A Bay Area man has died after contracting the rare hantavirus - a viral infection carried by mice and passed to humans by the rodents' feces or urine - that he was probably exposed to while staying in Yosemite's popular Curry Village tent cabins, public health officials said Thursday.
The 37-year-old man, whose name and hometown were not released, died in late July, about six weeks after his stay in Yosemite National Park. Another visitor to the park, a woman in her 40s who lives in Southern California, also became sick with hantavirus but is expected to survive, according to the state Public Health Department.
The woman and the Bay Area man were in Yosemite at the same time in mid-June and staying in cabins about 100 feet from each other, but did not know each other, Yosemite officials said.
Lab tests taken after the two fell ill confirmed that the virus was present in fecal matter from mice trapped near Curry Village, a collection of tents and cabins in the eastern end of Yosemite Valley.
"The mice shed the virus in urine, in feces, and when the urine or feces, or nests, are disturbed, the virus can become airborne and infect people," said Vicki Kramer, chief of the state health agency's vector-borne disease section.
Both victims suffered from hantavirus pulmonary syndrome. It can take up to two weeks for symptoms to appear after exposure to hantavirus.
Most people suffer flu-like symptoms first, including fever, headache and muscle pains, often in the thighs, back and hips. After two to seven days, many patients have severe difficulty breathing and can die.
There is no cure or virus-specific treatment for hantavirus. Patients typically are hospitalized and get help breathing while their body tries to fight off the virus.
"It's supportive treatment only. We have pretty unacceptably bad options for treating hantavirus," said Dr. D. Scott Smith, chief of infectious disease and geographic medicine at Kaiser Permanente Medical Center in Redwood City.
"By the time someone comes in with a bad cough and a fever, sometimes it's too late."
There have been about 60 cases of hantavirus pulmonary syndrome reported in California since the virus was identified in the United States in 1993. About a third of those patients died. So far this year, there have been four cases of hantavirus reported in California.
The virus is most commonly seen in the eastern Sierra and is rare in lower-elevation parts of the state. These two most recent cases are the first ever to be reported from Yosemite Valley, although the national park has had two cases in past years, both in visitors to the higher-elevation Tuolumne Meadows, said park spokesman Scott Gediman.
In California, the virus is spread primarily via deer mice, which have solid-colored backs and white bellies and generally live at higher elevations. Yosemite officials regularly monitor the activity of deer mice in the park, and crews that clean tent cabins are instructed to inspect rooms for mouse droppings, Gediman said.
After the recent hantavirus cases were connected to the park, officials with the state Public Health Department and the U.S. Centers for Disease Control and Prevention visited Yosemite and found no evidence of mouse infestations or unclean lodgings, Gediman said.
He and public health officials advised visitors to Yosemite and elsewhere in the Sierra to take precautions against contracting hantavirus.
People should avoid leaving food in the open, which can draw mice, and they should avoid contact with mouse feces or nests.
General Manager - Staff Entomologist