mice droppings or from another mouse," said Leslie. "All rodent droppings should be treated as if they're contaminated and infected."

Warren King: 206-464-2247 or wking@seattletimes.com. Seattle Times news researcher Miyoko Wolf contributed to this report.