In his day job, Marshall Bloom is the associate director for scientific management at the Rocky Mountain Laboratories, a cutting-edge federal research campus in an unlikely place: Hamilton, Mont., a town of about 4,500 in the beautiful Bitterroot Valley. Nearly 500 workers in dozens of lab buildings are dedicated to studying "emerging infectious diseases" like the Ebola virus (from Africa), Lassa fever (caused by another African virus) and chronic wasting disease. The effort began more than a hundred years ago, when a few tent-based researchers started studying a disease that killed loggers; they discovered tick-borne Rocky Mountain Spotted Fever. Today, the campus is part of the National Institute of Allergy and Infectious Diseases network, and it includes a "Biosafety Level 4" lab, where researchers wearing "positive-pressure suits" work with the planet's most dangerous diseases, some of which could be exploited by bioterrorists.

Bloom, who holds a medical degree from Washington University, has worked here for more than 40 years. He focused on tick-borne diseases to begin with, and then beginning in 2002, he oversaw the construction of the Level 4 lab. Today, he’s an administrator. Away from the lab, he's an avid fly fisherman and conservationist; his license plate says DRTROUT. Now 67, he's spent more than two decades as a voluntary leader of Trout Unlimited, working locally and nationally, lobbying the Montana Legislature, and organizing fund-raisers and so on. Bloom's conservation efforts -- securing water for fish and coping with fish-killing whirling disease -- have been "amazing" and had "an enormous impact on fish habitat" in the state, according to a former director of Montana Fish, Wildlife and Parks. High Country News’ Montana-based senior editor Ray Ring interviewed Bloom recently about his career and conservation efforts.

HCN: What makes your work so important? Is it because we're worried about terrorism, as well as diseases spreading from monkeys in Africa?

Bloom: When I was in medical school (in the early 1970s), the era of infectious diseases was thought to be over. We had antibiotics, and we had vaccines. However, that feeling proved to be extremely premature. Since the mid-1970s, we've identified somewhere in the neighborhood of 50 to 60 brand-new infectious diseases which people had never heard of before. A few examples are HIV-AIDS, Hepatitis C, Ebola virus, SARS, avian influenza, Marburg virus, multi-drug resistant tuberculosis, multi-drug resistant staph. Some are intentionally emerging infections like anthrax (spread by bioterrorists). The other causes include development moving into remote parts of the world -- that's probably one of the reasons for the emergence of HIV-AIDS, people going into the jungle harvesting wood and things like that, going into these areas where these diseases probably existed in small populations. (Back then) if there was an outbreak, it probably burned itself out and didn't have the opportunity to spread, but once you have a highway going into an area like that, and trucks going back and forth, the opportunity to spread those infections goes up.

HCN: So, disturbing ecosystems comes back to bite you in the ass?

Bloom: Well, I would say it that way, but probably shouldn't for an article like this.

HCN: With the climate change dynamic now underlying everything, are we in a particularly different or transitional period in terms of these emerging infectious diseases -- are we seeing more and will we see even more in the future?

Bloom: To me, one of the most important and predictable causes of the increases in emerging infections is climate change. Many are carried by arthropod vectors like mosquitoes. One usually thinks of these mosquito-borne infections as tropical. As the climate changes, the boundary between tropical and temperate zones becomes a little blurred. Insects, mosquitoes that were once confined to tropical areas, are now able to survive in more temperate zones. We have an example: There’s a virus called dengue, which had always been considered a tropical infection, but now they're starting to see cases in southern Florida. That is very likely a consequence of climate change.

HCN: What was your upbringing? How did you become what you are?

Bloom: I was born in Dallas; my dad was a pharmacist, and a lot of family friends and one of my cousins were physicians. There was an unstated expectation that I would go into medicine. I graduated medical school in St. Louis in 1971 and was a pediatric intern for one year. But during my medical training, I had become very interested in virus infections, and in particular virus infections of the kidney, and the only program that the National Institutes of Health had (with that focus) was here, so I was assigned to the Rocky Mountain Labs in 1972. My wife (Tonia) likes to say, we're the only people who didn't move to Montana on purpose (for the scenery and other amenities). We were sent here on government orders. ... The opportunity to do this kind of work, with this level of sophistication and technology, in a relatively small town, in an extremely beautiful part of the world, is unique.

HCN: Tell us a little about your fishing, and anything else you like about the outdoors.

Bloom: I didn't do much fishing or hunting, until I moved here. But another scientist who came at the same time was an avid fisherman and an excellent hunter, and he got me very hooked on fishing and hunting. Trout fishing and trout conservation have become major areas of my life. Over the years in Trout Unlimited, I've had the good fortune to be associated with three major conservation successes. The first was in the Bitterroot Valley, working with conservation groups, local irrigators and the Bonneville Power Administration and the state of Montana to secure water from Painted Rocks Lake (a 32,000-acre-foot reservoir) to supplement instream flows of the Bitterroot River during the summer -- a cooperative agreement that is a paradigm for similar activities across the West.

The second was the Montana Arctic Grayling Recovery Program. Those fish face enormous pressures from climate, because they have very specific water and habitat needs, and the Big Hole River gets completely dry in very dry years, so (the program) works with the farmers to try to come up with ways to mitigate that (by leaving more water in that river).

The third project was whirling disease. Until that parasitic infection emerged in Montana's trout in the early 1990s, it was not known to occur in wild populations, but was thought to be a disease of hatchery-raised fish. Emerging infections not only affect people, they affect and afflict animals and plants. As chairman of Gov. Marc Racicot's Whirling Disease Task Force from 1994 to the early 2000s, (I helped) draw together everybody from county commissioners to trout advocates to landowners to legislators. We got things going in the right direction -- leave the fish alone, don't try to intervene by stocking or anything like that, and the fish will on their own discover a way around this problem. We let that infectious disease burn itself out and gave the fish breathing room to evolve resistance to the parasite. In the Madison River in 1994 (the most famous example),  rainbow trout had declined by 90 percent, and now those numbers are almost back up to what they were prior to the whirling disease. We were able to recruit to that cause world-class scientists, including a number from the National Academy of Sciences and one Nobel Prize winner, because of their love of Montana and their love of fishing.

HCN: So you're not the only top-notch scientist who's out there enjoying nature?

Bloom: That's for sure. The first few lines of Norman Maclean's novel (A River Runs Through It) are something like, ”In our family, there was no clear difference between religion and fishing.” In my case and for a number of my friends, the distinction between science and fishing is also a little tenuous.