If you mention fever ticks to a Texas beef producer, chances are he knows what you're talking about. But animal health activists say a reduction in outbreaks in recent years has made the risks posed by the ticks seem less dangerous and threatening.
But Texas Animal Health Commission Communications and Emergency Management Specialist Thomas Swafford warns that when it comes to fever ticks, not fully understanding the risks involved in an outbreak is a terrible mistake.
Cattle fever ticks, carriers of a blood disease that once nearly wiped out the U.S. cattle herd, has landed farther north in the Texas interior in recent months, violating a permanent tick quarantine zone established by USDA and causing the establishment of a host of temporary quarantine zones that currently affect over 500,000 acres of Texas ranch country, worrying state and federal inspectors that the disease may be putting the state's cattle industry at risk once again.
The ticks are believed to be slipping through 500 miles of the permanent quarantine zone, which runs up the Texas-Mexico border from Brownsville through the rugged border country to a point just north of Del Rio. The zone varies in width from 1 to 12 miles, an area where USDA and TAHC tick riders constantly patrol the zone in search of stray cattle and equine that have wandered across the Rio Grande from Mexico, inspecting animals as they are found. Inspectors are also on watch for the movement of wildlife that may be carrying the ticks farther north across the border and on to South Texas ranches.
For years a comprehensive program of inspection and treatment has been the best defense against the ticks and the diseases they carry say animal health officials. In more recent times, tick eradication efforts in Mexico have improved as well, and the two-nation fight to keep the risks posed by cattle fever ticks in check have proven successful.
TICK PRESSURE INCREASING
But the sheer number of the ticks invading Texas across the quarantine zone has become alarming in recent months. As of the Feb. 6 update, more than 140 infested quarantined premises have been established in Texas, 98 exposed premises uncovered, and an additional 2,000-plus premises being watched by inspectors all across the state.
Counties with exposed, adjacent or check premise quarantines include Bastrop, Bee, Caldwell, Calhoun, Cameron, Colorado, Denton, Dewitt, Dimmit, Falls, Fayette, Frio, Goliad, Gonzales, Hidalgo, Jim Wells, Karnes, Kendall, Kinney, Kleberg, Live Oak, Maverick, McMullen, Milam, Mills, Parker, Runnels, Starr, Uvalde, Val Verde, Webb, Wharton, Willacy and Zapata.
Live Oak County dipping vat inspections and treatments alone have almost reached 3,000 animals, and each week more ranchers are being encouraged to inspect and dip their herds if ticks are spotted on their premises.
In the past, fever ticks created a devastating setback in the Texas cattle industry. The ticks are often carriers of Texas cattle fever, or babesiosis, a damaging disease that can wreak havoc on an entire herd in a short period of time. Cattle fever was the cause for the near-downfall of the Texas cattle industry in the late 1800s.
The culprits that spread the disease include a pair of arthropods, in this case fever ticks, scientifically known as Rhipicephalus (formerly Boophilus) annulatus and R. microplus, parasites that pose a significant threat to livestock and wildlife because of their ability to carry and transmit various animal diseases. One of the most feared diseases include cattle fever. These ticks are capable of carrying protozoa, or microscopic parasites, Babesia bovis or B. bigemina, and as the ticks drop off infected host cattle, then lay their eggs in pastures that hatch and subsequently attach to new hosts as they become available.
VIGILANCE CALLED FOR
Complicating the fight against these ticks and the cattle fever they may carry is that a great deal of time has expired since a major outbreak. While limited outbreaks can occur outside the permanent quarantine zone, one to rival the current outbreak has not occurred in many years. USDA and TAHC inspectors say this may contribute to passive resistance from cattle producers who may either not realize the seriousness or the threat or who have been lulled into thinking safeguards are adequate to prevent a major episodic outbreak.
While one of the major pitfalls of even small outbreaks is the restriction of movement of cattle outside permanent and temporary quarantine zones, the treatment of cattle on infected premises is also challenging for beef producers.
Juan Delgadillo is a South Texas rancher who raises cattle near the quarantine zone. He is not happy with the USDA/TAHC tick eradication program because he claims dipping his cattle is causing death among his herd. Delgadillo took legal action on Feb. 3 when he filed a federal complaint seeking more than $1 million in damages for the program he says has killed several of his cattle, and made others lose weight, reducing their value at market.
He says under threat of criminal charges, USDA inspectors have imposed "nonexistent" rules that tick-carrying cattle must be dipped in, or sprayed with, Co-Ral Flowable Insecticide, the brand name of a product that contains 4.2 pounds of the active ingredient coumaphos per gallon. The rancher blames the death of some of his cattle to inhaling or swallowing the insecticide.
He further claims he was not allowed to hand spray the cattle and told he must submit the animals for dipping in special vats prepared to combat the current outbreak.
But TAHC and USDA officials say ranchers have a choice between three methods of treating infected cattle, by dipping at federal vats, injecting the cattle with Doramectin, a Food and Drug Administration-approved drug that treats stomach parasites in cattle, or by dipping or spraying and moving cattle to a non-infected premise.
Each method comes with specific requirements; for example, if a producer chooses to have his animals dipped, all the cattle in the herd must be sprayed with insecticide on the ranch or transported to a dipping vat for treatments every seven or 14 days for up to nine months.
Delgadillo is not the only South Texas rancher seeking retribution for losses caused by an intense eradication program. Two other lawsuits were filed in Brownsville charging similar allegations over required dipping procedures by Cascabel Cattle Company and South Texas ranchers Luis Ramirez and Santiago Martinez respectively.
As of this writing, attorneys for USDA have not offered comment on the impending complaints, but state and federal animal health officials who are involved in eradication program say an accelerated eradication program is the industry's best hope of managing the current outbreak.
A 2010 Texas A&M University study of the risks involved in an outbreak of cattle fever in modern times illustrates the economic threat to the state's cattle industry. According to that study, the cost of a relatively small fever tick outbreak outside the permanent quarantine zone in Texas would cost an estimated $123 million in the first year. Annual costs for similar sized outbreaks, once capital costs were paid, would be about $97 million according to the study.
TICK GEARS IN MOTION
According to the Texas A&M Department of Animal Science, inspectors are using genetic tests and epidemiological investigations to try to pinpoint how the ticks ended up in Live Oak County north of Corpus Christi – from transporting animals from quarantine areas near the border or from wildlife such as white-tailed deer and exotic nilgai antelope carrying them farther into Texas. The latter is the biggest concern, indicating that previously successful efforts to contain the ticks to the border region are failing.
TAHC officials also point out that while fever ticks can be the carrier of babesiosis, so far no cattle have been diagnosed with the disease associated with this outbreak. In fact, the disease has not been detected in U.S. cattle for decades. Officials warn, however, the risk is there.
"Where there are cattle fever ticks, there could be cattle fever," one inspector commented.
To understand how quickly ticks can infest large herds, ranchers are encouraged to consider the process of tick propagation in the wild. Female fever ticks live on their hosts for the ticks’ entire life cycle, only dropping off to lay up to 4,000 eggs on the ground, usually in a pasture used for grazing. According to TAHC, these eggs will hatch into larvae, which will then attach to animals that walk by. Without a successful management and control effort, such as an aggressive eradication program, the process will repeat itself over and over again.
State and federal animal control officials say they recognize an outbreak of fever ticks is a troubling and costly burden for ranchers, government agencies and the cattle industry in general. But they warn aggressive eradication efforts are the best and possibly last safeguard to prevent a regional problem becoming much larger—and much more devastating to the industry.