Mixed infection of Leishmania (Leishmania) infantum and Leishmania (Viannia) braziliensis in a mare (Equus ferus caballus) from Minas Gerais State, Southeastern Brazil.

Plain Language Overview

• This research reports a case of a horse in Brazil infected with two different species of Leishmania parasites, which cause leishmaniasis, showing skin lesions but otherwise healthy.
• The study confirms mixed infection by molecular tests and highlights that horses may play a role in the spread of this disease.

Background

• Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania.
• In Brazil, equine (horse) leishmaniasis is common and primarily caused by Leishmania (Viannia) braziliensis.
• Leishmania (Leishmania) infantum can occasionally infect horses, but its presence is less frequent.
• The study comes from Minas Gerais State in Southeastern Brazil, a region where leishmaniasis is endemic.

Case Description

• A 6-year-old mare (female horse) from a rural area in Itabirito, Minas Gerais, presented with nodular cutaneous (skin) lesions on all of its limbs.
• Aside from these lesions, the mare showed no other signs of illness, suggesting a localized infection.

Methods

• Samples were collected from the mare’s skin lesions and bone marrow for investigation.
• Parasitological techniques were used to attempt parasite culture and microscopic examination.
• Molecular methods, specifically PCR targeting the heat shock protein 70 (hsp70) gene and the internal transcribed spacer 1 (ITS1) region, were applied to identify and differentiate the parasite species present.

Findings

• Both Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum were detected in the samples, confirming a mixed infection.
• This is the first confirmed isolation of L. (V.) braziliensis specifically from equine cutaneous lesions, marking a novel finding.
• The presence of L. (L.) infantum in the horse also underscores horses’ potential involvement in the epidemiology of visceral leishmaniasis, which is caused by this species.

Implications

• This case highlights that horses can harbor different species of Leishmania simultaneously, which may affect how the disease spreads in the environment.
• Given that horses live close to humans and can be bitten by sandflies (the vectors transmitting leishmaniasis), they could act as reservoirs, maintaining the parasite lifecycle and contributing to transmission.
• The findings suggest that control measures for leishmaniasis should consider equids as part of epidemiological surveillance programs.
• The study encourages further research into the role of horses in the ecology of leishmaniasis to improve public health interventions.