Fever Tick Proposal Includes Grazing Wildlife Refuges

The USDA initiated its Cattle Fever Tick Eradication Program (CFTEP) in 1906. The ticks, including Rhipicephalus annulatus and R. microplus, carry Babesia bovis or B. bigemina, protozoan parasites that destroy red blood cells in cattle and result in mortality rates of 80 to 90% in susceptible naive cattle. The ticks at that time were common across much of the southern United States and caused significant losses among cattle herds. During the 1940s, the USDA’s Animal and Plant Health Inspection Service (APHIS) successfully eradicated the ticks from the United States and established a permanent quarantine zone along the border with Mexico.

Today, while the ticks remain uncommon north of the border, populations have become established in Southeastern Texas, particularly in the Laguna Atascosa National Wildlife Refuge and Lower Rio Grande Valley National Wildlife Refuge. Movement of wildlife that serve as hosts to the parasitic ticks, specifically white-tailed deer and nilgai antelope, an exotic species introduced to Texas, have complicated eradication efforts in the area. Cattle producers in the region are naturally concerned that the ticks could spread.

To address the problem, APHIS, along with the U.S. Fish and wildlife Service and in cooperation with the Texas Animal Health Commission, recently released an environmental assessment, including recommendations for eradicating the ticks from the two wildlife refuges.

The first alternative in the assessment would continue with current programs including temporary quarantine zones, prescribed burning, reductions in deer and nilgai populations through hunting and using ivermectin-treated corn to control ticks on wildlife outside the wildlife refuges.

The second alternative, which APHIS recommends, would include those steps, and add parasite treatments in wildlife populations within the refuge areas and experimental cattle grazing on refuge lands within the established quarantine areas. Cattle grazing would serve two purposes, as a means of monitoring tick populations and as a way to attract and kill ticks, since cattle are the preferred host. The plan includes specific requirements for grazing, such as the type of cattle, locations for grazing and stocking rates, along with the following plans during two management periods:

During the cattle treatment period:

• Cattle will be maintained under direct systematic treatment using doramectin injectable while grazing for up to 9 months.
• Cattle will be gathered every 21-28 days, scratch inspected for cattle fever ticks (CFTs), then injected with doramectin.
• After the first scratch inspection that is free of CFTs, the systematic treatment period will continue for up to 9 months assuming no CFTs are found on future cattle or wildlife inspections.
• If CFTs are found during the subsequent scratch inspections, the systematic treatment period will start over.

During the cattle sentinel period:

• After the completion of the systematic treatment period listed above, cattle will be grazed for up to 9 months under no treatment.
• The cattle will be scratch inspected at least every 90 days to assess the risk of CFTs on the pasture.
• If during this sentinel period the cattle or wildlife are determined to be infested with CFTs, the systematic treatment period will start over.
• At the conclusion of required sentinel period, USDA-APHIS/TAHC will remove all livestock from the property within 30 days.

 Read the full environmental assessment here.