Abstract in English:

ABSTRACT Snakebite envenomations have a disproportionate burden in the Brazilian Amazon compared to other regions of Brazil. Studies conducted in the state of Amazonas show that Bothrops atrox snakebites are the most common, occurring in every municipality of the state. All the 62 municipalities in the state have at least one urban health unit that offers antivenom treatment. The most affected populations in terms of incidence and fatality rate are riverine communities and indigenous people, who have limited access to antivenom treatment. A significant proportion of cases are not reported to the official surveillance system, and many deaths occur due to lack of medical care. In the last decade, important advances have been made in research into snakebites in the state of Amazonas, in a collaborative network led by the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, a referral institution for patient care, teaching and research in tropical medicine. Findings on the burden of disease in vulnerable populations; clinical, therapeutic and pathophysiological aspects; long-term disabilities; barriers to antivenom treatment; and cultural aspects of snakebites, are presented in this paper. We highlight the findings of the SAVING Program, which aimed to implement a culturally tailored antivenom decentralization program in indigenous community-health centers. We conclude by presenting a priority research agenda for snakebites for the coming years in the Amazon region.

Abstract in English:

ABSTRACT Leprosy remains a major public health challenge in the state of Amazonas, Brazil, despite a remarkable 95.7% reduction in detection rates between 1981 and 2024. In 2024, 326 cases were reported, 80.4% of which were new diagnoses, predominantly multibacillary forms, with 9.3% presenting grade 2 disability on diagnosis. The continued occurrence of cases among children under 15 years of age (3.4%) indicates active transmission, particularly in geographically isolated municipalities. The Fundação Hospitalar Alfredo da Matta (FUHAM) serves as the main regional reference center, coordinating surveillance, diagnosis, rehabilitation and research activities. The decentralization of primary care and the integration of telehealth strategies have strengthened diagnostic capacity and improved the management of leprosy reactions. Historically, Amazonas has played a pivotal role in advancing scientific knowledge on leprosy, from early reports of dapsone resistance to participation in key clinical trials such as U-MDT/CT-BR, and studies on leprosy/HIV coinfection, immunopathogenesis and host genetic susceptibility (NOD2, IFNG, PKLR). More recently, genomic surveillance in the region has identified both classical and novel antimicrobial resistance mutations, consolidating Amazonas as a sentinel site for molecular monitoring. Persistent challenges include limited professional training, delayed diagnosis and ongoing social stigma. Research priorities for the next decade include strengthening active case detection, validating simplified diagnostic algorithms, expanding antimicrobial resistance monitoring, exploring genetic determinants of susceptibility and adopting One Health approaches to understand environmental and zoonotic transmission. These integrated strategies are crucial to sustain progress toward the elimination of leprosy as a public health problem in the Amazonian context.

Abstract in English:

ABSTRACT The Amazon Basin is undergoing rapid climatic and environmental changes, with direct impacts on infectious disease transmission and public health. Rising temperatures, altered rainfall patterns, and more frequent extreme events are reshaping vector and pathogen dynamics. Additionally, deforestation and land-use change increase human and animal exposure. These combined factors intensify the risk of disease transmission in the region. This narrative review synthesizes evidence generated by researchers from a reference center in tropical medicine in the Amazon, integrating epidemiological analyses, experimental studies, ecological and predictive modelling, and health systems research conducted over the past decade. The evidence indicates that temperature and hydrological variability affect vector competence, pathogen development, and host-vector contact rates, producing nonlinear and context-dependent transmission outcomes. Extreme hydroclimatic events additionally disrupt healthcare delivery, hinder surveillance, and compromise continuity of care for infections requiring sustained treatment, such as tuberculosis and HIV. Emerging advances, including species distribution modelling, remote sensing, and integrated climate-epidemiological surveillance, provide predictive capacity to anticipate outbreaks and identify emerging hotspots. However, substantial research gaps persist, particularly regarding multi-stressor interactions, mechanistic pathways of climate-pathogen-vector adaptation, and health system resilience under climatic extremes. From the perspective of a reference center that integrates education, research, and healthcare delivery in tropical medicine, this article articulates a research agenda for climate-informed tropical medicine, highlighting priorities for interdisciplinary research, surveillance innovation, and adaptive public health strategies in the Amazon and other climate-sensitive regions.

Abstract in English:

ABSTRACT Scorpion sting envenomations impose an increasing burden in the Amazon and result in a considerable impact on public health. The genus Tityus accounts for nearly all clinically relevant cases, with T. metuendus, T. silvestris and T. obscurus being responsible for most of envenomations in the region. In the state of Amazonas, Manaus and Apuí account for most of cases reported, with an evident expansion to other regions, including the Solimões River region and the Upper Negro River region, where most of the exposed population is found in Indigenous and riverine communities. The increasing burden and high severity rates of scorpion stings in the Amazon may result from the capacity of adaptation of the endemic species to the environmental changes and limitations in providing adequate healthcare to patients. The clinical profile of patients stung by different species has similar local and systemic manifestations. In Manaus, T. metuendus is the species that is most commonly responsible for severe cases observed in children, due to them presenting circulatory collapse and acute respiratory distress, while T. apiacas and T. silvestris present systemic neurological manifestations, characterized by generalized muscle spasms described as the sensation of receiving an electric shock, apparently not reversed by the available antivenom. Scorpionism in the Amazon combines the biological complexity and variability of Tityus species and their venoms, social and environmental determinants and healthcare challenges. These features require solutions of interinstitutional, interdisciplinary networks that are capable of integrating biology, venomics, clinical medicine, public health, environmental sciences and the social sciences.

Abstract in English:

ABSTRACT Hepatitis B and D display a distinctive epidemiological pattern in the Western Amazon, disproportionately affecting Indigenous peoples and riverine populations across Brazil, Peru, Colombia, Venezuela, and Ecuador. Despite more than three decades of universal hepatitis B vaccination, moderate endemicity and a high burden of chronic carriers persist in the region. In the state of Amazonas, Brazil, the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD) has played a pivotal historical and contemporary role in the recognition, diagnosis, clinical management, surveillance, and research of HBV and HDV infections, serving as a major reference center for the region. The local health-care network is aligned with national policies but faces substantial challenges related to the vast geographic territory, strong centralization of specialized services in Manaus, and limited availability of trained professionals in endemic and remote areas. Logistical, socioeconomic, and cultural barriers continue to restrict timely access to diagnosis and treatment, while universal vaccination, widespread rapid testing, and ongoing decentralization efforts represent key facilitating factors. Looking ahead, the proposed research agenda emphasizes integrated surveillance, genomic and clinical-epidemiological studies, evaluation of the care cascade, and strengthening of primary health care as essential strategies to reduce regional inequalities and accelerate progress toward the elimination of viral hepatitis by 2030.

Abstract in English:

ABSTRACT This narrative review examines how interdisciplinary and participatory research has advanced the understanding and control of socially determined diseases in the Brazilian Amazon. The integration of social sciences into the Tropical Medicine Foundation Dr. Heitor Vieira Dourado marks a shift from purely biomedical approaches toward those recognizing the cultural, environmental and territorial dimensions of health. Qualitative studies on snakebite envenoming among Indigenous populations revealed that treatment integrates biomedical and spiritual practices, highlighting the need for intercultural dialogue. In malaria elimination, research emphasized evaluating the acceptability and feasibility of new tools such as point-of-care G6PD testing and single-dose tafenoquine, demonstrating that understanding perceptions of innovations is indispensable for effective implementation. Studies on human immunodeficiency virus (HIV) prevention and trachoma among Indigenous and urban populations illustrated how stigma, gender relations and structural inequalities shape health outcomes. Extreme climate events, such as the 2023 Amazon drought, exacerbate vulnerabilities by disrupting livelihoods and healthcare access. The article concludes by proposing an interdisciplinary research agenda aligned with Brazil's Healthy Brazil Program, emphasizing community engagement, intersectional analysis, One Health integration and implementation science as key strategies for equitable disease elimination in the Amazon.

Abstract in English:

ABSTRACT Malaria continues to be a major public health issue in the Brazilian Amazon, with the state of Amazonas accounting for approximately 40% of all national cases. The region presents diverse epidemiological scenarios and different infrastructure conditions, which hinder the implementation of diagnostic, treatment, management, and control strategies. Through dedicated control, surveillance and research initiatives, considerable progress has been made in reducing the incidence of cases, hospitalizations and deaths attributed to the two endemic protozoan species, Plasmodium falciparum and Plasmodium vivax. This article provides an overview of the key research and surveillance endeavors undertaken in the state of Amazonas. These efforts aim to achieve the objectives outlined in the national malaria elimination plan, enhance the understanding of the disease’s pathophysiology and associated comorbidities, and leverage the advances and contributions of research groups within the state, which are focused on comprehending vector behavior and developing effective control strategies, creating more efficient diagnostic tools and researching and developing safe and effective drugs for treatment, relapse prevention and the elimination of transmission reservoirs.

Abstract in English:

ABSTRACT American tegumentary leishmaniasis (ATL) remains a significant public health problem in the Americas, with the Amazon region standing out in Brazil for its high number of cases. This article aimed to present advances in the understanding of epidemiology, diagnosis, treatment and control of ATL in the state of Amazonas over the past decades. This study is a narrative review of scientific studies published in the literature between 2011 and 2025, retrieved from databases such as PubMed and SciELO, as well as public data from the Notifiable Diseases Information System (SINAN), official reports from the Ministry of Health and technical notes from the Amazonas Health Surveillance Foundation. The evolution of disease incidence is reported, highlighting the predominance of Leishmania (Viannia) guyanensis and the environmental factors associated with the increase in cases, such as deforestation and unplanned urbanization. Advances in diagnostic strategies include the expanded use of molecular techniques and the strengthening of the primary healthcare network. Regarding therapy, clinical trials with drugs such as pentamidine, miltefosine, tamoxifen and itraconazole have demonstrated their efficacy in treatment. The review also includes socio-environmental, genetic and experimental studies that have contributed to a better understanding of the disease. It emphasizes the need to establish a priority agenda that includes the use of telemedicine and the institutionalization of collaborative research for therapeutic innovation, integration between research and healthcare services and strategies adapted to the Amazonian context. Regional scientific advances can support more effective control policies and reduce the burden of ATL in this highly endemic setting.

Abstract in English:

ABSTRACT Background: Arboviral infections continue to be a significant public health challenge in the Brazilian Amazon. Overlapping symptoms, limited laboratory access, and the circulation of multiple arboviruses hamper clinical diagnosis. This study aimed to characterize the epidemiological, clinical, laboratory and genomic profiles of arboviral infections in febrile patients in Manaus, Brazil, and explore additional viral agents using metagenomic sequencing. Methods: A cross-sectional study was conducted between February 2021 and February 2023 at a tertiary reference center in Manaus, Brazil. Patients aged ≥ 5 years of age presenting with a rash and either a fever or a history of fever lasting <7 days and a negative thick blood smear for malaria were enrolled. Serum samples were tested for dengue virus (DENV), Zika virus (ZIKV), Chikungunya virus (CHIKV), yellow fever virus (YF), Oropouche virus (OROV), and Mayaro virus (MAYV) using ELISA and RT-qPCR. Positive samples were subjected to amplicon-based genome sequencing for phylogenetic analysis. A subset of RT-qPCR negative samples was analyzed using de novo shotgun metagenomic sequencing. Results: Among the 708 enrolled participants, 243 (34.3%) had a laboratory-confirmed arboviral infection: 92 (37.9%) DENV, 64 (26.3%) CHIKV, and 4 (1.6%) ZIKV, while 83 (34.2%) laboratory profiles were compatible with coinfection, predominantly DENV+CHIKV (55/83; 66.3%). Circulation of DENV-1 genotype V and DENV-2 genotypes III (Asian American) and II (Cosmopolitan) was identified. Metagenomic analysis of 35 samples detected Pegivirus hominis and Erythroparvovirus primate 1. Conclusions: These findings demonstrate complex arbovirus co-circulation in Manaus and support integrated surveillance strategies combining molecular, serological, and genomic approaches.

Abstract in English:

ABSTRACT Background: Infectious and parasitic diseases remain a significant cause of mortality in the state of Amazonas, and are shaped by structural, environmental, and social vulnerabilities. Methods: This descriptive, population-based study examines the temporal evolution and spatial distribution of mortality caused by infectious disease in Amazonas between 2013 and 2024. We analyzed monthly mortality rates using data from the Mortality Information System (SIM), focusing on International Classification of Diseases, 10th Revision (ICD-10) Chapter I (A00-B99) and selected codes from Chapter X (J09-J18). Results: Despite initial stability (2013-2018), mortality rates increased markedly from 2019 to 2021, associated with the direct and indirect impacts of the Coronavirus Disease (Covid-19) pandemic. After 2022, rates stabilized but remained elevated, indicating a shift toward a new endemic level. Spatial analysis revealed a persistent concentration of deaths in metropolitan areas and riverine municipalities, with recent expansion into medium-sized towns of the interior. Pneumonia, human immunodeficiency virus / acquired immunodeficiency syndrome (HIV/AIDS), septicemia, and tuberculosis accounted for most deaths, with a predominance of older adults and people identified as mixed race or Indigenous. High proportions of ill-defined causes and non-specific diagnoses, particularly in pneumonia and sepsis, highlight diagnostic limitations and the urgent need to strengthen death investigation services and expand etiological investigation. Conclusions: Our findings highlight persistent inequalities in health access and call for integrated public health strategies, including improved surveillance systems, expanded diagnostic capacity, and intersectoral approaches adapted to the Amazonian context.

Abstract in English:

ABSTRACT Background: Tuberculosis (TB) remains a major public health challenge in Brazil, particularly in the state of Amazonas, where geographic, socioeconomic, and health system barriers hinder the implementation of TB preventive treatment (TPT). This study describes the scale-up of TPT, supported by integrated actions across surveillance, health services, and academia in this high-burden setting. Methods: We conducted a retrospective implementation analysis of TPT in Amazonas, Brazil (2016-2024), using data from the IL-TB system, SINAN-TB, and HIV/AIDS Clinical Monitoring Panel. A structured set of indicators was used to assess TPT delivery, decentralization, diagnostic practices, regimen uptake, and treatment outcomes. Proportions and rates were estimated with 95% confidence intervals (95% CI). Results: A total of 8,120 individuals initiated TPT, including 5,001 TB contacts, whereas more than 70,000 contacts were recorded in the SINAN-TB. Following the IL-TB implementation in 2019, the indicators showed a sustained expansion of TPT delivery. By 2024, TPT initiation among contacts reached 18.4% (95% CI: 17.6-19.3), and 959 PLHIV initiated TPT, corresponding to 441.33 per 1,000 antiretroviral therapy. The proportion of TPT initiation in primary health care increased from 19.3% (95% CI: 13.8-26.4) in 2018 to 55.2% (95% CI: 53.3-57.1) in 2024. Use of 3HP (weekly rifapentine plus isoniazid for three months) rose from 12.7% (95% CI: 10.6-15.1) in 2021 to 93.3% (95% CI: 92.3-94.2) in 2024. Completion reached 84.8% (95% CI: 82.9-86.6) and remained above 80% thereafter. Conclusions: TPT scale-up in Amazonas was accompanied by expanded access, greater decentralization, and rapid adoption of shortened regimens, although important coverage gaps among priority populations remain.