A Disease Cowboy Turns to Trout

If anyone has earned a peaceful retirement, it is Karl Johnson, but this is not to be. Another disease has struck.

For 40 years, Johnson confronted the world’s deadliest microbes and, in the process, twisted politics and grotesque poverty, work that led him to be called the “Disease Cowboy.” He retired in 1987 to fly-fish in Montana--a supposed refuge from all of this--only to find the trout there sick and dying. The disease cowboy is back in the saddle.

The viral epidemiologist headed the team at the Centers for Disease Control and Prevention that named the Ebola virus. His microscope was the first to see the Hantaan virus, one strain of which killed about 30 people in the Southwest in 1993. In the early ‘60s, he cracked the case of Bolivian hemorrhagic fever, but not before he caught it. It nearly killed him, as it killed almost half the people it infected.

In 1976, a deadly strain of Ebola swept Zaire. Hundreds of victims bled to death internally in a matter of days. Johnson waded into the contagion to head the international commission that beat back the epidemic. He worked on Lassa fever in Sierra Leone. He chased hemorrhagic diseases throughout the former Soviet Union. Besides the CDC, his hat has hung at the National Institutes of Health and the Army’s Medical Research Institute of Infectious Diseases.

With a full gray beard and gray hair, Johnson could be mistaken for a slimmed-up Santa in khakis, except that no one is likely to accuse him of being jolly. He deals in facts. Period. He is a snake charmer who has stared down the unseen world’s most efficient killers, but all he really ever wanted to do, ever since he was a kid in New Jersey, was to fish.

“I always wanted to come here since I was 10 years old, fly rod in hand,” he says from his new hometown in Bozeman, Mont. “I had to pay a lot of dues and lived a lot of places in the world so I could, and it was just--” (there is a long pause here to allow the shift to the subjunctive of dashed plans). “Well, this was going to be my first year of virtual retirement.”

This interview was supposed to have taken place on a river where we were to fish, probably because it is Johnson’s habit to suffer reporters while fishing; no sense in the day being a total waste. Richard Preston had fished on Montana’s Bighorn River when he interviewed Johnson for the bestseller, “The Hot Zone,” the account of a near outbreak of Ebola in the United States in 1989.

But Johnson canceled our fishing plans a few days before we were to go. Something about a schedule to keep and something about not having the heart to take a reporter to the Madison River, his home stream, one of Montana’s finest, where the trout are dying of whirling disease.

For the past eight years, Johnson, 66, who was in semi-retirement, has lived mostly in Bozeman, set where the headwater streams of the Missouri River braid together from mountain meadows resting against the Great Divide, a fly-fisher’s mecca. Late last year, though, state fisheries biologists realized a parasite that kills rainbow trout had spread into Montana.

Little was known about the disease, and its complexity is beyond the meager resources of most state fish departments. Enter Johnson, who volunteered his expertise, but his motivation probably has as much to do with the thrill of the chase as the love of the fish. Now he can read in this fish disease an all-too-familiar sign: tinkering with nature.

“Here’s a situation where man is the culprit again. The things we have done to nature have given us something we have all enjoyed, but we poisoned our own well,” he says. “Almost all of these things that come at us from nature are our responsibility.”

Man’s meddling is killing trout in Montana and at least 20 other states. It is caused by a protozoan, a microscopic jelly-blob of life that eats the flesh of trout. It enters young fish as a spore, develops, then attacks cartilage, mostly in the skull. This causes deformities--humped heads and twisted jaws--and a lack of coordination that makes the sick fish chase their tails, or whirl. It either kills the fish outright or leaves them vulnerable to predators. The disease, however, is harmless to humans even if they eat infected fish.

The parasite itself, Myxobolus cerebralis , was brought here by man, likely in a shipment of ground-up fish from Europe imported to feed hatchery fish in Pennsylvania in the mid-’50s. Because hatcheries stock sport fisheries, whirling disease spread.

Salmonids native to Europe, such as the brown trout, spent thousands of years negotiating a genetic truce with the parasite through co-evolution. Nature deals with disease through evolved immunity. Thus the browns that were imported to American streams do not suffer. Many trout native to this continent, however, are devastated.

There was more meddling: As early as the 1870s, native trout populations were manipulated, mostly beginning in California. Even then, anglers were looking for bigger and livelier fish and were not above re-engineering whole watersheds to have them.

The highly regarded rainbow trout of Rocky Mountain riffles were drawn from Northern California stocks. Biologists suspect that those early fish stockers drew from a very narrow population, which would leave the fish vulnerable. Narrow gene pools invite disease.

Subsequent selective breeding has made matters worse, yielding an animal somewhat unsuited to ward off the threats of wild living. As a result, rainbow trout populations, the foundation of fly-fishing throughout the West, are being diminished, in some cases decimated.

Until 1987, the disease was thought to be a hatchery problem and an eastern problem at that, but then it worked its way into a series of rivers in Colorado, with disastrous results. It also infects New Mexico, Nevada, Utah, Wyoming, Idaho and Oregon. California has had it since the 1950s but has not seen massive numbers die off, perhaps because of the broader genetic base or perhaps because of environmental factors such as irrigation, nitrate pollution or overfishing, which have thinned the population, making it difficult for the parasite to spread.

Montana was the last to be invaded, largely because the state had not stocked hatchery fish, concentrating instead on natural propagation through support of native habitat. When the parasite did hit last year, however, it killed as many as 90% of the young trout on the famed Madison River and is now spreading throughout the western end of the state. Ironically, it hits hardest in the best streams, simply because healthy fish populations make the healthiest pickings for parasites.

After hearing about the die-off last winter in news reports, Johnson and a few fishing buddies sat down “over a few beers” and decided to start a foundation to do what Johnson has always done: crack a case. The foundation has formed a sort of ad hoc umbrella over research into whirling disease nationwide.

“It’s my own fault. They would have let me [retire]. I didn’t have to do this,” he says. “It’s just that insistent habit of saying, ‘Gee, funny thing. What the hell is going on here?’ You start reading and you start asking a million questions, then you try and find answers and then you realize pretty soon they’re not there.”

At first, fisheries biologists in the various states disagreed whether whirling disease was the cause of the deaths. Some suggested other factors such as predation, overfishing and agricultural runoff. In May, scientists from most of the affected states sifted through the information at a conference that Johnson raised funds for and organized.

“He could talk to a geneticist, an immunologist or a molecular biologist. He was able to challenge these people in their individual areas,” says Tom Anacker, a Bozeman lawyer and a friend of Johnson. “The best way to put it is he’s a leader. He’s focused on an issue, has very high intellectual standards and challenges people to think.”

Johnson used that May session to push and prod the state scientists toward consensus. There is more agreement now that whirling disease is the cause of the die-off, but there is little hint as to what to do about it.

There’s no magic bullet, no way to vaccinate a stream full of fish. Some drastic experiments, such as killing all the fish in a given stream and then waiting for the disease to die off, have been tried, but the parasite has an alternate host, a bottom-dwelling worm. It can survive fishless streams for many years.

Johnson sees a glimmer of hope: Restocking decimated streams with more fish from Northern California. The hunch is this would work because a native parasite similar to the one that causes whirling disease lives in the streams around Mt. Shasta. Some strains of rainbow trout there are resistant. The thinking goes that those original 19th-Century fish stockers got the vulnerable strain, and that the native immunity of some of the Mt. Shasta fish may extend to defeat the exotic parasite.

Johnson’s group hopes to raise a $20-million endowment to pay for research, build laboratories and further develop a state-of-the-art genetic test for tracing the disease--”Real O.J. Simpson stuff,” he says. One of the key questions would be to test that notion of native immunity. If it’s true, resistant strains or crosses of resistant strains could restock ravaged streams.

And that clearly is more meddling. The Faustian bargain continues, making the trout disease no different than any Johnson has faced. It is true that the meddling doesn’t have to happen; nature could, given time, evolve a strain of trout to inhabit the Madison and any other infected stream.

“There are people who say we ought to not spend anything and let the Madison and the other rivers recover by themselves. They will [recover]. I think that’s probably true. I have no idea what the time frame is, but I’m very suspicious it’s hundreds of years, which I ain’t got,” he says. “I don’t know where else I’d move to have my final fishing place. It’s like the end of the road.”

This trout disease isn’t the only one that’s man’s fault; so is virtually every other headline-making outbreak that has driven Johnson’s career. The hemorrhagic fever that nearly killed him arose from deforestation committed to raise beef and then corn in Bolivia. This upset the natural habitat of rodents, causing them to overrun and infect villages.

Ebola spread in Zaire and Sudan through used syringes in hospitals. Modern-day outbreaks of cholera roam the seas on algal blooms that come from urban and rural nitrogen pollution.

The transportation system imported the trout parasite, but transportation’s role in disease is not new. AIDS spread on a highway in Africa via truckers and when the breakup of traditional villages created a transient working population. The original vectors of AIDS in Europe and North America were sailors and flight attendants. Many of the emerging viruses of the headlines have a strong link to wild primate populations, yet hundreds of monkeys are jetted each day around the globe. The transportation of monkeys brought a strain of Ebola to Reston, Va., the case described in “The Hot Zone.”

When diseases have erupted, man has asked science to interfere some more and develop vaccines. Those vaccines, in turn, create experiments inside human bodies, resulting in the evolution of new and resistant strains of disease.

E. coli was once harmless, one of the most common bacteria on the planet and a resident in everyone’s intestines. Widespread use of antibiotics has created a mutant E. coli that kills. Tuberculosis, malaria, cholera, gonorrhea, syphilis and a range of common diseases once thought assigned to history by antibiotics are again among us in resistant strains.

In her book “The Coming Plague,” science writer Laurie Garrett argues that there is an ecology of disease. Killer microbes are not just the result of the roll of the dice, or finger of fate. Rather, they are a consequence of man’s overpopulation, poverty and technology’s subversion of the natural world.

Johnson supports this explanation. Disease is a result of man’s ravaging the planet. In setting his sights for retirement, Johnson suffered no illusions he was returning to an Eden of pure nature. The web of streams he haunts are dammed and filled with bred trout, “the natural, man-made modified world,” he calls it. Still, there is nature in the mix, and his retirement is a retreat from the world Garrett describes.

What is his personal reaction to man’s role in the evolution of disease? Johnson quickly deflects the question: It does not compute. Just the facts, please. He is controlled, brusque and blunt, and the clearest flash of this comes in response to an impolitic question. He knows as well as anyone that people the world over are dying from what we call disease, but in truth is poverty. The viral monsters are really amplifications of deficiencies no more complicated than access to sanitation and square meals.

An outbreak of Ebola killed 244 people in Zaire this summer. The average Zairian spends less than $10 of his annual $500 salary on health care. The average buyer of Orvis fly rods makes $100,000 a year. A member of the fly-fishing organization Trout Unlimited spends nearly $3,000 annually on fly-fishing trips. What do we tell Johnson’s colleagues in Zaire about Americans who raise $20 million to protect sporting fish from a disease of our own devising yet give nothing to aid ailing children in Zaire?

“The thing you learn after a while is you can’t give people these things, because there are real reasons why they don’t have those things,” Johnson says. “We don’t change that ecology, and we don’t change those reasons by donation. Every culture has to do its own thing for itself.”

Skewed priorities about protecting human health show up in internal American comparisons as well.

“That’s like saying, ‘Well, if I just had the money of one fighter plane, think what we could do,’ ” he says. “That would mean a basic revision of the paradigm under which we function, and that doesn’t happen overnight. I’m wondering if, in this society, it ever will.”

Excuse his pessimism; it has become an endemic disease to mountain retreats.

When we initially met, we spoke first, as Montanans have for centuries, of the weather. A fierce storm had swept over the ridges the night before. To see it flash over the broad valleys was to comprehend the privilege of our place.

After weather, our small talk moved to growth. It is not clear whether Montanans have worried about newcomers for centuries, but we do now. In the eight years he and his wife, Merle, have lived in Bozeman, Johnson has watched the subdivisions storm across the valleys, as wealthy urbanites flee to build trophy homes on 20-acre ranchettes cut from a remaining piece of nature. It has been the same in my town of Missoula during recent years, and we compared notes.

It is in this context that he acknowledges that spending as much as $20 million to combat a fish disease means, at least by the world’s standards, that we have sufficient affluence to flee from and insulate ourselves from the more wretched aspects of the world. “Of course,” he says, “for a little while longer, but not forever.”

The subdivisions are evidence that the world is closing in. This foreboding sense of decline translates to fish or, rather, the wild, and that decline, not disease, is really the issue here.

“The wild fish to me have a tremendously evocative, soul-filling niche of my heart,” he says. “I full well know the difference in a river between a hatchery fish in a place that it doesn’t belong and a fish that grew up and was hatched there. If the only thing I could do anymore is to go and catch fish that have been planted in the river, I would stop fishing.”

Johnson is not alone. In the face of a diminishing and diseased natural world, many seek sanctuary, and some find it in wild fish. We can reach into the mystery of nature and feel its vitality hum and buzz through the arc of a taut fly rod. This is a tangible signal through which we may assure ourselves that nature is still alive.

When it doesn’t respond, as is the case now on the Madison, we would do most anything to restore it.