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Those of us in regulatory veterinary medicine usually think of Brucellosis (Bang’s Disease) as the standard when considering disease control and eradication.
The process that proved to be quite successful in getting rid of that disease was: test, quarantine, slaughter, vaccinate, retest. While under quarantine, a producer would depopulate the positive and suspect animals, then retest. Toward the end of the program, producers that had positive herds were often paid indemnity to just depopulate the complete herd. But does any of that process translate to controlling or eradicating diseases in wildlife, especially those that could be passed from wildlife into the livestock population? The short answer to that question is, “Probably not.”
The normal movement of wildlife and the inability to contain a population of wildlife such as deer by a quarantine is likely impossible and certainly not practical. And even with state wildlife laws that restrict importing of wildlife into the state of Alabama, we do not have a fence around our state line. Therefore, wildlife is able to cross back and forth from our neighboring states. Additionally, even though wildlife officials are able to randomly test various species for certain diseases, it is impossible to get a complete herd test. The fact that certain diseases pass from wildlife to livestock and from livestock to wildlife is a cause for concern. While we may not lie awake at night and worry about it, on those occasions when we have eaten one too many slices of pepperoni pizza and are awake anyway, it is something to think about.
Wildlife species are generally susceptible to the same disease-causing agents as livestock and poultry. The threat is increased by the commingling of livestock and wildlife. In some areas, especially in states like Alabama, development and urban sprawl has increased some of the commingling of wildlife with livestock. Also, many of the problems are caused by unnatural or artificial situations. An example of this is feeding areas that have been established for deer and elk that are in close proximity to where livestock live. In natural situations, diseases may not easily spread through a wildlife population because they tend not to be so concentrated. However, when they congregate to be fed, diseases spread more easily among animals, just like the stomach virus that goes through kids when they congregate at school.
Some of the concerns we deal with today get a great deal of news coverage; others, though not as well publicized, present challenges to both animal agriculture and wildlife. Avian influenza is an excellent example. Water fowl is the normal reservoir for that virus. Typically, water fowl may harbor the virus without becoming ill, yet when exposed to infected water fowl, commercial and backyard poultry get sick. West Nile Virus and Eastern Encephalitis Virus are mosquito-borne viruses that may be harbored in birds, often without causing illness that can cause very severe disease in the horse.
Feral swine, or “wild hogs,” are a concern to the swine industry, especially in mid-western states where there is a large swine industry. Feral swine are known to carry Brucellosis and pseudo rabies. In some western states, bison and elk carry the Brucellosis organism, posing some degree of threat to cattle that are in close proximity to them. And there are the concerns that wildlife could make it even more difficult to contain a foreign animal disease if it passed from livestock into wild animals.
In Alabama, we are fortunate to have a good working relationship with state and federal wildlife officials. We have had a partnership in testing for Chronic Wasting Disease in deer in the state. We have never found a positive. We have had some involvement in the rabies vaccine drops conducted in Alabama. This is a process in which oral rabies vaccine is mixed with type of bait that will attract raccoons and dropped out of planes over designated areas. This on-going program has been very successful. There are other projects in which wildlife are monitored for certain diseases. Currently, there is an on-going testing of ducks and other wild birds to monitor for avian influenza.
It is important that we remind ourselves that livestock disease cannot always be contained and controlled by fences, quarantines, testing, vaccination, and depopulation. The rules that work for livestock usually do not apply to wildlife. That is why we will continue to work with our colleagues in the wildlife arena to deal with the interface between diseases in wildlife and animal agriculture. If you have questions or suspect disease in wildlife in you area, contact our office at 334-240-7253 and we will try to point you in the right direction. |
