It's a long and lonesome border that separates the United States and Mexico, about 1,900 miles of largely desolate and arid land. Just over 1,250 miles of that international border separates Texas from Mexico, a unique border frontier for nearly 200 years.

While illegal immigration and the movement of contraband catch the spotlight when it comes to modern border issues, of equal or even greater risk is the unavoidable movement of animal and plant diseases across the vast, remote and poorly monitored region. Many of these diseases have been contained or eradicated on the U.S. side of the border for decades but continue to thrive in parts of the harsh, desolate northern regions of Mexico.

In spite of diligence and strict monitoring of well-established border crossings to prevent the introduction or re-introduction of these threats, some of them find their way back across the border in spite of programs designed to keep them out. While plant and animal inspection stations are operated by the U.S. Department of Agriculture to help monitor and inspect all goods that enter the United States, stray animals, often carrying diseases or that serve as a host to parasites that carry diseases, cross undetected at points where the Rio Grande River is shallow. Disappearing into the rangeland or mingling with herds of animals in Texas, it is extremely difficult to secure and protect an area that encompasses nearly 67,000 square miles of open range.

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As much as this happens with stray cattle and equine, it also involves wildlife like deer, elk, bear, mountain lions, and such smaller animals as raccoon and coyotes. Some of these animals carry diseases, some of which represent a major threat to wildlife and livestock in Texas. Once an animal crosses the river, fleas, ticks, flies and pathogens can be transferred to soil, water or other animals.

Mounted inspectors

To protect those remote border areas, the USDA-APHIS Cattle Fever Tick Eradication Program, headquartered in Laredo, Texas, operates the "mounted tick riders," a group of modern-day cowboys who ride the range in search of strays that cross the river. For over 100 years these riders, a group of specially trained and mounted inspectors, have combed the rugged backcountry of the border region in search of stray cattle and horses and for smugglers who attempt to bring illegal animals across the Rio Grande.

Of concern is the movement of Mexican ticks and other insects that can rapidly spread bovine babesiosis, or Texas Cattle Fever, a disease that has historically troubled the cattle industry in the Southern United States and devastated cattle operations in Texas on more than one occasion. But stray animals are tested for a number of possible infections.

Recently a team of tick riders stumbled upon stray Mexican donkeys that had found their way across the river. The Texas Animal Health Commission (TAHC) reports a USDA mounted quarantine enforcement inspector apprehended the five Mexican donkeys just north of Presidio. The animals were transported to USDA-Presidio holding pens where they were isolated.

Glanders detected

One of the five donkeys subsequently tested positive for Glanders, a highly contagious, bacterial disease of the equine family. It is characterized by the development of ulcerating growths most commonly found in the upper respiratory tract, lungs, and skin. Infections are usually fatal. Humans and other animals are also susceptible.

"It is imperative that we remain vigilant in protecting our borders from disease intrusions such as Glanders," Dr. Dee Ellis, State Veterinarian and TAHC Executive Director said. "Mexican strays continue to pose a huge threat to Texas livestock and to our animal agriculture industry."

The TAHC is working closely with USDA personnel in monitoring the situation along the border, and protecting the state and the nation from possible disease threats.

"Early detection of Glanders and the immediate quarantine of these donkeys was critical in preventing and protecting against the spread of this foreign disease," Ellis added.

The disease is commonly contracted by consuming food or water contaminated by the nasal discharge of carrier animals. The organism can survive in a contaminated area for more than one year, particularly under humid, wet conditions.

No vaccine is available for Glanders and prevention and control depend on early detection, elimination of affected animals, and complete quarantine.

Glanders was once prevalent worldwide, but has been eradicated or effectively controlled in many countries, including the United States. The last naturally occurring equine case in the U.S. was in 1942.

TAHC says if not for the interagency cooperation between federal and state animal health officials, the infected donkeys could have spread the disease to domestic equine, posing a serious animal health problem in Texas.