Leishmaniasis in migrants crossing Central America and Mexico: An emerging epidemiological threat

BackgroundIrregular migration across Central America and Mexico has increased in recent years, exposing migrants to various health risks, including vector-borne diseases such as leishmaniasis. The migration corridor from South America, through the Darien Gap, to northern Mexico traverses multiple leishmaniasis-endemic regions with active Leishmania spp. transmission, where environmental exposure during migrants transit may increase the risk of infection. Methodology / Principal FindingsFrom 2023 to 2025, clinical and epidemiological data were collected from 365 migrants transiting through Mexico, including a subset of individuals with clinical suspicion of cutaneous leishmaniasis (CL). Migrants were evaluated at two shelters in northern Mexico and at the Centro de Medicina Tropical (CMT) of the Universidad Nacional Autonoma de Mexico (UNAM). Diagnostic testing included serology and polymerase chain reaction (PCR) for species identification. Sociodemographic data, country of origin, and migration routes were documented. A complementary literature review was conducted to map the geographic distribution of sand fly vectors along migratory pathways. A total of 26 leishmaniasis clinical cases were identified, namely a 7.1% prevalence (95%-CI = 4.6-9.9%). Most individuals originated from Venezuela (n = 12), Honduras (n = 3), and Mexico (n = 3), with additional cases from Haiti and the Czech Republic. Six participants did not disclose their country of origin but reported traveling from South America. Polymerase chain reaction confirmed active infections with Leishmania (Viannia) panamensis (7 cases) and Leishmania (Viannia) braziliensis (1 case), both detected among Venezuelan migrants. Additional PCR-positive cases were classified within the Viannia subgenus. Conclusions/SignificanceThese findings underscore the urgent need for tailored surveillance strategies and integrated cross-border healthcare interventions to address migrant populations, who may also contribute to the introduction of Leishmania species into Mexico, including those belonging to the Viannia subgenus. The presence of competent sand fly vectors along migration routes heightens the risk of transmission to both migrants and local resident communities. Author SummaryLeishmaniasis is a neglected tropical disease transmitted by sand flies which remains a major public health concern in many parts of Mexico, Central, and South America. In recent years, irregular migration from South America to northern Mexico has increased, exposing migrants to endemic disease risks. Here, clinical and epidemiological data from migrants transiting Mexico between 2023 and 2025 were examined, and 26 cases of cutaneous leishmaniasis were identified. Species-level identification confirmed infections with L. (V.) panamensis and L. (V.) braziliensis, underscoring the importance of precise diagnosis to help guide treatment and clinical follow-up of migrants. The presence of competent sand fly vectors along migration routes further highlights the vulnerability of the migrant population. These findings emphasize the urgent need for active surveillance and integrated healthcare strategies to protect both migrant and local populations, while also considering social and ecological factors. Addressing leishmaniasis in an integrated context requires coordinated medical and educational interventions to prevent transmission, reduce disease burden, and support vulnerable communities.