Yosemite Park Officials Find Two More Victims Of Rare Hantavirus
August 31, 2012

Yosemite Park Officials Find Two More Victims Of Rare Hantavirus

Lawrence LeBlond for redOrbit.com - Your Universe Online

Less than a week after Yosemite National Park officials reported the death of a second person who had contracted Hantavirus while staying at the park´s popular Curry Village on the eastern edge of Yosemite Valley, two more visitors have been diagnosed with the deadly rodent-borne virus. The total infection count is now up to six, according to health officials on Thursday.

Of the six people infected with the rare lung disease hantavirus pulmonary syndrome, two have died. The other four were able to fight off the infection. Park officials believe all infected persons contracted the disease while camping at Yosemite´s Curry Village tent cabins over a one-week period in mid-June.

The new discoveries were made while California Department of Public Health officials investigated the outbreak, said agency spokeswoman Anita Gore.

Park officials had shut down 91 of the 408 cabins, which were called “signature tent cabins,” because they were insulated and believed to be more prone to rodent infestation. Workers continued to survey the cabins and work to better improve the safety of the cabins.

Furthermore, park officials notified more than 2,900 past visitors who rented the cabins between June and August to alert them of the possible exposure to the deadly disease.

“Our investigation is trying to determine which area of the park that person visited,” Gore told Jason Dearen of the Associated Press.

Four of the infected victims who visited the park stayed at Yosemite´s tent cabins; one slept elsewhere in the village; and the last one is still under investigation. Of the two deaths, one was a man from northern California and the other was a woman from Pennsylvania, California health officials said in a press release.

Experts are continuing their investigation and said the number of cases could rise as potentially exposed visitors may have yet to show symptoms of the illness, the agency noted. Roughly 70 percent of the park´s 4 million annual visitors camp at Curry Village, making the risk for more infections significant.

Hantavirus begins with flu-like symptoms but can quickly affect the lungs, making it hard to breathe and can lead to death. The disease can take up to six weeks to incubate.

The hantavirus outbreak surprised park officials, who last April stepped up protection efforts in the park after a 2010 report warned that rodent inspection efforts should be increased after a visitor to the Tuolumne Meadows area of the park became infected. The new hantavirus policy established on April 25, was designed to provide visitors a safe place, “free from recognized hazards that may cause serious physical harm or death.”

Hantavirus is carried in rodent feces, urine and saliva that dries out and mixes with dust. When the dust is breathed in by humans, especially in small, enclosed spaces, such as the tent cabins, it can be infectious. But infection can also occur when people eat contaminated food, touching contaminated surfaces and being bitten by infected rodents.

In Yosemite, the hantavirus is typically carried by deer mice. And since deer mice are so tiny, they can squeeze through small spaces less than a quarter-inch in diameter, such as cracks and holes that may be found in buildings, such as the Curry Village tent cabins. The signature cabins, which are well insulated, make a prime nesting spot for deer mice.

Data from the US Centers for Disease Control and Prevention (CDC) estimated there were 24 cases of hantavirus in 2011. Half of those cases resulted in death of the victim. The average death rate for hantavirus infection, however, is 36.39 percent, a little more than a third of all cases, according to CDC data.

Although there is no cure or vaccine for hantavirus, early treatment after detection can save lives. The good news with hantavirus is that it has never been known to be transmitted between humans.

“The earlier it's caught and supportive care is given, the better the survival rate,” Dr. Vicki Kramer, chief of vector-borne diseases at California´s Public Health Department, told Reuters´ Ronnie Cohen.

Dr. Charles Chiu, an infectious disease expert at the University of California at San Francisco, said he made it a habit of airing out his tent-cabin before occupying it as a precaution when he visited the park and stayed at Curry Village a few years ago. Yet, he was surprised to learn that hantavirus had killed two people who slept in the same cabins earlier this summer.

“It wasn't something even I had thought of at the time,” Chiu, who studies hantavirus, told Reuters.

Melanie Norall of Palo Alto, California, said she and her daughter had stayed in a cabin at Yosemite´s north entrance at the end of July and awoke to scurrying mice that had been eating food out of their luggage. She said that her daughter now has the sniffles and she is monitoring her closely.

Chiu said the majority of victims are young and middle-aged adults. He noted this could be that they are the most likely to engage in activities that would expose them.

“The message should not be you should stop camping. The important thing is general awareness of this disease and to avoid wild rodents in general,” Chiu said.