Infection of the equine population by Leishmania parasites.
Authors: Mhadhbi M, Sassi A
Journal: Equine veterinary journal
Summary
# Editorial Summary: Leishmania Infection in Equines Leishmania parasites, traditionally associated with human and wildlife populations across Central and South America, have increasingly been documented in horses across both endemic regions and non-endemic countries including Germany, Portugal, Spain and Texas, with *L. infantum* and *L. martiniquensis* identified as the primary causative species in autochthonous cases. The condition manifests as cutaneous leishmaniasis with clinical signs limited to single or multiple skin lesions typically appearing on the head, ears, scrotum, legs and neck, though subclinical infection prevalence remains extremely low and visceral involvement has not been reported. What makes this parasite particularly noteworthy from an epidemiological standpoint is not the overt disease burden in equines—which remains limited—but rather horses' potential role as a maintenance or amplification host within transmission cycles involving phlebotomine vectors, thereby creating a theoretical risk of parasite spread to other susceptible species and humans sharing endemic areas. The mild clinical presentation and tendency for spontaneous regression of skin lesions likely means Leishmania infection in equids is substantially underdiagnosed, particularly in endemic regions where clinical surveillance may be limited. Given the emerging distribution of Leishmania in temperate climates and the parasite's public health implications, equine practitioners working in or treating horses imported from endemic areas should maintain awareness of this differential diagnosis for unexplained cutaneous lesions and understand the potential zoonotic considerations for their clients and practices.
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Practical Takeaways
- •Leishmania-related skin lesions in horses are likely underdiagnosed due to mild clinical presentation and spontaneous regression; consider differential diagnosis in endemic areas
- •While equine leishmaniasis prevalence is low, infected horses may contribute to parasite transmission cycles—implement vector control measures in endemic regions
- •No visceral disease has been documented in infected equids, reducing concern for systemic complications, but cutaneous lesions warrant investigation for zoonotic transmission risk
Key Findings
- •Leishmania infection in equids occurs in both Old and New World, caused primarily by L. braziliensis and L. infantum species
- •Prevalence of subclinical infections is extremely low with clinical cutaneous leishmaniasis appearing in only a small proportion of infected animals
- •Cutaneous lesions present on head, external ear, scrotum, legs and neck with no documented visceral abnormalities to date
- •Equids may serve as a source of infection for phlebotomine vectors and other susceptible mammalian hosts despite low prevalence in equine population