Two people—one from Pennsylvania and one from northern California—who died after hiking at Yosemite National Park may have had the rare disease hantavirus, health officials say. Another camper who was near the deceased is recovering from the disease.
Deer mice and other rodents are asymptomatic carriers of the virus. That means that while they spread the disease, the rodents don’t get sick themselves. Humans get it when they come into contact with a carrier’s droppings. It often affects campers and hikers who bed down on the forest floor, but a large majority of patients were exposed to the virus at home.
There have only been fewer than 600 hantavirus cases reported in the 20 years since the virus was first identified in the United States. Hantavirus disease starts out like flu, with chills, fever, and achiness. Symptoms that develop after that include a dry cough, a headache that won’t go away, shortness of breath, abdominal pain, and vomiting, in addition to a general overall sick feeling.
The three people confirmed to have contracted the disease at Yosemite—as well as a suspected fourth case, though park officials are still investigating—had all been in a part of the park called Curry Village sometime after mid-June. All the patients had stayed in one of the campsite’s 90 insulated canvas “Signature Tent Cabins”; all 1700 guests who used those accommodations in the past three months have been contacted, park officials say, and staff have been reviewing the cleaning procedures for Curry Village and the rest of the park.
This is not the first hantavirus outbreak recorded at Yosemite. In 2000, and again in 2010, people were exposed to the disease in the Tuolumne Meadows section. Both of those patients survived. The disease has an overall mortality rate of about 30 percent.
Diagnosis is unreliable immediately after infection because the symptoms are so similar to flu, though exposure to rodent droppings is usually an indicator that tests need to be done. If you are having hantavirus disease symptoms and you’ve been around rodent droppings, be sure to let your doctor know, since treatment gets less effective as the disease progresses. If you might have been exposed, a blood test will be given to look for signs of hantavirus infection. Treatment is typically oxygen therapy until the patient’s breathing is normal again.