Amazon environment sharing featuring humans - dogs - capybaras and more. Adapting a one-health approach to leptospirosis prevention in Indigenous riverine communities in Ecuador and beyond

Dear Editor,

Leptospirosis is endemic yet chronically under-detected in Ecuador. A century-spanning national review reports transmission across all ecoregions, involving nine Leptospira species and more than 250 serovars, with outbreaks peaking during rainfall and El Niño–Southern Oscillation events [1]. Diagnosis still largely depends on the Microscopic Agglutination Test (MAT), and national surveillance and diagnostic approaches remain incomplete, contributing to underestimation of the true burden in the Amazon. Against this backdrop, recent correspondence described a lethal outbreak among Achuar children in Taisha (Morona-Santiago) with at least 46 symptomatic cases, eight deaths, a 17.4 % case fatality, and 29.8 per 100 000 mortality (nearly 600 × the long-term national average); arising at the intersection of remoteness, delayed access to care, and environmental exposure [2]. In early May 2025, our team responded to an emergency call from the Achuar village of Mashuim (Taisha, Morona-Santiago, Ecuador) after the deaths of four children over two months (two within the preceding week) (Fig. 1a, Fig. 1b). Two presented with bloody diarrhea, jaundice and acute renal failure; heavy rainfall had occurred around 48 h before symptom onset. Extreme isolation, river-dependent access, and lack of rapid diagnostics meant burials occurred before clinical intervention could be provided.

Fig. 1a.

Map of the region.

Fig. 1b.

Overview map.

Beyond commensal rats, two reservoirs plausibly sustain exposure at Taisha's river–forest–settlement edge. First, peridomestic, free-ranging dogs in neighboring Indigenous Amazon communities show very high active shedding of pathogenic Leptospira spp. - 94.7 % of urine samples were qPCR-positive, with L. noguchii, L. santarosai, and L. interrogans identified -positioning dogs as a bridge between sylvatic hosts and household spaces where children play and fetch water [3]. Second, semi-aquatic capybaras (Hydrochoerus hydrochaeris) in the western Amazon (Rio Branco) exhibit chronic infection – with a MAT seropositivity of approx. 44 % with generally low titres – and approx. 32 % PCR-positive urine and isolates belonging to serogroups Icterohaemorrhagiae, Grippotyphosa, Shermani from rural and peri-urban sites, consistent with sustained environmental shedding in the creeks and backwaters used for bathing and cooking [4]. Capybaras regularly occupy human-used shorelines, bringing people within metres of their natural latrines, haul-outs, and foraging edges where dogs also congregate.

These convergences reinforce why capybaras remain an underrepresented - but epidemiologically and clinically important - reservoir in Amazon leptospirosis risk frameworks that emphasize shared shorelines and post-rain floodplains.

Environmental conditions intensify these convergences: warm, humid waters and soils sustain leptospires, and flood pulses rapidly distribute contamination along riverbanks and through settlements, collapsing spatial separation between human and animal zones. In villages like Mashuim, capybaras occupy the same shorelines where families bathe and draw water. This reciprocal, overlapping use of aquatic spaces—where household and forest boundaries effectively vanish—may be described as ‘Amazon environment sharing’. It is not a generic zoonotic-exposure pattern but rather an anthropogenically intensified ecological convergence: flood pulses and climate variability compress the distance between reservoir hosts and vulnerable populations, erasing buffers that once separated them. Prevention must therefore be watershed-aware and interface-focused—planned at the creek-and-floodplain scale, targeted to precise human–animal–water contact points (bathing steps, fish-cleaning rocks, boat landings, child shallows), not confined to household hygiene alone. In this context, three Indigenous-led One Health priorities follow. First, Achuar health promoters should serve as primary responders and co-investigators, as shown during the COVID-19 response when empowered with resources and decision authority. Second, integrated, rainfall-linked molecular surveillance should concurrently sample humans, peridomestic dogs, small mammals, and key water points using portable qPCR or LAMP assays—protocols already piloted during Ecuadorian outbreaks and feasible in remote settings [5]. Third, immediate, culturally adapted risk-reduction should focus on shared nodes: establishing animal-excluded safe-water points, adding brush or bamboo barriers at intakes, tethering dogs near creeks at night, promoting the use of shoes, and implementing community protocols for carcass handling during suspected outbreaks. Participatory, community-owned mapping of water-use sites and capybara haul-outs, targeted messaging and low-cost engineering fixes should be encouraged —without imposing incongruent solutions.

Pre-positioning of first-line antibiotics, point-of-care tests for organ function, and solar/hand-crank communication, together with evacuation routes co-designed with communities, is time-critical. Where hospital care is separated by long river journeys, survival often depends on early, protocolized actions led by trained local health workers. An environment-sharing lens directs scarce resources to high-yield interfaces—shared water points where human activity and animal presence converge. These considerations complement the recent spotlight on syndemic inequities [2]. Emphasis should shift from description to place-based prevention: in Indigenous riverine territories, the decisive ground is the shared environment. Aligning surveillance, treatment readiness, and simple environmental protections at these interfaces—under Indigenous leadership—offers a practical route to reducing preventable deaths among rainforest children. Finally, the presence of bloody diarrhea in some children, a symptom atypical of leptospirosis, suggests another pathogen may have been involved.

CRediT authorship contribution statement

Jacob van der Ende: Writing – review & editing, Writing – original draft, Visualization, Investigation, Data curation, Conceptualization. Jacob M. Bezemer: Writing – review & editing, Investigation. Thomas Hanscheid: Writing – review & editing, Supervision, Methodology. Martin P. Grobusch: Writing – review & editing, Writing – original draft, Validation, Supervision, Resources. Gabriel Trueba: Writing – review & editing, Supervision.

Funding

Emergency visit support: Tiyua Uyunkar (Prefect of Morona Santiago), Hospital San Miguel (Quina Care Foundation), and Shell Hospital (Fundación Misión Cristiana de Salud).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.