A rare disease that killed one man and sickened a woman has been linked to a camping spot in Yosemite National Park. The Associated Press (AP) is reporting that a man who stayed at the Curry Villiage camping spot in Yosemite died from hantavirus. A woman who stayed near the man during the same time also contracted hantavirus and has become sick, but is expected to survive.

Park officials told the AP that this is the first hantavirus-related death in the park’s history, though two other cases of hantavirus have been recorded in the past 12 years. Hantavirus symptoms can take weeks to appear in those infected, so campers are being advised to seek medical treatment if they develop any symptoms, which are listed below.

The U.S. National Institutes of Health (NIH) describes hantavirus as a life-threatening disease spread by rodents, especially deer mice. The early symptoms of hantavirus, such as fever, chills, and muscle ache, are similar to the flu. After this period, those infected can begin to feel better, but find it hard to breathe within 1-2 days. A dry cough, malaise, headache, nausea, vomiting, and shortness of breath are further symptoms of hantavirus. If not admitted to a hospital promptly, the virus can cause lung, kidney, and/or heart failure, leading to death. According to the NIH, there is no effective treatment for hantavirus infection involving the lungs, and more than half of those infected in their lungs die, even with aggressive treatment including breathing machines.

The NIH advises that people avoid exposure to rodent urine and droppings to decrease their risk for hantavirus. The NIH website even contains detailed instructions on working in an area where rodent droppings are likely to be. The process involves airing out the area, disinfecting it, and spraying mouse nests with a bleach solution before incinerating them.