Dr. Calisher explains the complexities of the hantavirus and why we need to stay vigilant in our studies of viruses. He tells us what he knows about viruses and how his understanding relates to our study of earth sciences.
In 1993, Dr. Calisher, a career epidemiologist then working at the Centers for Disease Control, was asked to investigate a new and unknown virus that was plaguing the American southwest. Having dedicated his life to identifying and monitoring emerging diseases, Dr. Calisher decided he was up for the challenge. For the next 13 years, Dr. Calisher trapped deer mice and collected data regarding the rodent-borne hantavirus. His work on the hantavirus showed that environmental conditions such as local rainfall can influence the virulence and prevalence of the virus in rodents, which in turn can impact human health.
Dr. Calisher has published more than 25 papers on the hantavirus and deer mice alone, having served as Director of the World Health Organization’s Collaborating Centre for Arboviruses in the Americas, as Chief of the W.H.O’s Arbovirus Reference Branch and as Assistant Director for International Programs at the Centers for Disease Control. A deeply serious scientist, Dr. Calisher is notable for his wise humor and humble perspective on the limits of human understanding of life. Access his Curriculum Vitae here.
Charlie Calisher: Anybody who tells you they know something is arrogant and probably full of crap. I don’t know anything. I know a lot of facts. A lot of people know a lot of facts or what they think are facts, but I can’t put it together because its too big a picture. It’s the earth we’re talking about. You know we’re not talking about our backyard or Larimer County, talking about the whole world. Basically I’m a baseball umpire who really likes science. My interest has always been in predicting epidemics. It’s not easy. You know if you read the newspaper, you find that there was an epidemic of whooping cough, 7 kids died and had 130 cases or you had meningitis in a college and 2 kids died and there were others hospitalized. These, these kinds of things are predictable, but what about viruses that have never been identified before? The more we go into the rainforest and dig in places where nobody’s ever dug before and find oil or whatever it is that they’re looking for and make a big mess out of the place, there are also insects there and there are viruses and other infectious diseases in the local animals which nobody ever contacted because nobody was looking for oil before. Who wants to go into that place? You know it’s just got a lot of bugs and stuff and jaguars and who knows what. So we’re not going to be able to predict when an epidemic hits a bunch of oil field workers. There are a lot of people in this world who know a great deal about ecology, but ultimately they’re going to admit that they only know about part of it. I wouldn’t call myself an ecologist by any means but I got pretty good with rodents.
Charlie Calisher: There was an epidemic, an outbreak of a disease which they called Hantavirus Pulmonary Syndrome. This was a brand new virus that had never been found before. There were other hantaviruses, you know they all related somehow and each one was found in a different rodent. Well, there are 22 hundred species of rodents which means there could be 22 hundred different hantaviruses. The virus was found in a rodent called a deer mouse. So we got some money from CDC, we chose Durango to start because that’s Southwest Colorado and that’s where the first cases were found. We really characterized these animals and I’m collecting data and I’m sure its going to be good data. We’ve got weather data. We’ve got acorns. We’ve got this and that and something else. But what are these things doing when it’s not raining? Because when it’s not raining there’s nothing growing. So how does the virus persist when there’s no transmission going on between the rodents? And we could see that the prevalence of the virus was decreasing and then would stay the same for a long period of time. I got to thinking that I wonder what they’re eating. It was pretty clear when we opened up some of the stomachs of these dead – we did find insects in them and their urinary PH was low enough to inactivate whatever virus they might be shedding from their kidney’s which would account for low transmission rate during droughts. As soon as it rains, green stuff comes up. They eat that, urinary PH goes up, start peeing on each other and you get transmission. Great idea. NIH didn’t want to fund it.
Charlie Calisher: What’s important? What’s not? What’s important is what’s politically important and what’s not is what you can’t afford to do. And you can’t afford to do it because politicians don’t want you to. Then you have the Army Corp of Engineers, it just may be my opinion, one of the worst organizations that was ever put together. They say “what we have to do is you see that river over there? We’re going to move it over there and we’re going to spend the next 10 years writing an environmental impact statement, it’s going to be very impressive. It’s going to be you know volumes thick and we will look at absolutely everything,” when in fact they have no idea what they’re talking about. Let’s talk about God for a second. God put this here and he put that there and he put – or she put this here and everything was working fine. Working fine for the Native Americans and then somebody in the military uniform came along and said “I think that river belongs over there.” It’s crazy. I mean it’s really crazy.
Charlie Calisher: This is an unbelievable system, the earth. What’s the last thing we can destroy without destroying ourselves and we don’t know. We don’t know enough to know about what we need to do because its far too complicated, so all we can do is try to extrapolate from some small study to a larger study. Is that legitimate? I don’t know. I doubt it, but I don’t really know. I know that if you took – if you went outside here and dug a hole in the ground say 3 feet by 3 feet by 3 feet deep, take out everything in that hole, 3 by 3 by 3 and then spend the rest of your life analyzing what’s in there, larvae, eggs, worms, rocks, certain amount of soil, what kind of soil, how much moisture will it hold, plants of all kinds, it’s a huge amount of work and we’re talking about a 3 foot by 3 foot by 3 foot chunk. What if you dug a hole 3 by 3 by 3 right next to it, is it going to be the same, exactly the same? Probably, possibly not. And how about a mile from here or up on one of the hills which is going to be very different, so lack of information. On top of absolute ignorance leaves us where we are.
Charlie Calisher: I think we certainly need to continue to support people who are studying ecology; particular habitats, infectious diseases and maybe we’ll be able to predict something. That was the whole idea of the CDC study. If we had enough data, maybe we could predict when there would be an outbreak of Hantavirus Pulmonary Syndrome. And you know maybe we could, but it would only be in the next pasture. It wouldn’t be 5 miles or in the western United States or anything like that. It’s just too complicated. Try to put all these data together and they only mean something for this particular place. So in the meanwhile, we only study little stuff and that’s fine. I mean that’s all we can do, then that’s what we should do. Let’s end with this, what do we know about anything? If we don’t know everything, how can we simply pretend we know everything? And should we act if we don’t know everything? Is it too dangerous? But you can’t- you’d be paralyzed if you said “well we don’t know everything so we’re not going to do anything.” But there’s got to be some middle ground in there that makes sense and its not the Corp of Engineers that says “let’s move the Mississippi River to the Rocky Mountains because they need water.” Hello?