The cattle fever tick is a pest Texas ranchers, particularly those operating along the Mexican border, have dealt with for more than a century. Although “cattle fever,” the actual disease that can be transmitted by these ticks was officially eradicated from the United States back in 1943, it has never been eradicated from Mexico. The long standing control measure that has served as the first line of defense against the spread of these diseases has been a permanent quarantine zone that parallels the Rio Grande River. Its goal is to stop the spread of the tick species capable of carrying this disease.
That zone has been monitored by a small force of USDA employees who work in the Animal and Plant Health Inspection Service (APHIS) division. These individuals are commonly referred to as “Tick Inspectors.” They have a lot of remote, brushy rangeland to cover. They must supervise the dipping and inspection of all cattle in the zone to make sure they have no fever ticks. Boophilus annulatus or Boophilus microplus are the only tick species known to transmit the cattle fever organism.
All quarantine regulations must be in effect before cattle raised in the zone can be shipped to market or moved to other pastures outside the permanent quarantine zone. When conditions that favor the development of tick populations and wildlife species that can also carry these ticks are increasing in numbers, the task of tick inspection and control can easily overwhelm the current resources.
In late April, I attended a briefing on the current fever tick situation conducted in Alice, Texas. It was presented by Dr. Bob Hillman, state veterinarian and executive director of the Texas Animal Health Commission.
The mere mention of “fever ticks” brings back unpleasant memories for long-time brush country cattle ranchers. It was Aug. 22, 1972, a typical hot summer day at the South Texas Auction Company in Alice, Texas, when the last major fever tick outbreak was discovered during a routine inspection of sale barn cattle. That discovery resulted in a six-year effort of quarantine measures and twice monthly cattle dipping in vats of insecticide solutions.
That battle created a great deal of economic hardship on small and large beef producers. I served as county Extension agent for Kleberg and Kenedy Counties during most of that outbreak. Unfortunately, liquidation was the most economical alternative for most of the “mom and pop” cattle operators that had limited labor and cattle hauling capabilities. More than two-dozen small cattle producers chose to sell off their cattle and vacate pastures rather than load and haul them to the county dipping vat every two weeks.
Recent information indicates that vacating cattle from pastures may not be as effective in eliminating these ticks as it once was due to increased deer populations.
Dr. Hillman said that since 2005 more than 100 pastures in the counties along the Rio Grande have been infested with fever ticks. Although most are inside the permanent quarantine zone, the trend is disturbing. During the past three years, 20 percent to 25 percent of premises with new tick infestations have been in pastures just outside the zone. And even more disturbing is that last year some 15 pastures that had livestock vacated for months were discovered with fever tick infestations on deer trapped or harvested from those pastures.
Only days before this meeting, the Texas Animal Health Commission had to enlarge a temporary preventive fever tick quarantine zone in Star County by some 24,000 acres after ticks were discovered outside that county's existing quarantine zone. More manpower and additional control measures must be approved to effectively suppress the spread of this potentially devastating problem before counties beyond those bordering the Rio Grande River become infested.