Equine Piroplasmosis: Emerging Threat to the Horse

Industry

Lauren Lewis1 and Pete D. Teel2

Department of Entomology, Texas A&M University, College Station, Texas1Senior Biomedical Science and Entomology Double major, 2Professor and Associate

Department Head

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Equine Piroplasmosis (EP) :

• Acute tick-borne disease of Equids (horses, mules, donkeys, and zebras)

• >50% mortality in naïve animals• Difficult to diagnose • Recent increase in serologically positive US horses• Effects breeding, working, and performance horses• Major constraint to interstate and international

movement of horses

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Geographic Distribution

• US Not endemic in the US Eradicated from the US by the

1980s In 2008, an outbreak occurred

in Florida

• Global Endemic in many tropical and

subtropical regions including parts of Africa, the Middle East, Asia, Central and South America, the Caribbean and Europe

Australia, New Zealand, Canada, Japan are considered EP free

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Problem: U.S. threatened by occurrences of EP outbreaks

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Transmission

• Pathogens transmitted by ticks Babesia caballi

• Transovarial transmision

Theileria equi (formerly Babesia equi)• Transovarial transmission uncertain or absent • Intrastadial transmission

• Known US Tick Vectors Dermacentor nitens

• Experimental US Tick Vectors: Amblyomma americanum Dermacentor albipictus D. variabilis Rhipicephalus (Boophilus) microplus

• Known Global Tick Vectors: Dermacentor Rhipicephalus Hyalomma

Infected

Uninfected

Infected red blood cells

Normal red blood cells

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Negative Effects of EP:

• Travel Restrictions• Mandatory Serological Testing• Quarantine • Loss of non endemic status

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Diagnosis: Clinical Signs

• Variable and nonspecific• EP should be suspected in horses with anemia,

jaundice and fever • T. equi causes more severe disease than B. caballi• Incubation period is 12 to 19 days when caused by

T. equi and 10 to 30 days when caused by B. caballi• EP is a reportable disease; suspect cases should

be reported to state & federal authorities

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Prevention and Control

• Prevention with acaricide applications – to animals prior to exposure, and

post-exposure if needed• Vegetation free zones• Avoidance of Tick infested areas• Post exposure tick checks• Pre-purchase evaluations & testing

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Tick Inspections for Equines

• Preferred Tick Feeding Sites– Ears– Nasal openings– Mane– Tail– Perianal area– Genital area– Leg auxilaries

Use as guide for tick treatment

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Acaricide Applications for Equines

• Several classes of acaricides available • Formulations include

– Sprays – Pour-ons and Spot-ons– Wipe-ons– Dusts– Protective covers impregnated w/acaricides

Use all materials with caution; read the labels and follow instructions carefully.

Focus attention on preferred feeding sitesSee http://tickapp.tamu.edu for further

information and suggestions.

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Resources Available•  “Iowa State Center for Food Security & Public Health Brochure”

http://www.cfsph.iastate.edu/Factsheets/pdfs/equine_piroplasmosis.pdf • “Gray Book on Foreign Animal Diseases”

p. 147 “Babesiosis”http://www.aphis.usda.gov/emergency_response/downloads/nahems/fad.pdf

• “USDA Website”• http://www.aphis.usda.gov/animal_health/animal_diseases/piroplasmosis/• “Equine Babesiosis-Review”• http://www.vet.uga.edu/VPP/clerk/edwards/index.php• “The TickApp”, a mobile smart phone app for ticks of Texas and the Southern Region• http://tickapp.tamu.edu • USDA suggestions for “Protecting your horses”• http://www.aphis.usda.gov/animal_health/animal_diseases/piroplasmosis/downloads/ep_

protect_your_horses_en_sp.pdf• A Literature Review of Equine Piroplasmosis• http://www.aphis.usda.gov/animal_health/animal_diseases/piroplasmosis/downloads/ep_l

iterature_review_september_2010.pdf• Equine Piroplasmosis and the World Equestrian Games• http://www.aphis.usda.gov/animal_health/animal_diseases/piroplasmosis/downloads/ep_

2010_weg_wp.pdf• USDA, APHIS Factsheet• http://www.aphis.usda.gov/publications/animal_health/content/printable_version/fs_equi

ne_piro.pdf