BRUCE LAWHORN, DVM, MS, Extension Veterinarian and Assistant Professor,
Texas A&M University, College Station, Texas
Feral swine are considered a pest species and nuisance by the Texas Parks and Wildlife Department. They destroy habitat and compete directly or indirectly with all other species of wildlife. This agency encourages harvesting of feral swine by allowing year round trapping and hunting. The Texas Animal Damage Control Service removes feral swine at the request of landowners, ranchers, farmers, and citizens reporting losses. In the 1990′s, approximately 2000 feral swine were removed annually from as many as 36 counties. This trend is expected to continue since an estimated one million feral swine populate Texas.
Although income from hunting feral swine is of economic benefit to some landowners, most domestic swine (DS) producers in Texas share the point of view that feral swine are a liability. Domestic swine production is an important and growing Texas industry. An estimated $100 million in yearly gross income is produced. Current expansion represents a projected increase of 33.3 percent over the next several years.
Because many DS producers in the state have diversified agricultural and livestock businesses, they are quite aware of the physical damage feral swine cause to crops, pasture land, gardens, and livestock losses to predation. In addition, feral swine are reservoirs of diseases transmissible to DS, other livestock and humans. Texans have historically enjoyed domestic pork production with fewer disease problems than larger swine producing states. Pseudorabies (a Herpesvirus disease) and swine brucellosis (from Brucella suis) are important porcine diseases, but these are uncommon in Texas-raised DS. Federal and state laws make the diagnosis of either disease reportable, resulting in swine herd quarantine. Since exposed pigs from infected, quarantined herds may only move directly to slaughter, economic losses result not only from the disease but through interruption of marketing and loss of valuable breeding herd genetics.
Recent surveys have demonstrated the importance of feral swine as reservoirs for both swine brucellosis and pseudorabies. Feral swine have been incriminated as the source of some of these infections in DS disease outbreaks in Texas. Although swine brucellosis in humans is uncommon in the general U.S. population, it is important because it causes severe illness that may recur, and even cause death. The majority of human cases result from occupational exposure through swine slaughter and processing businesses. Rarely, feral swine exposure has been associated with brucellosis in hunters (in Texas and Florida). Pseudorabies is not a disease risk to humans.
Currently, Texas and all other DS producing states are engaged in a national pseudorabies and brucellosis eradication effort. To remain economically competitive in DS production, it is imperative that each state involved in this effort be successful. This eradication program is in jeopardy in states with feral swine because of possible reintroduction of disease into domestic swine.
The USDA, in cooperation with allied scientific and regulatory groups, is currently studying and evaluating the entire feral swine issue in applicable states (i.e., Texas, California, Southeastern States). The Texas Animal Health Commission, in cooperation with the Texas Pork Producers Association and the Texas Agricultural Extension Service, has recently updated regulations to monitor the movements of feral swine. These regulations accomplish diseases surveillance and encourage utilization of this species. Since Texas will likely continue to be populated with feral swine, we must control the risk of disease transmission from feral to DS through surveillance and use of available technology.
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