The U.S. Centers for Disease Control and Prevention in Atlanta issued a warning to healthcare providers Friday stating as many as 10,000 recent visitors to Yosemite National Park were potentially exposed to a rare, rodent-borne disease that has already killed two people.
Between June 10 and Aug. 24, an estimated 10,000 people stayed in the “signature tent cabins” in Yosemite Valley’s popular Curry Village lodging area, which has been at the center of a recent outbreak of hantavirus pulmonary syndrome, according to the advisory sent out through the CDC’s Health Alert Network.
“People who stayed in the tents between June 10 and Aug. 24 may be at risk of developing (hantavirus pulmonary syndrome) in the next 6 weeks,” the advisory stated. “Providers are reminded to consider the diagnosis of HPS in all persons presenting with clinically compatible illnesses and to ask about potential rodent exposure or if they had recently visited Yosemite National Park.”
Six hantavirus cases throughout the United States have been linked to Yosemite, prompting park officials to send letters and emails to the roughly 3,000 registered guests who stayed in the Curry Village tent cabins this summer.
The first Yosemite-related case, a 49-year-old Southern California woman who stayed in Curry Village between June 10 and 13, became ill at the end of June and was hospitalized. She was released July 18 and is expected to survive.
A 36-year-old Alameda County man, who stayed in the tent cabins in Curry Village over the same period as the Southern California woman, became sick around July 23 and died July 31, just 24 hours after going to the hospital.
The California Department of Public Health made the public aware of the outbreak Aug. 16 after the two cases were linked to the park. Since then, four other possible cases have been identified.
One of the four additional people diagnosed with hantavirus has also died.
Hantavirus pulmonary syndrome is contracted by coming in contact with the droppings, urine or saliva of rodents carrying the disease.
Studies have shown hantavirus present in deer mice in Yosemite National Park. A 2010 report by the California Department of Public Health warned the park about the dangers of the virus and the need for a comprehensive rodent control program.
Two previous cases coming out of Yosemite, one in 2000 and the other in 2010, were linked to stays in the remote Tuolumne Meadows area of the park. Neither person died in those cases.
Instances of hantavirus in the U.S. first began to appear after 1993 outbreaks in several Southwestern states. There have been 587 cases identified nationwide since that time, with 60 of those from California.
About one-third of hantavirus cases result in death.
It takes on average one to six weeks after being exposed to hantavirus for flu-like symptoms such as fever, dizziness and aching muscles to appear. After the virus progresses to the lungs, people may begin experiencing respiratory problems that lead to death.
Yosemite spokeswoman Kari Cobb said the CDC’s estimated number of people at risk for hantavirus includes the friends and families of registered guests who were staying in the Curry Village tent cabins this summer.
“We would only have your name if you registered and brought three other people with you,” she explained.
Each tent cabin has room for up to four guests, Cobb said.
After the additional cases were reported last week, the park ramped up efforts to rodent-proof 91 tent cabins and set up an information hotline for people concerned about the outbreak.
Cobb said Friday the hotline had received at least 1,500 calls from people wanting to know more about hantavirus or worried they were exposed to it during a recent stay.