Spread of fever tick
spooks Texas cattle industry
Fever ticks are turning
up farther north of the border, alarming inspectors
January 14, 2017
The dreaded cattle fever tick, carrier of a blood disease
that once nearly wiped out the U.S. cattle herd, has landed farther north in
the Texas interior, worrying state and federal inspectors that the
once-eradicated pest is no longer under control.
Texas animal health inspectors recently found new fever
ticks Nov. 30 on a bull on a Live Oak County farm, about 110 miles
north from the Mexico border where they were thought to have been permanently
quarantined. Since then, the ticks have been found on seven neighboring
premises, prompting the Texas Animal Health Commission to set up a temporary
"Control Purpose Quarantine Area." It's the fourth such quarantine
zone, following ones set up in Willacy, Kleberg and Jim Wells counties.
There are more than 450,000 acres in Texas under various
types of fever tick quarantines that have been set outside of the permanent
quarantine zone since the ticks started showing up farther inside U.S.
territory in 2014. The most recent quarantine zone has grown by nearly 45,000
acres in the past six weeks as more fever ticks have been found, and now covers
57,541 acres.
Inspectors are using genetic tests and epidemiological
investigations to try to pinpoint how the ticks ended up in Live Oak - from
transporting animals from quarantine areas near the border or from wildlife
such as white-tailed deer and 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.
The ticks are carriers for bovine babesiosis, a blood
disease that in the 1800s wiped out much of the U.S. cattle herd and caused
Kansas and other states to shun or restrict cattle from Texas.
In 1943, the ticks were declared eradicated from the U.S.
save for a permanent quarantine zone along the Rio Grande established to
control ticks that find their way across the river from Mexico. But during the
past few years, the ticks have increasingly been found outside that zone,
prompting expanded quarantine zones in border counties and temporary quarantine
zones in three counties farther north.
"I don't want to jump to conclusions," Schwartz
said of the possibility the ticks are migrating north on the backs of wildlife
such as nilgai, a non-native antelope that's become a nuisance carrier of the
tick. "The concerning thing is we haven't determined the source of those
ticks yet."
While cattle owners in quarantine areas are required to
round up, inspect and treat cattle for ticks, the Live Oak County discovery was
unexpected. A veterinarian called to examine the sickly bull called a state
livestock inspector to check some of the ticks he found on the animal's skin.
"That day she tentatively identified those as fever
ticks, that's the day we sprang into action there," Schwartz said of the inspector.
The bull likely was anemic from all the ticks drawing his
blood, Schwartz said, but did not suffer from babesiosis.
While babesiosis is still an issue for cattle south of the
border, it has not shown up in U.S. cattle for decades, he said.
"I think it's a tribute to the success of the program
to have kept the fever ticks, the hot fever ticks with babesiois, out of the
country," Schwartz said. "We've had some fever tick incursions, but
none of them have been carrying babebiosis."
As in other quarantine zones, cattle in the Live Oak area
must be "dipped" in a treatment solution every 10 to 14 days or
injected with a vaccine every 25 to 28 days, which in either case usually
involves costly helicopter roundups that are stressful to cattle. Hunters also
are required to call inspectors to check any harvested deer for the ticks.
Once hunting season is over, state and federal officials
also plan to set up feeders full of deer corn treated with a poison that kills
the ticks and is aimed at preventing them from spreading from the infested
ranches. Nilgai, which aren't native to the U.S., have become particularly
worrisome in South Texas as they travel long distances and can easily jump
fences, but they are not believed to have strayed as far north as Live Oak
County.
Ron Gill, head cattle extension specialist at Texas A&M
University, said the Live Oak County discovery worried ranchers who thought
that as long as they followed protocol the fever tick wouldn't spread.
"It periodically jumps out of the quarantine zone but
not that far out," he said. "Normally it will be one of the adjacent
counties and they'll fight it back into the quarantine zone. So I think the
thing that's got everybody more vocal about it now is it jumped a little
further than usual."
Coleman Locke, who runs cattle in affected areas in Kleberg
and Willacy counties, fears the tick could once again threaten the entire Texas
cattle industry.
"It concerns me as a cattleman," he said.
"We've got to get it under control. … A lot of Texas cattle go to feed
yards in Kansas and Nebraska to feed out. We need our Texas cattle to be able
to go anywhere."
