18 April 2008

5 minute read

North America

Inspectors have used livestock market records to locate the 94 head of cattle sold by the ranch March 28, 2008. Using livestock market records, inspectors have contacted the nine initial buyers of the cattle, which are considered to be tick-exposed or infested.

The animals are being quarantined, inspected and treated to eliminate the spread of fever ticks. Due to cattle movement, three livestock markets also are being subjected to cleaning and disinfection.

The U.S. Department of Agriculture’s Tick Force and the Texas Animal Health Commission (TAHC) also is conducting an epidemiological investigation to identify and locate any other cattle that have been moved from the premises during the past year, so the animals can be inspected, treated and, if necessary, quarantined.

Fever ticks are capable of carrying “babesia,” a blood parasite that can cause “cattle tick fever,” a deadly cattle disease that does not affect humans. The tick was eradicated from the U.S. in l943, but it is still present in Mexico, and a permanent quarantine zone on the U.S. side of the Rio Grande is patrolled on horseback by USDA Tick Force personnel to prevent the introduction of “ticky animals.” In 2007, the fever tick was detected beyond the permanent quarantine, and three temporary fever tick quarantine areas were established in Starr and Zapata counties, and in a contiguous area of Maverick, Dimmit and Webb counties.

“Discovering that fever ticks have pushed outside the temporary preventive quarantine area is very serious and the situation is being addressed with great urgency by the TAHC and USDA Tick Force,” said Dr. Bob Hillman, Texas’ state veterinarian and head of the TAHC, the state’s livestock and poultry health regulatory agency. “The TAHC has expanded the temporary quarantine area in Starr County that originally encompassed about 40,000 acres, and the USDA Tick Force is inspecting and treating cattle within the newly enlarged temporary quarantine area to determine the extent of tick spread.”

“Additionally, we are conducting a complete epidemiological investigation to find cattle moved within the previous year from newly detected tick-infested premises,” said Dr. Hillman. “Without identification on animals, it will slow the process, but we use every method available, from sale barn, feedlot and slaughter plant records, to recollections and hearsay from cattle owners.” The TAHC and USDA last year successfully traced 783 cattle moved from premises involved in Maverick, Dimmit and Webb County temporary quarantine areas.”

Dr. Hillman asked for cattle owner cooperation to speed up the investigation process. “We will move as quickly as possible to locate, inspect and, if needed, treat and quarantine cattle,” said Dr. Hillman. Animals may be moved legally from or within the permanent or temporary fever tick quarantine areas only after they are inspected for fever ticks, dipped or sprayed and permitted for movement by Tick Force or TAHC personnel.”

“Fever ticks have demonstrated their adaptability to hosts besides cattle, which perpetuates the population of these pests within tick-infested areas,” said Dr. Hillman. “The pests have been detected not only on white-tailed deer, nilgai, and elk, but also on axis, fallow deer and aoudad sheep within the permanent and temporary quarantine zones.”

“Although we can dip or spray cattle, treatment for other species is limited to feeding ivormec-laced corn,” he said. “We cannot be certain all animals get the medicated feed, and the treatment cannot be used during hunting season, as there is a 60-day withdrawal period before slaughter. The other wildlife treatment method is the four-poster treatment system, where animals rub against pyrethrin-treated posts, which transfers the chemical to the head, neck and ears of animals and kills the ticks. To prevent spreading fever ticks from quarantine zones during hunting season, hides of harvested animals were inspected before being hauled away. To address the population growth of fever ticks on cervid and exotic species, however, we are in dire need of additional approved products.”

“Producers in the quarantined areas have been cooperative, but they are being hit financially, absorbing the cost of rounding up cattle time and again,” stressed Dr. Hillman. “Although inspections and treatment are provided at no cost to the producer, the cost of gathering cattle in the south Texas’ brush country can be high, due to the need for cowboys in helicopters and on horseback. Extending the Starr County quarantine will take in additional ranches, but this action is necessary, if we are to win the battle against this pest.”

The expanded quarantine area in Starr County will now begin at the intersection of Ebanos Road and U.S. Highway 83 in Los Saenz, moving west and northwest along Highway 83 to the county line, then northeast along the county boundary to the northeast corner of the RR Guerra Las Lomas pasture. The quarantine line turns southeast along the Las Lomas and Dr Narro fence lines to Loma Blanca Road, where it runs south to the northwest corner of the Amando Pena pasture (previously known as the AV Margo pasture). The meanderings of this pasture’s fence line is followed to the northeast, then southeast to the Sanchez Ranch Road. It then follows the Sanchez Ranch Road east to the intersection with the San Julian Road. The line follows San Julian Road south to the intersection with the Ebanos Road and continues along this road to the quarantine starting point at its intersection with U.S. Highway 83.

Dr. Hillman said there is one bright spot in the battle against fever ticks­in Dimmit County. “After thoroughly inspecting livestock in the area, the USDA Tick Force has determined a small area of the temporary quarantine in Dimmit County is fever tick-free and can be excluded from the temporary quarantine zone.”

The boundary of the area to be excluded from the temporary quarantine begins in Eagle Pass at the intersection of FM 1021 (Mines Road) and U.S. Highway 277 and continues to the junction with Loop 225 (also known as 5th Street) in Carrizo Springs. The boundary follows Loop 225 to its intersection with US Highway 83 in Carrizo Springs. The boundary moves south on US Highway 83 until it turns southwest on FM 2688 and continues to FM 1021 (Mines Road). The boundary follows the Mines Road to its point of origination at the intersection of US Highway 277 in Eagle Pass.

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