Equine infection with Leishmania spp. in Costa Rica: Study of five cases

Abstract

Background: Cutaneous forms of leishmaniosis due to Leishmania braziliensis have been reported in horses in the NewWorld. Domestic animals play a role in the transmission of the disease. In Costa Rica, human cases of L. braziliensis, L. panamensis and L. infantum have been reported. Objectives: The present report describes five cases of equine cutaneous leishmaniosis in Costa Rica. The aetiological diagnosis was based on the presence of the parasite within the lesions. Methods: Skin biopsies were used to perform histopathological analyses of the lesions. Immunohistochemistry was used to detect the presence of the Leishmania spp. antigens in tissue sections. Laser-capture micro-dissection and quantitative real-time PCR techniqueswere carried out to detect the pathogen nucleic acid within themicroscopic lesions. Results: Histopathological analyses showed a granulomatous inflammation within the dermis, with multi-nucleated giant cells, macrophages, lymphocytes and few neutrophils and eosinophils.We detected the parasite by immunohistochemistry, using a rabbit polyclonal antibody raised against Leishmania spp. However, we could not identify Leishmania spp. by quantitative real-time PCR in formalin-fixed paraffin-embedded tissues, using specific primers for the conserved region in the minicircle of the Leishmania DNA kinetoplast. Conclusions: Our results emphasise the importance of Leishmania spp. not only as a causative agent of equine cutaneous disease in the NewWorld, but also as a possible emerging pathogen. Leishmaniosis is one of the most prevalent parasitic public health problems worldwide, and equinesmay have a role in the epidemiology of the disease.