During the past couple of weeks we have received numerous e-mails and phone calls with questions about the recently diagnosed cases of equine piroplasmosis. As many of you are already aware, animal health authorities are investigating an outbreak of equine piroplasmosis on a South Texas ranch (located in Kleberg County) that includes over 317 positive horses. 288 of the positive horses are on the original premises and seven are on adjoining premises. The balance of the positive horses have now been identified in states across the United States. To date these states include Alabama, California, Colorado, Florida, Georgia, Hawaii, Kentucky, Louisiana, Minnesota, Montana, New Jersey, New Mexico, North Carolina, Oklahoma, Tennessee, Washington and Wisconsin, and the list appears to be growing daily. All of the positive horses are now under quarantine and any horses that may have been kept in proximity to the positive horses are undergoing testing.

As a result of the positively diagnosed horses in the United States, Canada has imposed restrictions on the movement of horses from the United States, especially from Texas. Several states have also imposed restrictions on the movements of horses from Texas. The number of states imposing restrictions is growing daily.

Equine piroplasmosis (EP) is a tick-borne disease that affects horses, donkeys, mules and zebras. The disease is transmitted via tick bites from as many as 15 different species of ticks. It can also be transmitted through mechanical transmission by improperly disinfected needles or surgical instruments. The causative agent is an organism formerly known as Babesia caballi and Babesia equi that has been renamed Theileria caballi or Theileria equi. Transmission of the disease occurs when ticks ingest blood from infected equine and then bite uninfected equine, spreading the disease through blood contact. Ticks carrying the parasites can be moved via hay, feed, bedding, and vegetation.

Equine piroplasmosis occurs primarily in Africa, Europe, Asia, and both South and Central America. Only Canada, Australia, Japan, England, Ireland, and the United States are not considered endemic areas for the disease.

A piroplasmosis-infected horse can take 7 to 22 days to show signs of the disease. Cases of piroplasmosis may be mild or acute. Mild forms of the disease cause affected horses to appear weak and show lack of appetite. More acute cases can occur in areas where piroplasmosis is not commonly diagnosed and horses have not built up a resistance to the disease. Signs of the acute phase of piroplasmosis include fever, anemia, jaundiced (yellowish-colored) mucous membranes, labored breathing, and occasionally a swollen abdomen. Other signs of piroplasmosis can include roughened hair coats, central nervous system disturbances, constipation, colic, and hemoglobinuria (which will cause urine to have a brownish color). In some cases, death may occur. Some infected horses, however, may show few symptoms (or even no symptoms at all) in the acute phase and may not experience any decrease in performance. Horses that survive the acute phase of infection may continue to carry the parasites for long periods of time. These horses are potential sources of infection to other horses through tick-borne transmission or, less commonly, mechanical transfer by contaminated needles or surgical instruments.

Equine piroplasmosis was officially eradicated from the United States in 1988, but in August 2008, Florida’s Department of Agriculture and Consumer Services announced a positive horse in that state. During the investigation, Florida officials quarantined 25 premises and tested more than 200 horses for the disease before the incident was declared resolved in February 2009. In all, 20 horses on seven premises were euthanized after they were found to be infected with one of the causative organisms. Piroplasmosis occurs only occasionally in man (mainly cattle farmers in an area that has a high potential for infection) and the disease is often misdiagnosed as drug-resistant malaria due to the similarity of symptoms.

Back in July 2008, Texas State Veterinarian Dr. Bob Hillman expressed concern about the potential for a major outbreak because fever ticks (Boophilus microplus or Rhipicephalus microplus), which are capable of carrying the protozoal parasites that cause piroplasmosis, seemed to be making an incursion into Texas in large numbers. Animal health officials had designated a preventive tick quarantine area covering more than one million acres to deter establishment of tick-borne diseases, including piroplasmosis, in the State.

As an example of the seriousness that other states place on this situation, Oklahoma passed an emergency order as follows:

“PURPOSE: This Emergency Order is issued as an emergency measure for the specific and limited purpose of formulation and maintenance of an Equine Piroplasmosis eradication and control program pursuant to the following plan adopted and recommended by the State Veterinarian of Oklahoma and the United States Department of Agriculture, Animal and Plant Health Inspection Service:

Equids originating from any premise under quarantine for Equine Piroplasmosis shall not enter Oklahoma.

Equids originating from any part of Kleburg County or adjacent counties not under quarantine may enter Oklahoma so long as accompanied by a Certificate of Veterinary Inspection prepared and signed by an accredited veterinarian within ten (10) days prior to entering Oklahoma and containing the following information:

A negative Piroplasmosis cELISA test within fourteen (14) days of entry into Oklahoma and including an original copy of the test or NVSL accession number;

A negative EIA test within the past twelve (12) months, including an original copy of the test;

An Oklahoma entry permit number; and The following statement by the accredited veterinarian signing the Certificate of Veterinary Inspection, “I personally inspected these animals and 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.

The Certificate of Veterinary Inspection shall include all other information otherwise required on the document, including complete identification for each animal listed, complete name, address and telephone number of the consignor, consignee, and accredited veterinarian, the physical address of the equids located in Texas the physical address of the Oklahoma destination.

Treatment for ticks shall include any topical pyretroids or equine labeled tick spot on product.

Upon arriving at the destination in Oklahoma, equids shall be physically examined by an authorized agent of the Board prior to commingling with other equids.

While other states will probably structure their emergency orders regarding piroplasmosis slightly differently, this will give you an idea of the type of restrictions that will be in place.

One major problem that veterinarians are experiencing involves the turnaround time for testing of the suspect horses. Currently the only laboratory that is approved for this testing is in Aimes, Iowa and there is a long turnaround time (the time that elapses from the veterinarian sending the samples until the result of the testing is received) in the Aimes laboratory. This may be due to the increased number of samples being sent because of the current problem. It often exceeds 10 days instead of their usual 5 days. There is also the additional expense incurred by the horse owner of sending samples to that laboratory.

Representatives of the Equine Committee of the Texas Veterinary Medical Association met with the Texas Veterinary Medical Diagnostic Laboratory (TVMDL) located at Texas A&M to discuss this problem and learned that the laboratory has both the capability and the desire to test for piroplasmosis. The director of the laboratory indicated that an application had been submitted through the proper channels to allow this testing but it appears to have reached a dead end. Both the Equine Committee of the Texas Veterinary Medical Association and the recently formed Texas Equine Veterinary Association support this effort to obtain approval for the TVMDL to conduct piroplasmosis testing. This would allow for a much faster turnaround time allowing for completion of the required paperwork necessary for shipment of the horses.

Obviously transportation of racehorses is the concern of our subscribers but we need to remember that the 2010 FEI World Equestrian Games will be held in Kentucky. Breeding season is upon us and transportation of the broodmares will soon begin in earnest. Rodeo horses and horses involved in other equine competitions are also affected by the delay in testing. It appears that some pressure from the USDA APHIS office in Washington, D.C. may help expedite the favorable decision regarding the TVMDL situation. In the meantime, be sure to factor the long laboratory turnaround time into your scheduled obtaining of any necessary paperwork needed to transport the horses.

Remember that the situation changes hourly when a disease like piroplasmosis is discovered in the United States causing the various states to constantly monitor the situation and modify their regulations accordingly. Dr. Hillman, head of the Texas Animal Health Commission (TAHC), the state’s livestock and poultry health regulatory agency said, “Before moving horses from Texas, we urge you and your veterinarian to check with animal health officials for any state of destination, to ensure the animals have met all entry requirements. Regulatory requirements can be fluid as disease situations evolve, so it is essential to call each state each time you haul.”

As states provide entry restrictions and requirements, the documents are posted on the TAHC web site at http://www.tahc.state.tx.us Dr. Hillman urged equine owners and veterinarians to call state animal health officials directly before hauling, as many states have not yet distributed entry requirement information. Contact information for state veterinarians may be obtained from the TAHC at 800-550-8242, ext. 710.

Equine piroplasmosis is transmitted by tick bites.

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