Work

Presence of Dengue Virus NS1 antigen and IgM and IgG antibodies in asymptomatic individuals in Ecuadorian Amazonia - a descriptive repeated cross-sectional community-based survey

Year: 2026

Type: article

Abstract: Background: As malaria approaches elimination in Ecuadorian Amazonia, dengue virus (DENV) has emerged as the dominant vector-borne disease. A recent study documented circulation of DENV in the Putumayo northern border region, but could not determine whether transmission extended beyond road-connected areas into remote riverine communities. We conducted a community-based assessment to quantify dengue virus transmission across an urban-riverine gradient. Methods: This repeated cross-sectional community-based survey screened in total 293 asymptomatic individuals in four communities with, in total, an estimated 4.240 inhabitants along the Putumayo River during the 2023 rainy season. Participants were tested using an NS1/IgM/IgG combination rapid diagnostic test. Acute or recent infection was defined as NS1 and/or IgM positivity; past exposure as IgG-only positivity. Results: Overall, 8.5% (25/293) of asymptomatic participants had acute or recent DENV infection, and 28.7% (84/293) showed any serological evidence of exposure. The road-connected hub Puerto El Carmen had the highest total prevalence (50.9%), predominantly representing past infection (IgG-only: 42.5%). In contrast, remote riverine communities showed lower overall exposure but a higher proportion of acute/recent infections among positives-reaching 60% in Puerto Rodríguez-suggesting recent viral introduction into immunologically naïve populations. Conclusions: Dengue virus transmission in the Putumayo Amazonia region extends beyond hospital-detected cases into river-access-only communities. The inverted ratio of acute-to-past infection between urban and riverine settlements suggests source-sink dynamics with ongoing viral movement along fluvial networks. As malaria elimination progresses, integrated arboviral surveillance incorporating community-based RDT screening and field laboratories is essential to detect emerging viral transmission invisible to facility-based systems.

Source: New Microbes and New Infections

DOI: 10.1016/j.nmni.2026.101728

Authors: Jacob van der Ende, M. Vanessa Davila, Josefina Coloma, Henk Schallig, Thomas Hanscheid, Martin P. Grobusch