Equine Piroplasmosis Fact Sheet
What is equine piroplasmosis?
Equine piroplasmosis is a tick-borne disease, affecting all equine species, such as horses, mules, donkeys and zebras. Theileria equi (T. equi) and Babesia caballi (B. caballi) are the agents that cause equine piroplasmosis.
Is equine piroplasmosis a risk to human health?
Infected horses pose no risk to humans.
Ticks infected with the parasite may be able to spread the disease to humans through biting, but this has not been proven. Human piroplasmosis is uncommon and is usually associated with different strains of Babesia.
What are the clinical signs of equine piroplasmosis?
The clinical signs of equine piroplasmosis vary and are often non-specific; the disease can easily be confused with other conditions. Equine piroplasmosis can occur in several different forms:
- Per acute: In some per acute cases, animals may be found dead with no previous signs of being sick.
- Acute: The acute form is characterized by fever, loss of appetite, sudden onset of immobility and reluctance to move, and severe lethargy. The fever may subside after one day and become intermittent. Other signs include anemia, jaundice and an enlarged spleen and liver. Severe cases can result in death.
- Sub-acute: Clinical signs in sub-acute cases are similar to acute cases except that affected animals may show weight loss and an intermittent fever.
- Chronic: Chronic cases usually present non-specific clinical signs such as mild loss of appetite, poor performance and loss of body weight. Severe cases can result in death. In young horses and newborn foals the symptoms are more severe.
- Carrier: A large proportion of infected horses are carriers of the disease. These horses show no apparent signs of infection and are the most difficult horses to control in the spread of the disease. Persistent infections of mares may cause abortions. Foals can become infected before birth, resulting in either weak, anemic foals or healthy carrier foals. Carrier horses may become sick when they are stressed or after the administration of immunosuppressive medications.
Where is equine piroplasmosis found?
Equine piroplasmosis has never been found in Canada. However, competent tick vectors do exist in Canada. Equine piroplasmosis is found in parts of Europe, Africa, South and Central America, the Middle East and Asia. The U.S. has reported localized outbreaks in the past few years.
How is equine piroplasmosis transmitted and spread?
Equine piroplasmosis is not directly contagious. It is transferred by blood from an infected animal to a susceptible animal or insect. Ticks are the main vector of transmission as they are a natural host for the parasites. It can also be transmitted by contaminated needles and syringes. Foals can become infected while in the uterus, particularly with T. equi.
Some horses can carry the parasite in their blood for a long time and can act as sources of infection for ticks. Introduction of these carrier animals into disease-free areas can lead to new cases of piroplasmosis if ticks are prevalent.
Infection is seasonal and is most likely to occur shortly after peaks in the tick population. Tick activity tends to increase with warmer temperatures.
The main risk factor for introducing equine piroplasmosis into Canada is through importing infected animals.
How is equine piroplasmosis diagnosed?
The disease is suspected in horses with a history of travel that have anemia, yellowing of the gums or eyes, or fever. Laboratory tests are necessary for a definitive diagnosis.
How is equine piroplasmosis treated?
Equine piroplasmosis can be difficult to treat. New treatment protocols have been established that have shown to be effective in clearing equine piroplasmosis caused by either B. caballi or T. equi.
The medications used to treat piroplasmosis may cause horses to become ill. Side effects include colic, diarrhea and rarely, death.
What is done to protect Canadian livestock from equine piroplasmosis?
The Canadian Food Inspection Agency (CFIA) places strict regulations on the import of animals and animal products from countries where equine piroplasmosis is known to occur. These regulations are enforced through port-of-entry inspections done by both the CFIA and Canada Border Services Agency.
Equine piroplasmosis is a reportable disease under the Health of Animals Act. This means that all suspected cases must be reported to the CFIA for immediate investigation by inspectors.
How would the CFIA respond to an outbreak of equine piroplasmosis in Canada?
Canada's emergency response strategy to an outbreak of equine piroplasmosis would be to:
- eliminate the disease; and
- re-establish Canada's disease-free status as quickly as possible.
In an effort to eliminate equine piroplasmosis, the CFIA may use some or all of the following disease control methods:
- the treatment or humane euthanasia of infected animals;
- surveillance and tracing of potentially infected or exposed animals;
- strict quarantine and animal movement controls to prevent spread; and
- zoning to define infected and disease-free areas.
If an owner has an animal that is ordered euthanized, they may be eligible for compensation.
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