Deer mice (Peromyscus maniculatus) are implicated as carriers of hantavirus pulmonary syndrome (HPS) in Yosemite and other parts of the U.S. Photo from Centers for Disease Control and Prevention.

Cleaning crews scour cabins, cottages and yurts at Pennsylvania state parks, in part, to block a disease that killed three campers and infected four others who rented cabins at Yosemite National Park in California this summer, the Standard Speaker, Hazelton, Pa., reported.

The hantavirus that causes the disease spreads through the feces, urine and saliva of mice and rodents so regular cleaning routines prevent disease, as does plugging holes to keep mice outside tents and cabins. Because the virus can spread through the air, janitors try not to kick up dust that the droppings might have fouled.

“We use a Lysol spray when cleaning the yurts; they spray and wipe down the counters, kitchen table, furniture arms, coffee table, beds, mattresses, top of room partitions, appliances, and inside the drawers and cupboards,” Christina Novak, spokeswoman for the Department of Conservation and Natural Resources that runs Pennsylvania’s state parks, said by email.

At Yosemite, one of the visitors infected by the virus died in Pennsylvania. The other deaths occurred in California and West Virginia.

Hantavirus is rare.

Since its discovery in 1993, the U.S. Centers for Disease Control and Prevention reported 587 cases nationwide through the end of last year. No treatment exists, however, and 36.4 percent of those cases caused death.

Before the outbreak at Yosemite, Pennsylvania’s Department of Health recorded seven cases, two of which began in another state.

In one Pennsylvania case in 2007, a maintenance worker at a Scout camp in Clearfield County survived after getting infected.

Victims develop Hantavirus Pulmonary Syndrome. From one to five weeks after exposure to droppings, patients become tired, run fevers and start to ache, especially in their large muscle groups such as hips, legs, back and, sometimes, shoulders, the CDC says.

About half, but not all, patients become nauseous, vomit, have diarrhea, chills and headaches.

In latter stages, the patients labor to breathe as their lungs fill with fluid.

The Pennsylvania Health Department said deer mice, white-footed mice, cotton rats and rice rats spread hantavirus.

In a fact sheet distributed last year, the department recommended filling holes with steel wool, metal or caulk to deny entry to rodents.

The department also details procedures for cleaning cabins and other quarters that rodents might have occupied.

At Tuscarora State Park, maintenance workers follow the precautions, but they haven’t noticed signs of mice or rats in the six cottages and four Mongolian-style tents called yurts that the park rents, park Manager Lew Williams said.

“I told the maintenance supervisor to review the procedures for cleaning those things up,” Williams said.

Workers clean the cottages and yurts after each tenant leaves and also remove food and other leftovers that might attract rodents.

The cottages and yurts are “pretty much occupied from the beginning of April to mid-October. We get them cleaned more than once a month,” Williams said.

At Yosemite, the park’s officials notified 3,000 people who rented the signature cabins, which have canvas sides. Because of the cabins’ size, officials estimated up to 10,000 people might have been exposed to hantavirus.