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A resurgence of the cattle fever tick has left more South Texas land under quarantine than in years past, according to Texas Cooperative Extension.
"It's quite likely what we're seeing here is the discovery of ticks that are rebounding after the drought periods of the late 1990s that caused the Rio Grande to get really, really low," said Dr. Pete Teel of College Station, Texas Agricultural Experiment Station entomologist.
Thanks to high amounts of rainfall and snow, the river is coming back and reservoirs are re-filling, he said. With rising water comes rising cattle fever tick populations.
"The entire state of Texas is at risk, even up in the Panhandle and West Texas," Teel said.
The cattle fever tick, which causes cattle fever—a disease described as "cattle's malaria"—is not new to Texas. The insect arrived in the early 1900s, and the state has been in cattle fever tick eradication ever since.
"Eradication means biological zero," he said. "One tick is sufficient to quarantine the land. Eradication eliminates the vector. That leads to the elimination of the disease."
Cattle are the ticks' desired host, but white-tailed deer are also affected, adding complexity to the problem, he said.
Cattle can be treated and moved to a tick-free environment with minimal effort, but wildlife such as deer are not as easily corralled. With the Rio Grande still at a low water level, these animals can cross from Mexico to Texas, both legally and illegally, he said.
"On several occasions within the last 25 years, cattle have been smuggled in from Mexico and been put into sale yards," Teel said. "The cattle turn out to be `ticky,' people buy them and bring them to their homes. The next thing you know you're infested."
In addition to land being quarantined, Teel said, another problem is resistance to the only acaricide allowed in the United States.
"We know that there are ticks in Mexico that are resistant to the only acaricide that the United States is permitted to use," he said. "If we get those resistant cattle fever ticks in the U.S., it will make our problem much worse."
The mortality rate for cattle infected with cattle fever for the first time is higher than 70 percent.
"This becomes very important economically because there is not a real efficient way to treat the disease besides the single acaricide," Teel said. "There are no other approved methods in North America. There are no vaccines for the disease."
Other tick populations are up too, as more ticks were able to survive the winter.
