National Parks Are on the Alert for Hantavirus

Visitors to national parks are often reminded of safety precautions such as boiling stream water and keeping food stashed away from bears. This year, they will also be reminded to take precautions against hantavirus, a rodent-borne virus that can cause severe respiratory problems and even death.

The reminders will be especially frequent in parks where the virus has been found in rodents. But all national park visitors should take precautions, health officials say.

“Essentially, we assume all parks have hantavirus,” says Joseph Winkelmaier, a public health consultant for the Pacific West region of the National Park Service. In the past few years, testing has been conducted in Lassen National Park, Point Reyes National Seashore and Yosemite, he says. Of 214 rodents sampled, 14 tested positive for the virus.

Hantavirus also has been detected in deer mice at Channel Islands National Park in Ventura, but there have been no documented cases of people on the islands contracting it, says Carol Spears, a park spokeswoman. The virus was found on Santa Rosa, Santa Cruz and San Miguel, the park reports, but not on Santa Barbara or Anacapa.

Park and health officials say visitors should not worry about getting the virus nor should they cancel trip plans. “The risk is low,” says John Hanley, director of public health programs for the National Park Service.

Hantavirus first made news in the United States in 1993, when a mysterious pulmonary illness broke out among otherwise healthy young adults in the Four Corners region of New Mexico, Arizona, Colorado and Utah. Public health officials diagnosed the illness as a form of hantavirus. Since then, the federal Centers for Disease Control and Prevention has documented 249 cases, 101 of which were fatal, according to Tom Skinner, a CDC spokesman.

Rodents shed the virus in their urine, droppings and saliva, according to the CDC. When these materials are stirred up, such as by sweeping a cabin, tiny droplets containing the virus get into the air and people may inhale them and become infected. Touching something contaminated then touching one’s mouth or nose might also be a path for the virus.

Less commonly, a rodent bite can transmit the virus.

The virus is not spread from person to person, the CDC says, or from pets or other animals.

An infected person will have fatigue, fever and muscle aches one to five weeks after exposure, according to the CDC. There can also be headaches, chills, nausea, vomiting, dizziness, diarrhea or abdominal pain. Later, coughing and shortness of breath can occur.

Prompt medical attention is crucial. There is no cure for the disease, but patients are given oxygen therapy and put in intensive care.

Among the precautions for park visitors: Avoid contact with rodents, and do not disturb rodent dens. “Keep food in locked containers,” Spears says. “Keep tents zipped so mice don’t come in.” Park visitors should also discard garbage in rodent-proof containers and remind children not to play with any animals in the park.

Healthy Traveler appears the second and fourth Sundays of the month. Kathleen Doheny can be reached at kdoheny@compuserve.com.