Equine Piroplasmosis
Equine piroplasmosis, also called equine babesiosis, is a blood parasitic disease affecting equines, including plains zebras. It is caused by tiny parasites (Babesia caballi or Theileria equi) transmitted by ticks. These parasites invade re...
What is it?
Equine piroplasmosis, also called equine babesiosis, is a blood parasitic disease affecting equines, including plains zebras. It is caused by tiny parasites (Babesia caballi or Theileria equi) transmitted by ticks. These parasites invade red blood cells and progressively destroy them.
The plains zebra, like the horse or donkey, can be infected in regions where vector ticks are present. In the wild as in captivity (zoos, reserves), the animal remains exposed to the risk of tick bites.
This disease is found in many parts of the world, including Africa where the plains zebra lives in the wild, making it a health threat to monitor closely in captive or semi-captive populations.
Key point
Severe acute forms can be life-threatening without prompt treatment.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Clinical signs vary depending on the form of the disease.
In the acute form, fever, marked depression, loss of appetite and significant fatigue are observed. The mucous membranes (gums, around the eyes) may become pale or yellowish due to the destruction of red blood cells. Urine may become dark, almost reddish in colour.
In more severe forms, swelling (oedema) may appear, particularly in the limbs or abdomen, and the animal may show difficulty breathing.
Some animals, particularly those born in areas where the disease is very common, may become carriers without showing visible symptoms for a long time, while still remaining a source of infection for ticks.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by microscopic blood parasites, Babesia caballi and/or Theileria equi, which invade and destroy red blood cells. These parasites are transmitted by the bite of infected ticks, which act as vectors.
Living in a tick-infested region, a warm and humid environment that favors these parasites, the lack of a parasite control program, stress (transportation, captivity, cohabitation with other infected equids), and a weakened immune system all increase the risk of developing clinical disease.
Transmission
Transmission occurs mainly through ticks, which become infected by biting a carrier animal and then transmit the parasite to another animal during a subsequent bite. Transmission can also occur through blood, for example through the use of non-sterilised equipment between animals, or from mother to foetus in some cases.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian suspects the disease based on symptoms and context (presence of ticks, geographic area). Confirmation is made through a blood test, with microscopic examination of a blood smear to look for the parasite inside red blood cells, supplemented by more sensitive serological or molecular tests performed by a specialized laboratory.
Treatment
Treatment relies on specific antiparasitic medications targeting Babesia/Theileria, prescribed and administered only by a veterinarian given their narrow margin of safety in wild equids. Supportive care may be added: fluids to combat dehydration, and monitoring of kidney and liver function.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention relies above all on tick control: regular inspection of the coat, appropriate external antiparasitic treatments, and environmental management (clearing brush, reducing tick-prone areas).
In zoos or wildlife reserves, quarantine and blood screening of new animals before introduction into a group help limit disease introduction. Veterinary equipment (needles, instruments) must be properly disinfected between each animal.
Possible complications
Possible complications include severe anemia, kidney failure related to massive red blood cell destruction, clotting disorders, and even circulatory collapse in severe forms. In wild animals, the handling and restraint necessary for treatment themselves represent an additional risk of significant stress.
When to see a veterinarian
Unusual fatigue or reluctance to move in the zebra.
Pale or yellowed mucous membranes noticed on close examination.
Abnormally dark urine.
Fever or persistent loss of appetite.
Unexplained swelling of the limbs or belly.
Prognosis
The prognosis depends on how quickly treatment is started. A case detected early and treated correctly generally carries a favorable prognosis. Severe acute forms, particularly in an animal weakened or stressed by captivity, can be life-threatening without prompt treatment. Some animals that recover remain chronic carriers of the parasite.
Frequently asked questions
Can plains zebras transmit piroplasmosis to humans?
No, this disease is not transmissible to humans. It spreads only between equines through tick vectors.
Can a healed zebra become sick again?
Yes, a healed animal can remain a carrier of the parasite without symptoms, but can develop clinical signs again in case of stress or a drop in immunity, and remains a possible source of contamination for ticks.
How to protect a captive zebra against this disease?
The best protection consists of limiting tick exposure through environmental management and regular antiparasitic treatments, as well as screening before any introduction into a new group.
Is piroplasmosis frequent in wild zebras?
In African regions where vector ticks are present, a significant proportion of wild equines, including zebras, can carry the parasite without necessarily developing visible disease.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 30 August 2026
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