22-year-old contracted the often fatal hantavirus at state park

If you’re visiting Yosemite National Park in California or the surrounding areas this year, you should be aware of hantavirus. In the past five years, 11 people have contracted the often deadly pulmonary disease while visiting Yosemite and surrounding parks.

Spencer Fry, a 22-year-old recent college graduate was working as a park aide at Bodie State Historic Park, just northeast of Yosemite, when he contracted the virus. Fry believes that he contracted the rodent-borne disease through mice in the cabin where he was living.

The state park—which is a ghost town that was once a bustling gold mining outpost—is about 75 miles southeast of Lake Tahoe, not far from the California-Nevada state line.

Fry was complaining of headaches for five days before he ended up in the emergency room with a 104-degree fever. According to a crowd-funding page set up by Fry’s family to help pay for his medical bills, the man’s lungs began to fill with fluid and he began vomiting while in the emergency room. He was placed on a ventilator and spent 10 days in the intensive care unit. He is now in stable condition.

Although Fry survived, others have not been so lucky. According to the CDC, the virus has a mortality rate of 38 percent.

A spokesperson for the California State Parks told ABC the investigation is still ongoing and that they cannot yet say whether Fry got the virus from the cabin where he lived.

“The health of our employees and the public is our priority,” read a statement from the State Parks. “As such, we took precautions and worked with the Mono County Health Department. On July 10, a public health officer conducted an inspection of all the areas where employees and the public have access and deemed them safe to remain open.”

If you believe you have been exposed to the hantavirus, according to the Centers for Disease Control, you should watch for the following early symptoms: fatigue, fever and muscle aches, especially in the large muscle groups (thighs, hips, back and sometimes shoulders) as well as headaches, dizziness, chills and abdominal problems, such as nausea, vomiting, diarrhea and abdominal pain.

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Advanced symptoms, which appear four to 10 days after the initial phase of the illness, include coughing and shortness of breath as the lungs fill with fluid.

Humans can become infected with hantavirus by breathing air contaminated with the virus from rodent urine or droppings. As the Mayo Clinic notes, “because treatment options are limited, the best protection against hantavirus pulmonary syndrome is to avoid rodents and their habitats.”

If you have or have had a mouse problem in your house, first manage the infestation by blocking all off possible means of entry and/or using traps to catch the mice. If you aren’t up to the task, hire an experienced exterminator to help you manage the infestation. Then, be sure to clean any areas with mouse urine or droppings with rubbing alcohol, a household disinfectant or bleach.

If you have been exposed to rodents and are experiencing symptoms, you should see your doctor immediately. The earlier patients are brought into intensive care, the more effective their treatment will be.

According to the CDC, the following U.S.-dwelling rodents carry hantavirus:

1. Cotton Rats

Cotton rats are found in the southern U.S., and, as their name indicates, build nests out of cotton.

2. Deer Mice

Deer mice live pretty much everywhere throughout North America. The CDC says deer mice prefer woodlands and desert.

3. Rice Rats

Rice rats live in the southeastern U.S. and are slightly smaller than cotton rats.

4. White-Footed Mice

White-footed mice can be found throughout much of the U.S. save for the far west and southeastern parts of the country.