Fever Ticks and Primary Screwworm

Howdy,

I recently received an email from our Veterinary/ Medical Extension Entomologist. She shared a news article on fever ticks and some information on the primary screwworm, both of which can be found below.

Primary screwworm was detected on a stray dog on January 6 on the mainland of Florida, near Homestead (south of Miami). All previous reports of this insect were limited to the Keys. Efforts on sterile male release programs and treatment on animals are currently under way to control this insect. It has been 40 years since screwworms were seen in full force in Texas, and it is vital everyone knows what to look for. Please check out this link with information on this insect.

Spread of fever tick spooks Texas cattle industry

Fever ticks are turning up farther north of the border, alarming inspectors

By Lynn Brezosky, San Antonio Express-News

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."