Some deadly diseases you’ve never heard of lurk in our national parks. It's extremely unlikely that you'll ever be infected, but the odds are not zero. And if you are among of the unfortunate few, may the Good Lord have mercy on you.

If you are visiting or working in a western park and you are messing around in a backcountry cabin or other structure that gets closed up for lengthy periods (all winter, for example), for heavens sake don’t stir up the dust and breathe it. And if you soak in a backcountry hot spring while visiting a national park – the hot springs at Yellowstone and Death Valley’s Saline Valley leap to mind – think twice before you duck your head under water or allow water to be splashed into your nose. Inhaling a noseful of sealed-cabin dust or a few drops of hot springs water isn’t just unpleasant. There’s a credible chance it might kill you.

On March 25, 2004, Glacier National Park Deputy Superintendent Jerry O’Neal died after contracting hantavirus pulmonary syndrome (HPS). There is no evidence that he contracted the illness while performing his duties at Glacier, but he did become infected with HPS in that area,quite possibly at his home.  

HPS is extremely dangerous. There is no effective treatment for it, and about half of the victims die.

HPS, which was first recognized in the Four Corners area of the southwestern U.S. in 1993, is a type of hemorrhagic fever transmitted to humans primarily via inhalation of airborne dust containing infected rodent droppings. The disease, which begins with flu-like symptoms, can also be transmitted by ingesting contaminated dust, such as the dust that accumulates on the lids of canned soft drinks and foods. It can also be transmitted through contact with the saliva of an infected rodent.

While campers and hikers are at some risk of HPS (the virus lurks in the duff on the forest floor and other places with rodent droppings), the greatest threat is to park workers involved in the seasonal opening and cleaning of park structures in the western states. If the workers performing such duties want to stay healthy, they must use effective respiratory protection (!!). Park workers who poo-poo this precaution and refuse to wear respirators are rolling the dice with the devil.

Hantivirus is not as rare as you might think. The Centers for Disease Control and Prevention (CDC) reported that rodents (rats and mice) carrying hantavirus have been found in at least 20 national parks, and there is good reason to believe that they’re present in nearly all of the national parks. The empirical data support the conclusion. Rodents carrying hantivirus have already been reported in every single western state and in many eastern states as well.

Danger lurks in national park waters, too. A very nasty amoeba, the Naegleria fowleri, occurs naturally in bodies of warm fresh water. While it is found in some lakes, it is especially found in warm or hot springs – places where, given acceptable temperatures, visitors might reasonably choose to bide a while and soak. Warm water to ease your aches and pains at the end of a long day’s hike. Warm water to soothe your worries away. Warm water to cleanse and rejuvenate you. Aaaaaaaaaah!

The thing is, you don’t want that water to get into your nose. If you duck your head, or perhaps get water splashed into you nose, you might inhale a few drops of that water. And then, just possibly, you could be in very deep trouble. The water could have Naegleria fowleri in it.

The Naegleria fowler amoeba, which is sometimes called the “brain-eating amoeba,” is very dangerous (to put it mildly). It typically enters the body through the nasal passages, then attacks brain tissue. The results are usually catastrophic. There were 33 cases of Naegleria fowleri infection recorded between 1998 and 2007, and 32 of the victims (including all six infected in 2007) died. That’s a mortality rate of 97 percent. You’d have a better chance of surviving a bullet wound in your chest.

Research has established that this nasty amoeba very probably inhabits a lot of warm water sources in our national parks. A study that Montana State University researchers conducted in 2003 found it in nearly two dozen hot springs sampled in Yellowstone and Grand Teton. It is almost certainly present in hundreds and hundreds of pools and lakes that have not yet been tested.

The bottom line is that a park visitor who soaks in a warm spring would be foolish to assume that there are no Naegleria fowleri in the water. That being the case, warm water bathers should avoid ducking their heads in the water or splashing water in their noses.

Postscript: You need to be aware of the risk of plague in western parks as well. Transmitted primarily by the bites of fleas from infected rodents, plague is known to occur in parts of California, Utah, Arizona, Nevada, and New Mexico. The three most common forms of plague are bubonic plague (infects the lymph nodes), pneumonic plague (infects the lungs), and septicemic plague (infects the blood). Don’t contract plague if you can help it. Your chances of surviving bubonic plague are about fifty percent. Pneumonic plague is even more dangerous. You’ll probably live if it’s treated (only 5% mortality), but if it isn’t properly diagnosed and treated, your chances of survival are very close to zero.