What is Piroplasmosis?

May 27, 2019
Text: Lusitano World

In this article we will explain what equine piroplasmosis is and its potential impact on the exportation for the horses that test positive. We will also highlight the main exportation procedures you must be aware of in case you are buying a horse you will export outside Europe. Let’s get started!


What is Piroplasmosis?

Equine Piroplasmosis (EP), is a tick-borne disease that affects horses, donkeys, mules and zebras. It is caused by one of two protozoan parasites: Theileria equi or Babesia caballi. These organisms can be transmitted by ticks or through contaminated blood. Piroplasmosis is endemic in many tropical and subtropical areas including Africa, Central and South America, the Middle East, the Caribbean, and parts of Europe, such as Portugal and Spain. Therefore, many of the horse born in these areas test positive to Piroplasmosis.

DID YOU KNOW? Ticks are commonly thought of as insects but are actually arachnids, such as scorpions, spiders and mites. All members of this group have four pairs of legs as adults with no antennae. Ticks are among the most efficient carriers of disease agents because they attach firmly to a host when sucking blood, feeding slowly and may go unnoticed for a considerable amount of time while feeding. There are at least 850 tick species worldwide.

What are the signs of Piro?

A horse with piro can take 5 to 30 days to show signs of the disease. Mild forms of Equine Piroplasmosis can appear as weakness and lack of appetite. More severe signs include fever, anemia, weight loss, jaundiced mucous membranes, a swollen abdomen, swelling of the limbs and labored breathing. In an extreme situation, some cases may progress to death. However, this is a rare and unusual situation.

Most horses that test positive to piroplasmosis will not show any signs of disease. This is especially the case with horses in countries where piroplasmosis is endemic, as it is the case for Portugal and Spain. Horses will most probably be in contact with the agent of piro while they are still youngsters in the pastures and develop antibodies that will protect them for life.

These horses, even if they test positive for piro, will not show any signs of this condition.

What are the tests for Piroplasmosis?

Since symptoms of EP mirror many other health conditions, lab testing is necessary to make a definitive diagnosis. Various diagnostic modalities can be used alone or in combination to diagnose a certain horse condition. To determine positive or negative status, a horse must be tested by sending blood to an internationally approved testing lab. Positive horses can be identified by testing their sera for the presence of specific antibodies for both Babesia Caballi and Theileria equi.

DID YOU KNOW? Currently, there are 3 primary tests used for qualifying horses for exportation: (1) indirect fluorescent antibody test (IFAT); competitive enzyme-linked immunosorbent assay (C- ELISA) and the (3) complement fixation test (CFT). Horses must show a percentage below 30% to all tests to be considered negative, and therefore fitting the Piroplasmosis exportation criteria.


What are the impacts of Piro on Export?

Equine piroplasmosis is important since it is the main restriction on the import/export of horses to other countries. To prevent the spread of the EP, international restrictions for importing horses have been imposed by some of the countries where EP is not endemic.

If you plan to export your horse outside Europe, you must be aware of your country's importation policy! Some of the countries who follow a ‘PIRO-FREE POLICY’ are: USA, Australia, New Zealand, Canada, Japan, China, Thailand and Mexico.

If you export outside Europe, a horse that is POSITIVE – meaning, having >30% blood titer for both parasites in the testing for piroplasmosis – does not fulfill the exportation requisites. A word of advice: if you are buying a horse in a foreign country, make sure you work with a certified and experienced agent who can make your life easier and avoid some common mistakes and even some heartbreak!

Can Piroplasmosis be treated?

In endemic regions, treatment of piroplasmosis is used only as a means of decreasing clinical signs and reducing possible symptoms that might appear specially when a horse’s immune system is more fragile.

We should keep in mind that treatment to reduce a horse’s blood titer levels of the agent below 30% serves no purpose for importation to restricted countries, as life‐long immunity is assumed to be conferred with chronic, inapparent infection.

In non‐endemic regions attempting to remain free of piroplasmosis, treatment of infected horses with the intent of clearance is desired. Therefore, vaccination and treatment strategies are dependent on the infection status (endemic versus non‐endemic) of the region.

In a final note - if you think about buying a positive horse to treat and then export, our advice is DON’T DO IT!  

It has been proven that even if the treatments available can help to eliminate the presence of parasites from a horse, this treatment has serious side effects for the animal, including diarrhea, intense colic and even liver and kidney toxicity. There is also a high chance that if the horse’s immune system is stressed after a long period traveling, blood titer levels may rise above the 30% accepted level during the quarantine in the destination country. The alternatives for a horse that tests positive after importation are euthanasia, lifetime quarantine, or return to the country of origin. This again underscores the importance of a test by a reputable international lab prior to travel.



American Association of Equine Practitioners
USA Department of Agriculture: Animal and Plant Health Inspection Service 




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