February 3, 2010 - Oklahoma officials from the Department of Agriculture, racing commission and racetracks yesterday discussed the state’s requirements regarding equine piroplasmosis. The requirement for horses coming to Oklahoma racetracks must comply with current emergency import guidelines.

The guidelines state that equines entering Oklahoma from the following Texas counties: Kleburg, Brooks, Jim Wells, Kenedy, Nueces and Willacy shall be accompanied by:

* Oklahoma Entry Permit (call 405-522-6141)

* Certificate of Veterinary Inspection (CVI) dated within 10 days of entry

* Negative Piroplasmosis cELISA test within 14 days of entryshall carry an original copy of the test or NVSL accession number

*Statement on CVI by accredited veterinarian: “I have inspected these animals, they do not originate from an Equine Piroplasmosis quarantined area, do not display clinical signs of Equine Piroplasmosis, were inspected for ticks, including ear ticks, and were treated for ticks at the time of the inspection.” CVI shall include complete information on origin and destination of horse and the veterinarian.

Equine piroplasmosis (EP) is a blood-borne protozoan infection caused by Babesia caballi or Babesia equi (also known as Theileria equi).  It affects horses, donkeys, mules, and zebras.  The disease is spread by ticks or transfer of blood through shared needles, equipment and transfusions.  There is evidence of vertical transmission from an infected dam to foal.

The clinical signs of horses infected with EP are vague and varying. The mild form of the disease can cause lack of appetite and/or weakness.  More severe cases may show any of the following: fever, anemia, jaundice, swollen abdomen, labored breathing, rough hair coat, red urine, colic, depression or altered gait.  Chronic carriers are often asymptomatic.

USDA recently completed a study to determine the national seroprevalence of antibodies to B. caballi and B. equi.  The survey included serum samples from 35 Equine Infectious Anemia (EIA or Coggins test) laboratories located in 34 states.  The EP testing was performed as a blind survey with no link to the identity of the lab or horse.  The results of the survey estimate the seroprevalence of B. caballi is 0.054 percent or 54 positive horses per 100,000.  The estimate for B. equi is 0.007 percent or 7 positive horses per 100,000. For comparison, an estimate for the national seroprevalence of EIA positive horses is 0.006 or 6 positive horses per 100,000.

There have been four recent incidences of Equine Piroplasmosis in this country. In Florida during 2008, there were 20 horses positive for B. equi on 7 related premises.  All of the positive horses were euthanized.  In 2009, Missouri had 7 horses positive for B. equi on one premise.  Five of these horses were euthanized, two horses were illegally removed from the premise and have not been located.  In both incidents, the source was considered to be horses from Mexico involved in unsanctioned racing.  Information suggested the disease was transmitted through blood transfusions and sharing of needles among these horses.  Tick surveys found no competent tick vectors on the affected premises.

The largest and currently ongoing incident revolves around Texas. This incident to date has uncovered 370 horses positive for B. equi.  There are 343 EP positive horses in Texas and 27 positives are located in 12 other states.  All of the positive horses originated from the affected premise in Texas and information suggests the disease has been present on this premise for at least several years.  Testing over 600 exposed horses to date in 12 states has not found disease transmission other than what occurred on the affected premise.  The original source of the infection is unknown but tick vectors have been shown to be the mode of disease transmission on the affected premise.

Beginning January 1, 2010, New Mexico has required a negative EP test on all horses entering a racetrack.  Testing in excess of 3,000 horses in New Mexico has resulted in 13 positive for B. equi.

There is currently no treatment proven effective in clearing B. equi infection.  Research indicates some strains of B. caballi may be cleared with appropriate medication.

What happens when a horse tests positive for EP? The Oklahoma Department of Agriculture, Food, and Forestry (ODAFF) will initiate an epidemiological investigation and issue a quarantine for the positive horse and any potentially exposed horses.  Exposed horses are those from the same herd or having recent contact with a positive horse.  All exposed horses will be tested for EP before being released from quarantine.

Currently there are only three available options for an EP positive horse:

Permanent Quarantine (including isolation and tick control)
Euthanasia
Export and return to country of origin (if recent import into the U.S.)
What can I do to protect my horse from this disease? 

To protect a horse that travels infrequently from your home property:

§    Test all horses on the property and control movement onto the farm

To protect a horse that travels a lot and is exposed to other horses of unknown status:

§    Control tick vector and eliminate potential transfer of blood through shared needles, equipment and transfusions

§    To control ticks, combine regular grooming and thorough inspections with use of a spray or bath product labeled effective against ticks and safe for horses

§    Testing your horses will give you an accurate assessment of your situation and protections that are necessary

If you have any questions about Equine Piroplasmosis, please contact the State Veterinarian’s office at (405) 522-6131.