For a group of cowboys hired by the USDA, patrolling for stray cattle carrying a deadly tick species has become increasingly dangerous along the hostile Texas-Mexico border.

Story and photography by Ryan T. Bell

The international border between Texas and Mexico is a hot zone – in more ways than one. Climatically, high temperatures break 100 degrees for months at a time. Politically, the boundary is rife with tensions over immigration and drug trafficking from Mexico. And biologically, the region is home to one of the largest disease hot zones in the world, the “fever tick quarantine zone.”

The 700-mile long quarantine zone follows the Rio Grande River from Amistad Reservoir (near the Texas boot heel) to the Gulf of Mexico. It acts as a buffer against the spread of the tick boophilus annulatus, a.k.a. the “fever tick.” This dastardly arachnid sucks the lifeblood out of horses and cattle, and spreads the deadly disease bovine piroplasmosis.

Patrolling the area are 61 Texas cowboys known as Tick Riders, hired by the U.S. Department of Agriculture to round up stray livestock that transport the ticks from Mexico. That most Americans haven’t heard of the Tick Riders is a testament to how well they do their job. If fever ticks infiltrated the quarantine zone, the nation would know because cattle and horses would die by the thousands.

The first Tick Riders mounted up in 1906. That year, fever ticks were rampant in 16 states, from the Pacific to the Atlantic Ocean, and they inflicted an estimated $100 million in damages on the livestock industry. After four decades of hard work, the riders whipped the ticks back to the Texas-Mexico border, and the U.S. was officially declared eradicated of fever ticks in 1943.

Tick Riders have been holding the line ever since.

“A lot of young men aspire to become Tick Riders because they know it’s a good job,” says Ed Bowers, the program’s director. “We’re horseback most every day, and we’re paid a good salary with health insurance and government benefits. You can’t say that about most ranch jobs.”

But unlike most ranch jobs, Tick Riders work on the tumultuous U.S.-Mexico border. They regularly encounter illegal immigrants, smugglers and drug cartel violence that spill across the border from Mexico. Once, a man with an M-16 submachine gun stood on the Mexican side of the river and shot at Bowers while he was on patrol. But the risk of danger is part of what attracts young cowboys to the job.

“There’s a sense of adventure, for sure,” Bowers says. “I was attracted to it in my younger days. But the true reward of the job is the time we spend horseback on the river, doing what’s important – patrolling for ticks.”

Patrolling 700 miles of the Rio Grande for stray livestock isn’t an easy job. The landscape is a desert version of Dante’s Inferno, with sharp cliffs, gnarly arroyos, and the river’s constantly eroding banks that crumble without warning. Add to that mile-upon-mile of scrub brush, and it’s apparent that horseback is the only method to effectively patroll the quarantine zone.

“You have to like working horseback to do this job,” says Bill Coble, a veteran Tick Rider. “I think it’s the life of royalty. You get up and ride in the morning, rest during the hot part of the day, and go back out to ride again in the evening.”

Coble, like many of the Tick Riders, is a south Texas cowboy through and through. On patrol, he rides ranch quarter horses that deftly maneuver through the scrub brush. He wears batwing chaps, tapadero stirrups, and his lariat is tied hard-and-fast to the saddle horn. When you catch a stray in country this rough, you don’t want to loose it because the opportunity might not come again.

“Many guys ride colts out on patrol,” Coble says. “It’s good training for them. But I keep a well-broke mare for river patrol, and use my ranch rodeo horse for a backup.”

A typical patrol area is 15 miles long, encompassing upwards of 3,000 acres, and requires five hours to cover on horseback. Standard procedure is to ride parallel to the river, cutting for tracks. Tick Riders often work in tandem with their neighboring patrollers, coordinating truck and trailer pickups, helping each other to rope or trap strays, and to keep each other safe in the case of a hostile encounter.

“We’re armed for self defense,” Coble says. “The drug cartels are having a turf war in Mexico, and our main worry is a stray bullet from across the border. But you can get shot in downtown Austin, too. Our protocol is to stay low key, and to watch out for each other. We learn our neighbor’s plans and routines so that if something happens, you can get to him quick.”

These days, border hostilities are hotter than ever. In July 2010, U.S. intelligence was tipped off that Mexican drug cartels planned to send hit squads across the river to kill U.S. border patrol agents. Tick Riders aren’t border patrol agents (immigration and drug enforcement isn’t their jurisdiction), but there was the danger of mistaken identity, or being caught in the crossfire. So the Tick Riders were ordered off the river, until things cooled off. Serendipitously, hurricane Alex hit Mexico, causing several dams to overflow and flood the Rio Grande, making the cartels’ attacks impossible. But it also likely washed stray horses and cattle onto the U.S. side of the river, and no rider was there to catch them.

The fever tick is a master of reproduction that, if not held in check, can spread like wildfire. Ticks reproduce three times a year, on average. One female tick lays 4,500 eggs, meaning her subsequent generations could spawn another 22 billion tick eggs in a single year.

Fortunately, a tick’s lifecycle is complex, making it a long shot that a tick makes it to adulthood. A “seed tick” is born on the ground, where a fertilized female lays her eggs. It climbs the underbrush to catch a ride on an animal that walks by, such as deer, horse or cow (their favorite). The seed tick finds soft, warm tissue – like the groin, ear, or under the tail – and fires up the chain saw it has for a mouth to bore into the skin. It gorges on blood and becomes about the size of a Tic-Tac, then molts a layer of skin and enters the fertile stage of its life. Male ticks mate and die, while females return to suck more blood, tripling in size into those lima bean-shaped pouches of blood that gives people the heebie-jeebies. Then they drop to the ground, lay their eggs, and die.

Fever ticks don’t pose a threat to humans, but they wreak havoc on cattle and horses. In the case of one horse in South Africa, a collection of half the engorged ticks on the animal’s body weighed 14 pounds – most of that weight being horse blood. Tick Riders keep their horses safe by bathing them with a pesticide every two weeks.

Cattle are especially at risk from fever ticks because of the disease bovine piroplasmosis (horses are immune). A parasite transmitted through the tick’s saliva attacks a cow’s red blood cells. Symptoms include infection, increased body temperature, depression, loss of appetite, and reduced body weight. The cow slowly enters a coma and dies. Bowers keeps a photograph of an infested Texas cow that is so covered with fever ticks, her hide looks like reptile skin.

In the late 1800s, bovine piroplasmosis was known as “Texas Cattle Fever.” Cattlemen on overland routes like the Chisholm and Loving-Goodnight Trails observed that Texas cattle spread a disease that killed up to 90% of their local herds.

In 1893, scientists discovered that cattle weren’t the culprit, but rather the millions of fever ticks that hitchhiked on their backs. By then, the fever tick had already spread far and wide, from California to Virginia. Cattlemen reacted by embargoing Texas cattle, fencing off their ranges against intrusion. In retrospect, the spread of fever ticks played as much a role in closing the frontier, as did the advent of barbed wire.

Cattle born in an environment where fever ticks are prevalent, such as Mexico, develop immunity to bovine piroplasmosis. They are, however, still susceptible to health issues and fatalities stemming from blood loss.

As of yet, there isn’t a vaccine to protect cattle against bovine piroplasmosis. The only treatment is bathing infested cattle and horses with pesticides and preventing tick-baring livestock from entering the U.S.

An average of 120 strays cross the Rio Grande every year. Considering that 80% of Mexico’s livestock are tick infested, it only takes one to penetrate the quarantine zone and spread thousands, even millions, of fever ticks into tick-free Texas. Outbreaks are inevitable; and it’s up to the Tick Riders to stomp out the flare-ups in time.

The most recent major outbreak was discovered in 2007, near the town of Carrizo Springs, Texas. Ed Bowers keeps a detailed map of the area thumb-tacked to his office wall. It shows the boundaries of all the ranches affected by the outbreak, totaling 623,000 acres (approximately 180,000 acres are still in quarantine). The properties are color-coded according to tick status: infested (red), in danger (yellow), and tick-free (blue). Most of the map is yellow, evidence that with time – three years in the case of the Carrizo Springs Outbreak – Tick Riders can stop an outbreak.

Battling outbreaks is expensive and time-consuming work that requires Tick Riders to think like detectives. And Bowers is the prototypical cowboy-detective. He even looks like a cross between Gus McRae and Magnum P.I., with a trimmed policeman’s moustache, leather shoulder gun holster, palm leaf cowboy hat and plaid shirt.

“When we find a ‘ticky’ cow, we put the premises in quarantine and get to work finding out where that cow came from,” says Bowers. “She could’ve passed fever ticks to other cattle, and they could’ve taken them in sixty different directions.”

Tick Riders inspect every cow on an infested ranch by hand. They call the process “scratching” because it involves using their fingers to press deep into an animal’s flesh to detect even the tiniest tick. When they find one, they use a magnifying glass to see microscopic characteristics that differentiate a boophilus fever tick from other tick species that also inhabit the region. With nervous ranchers and cowboys looking on, a Tick Rider is under tremendous pressure to identify the tick correctly.

“These guys aren’t just dumb cowboys,” Bowers says. “They’re experts at identifying ticks, managing pesticides, handling livestock, and they’re responsible bearers of a government-issued weapon. There’s a lot of good buckaroos that would be dismayed if you threw them into these thickets on the Rio Grande and told them to catch stray cows.”

When cowboys hire on with the Tick Riders, they stick with the profession for life. Bowers has been with the unit for 41 years, and Coble for 35 years.

“My granddaddy patrolled the river as a Tick Rider in the 1930s,” Bowers says “We have a lot of guys with fathers and sons on the tick force. It’s like a family business. This isn’t a job that’s easy to walk away from. I could’ve retired a long time ago, but I stay because I love the cowboy work, and the feeling of doing a job that’s important. The U.S. livestock industry must be protected from fever ticks.”

Billions of fever ticks versus 61 south Texas cowboys. And every day the U.S. is fever-tick free, is another day the Tick Riders have successfully held the line.