June 08, 2012
To most people, it's either the answer to a question about bioterrorism or it's the name of a legendary heavy metal rock band. "Anthrax," however, is the answer to another question as well: Which infectious disease has the potential to kill both deer and humans?
You don't find folks at the Centers for Disease Control in Atlanta getting all that worked up over a new case or two of chronic wasting disease being found in whitetails. That's because CWD, while lethal to deer, apparently can't harm a person. Not directly, anyway. Same for epizootic hemorrhagic disease ("bluetongue"), which kills many thousands of deer annually. Bad? Sure. Put-on-your-tinfoil-hat-and-hide-in-a-bunker bad? Not from the perspective of the general public, or even the federal government.
It's another matter when the "A" word starts getting thrown around. After the deadly anthrax attacks in the wake of 9/11 — and the fact that the "Ames" strain used in those attacks is the same one found in deer habitat in part of Texas — you can be sure an anthrax case of any kind gets noticed. Even if the victim is a deer instead of a mailman.
As my good friend Dr. James Kroll notes anthrax is a fact of farm and ranch life in some places. While southwestern Texas is one of those, it's by no means the only one. In the decade following the end of World War II, anthrax cases in livestock were reported in 30 states. Worldwide, it's more a disease of warm-climate regions, but it can pop up far from the equator. Even North Dakota fairly regularly sees a smattering of new cases.
While transporting infected cattle from one area (or even hemisphere) to another likely got anthrax into some places that originally lacked it, deer are part of what keeps it going. The bacterium forms a cyst that stays dormant in the soil until conditions are right for it to begin the life cycle anew. When a warm-blooded animal ingests the spore, it begins to grow within the animal. In serious cases, that leads quickly to such symptoms as trembling and difficulty in breathing. Generally, within 48 hours the host is toast.
If you're in an area that has ever had a case of anthrax and you find a dead deer that doesn't appear to have been shot, killed by a predator or hit by a car, use extra caution. Don't touch the animal unless wearing protective gloves. Be even more careful if you find dark blood issuing from any orifice. And contact local wildlife authorities right away, so they can verify the deer's cause of death.
The carcass of an anthrax-killed animal can be an agent for infecting a large number of other animals. Horseflies, vultures and other such species can spread the bacteria, causing a localized outbreak lasting for an extended period. At some point the episode runs its course and dissipates, perhaps not to be seen again for years. The spores fall back into the topsoil, there to wait until conditions are right for another flare-up.
What causes outbreaks? More than anything, it's climate patterns. Anthrax in deer and livestock is most common during wet periods following prolonged drought. As that's a perfect description of the current scenario in parts of Texas and elsewhere in the southern Great Plains, some experts say we shouldn't be surprised if 2012 sees another significant outbreak.
Texas ranchers such as Bill and Robin Luce, who own land in Uvalde County, know all too well how difficult it can be to manage property during an anthrax outbreak. They lost many deer in the summer of 2001, coincidentally just months prior to the terroristic anthrax attacks by way of the nation's postal system. Fellow area rancher Ken Bailey, owner of Four Canyons Ranch, likewise lost a tremendous number of deer during the same period. Many other area landowners did as well.
Rick Taylor, a Texas Parks & Wildlife field biologist in Uvalde, has seen anthrax come and go over the years. He looks at it as just a fact of life in the area, with short problem periods separated by long periods of normalcy. As Rick points out, rural families in the area have come to accept anthrax as part of the ranching landscape.
There's a vaccine for humans, and for livestock as well. It even works in deer — if you can deliver it. While ranchers with captive herds can run deer through handling facilities to vaccinate them, that's not the case in the wild. There's currently no way to deliver the vaccine via feed or water, so nature just has to run its course.
According to recent research, in which scientists studied tree-ring growth patterns to determine the timing and severity of Texas droughts, 2011 was as dry as any other year back to at least 1500. Critically needed rains returned to the anthrax region last fall and have continued, for the most part. While the much-improved range conditions are a welcomed sight, the stage unfortunately could be set for yet another anthrax outbreak in the region.
We'll probably know in the next couple of months if that's going to happen or not. But even if we do see an anthrax outbreak this year, there's apparently little cause for fear it will become a human epidemic. It's just one of the more interesting mortality agents in the wide world of whitetails.
FOR YOUR INFORMATION
In Texas, anthrax is classified as a "reportable" disease, meaning any suspected case should be immediately reported to the Texas Animal Health Commission (TAHC). Reports can be made to TAHC area offices, or to the TAHC headquarters at 1-800-550-8242. (A veterinarian is on call at that number around the clock.)
Remember that while Texas historically has seen the vast majority of cases of anthrax in deer, they do crop up elsewhere from time to time. So no matter where you are, if you find a dead deer you suspect could have been killed by anthrax, be sure to notify the relevant wildlife or agricultural agency immediately.