B207
- EQUINE BABESIOSIS
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Nature of the disease
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Equine babesiosis (Equine piroplasmosis) is a vector born disease of
horses due to two protozoans: Babesia equi (or Theileria equi)
and Babesia caballi. Both parasites are transmitted by
ticks.
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Classification
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OIE, List B disease
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Susceptible species
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Equines: essentially horses but also donkeys, mules and zebra.
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Distribution
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Equine Babesiosis is distributed worldwide. It seems to be absent from the
Pacific region where it has not been reported since 1976 (Australia).
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Clinical signs
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Incubation for B. equi is 12-19 days and 10-30 days for B.caballi.
Disease is usually more severe with B. equi. Symptoms vary
from chronic to per acute form.
- In the per acute form horses are found dead or moribund before
apparition of premonitory signs.
- In the acute form, clinical signs include:
- Fever,
- Anorexia and depression,
- Anaemia,
- Icterus and hemoglobinuria,
- Colic
- The chronic form
usually appears after an acute phase, clinical signs are not
specific and include:
- Loss of condition,
- Poor exercise tolerance
- Slow recovery
- Rarely atypical forms include gastro-enteritis,
bronchopneumonia, abortions.
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Post-mortem findings
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- Intravascular haemolysis, jaundice
- Emaciation
- Enlarged spleen and liver
- Kidney pale or with haemorrhages
- Oedema in lungs
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Differential diagnosis
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Specimens required for diagnosis
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Blood smears can be submitted for parasitic observation but is rarely
probing. Blood samples on EDTA can be submitted for
transmission test.
Serological tests are more commonly used and techniques include the complement fixation (CF) test,
which is the primary test used for qualifying horses for importation, the indirect fluorescent antibody (IFA) test and
ELISA.
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Transmission |
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Equine babesiosis is transmitted by ticks where the parasite has a
compulsory stage of sexual reproduction. Some of the competent vectors
identified in the literature are listed below. Iatrogenic transmission by
injection material is possible.
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Ticks
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B. caballi
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B. equi
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Dermacentor reticulatus
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+
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+
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Dermacentor marginatus
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+
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+
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Dermacentor
silvarium
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+
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?
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Dermacentor
nitens
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+
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-
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Rhipicephalus bursa
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+
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+
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Rhipicephalus sanguineus
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+
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+
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Rhipicephalus turanicus
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?
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+
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Rhipicephalus evertsi
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?
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+
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Hyalomma excavatum
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+
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+
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Hyalomma
scupense
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+
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Hyalomma dromedarii
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+
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+
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Hyalomma plumbeum
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?
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+
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Risk of introduction |
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Equine babesiosis could be introduced by importation of infected horses,
in that case establishment of the disease depends on the existence of a
competent host. Risk of introducing infective ticks is low, provided that insecticide
treatment is required but associated danger is great.
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Control / vaccines
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There is no vaccine. Treatment using imidocarb is usually efficient.
If introduced best eradication is through slaughtering of infected
animals and vector control.
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| References
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- BUSSIERAS J, CHERMETTE
R, Protozoologie In Parasitologie Vétérinaire, Ecole
Nationale Vétérinaire D'Alfort, 1992, p 108-118.
- Equine Babesiosis, In Veterinary Medicine, Saunders, Eight ed,
1997, London p.1171-1179
- Office International des Epizooties, 2002
- SOULSBY EJL, Babesia of Horses In Helminths, Arthropods and
Protozoa of Domesticated Animals, Lea and Febiger Inc, 7th ed,
1982, Philadelphia, p 719-723
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