A Santa Fe County woman is in critical condition at University Hospital in Albuquerque with the state's first hantavirus case of the year.

The 25-year-old became ill sometime mid-last week, said Paul Ettestad, the state public-health veterinarian. It's unclear if she sought medical attention right away, he added.

The Department of Health is conducting an environmental investigation to see where she might have been exposed.

"It looks like there was a history of housecleaning, moving boxes around, but that's all we know," Ettestad said of the woman.

Hantavirus is transmitted to people when they breathe in the disease from the urine, droppings or saliva of infected rodents, he added.

"Most people are exposed to hantavirus in or around their homes, especially when they clean out enclosed areas that have lots of mouse droppings," Ettestad said.

Symptoms, which develop between one to six weeks after exposure, include fever, muscle aches, chills, nausea, vomiting, diarrhea, abdominal pain and cough. There is no cure, but chances for recovery improve greatly if a patient sees a doctor early.

The woman was taken to The University of New Mexico Hospital on Thursday, said Sam Giammo, a spokesman.

The hospital and university have done extensive research on the disease. The woman is using a piece of equipment that was specifically modified by UNM researchers for use with hantavirus patients.

It's called an Extra Corporeal Membrane Oxygenation device, Giammo said.

"It's like a lung bypass machine," Giammo said. "It circulates the blood and oxygenates it."

The machine was originally used on premature infants, but as cases emerged in New Mexico in the mid-1990s, doctors altered it for adult use, he said.

"Statistically, people with ECMO have a higher survival rate," Giammo said. "It sort of takes the place of the lungs."

In 2008 two people in New Mexico contracted hantavirus, one from Taos County and one from Otero County. Both died, officials from the Health Department said.

It's hard to predict what hantavirus season will be like in New Mexico this year. Since the weather has been relatively dry, there's some hope that the rodent populations are low and there won't be a lot of cases, but really it's all speculative, Ettestad said.

"There's always hantavirus in rodent populations here," Ettestad said. "It's very spotty and it's impossible to predict."

He declined to say where in the county the woman was exposed.

"I just hope she does well," Ettestad said.

To protect against exposure, the Health Department recommends avoiding contact with mice or rodents, airing out closed up areas of the home before entering and cleaning up any rodent nests or droppings with a disinfectant.

For more information visit www.nmhealth.org/epi/hanta.html.

Contact Sue Vorenberg at svorenberg@sfnewmexican.com.