Outside magazine, August 1995
Our special online forum with epidemiologist James Mills
Health: Warning--Killer Microbes Next 20 Miles
Is hantavirus lurking in your favorite neck of the woods?
By Miles Harvey (with Lia Mehos)
It seems like one of those hell-bent jungle diseases that could never happen to you. First you run a temperature, mild flulike symptoms, nothing more. Then a headache hits like a freight train, with nausea following right behind. Eventually, amid fits of vomiting and internal bleeding, a tide of fluid seeps into your lungs and slowly suffocates you.
The disease is hantavirus pulmonary syndrome. Caused by a distant cousin of the now-famous Ebola virus, which killed more than 200 in the town of Kikwit, Zaire, late last spring, it burst into the national consciousness in 1993 when 17 people died--mysteriously, at first--in the Four Corners area of the southwestern United States. And while experts say that your chances of coming down with the disease are considered to be minuscule, there is disturbing news out there: the federal Centers for Disease Control and Prevention recently reported that hantavirus-carrying rodents have been found in some 20 national parks, including Yellowstone and Shenandoah, and that it's possible that the virus is in all of the parks. Adding to the concern, warm El Niño weather last winter has given rise to the likelihood of a bumper crop of disease-carrying rodents. And still, some doctors and researchers complain, there isn't a coherent government-led effort looking into the disease.
"There are infected rodents just about everywhere," says CDC epidemiologist James Mills. "Even on Long Island."
Unlike Ebola, hantavirus, which kills about 51 percent of its victims, is not passed between humans, but rather is fostered by rodents, especially deer mice, and is usually transmitted to humans by airborne fecal matter. Since the 1993 outbreak, 110 cases of the disease have been reported in this country. Only two cases, those of a 49-year-old San Francisco woman and a vacationing 61-year-old Australian man, have been directly linked to hiking or camping. The woman died several weeks after backpacking in the Sierra and Cascades; the man became ill while hiking on the Appalachian Trail in Virginia, but recovered. Nevertheless, CDC epidemiologists now think campers and hikers may have a higher chance of contracting the disease than most people.
"All it takes is a microsecond of breathing infected air," explains Mills. "That could happen while stepping into a cabin that hasn't been lived in for a while."
Scientists, however, are at a loss as to why human infections are rare while infected rodents are seemingly everywhere. "That's the million-dollar question," says Judith Graber, coordinator of a CDC unit that tracks human hantavirus infections.
The answer may not be available very soon. Despite how uninviting America's campgrounds and cabins may sound at the moment, little is being done on a national level to monitor infected rodents. "Government money tends to go to the best and brightest, no matter what the field," says Brian Hjelle, a University of New Mexico pathologist who has been conducting some small-scale hantavirus research with a five-year, $960,000 grant from the National Institutes of Health. "And so far, hantavirus hasn't attracted the best minds in epidemiology, probably because it's still so rare."
Meanwhile, hikers on the Appalachian Trail are going about their business, pitching their tents on the forest floor and flopping their sleeping bags down on pine bunks in musty cabins and lean-tos. Occasionally they pass a sign that warns of hantavirus and offers such commonsense advice as "pitch tents in areas without rodent droppings."
"It's certainly something to think about while you're out on the trail," says Mills, adding that hikers and campers should avoid all rodent dens, drink disinfected water, and sleep on a ground cover and pad. Also, he says, never sweep out a cabin or bunkhouse infested with rodent feces. "Of course," Mills adds, "you're more likely to be eaten by a bear."