The most recent person killed by the rare hantavirus pulmonary syndrome was part of a growing group of Yosemite National Park visitors all believed to have been infected around the same time in June while staying in a specific style of cabin in a popular lodging area, park officials confirmed Friday.
Additionally, Yosemite officials are now saying that about 29,000 visitors since the beginning of June could have been exposed to the virus.
The victim, a tourist from Kanawha County, West Virginia, stayed in a “signature tent cabin” in Curry Village sometime in mid-June like those in all but one of the eight other hantavirus cases linked to the park this summer, according to Yosemite spokeswoman Kari Cobb.
She said the West Virginia victim died in late-July, but the death wasn’t officially confirmed as hantavirus and linked to the park until Thursday morning.
“That person died but they weren’t sure why, so they went back and did testing and confirmed it as hantavirus. That’s why we found out about it so late,” Cobb said.
The two other fatal cases, a 36-year-old Alameda County man who died July 31 and a 45-year-old man from Pennsylvania who died Aug. 12, are both linked to stays in Curry Village’s signature tent cabins sometime in June as well.
Officials are withholding the age, gender and date of death of the third victim at the request of family members.
The names of all eight people infected this summer have also not been released.
Symptoms of hantavirus pulmonary syndrome begin with fever and aches similar to the flu, but can move on to respiratory problems that can result in death.
The fatality rate for hantavirus is more than 30 percent.
All 91 signature tent cabins were shuttered late last month in response to the growing number of guests being diagnosed with the disease.
“The reason we shut down the signature tent cabins is that seven of the eight visitors (later diagnosed with hantavirus) stayed in those signature tent cabins in the middle of June. We can say that’s a strong enough link to close them.” Cobb said.
Yosemite spokesman Scott Gediman told The Union Democrat on Aug. 29 that officials are finding the design of the signature tent cabins may be more susceptible to infestation because deer mice are getting between the canvas siding, insulation and drywall.
Ways of sealing the cabins from pests are being assessed, but there is not an estimated date for reopening them.
Meanwhile, the California Department of Public Health is currently investigating how the outbreak started and why it was mostly concentrated to the Curry Village cabins, according to department spokesman Ralph Montano.
“Infected deer mice were found to be abundant in the area and that could have been a contributing factor,” he said, adding that rodent ingress into the cabins might have also played a role.
Humans contract hantavirus through contact with the urine, droppings or saliva of infected rodents, primarily deer mice in most of the United States. Sweeping can stir up dried particles into the air and make exposure more likely.
Tuolumne County Public Health Officer Dr. Todd Stolp cited a confluence of circumstances that could have contributed to the rapid spread of hantavirus in Curry Village in June.
“These are all basically ecological diseases, meaning they are dependent on a number of environmental factors,” Stolp said of vector-borne diseases such as hantavirus, West Nile Virus and malaria.
According to Stolp, some factors possibly influencing the rapid transmission of hantavirus include an influx of humans to an area where the disease has been dormant and an increased presence of rodents carrying the disease.
Food stores left unwatched, undergrowth beneath homes creating access points, cracks or holes in walls and windows without screens all could help lead to an increased number of disease carrying rodents in a given area, Stolp explained.
“One theory is that it may be the design of those tents that is contributing to some of those factors responsible for increasing vector-borne disease,” he said.
Stolp, along with public health officials across the state, has been circulating state guidelines for physicians to help them better identify hantavirus in patients. He said the disease is so rare that many private laboratories don’t maintain the resources to test for it.
There have been 602 confirmed cases of hantavirus since the disease was first identified in 1993, with 60 of those coming from California.
Stolp noted that only three have ever been recorded in Tuolumne County, and all were tied to the Tuolumne Meadows area of Yosemite National Park.
A park news release issued Thursday revealed one individual who visited Tuolumne Meadows and stayed in multiple High Sierra camps in July was recently diagnosed with hantavirus as well. That person exhibited mild symptoms and is recovering, according to the park.
Hantavirus was previously linked to Tuolumne Meadows in 2000 and 2010. Both people survived in those cases.
A 2010 study found hantavirus present in 18 percent of deer mice tested in various areas throughout the park including Tuolumne Meadows. The study concluded that the prevalence of the disease “underscored the importance” for the National Park Service to maintain a comprehensive rodent control program.
Cobb said Friday that all High Sierra camps in Tuolumne Meadows remain open because public health officials working with the National Park Service didn’t think the lone case warranted any further closures.
She said the recent case connected to Tuolumne Meadows prompted the park to send 13,000 notices to registered guests who stayed in those camps since the beginning of June, in addition to the nearly 3,000 already sent out to guests of Curry Village.
Reporter Brenna Swift contributed to this report.