Serological, molecular, and epidemiological assessment of Leishmania spp. in equids within a hotspot endemic area for cutaneous leishmaniasis in southeastern Algeria.

Abstract

Cutaneous leishmaniosis remains a major public health concern in Algeria, predominantly affecting humans and dogs. However, the role of other animal hosts, particularly equids, in the transmission cycle remains underexplored. This cross-sectional study presents the first systematic investigation of Leishmania spp. exposure and infection in equids, along with associated environmental and host factors, from southeastern Algeria, El Oued Wilaya, the third most affected region for human cutaneous leishmaniasis in the country. A total of 122 equids from eight communes were clinically examined and tested using three diagnostic tools: indirect fluorescent antibody test, conventional PCR targeting the ITS1 region, and real-time qPCR targeting the kDNA minicircle. Despite the absence of clinical symptoms, serological analysis revealed a 22.13% seropositivity rate for anti-Leishmania infantum IgG. ITS1-PCR and kDNA qPCR detected parasite DNA in 13.93% and 7.38% of samples, respectively. PCR-RFLP analysis confirmed the presence of Leishmania (Leishmania) infantum. Phylogenetic analysis revealed intraspecific divergence among isolates, with two sequences clustering in a distinct clade closely related to a Brazilian strain, indicating unexpected genetic diversity among Algerian isolates. Key associated factors included proximity to human settlements and age-related susceptibility. The detection of subclinical infections in equids suggests a potential but underrecognized epidemiological role in endemic areas. Although their reservoir competence remains unconfirmed, this evidence warrants further research on vector competence, molecular characterization, and entomological surveillance. Integrating equids into One Health surveillance frameworks could help clarify their role and guide targeted control strategies in Algeria where transmission dynamics of leishmaniosis may vary.