Ranchers, Regulators Weary from Cattle Fever Tick War

July 6, 2009 07:00 PM
By Carla Everett, Texas Animal Health Commission

Texas animal health officials have cast another wide net in the battle to eradicate cattle fever ticks in South Texas. The Texas Animal Health Commission (TAHC) has temporarily quarantined 152,716 acres in Starr and Hidalgo counties. In nearby Zapata County, five-mile quarantine perimeters are being drawn around fever-tick infested pastures. 

A foreign pest, the cattle fever tick has the capability to carry and transmit Babesia, a blood parasite that can kill adult cattle.  Although it prefers cattle, the fever tick can survive and be carried on horses, deer, elk, aoudad sheep and a number of other deer species.  

Since October 2008, (the beginning of the 2009 federal fiscal year) 127 fever tick-infested premises in eight South Texas counties have been detected and quarantined. Of these, 68 premises are in Zapata County, 51 are in Starr County, and the remainder are scattered among Maverick, Brooks, Cameron, Kinney, Dimmit and Webb counties. This year's infested premises tally will eclipse last year's count of 132, and could meet or beat the record set during the 1973 fever tick outbreak -- 170 infested premises.

"The Starr-Hidalgo temporary quarantine is the fifth since July 2007 and was implemented less than 70 days after we released nearly 375,000 acres from temporary quarantine in Webb, Dimmit and Maverick counties,” said Dr. Hillman.  "We had very good results in Webb, Dimmit and Maverick Counties, where the tick-infested premises count has dropped to five.  About 250,000 acres remain under temporary quarantine in the three counties.

"In rural Zapata County, there are no appropriate roads or easily identified boundaries for establishing a temporary quarantine. Therefore, to accomplish adequate tick surveillance in Zapata County, premises within five miles of an infested pasture are being temporarily quarantined.”  Dr. Hillman explained that ranchers in the temporary quarantines can move livestock after the animals undergo a clean tick inspection and treatment by the USDA Tick Force or TAHC.

Dr. Hillman explained that Tick Force and TAHC teams work inward from the outer edges of the temporarily quarantined area, inspecting ranches with cattle, horses and wildlife hosts to determine the outermost spread of the fever tick infestation.  Not only do animals become tick-infested, but so do the pastures, as fever ticks may wait in the grass for months, before finding a suitable onto a host animal.” said Dr. Hillman. 

"When infested premises are detected, the animals and pasture are quarantined for nine months or longer, and a variety of tick eradication measures are taken. Cattle are inspected and run through dipping vats spray boxes charged with the pesticide CO-RAL. Another treatment being evaluated in field trials is injectable doramectin.  Horses are sprayed, and wildlife are provided medicated feed or enticed to treatment stations where their ears and neck rub against pyrethrin-coated posts while they eat. 

Alternatively, once cattle are ‘tick-free,' the cattle may be moved to a new site, allowing the pasture to be ‘vacated' for months, causing the ticks will starve. Greater success is achieved, however, by leaving cattle in place and continuing to inspect and treat the animals every 14 days with CO-RAL or every 25 to 28 days with doramectin.  Ticks picked up from the grass by the cattle and destroyed by treatment, eventually leaves the pasture free of the pest. This long and costly process is a burden to the ranchers who must hire helicopters and cowboys time after time to round up the cattle from the thick brush,” said Dr. Hillman.                                                ​       

"With each new infested premises, costs rise for the fever tick program­more equipment, more personnel, more products and more time. Sadly, because we have worked so hard to keep this outbreak contained to South Texas, it is not fully recognized as a national animal health issue, with potential  international consequences,” said Dr. Hillman, Texas' state veterinarian and head of the TAHC, the state's livestock and poultry health regulatory agency.  "The longer it takes to eradicate this fever tick incursion, the greater are the chances fever ticks will be spread to other states, which will raise the costs exponentially.  More people, more national resources and new tick-fighting products are needed now to get this potentially deadly pest out of the U.S.” 

Dr. Hillman said the USDA's Natural Resources Conservation Service (NRCS) is helping ranchers with land management techniques to help reduce cattle fever ticks, including, but not limited to, cross-fencing, brush management, prescribed burning and prescribed grazing to help with livestock handling, to destroy cattle fever tick habitat, and to help manage wildlife.

For the 2010-2011 biennium, the Texas Legislature appropriated an additional $500,000 a year in state funds for the fever tick program.  The TAHC will some of the funds to hire five new fever tick personnel.

"The U.S. Department of Agriculture's Tick Force has received some funding to hire temporary and term workers, but sustainable, ongoing funding of about $15 million per year is needed to support this program, eradicate the current outbreak and prevent future problems.  I urge industry and lawmakers to support fever tick eradication while it is still a brush fire confined to South Texas. The situation with this foreign pest could become a wildfire, particularly if ticks begin transmitting Babesia, and we have cattle deaths. We don't need a replay of the 1800s, when thousands of cattle died from tick fever,” he said. 

Although the fever tick was declared eradicated from the U.S. in 1943, it has never been wiped out in Mexico, which serves as a continuous source for tick reinfestation in Texas.  The U.S. Department of Agriculture's Tick Force has fewer than 60 riders to patrol the 900 miles of the Rio Grande on horseback from Del Rio to Brownsville, and apprehend ‘ticky' Mexican cattle, horses, deer, elk and susceptible species that cross the river.  Detecting ticks in this narrow permanent fever tick buffer zone is expected, due to the prevalence of the tick in Mexico, explained Dr. Hillman. 

"Finding them farther inland indicates that our defenses are inadequate and that wandering wildlife or stray or smuggled livestock are spreading the foreign ticks.  Today, 60 percent of the fever tick infestations are encroaching deeper into the ‘free' areas of the state,” said Dr. Hillman.

A map of the temporary quarantine zone is posted on the TAHC web site at http://www.tahc.state.tx.us .

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