A woman in her 50s from the Squak Mountain area has been hospitalized with HPS, which is caused by exposure to hantavirus.

This is the second case of HPS in Issaquah in six weeks and the third case of hantavirus in King County in five months.

An Issaquah man in his 30s died of HPS in late February, just one day after going to the emergency room. He also lived in the Squak Mountain area, though on the other side of the mountain from the hospitalized woman.

A woman in Redmond was diagnosed with HPS in November. She has since recovered from the disease.

In Washington state, the deer mouse is the primary carrier of hantavirus. Deer mice tend to live in wooded areas, avoiding urban settings. Dr. Jeff Duchin of Public Health — Seattle and King County said at a press briefing on Tuesday that wooded areas of the county may be at a higher risk for the disease.

Duchin called Issaquah a possible “mini hot spot” for hantavirus.

“This is a rare disease in general, and to have two cases … in Issaquah around Squak Mountain and one case in Redmond, which isn’t that far away, suggests to us that there is something in the general vicinity,” Duchin said.

The county does not believe that the individual cases are linked.

The only other time that hantavirus was reported and contracted locally in the county was in 2003. Health professionals do not know what may have caused the recent spike in hantavirus cases.

“We are not exactly sure what might be responsible for this cluster of cases,” Duchin said. He speculated that high rainfall might have provided more food sources for mice and may have caused deer mice to seek shelter in places where humans could come into contact with them.

HPS is not spread from human to human. People contract hantavirus by breathing in dust that has been stirred up from rodent droppings or nesting materials, which can happen through activities such as cleaning houses, garages and cabins. It is also possible to acquire the virus from touching rodent droppings, urine, saliva or nesting materials and then touching one’s eyes, nose or mouth, or from being bitten by a deer mouse.

The first symptoms become apparent after one to eight weeks of exposure and resemble a flu virus. For three to five days, a person may experience fever, chills, aches, fatigue, nausea, vomiting and diarrhea.

Later, more serious symptoms develop, such as a cough, shortness of breath and difficulty breathing. This is where the disease becomes dangerous, and in some cases, fatal.

One-third of those with HPS die of the disease.

“It’s very serious,” Duchin told the Reporter in late March. “It causes the lungs and the blood vessels in the lungs to become leaky and the blood pressure to drop.”

The best way to prevent HPS from reaching this dangerous stage is to contact a health professional right away if you develop any HPS symptoms and were exposed to rodents or live in a wooded area. It is especially important to tell the health care specialist that you might have been exposed to deer mice.

“If you have the early symptoms … and you live in an area where deer mice are common or you know you’ve been exposed to rodent nests, I would seek medical care right away,” Duchin said. “The earlier the better.”

Unlike other illnesses such as the flu, hantavirus does not appear to be more dangerous or more common for the elderly or people with prior health conditions. Duchin said that people who contract HPS tend to be healthy young adults; this may be because these are the people who are typically performing the activities that put one at risk of exposure to rodent materials.

People risk exposure to hantavirus when cleaning houses or garages that may be infested with rodents; opening buildings that had previously been closed, such as summer cabins; using a cabin or shelter when camping or hiking; and working in construction, utility and pest control.

Residents of forested areas should prevent rodent infestations by removing potential sources of food, water and shelter for rodents. This can be done by sealing all pet food, trimming back trees growing next to houses, not allowing plants to grow alongside homes, stacking firewood at least 18 inches off the ground and away from buildings, and sealing all cracks and gaps in buildings over a fourth-inch wide.

If you have a rodent infestation, trap mice with snap traps anywhere that you have seen droppings. Before cleaning an infestation, make sure to ventilate the space for 30 minutes. While cleaning, wear gloves and a mask, do not vacuum, sweep or stir up dust in any way, and clean with a mixture of bleach and water.

For serious infestations, contact professionals. Duchin said serious infestations may include multiple rodent nests or dead rodents inside the house.

For a full list of precautions to take against hantavirus, visit http://www.kingcounty.gov/depts/health/communicable-diseases/disease-control/~/media/depts/health/communicable-diseases/documents/hantavirus-info-sheet.ashx.

“The message for the public is that hantavirus is really something that is present in Washington state all the time,” Duchin said. “And sometimes, although it’s a rare disease, it may increase. And when it does, we want to get that message out so the people just remember to take those precautions.”