Clinical and epidemiological characteristics of leptospirosis in patients under and over 5 years of age in primary health centers in the Peruvian Amazon, 2022–2024

Background Leptospirosis is an emerging zoonotic disease with high incidence in tropical regions such as the Peruvian Amazon. Although it affects individuals of all ages, knowledge about its clinical and epidemiological profile in children under 5 years remains limited. In this age group, leptospirosis may present with nonspecific manifestations, which may hinder timely recognition in primary care. Methodology We conducted a retrospective cross-sectional study using secondary data from medical records and epidemiological forms of MAT-confirmed leptospirosis cases evaluated between 2022 and 2024 at four primary health care centers in Belén, Loreto, Peru. A total of 2,325 patients with clinical suspicion of leptospirosis were evaluated during the study period, of whom 400 MAT-confirmed cases with sufficient information for analysis were included. Comparisons between patients under 5 years and those aged 5 years or older were exploratory. Results Among the 400 confirmed cases, 28 occurred in children under 5 years. In this age group, the most frequently recorded symptoms were malaise (78.6%) and fever (71.4%). Half of the children under 5 years lived in flood-prone areas, and 46.4% were evaluated within the first 3 days after symptom onset. Compared with older patients, children under 5 years more often showed nonspecific symptom profiles, whereas headaches and chills were less frequently recorded. Nutritional classification and selected symptom patterns also differed between age groups, although these comparisons were exploratory and based on a small pediatric sample. Conclusion In this series of MAT-confirmed leptospirosis cases managed at the primary health care centers, children under 5 years commonly presented with nonspecific symptoms such as malaise and fever. In an endemic Amazonian setting where multiple febrile illnesses coexist, this pattern may hinder early recognition. These findings support the need to strengthen clinical suspicion, diagnostic capacity, and epidemiological surveillance for pediatric leptospirosis in primary care. Further studies with larger pediatric samples are needed to better characterize age-related differences in presentation.