A first insight into the diversity of pathogenic Leptospira serogroups in human cases from Ecuador

With an estimated global incidence of nearly one million cases and nearly 60,000 associated deaths annually, leptospirosis is recognized as one of the most widespread zoonotic diseases worldwide. In Latin America, leptospirosis remains endemic and neglected, with recurrent outbreaks linked to climatic variability, flooding, and close human-animal-environment interactions. In this region, Brazil, Peru, Colombia, and Ecuador account for nearly 80% of leptospirosis reported cases. Despite advances in molecular diagnostics and species-level identification, serogroups remain central to leptospirosis epidemiology because they often exhibit preferential associations with specific animal hosts and geographic patterns making them useful indicators for inferring transmission pathways. However, the information about the Leptospira serogroups circulating in human cases in Ecuador is not available. In this study, we report for the first time the Leptospira pathogenic serogroups prevalence and diversity in human from cases diagnosed at the National Reference Center for Zoonoses of Ecuador. A total of 371 febrile patients suspected of leptospirosis were analyzed by microagglutination test, and 121 (32.6%) were positive and reported as human leptospirosis cases by the Ministry of Health. Without excluding potential cross-reactivity, a total of 14 Leptospira serogroups were identified, the most frequently detected been Bataviae (13.5%; 95% CI: 10.2-17.4), Sejroe (9.4%; 95% CI: 6.7-12.9), and Grippotyphosa (5.7%; 95% CI: 3.5-8.5). Comparison with published reports of Leptospira serogroups circulation in animal species in Ecuador revealed broad overlap between human serogroups and those detected in local animal reservoirs, underscoring the urgent need to address leptospirosis surveillance and control in Ecuador from a One Health perspective.