Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientist takes on malaria-like sickness in horses

30.08.2012
When Washington State University and U.S. Department of Agriculture veterinary scientist Don Knowles got word three years ago that a rare but deadly infection was discovered among a group of horses in south Texas, he felt a jolt of adrenaline. Not only were the horses infected with a parasitic disease similar to malaria in humans, but the epicenter of the outbreak was at no ordinary ranch.

It was the King Ranch, legendary for its world-class quarter horses, including former winners of the Triple Crown and Kentucky Derby. The 825,000 acre family-owned estate that stretches across four counties is one of the largest and most famous ranches in the world.

"Anyone who knows anything about quarter horses knows about this ranch,” said Knowles. "Universally, it’s on the map for the best horses and cattle.”

One King Ranch horse had tested positive for the disease when the federal government first alerted Knowles. A few days later, it was a dozen; then four dozen.

"The number just kept going up,” recalled Knowles at his WSU office, where a large photograph of Appaloosa horses in a field punctuates one wall and a road bike leans against another.

Knowles, in his silver-rimmed spectacles, hiking shorts and athletic shoes, resembles someone more at home on a bike trail than a scientist at the beck and call of deadly, infectious animal diseases that pull him to regions near and far.

"This kind of outbreak had never been seen in this country before,” he said. "People were asking ‘What’s going on down there?’”

And so, at the request of federal agriculture officials, Knowles boarded a plane and headed south to investigate. As leader of the USDA’s Animal Disease Research Unit at WSU, he had a Texas-sized riddle to solve.

Parasitic storm
Equine piroplasmosis is so feared in the U.S. that the government bans horses that test positive from entering the country. Until the outbreak in Texas, only a few sporadic cases had ever been reported.

"We had regarded piroplasmosis as a foreign animal disease and suddenly here it was on U.S. soil, with not one or two cases but nearly 300 – all concentrated at a ranch recognized for exemplary management practices,” said Dudley Hoskins, an attorney with the American Horse Council in Washington, D.C., at that time. "To say we were concerned would be an understatement.”

Piroplasmosis, also called equine tick fever, is transmitted to horses through the bite of a tick that carries either the Babesia caballi or Theileria equi parasites in its saliva. Similar to malarial parasites that infect humans, these pear-shaped creatures travel through the horse’s circulatory system, multiplying, drilling through red blood cells and multiplying some more.

Knowles, also a professor of microbiology and pathology at WSU’s veterinary college, teaches his students about it.

"I tell them that one of their responsibilities as a veterinarian will be to prevent piroplasmosis and how an outbreak could result in a great loss of horses and deal a severe blow to the horse industry,” he said. "Once the parasite becomes established in the tick and equine population, it could spread quickly as horses are transported to equestrian shows and races around the country.”

No treatment, painful options

Many infected horses exhibit little more than cold-like symptoms, but in regions where piroplasmosis is uncommon - such as the U.S. - horses have no natural resistance to the disease. Unimpeded, the parasites proliferate and destroy blood cells, triggering fever, anorexia and anemia.

"If a horse dies of piroplasmosis, anemia is often the cause,” said Knowles. "It’s a progressive process and a miserable way for an animal to die.”

Before the outbreak in 2009, no standard treatment existed. If a horse tested positive for piroplasmosis, the owner had three government-mandated options to keep the disease from spreading: euthanize, quarantine or ship the horse out of country.

"Our horses are vitally important to us,” said King Ranch manager Dave Delaney by cell phone from the ranch, 45 miles southwest of Corpus Christi. "The idea of euthanizing them was out of the question.

"Many of us had heard of piroplasmosis but had never dealt with it,” he said. "So when Don got here, whenever he spoke, believe me, people paid attention.”

On the trail

Long before Knowles boarded that Texas-bound plane in autumn 2009, he knew a lot about piroplasmosis. The periodic clusters that surfaced in temperate-climate states such as Florida proved the parasites sometimes slipped across the U.S. border in horses that had tested negative for the disease when, in fact, they were positive.

Because the test sometimes gave false negatives, Knowles was charged with developing a more reliable diagnostic test. He also was instructed to create a standardized treatment to kill the parasites.

"Until Texas, much of the work had been done in the lab,” he said.

This means that, after Knowles and his team arrived at King Ranch, "you might say we provided him with a real-world case to test the effectiveness of his preliminary work,” said Delaney.

Hungry vectors, vulnerable hosts

Armed with two decades of piroplasmosis research and a team of scientists from his USDA unit and WSU, Knowles not only contained the outbreak but he and colleague Glen Scoles also identified a new blood-sucking culprit that had spread it.

"Prior to that outbreak, we knew of two tick species capable of transmitting the disease. There, we discovered a third,” said Knowles.

He and his team identified the cayenne tick as the predominant carrier, a finding so important that the group later published a paper about it in the journal Emerging Infectious Diseases.

It’s likely a cayenne tick snagged a ride on an infected horse years before the outbreak, drawing parasites in through its blood meal then moving on, injecting and infecting other horses, said entomologist Scoles who, after the outbreak, proved that the cayenne species was involved.

The outbreak at King Ranch "could have coincided with climate factors which, in turn, caused an increase in tick numbers,” said Scoles.

"They saved our horses”

All said and done, Knowles and his team did more than identify a new eight-legged transmitter of piroplasmosis and develop an internationally accepted test to diagnosis it.

"How about, ‘They saved our horses?’ ” said Delaney of King Ranch.

With high doses of imidocarb dipropionate, a drug used to treat certain diseases in cattle, "The parasites appear to be eradicated. All of our horses are healthy,” he said.

The outcome of administering the drug was so successful that, after subsequent trials, it is now being evaluated as a standard treatment protocol in the U.S.

"If approved for use, the treatment would offer a way to clear horses of infection,” said Hoskins, who has followed Knowles’ research. "This would be huge.”

Which means that, largely because of Knowles’ work, the owner of a piroplasmosis-infected horse may have the option of curing the animal – and then one day watching it flash across a meadow or even a finish line.

Contacts:
Don Knowles, USDA Animal Disease Research Unit and WSU veterinary professor, 509-335-6022, dknowles@vetmed.wsu.edu

Linda Weiford, WSU News, 509-335-7209, linda.weiford@wsu.edu

Don Knowles | EurekAlert!
Further information:
http://www.vetmed.wsu.edu

More articles from Agricultural and Forestry Science:

nachricht New data unearths pesticide peril in beehives
21.04.2017 | Cornell University

nachricht New rice fights off drought
04.04.2017 | RIKEN

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>