Hantavirus Found in Four More Visitors to Yosemite National Park

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Date: August 30, 2012

The California Department of Public Health (CDPH) today reported four additional cases of Hantavirus Pulmonary Syndrome (HPS), bringing the total number of people infected with the hantavirus who visited Yosemite National Park to six.
"CDPH is working closely with the National Park Service and the Centers for Disease Control and Prevention to further investigate the cluster of Hantavirus Pulmonary Syndrome cases in Yosemite and reduce the risk of other visitors becoming ill from this virus," said CDPH Director, Dr. Ron Chapman. "CDPH is continuing to monitor cases of Hantavirus Pulmonary Syndrome in persons who visited Yosemite National Park."
To date, HPS has been confirmed in six persons who visited the park between early June and mid July 2012. Five are California residents and one is a resident of Pennsylvania. The PA patient and one CA patient have died, three have recovered and one is currently hospitalized but improving. Four, including both fatalities, lodged in the "signature cabins" of the Boystown area of Curry Village, one lodged in an unspecified area of Curry Village, and one is still under investigation.
The six individuals infected are residents from the Sacramento region, San Francisco Bay area, Southern California and one from Pennsylvania.
On August 28, per recommendations from CDPH, Yosemite National Park closed all tent cabins in the Boystown area indefinitely. The National Park Service has issued communications to guests who had stayed in the Boystown area between June 10 and August 24, alerting them to the HPS concerns and recommending that they seek medical attention if ill.
Since HPS was first identified in 1993, there have been 63 cases (21 fatal) in California. The recent cases bring the total California case count for 2012 to seven; one of the recent patients infected in Yosemite was not a California resident.

HPS is caused by a virus that individuals get through contact with aerosolized urine, droppings or saliva of infected wild mice, primarily deer mice. Breathing small particles of mouse urine or droppings that have been stirred up into the air is the most common means of acquiring infection. The illness starts one to six weeks after exposure with fever, headache, and muscle ache, and progresses rapidly to severe difficulty in breathing and, in some cases, death.
When you are in wilderness areas or places where mice are present, you can take the following steps to prevent HPS:

  • Avoid areas, especially indoors, where mice are likely to have been present.
  • Keep food in tightly sealed containers and store away from mice.
  • Keep mice out of buildings by removing stacked wood, rubbish piles, and discarded junk from around homes and sealing any holes where mice could enter.
  • If you can clean your sleeping or living area, open windows to air out the areas for at least two hours before entering. Take care not to stir up dust. Wear plastic gloves and spray areas contaminated with rodent droppings and urine with a 10% bleach solution or other household disinfectants and wait at least 15 minutes before cleaning the area. Place the waste in double plastic bags, each tightly sealed, and discard in the trash. Wash hands thoroughly afterward.
  • Do not touch or handle live mice and wear gloves when handling dead mice. Spray dead mice with a disinfectant and dispose of in the same way as droppings. Wash hands thoroughly after handling dead mice.
  • If there are large numbers of mice in a home or other buildings, contact a pest control service to remove them.
A non-emergency phone line for questions and concerns related to hantavirus in Yosemite has been set up. Visitors with questions can call (209) 372-0822. The phones will be staffed from 9:00 a.m. to 5:00 p.m. daily. For media inquiries related to Yosemite National Park activities, contact Scott Gediman of the National Park Service at (209) 372-0248.
For additional information on preventing HPS, visit CDPH's Hantavirus Cardiopulmonary Syndrome and the federal Centers for Disease Control and Prevention's Hantavirus Web site page.

Last updated: March 1, 2015

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