Horse Welfare Alliance of Canada

In Canada Equine Piroplasmosis is a federally reportable disease.

• Canadian Food Inspection Agency (CFIA) Equine Piroplasmosis

• Horse in Ogden area has deadly disease - equine piroplasmosis (Feb 3)
• Letter to Dr. Samira Belaissaoui, Senior Staff Veterinarian – Imports, Canadian Food Inspection Agency regarding Piroplasmosis Status (Jan 26, 2010)
• Screening reveals more piroplasmosis cases in US (Jan 28, 2010)

Word from Woodwedge – An Equine Piroplasmosis Primer (written Dec 2009)

Equine piroplasmosis (EP) is not endemic to the USA or Canada, but it is present in the Caribbean, South and Central America, Eastern and Southern Europe, Africa and the Middle East. The greatest risk for introduction of this disease is through the trading of animals or international equestrian sports where infected and non-infected animals are in contact. If an outbreak occurs in a country such as the USA (or Canada), the World Organization for Animal Health (OIE) must be notified and made aware of the steps that will be taken to eradicate the disease. (6)

USDA Animal Health authorities investigating an outbreak of EP on a South Texas ranch have now located 317 positive horses. These include 288 on the index ranch, with 29 positive cases tracing out from the Texas herd into 11 States. All known positive horses are under quarantine, and testing of all epidemiologically linked horses is ongoing. (Source -OIE and APHIS release Nov. 13, 2009)

Restrictions for import into Canada are currently in place (Nov. 20, 2009), as a CFIA precautionary measure. Horse owners may access information through their CFIA District Office, the CFIA website or from the CFIA Automated Import Reference System (AIRS). (2,1,8)

North American horse owners and veterinarians generally are not as familiar with EP as we might be…..logically, because we have not had to deal directly with the disease until recently on this continent. Incursions in the past have thought to have been controlled, and it is hoped the regulatory authorities stateside will be enabled to do so now. The cost of losing EP-free status is high, with immeasurable impact on the horse industry, here and elsewhere.

EP is a tick-borne protozoal disease of horses, mules, donkeys and zebra. The causative agents are blood parasites named Theilera equi (previously designated as Babesia equi) and Babesia cabelli. The parasites are found inside the red blood cells of infected animals. Identification of the agent is accomplished (with difficulty) by demonstrating the parasites in stained blood or organ smears. Infections in carrier animals are best demonstrated by testing their sera for the presence of specific antibodies. The cELISA and IFAT are the blood tests of choice for diagnosing latent infections. The PCR is an additionally available test. False positives and false negatives can occur on common tests, further complicating definitive diagnosis. (“A Comparative Study of Serological Tests and PCR for the Diagnosis of Equine Piroplasmosis” is scheduled to be published in an upcoming edition of The Journal of Parasitological Research.) (7)

The clinical signs of EP are often non-specific, and the disease can be confused with other conditions.

Mild forms may show only loss of appetite and weakness. More acute cases can occur where EP is not common and the animals have not built up a resistance to the disease. Signs of the acute phase include fever (often above 40^oC), anaemia, jaundiced mucous membranes, a swollen abdomen, laboured breathing, central nervous system disturbances, roughened hair-coats, constipation, colic, and haemoglobinuria – a condition which gives urine a red colour. Equidae surviving the acute phase of infection may carry the parasite for long periods of time. These animals are potential sources of infection to others through tick-borne transmission or mechanical transfer by needles or surgical instruments. (8) Ticks carrying the parasites may be moved via hay, bedding, feed and vegetation. Intrauterine infection may occur, resulting in abortion or the birth of a weak, anaemic foal. (3) Chronic cases may also present non-specific signs. The spleen is often found to be enlarged. Swelling of the lower limbs may occur during this phase. A rare per-acute form, where horses are found dead or moribund, has been reported. (4)

Currently, there is no vaccine for EP. In endemic regions symptoms are treated with drugs. Proper sanitation is important, but preventing the transfer of blood between animals through biting ticks or mechanically is crucial to preventing the transmission of EP. (3)

Meanwhile, back on the Canadian ranch, it is strongly recommended that horse owners planning on travelling south of the 49th with their horses seek current information on the status of EP eradication measures being vigorously pursued by the USDA, and precautionary measures undertaken by the CFIA. As has long been the case for the Pan Am Games, getting competition horses safely to and from the 2010 World Equestrian Games in Kentucky may present unanticipated challenges, setting aside our normal commerce.

“Knowing is always better than not knowing.”

- B.W.R. Rothwell, D.V.M.

References

1. Althouse B, Disease Control Specialist CFIA, personal communication 09.11.26
2. Allen RW, District Veterinarian CFIA, electronic communication 09.11.30
3. USDA-APHIS Veterinary Services, EP Fact Sheet July 2008
4. World Organization for Animal Health (OIE), OIE Terrestrial Manual 2008 summary of EP
5. Lohmann K, WCVM electronic communication 09.11.20
6. Waal, D.T. Review Series BVJ 1992 Equine Piroplasmosis
7. AAEP (thehorse.com)
   
8. EC BID News Release Import Restrictions Announced 09.06.22