Acta Tropica

A field trial was conducted using 10% lambda-cyhalothrin microcapsule suspension to provide a method for killing ticks and preventing diseases in outdoor gatherings of people or temporary resettlement places after disasters. In this study, three field experimental sites were selected, and each experimental site was set up with a test area and a control area. Before pesticide application, the tick density in three test areas and three control areas was surveyed using the flagging method. Subsequently, two methods were used for pesticide spraying: motorized fogging and electric constant-volume spraying (with the pesticide diluted 300 times). The relative density decline rate of ticks was calculated in three test sites on days 1, 7, 14, 21, and 28 after spraying, and all experimental areas achieved good tick-killing effects. Even without prohibiting wild animals, grazing sheep, and dogs (which are often infested with ticks and not treated) from entering the trial sites, spraying 10% lambda-cyhalothrin microcapsule suspension could maintain a tick-free (low-density) state for approximately 3-4 weeks. Our study provides an idea for controlling epidemics through tick elimination during the high incidence period of tick-borne diseases.

Background: Dengue is a major public health problem in Brazil, and Minas Gerais is one of the states with the highest burden. In January 2019, the Brumadinho dam collapse released about 12 million cubic meters of iron ore tailings into the Paraopeba River basin, causing environmental disturbance that could plausibly affect vector habitats and dengue transmission. We evaluated the spatiotemporal dynamics of dengue in Minas Gerais from 2014 to 2023 and tested whether the disaster was associated with changes in affected municipalities. Methods: We performed an ecological spatiotemporal analysis using dengue notifications from SINAN for all municipalities in Minas Gerais (2014-2023). Municipalities were classified as Paraopeba basin, regional controls, or state controls. Temporal similarity was assessed using Pearson correlation-based hierarchical clustering and non-metric multidimensional scaling (NMDS). Sources of variation were examined with PERMANOVA and principal component analysis (PCA). A linear mixed-effects model with municipality as a random effect was used to test changes after 2019, with pre/post contrasts estimated from marginal means. Results: Dengue showed strong temporal synchrony across the state, with major epidemic peaks in 2015-2016, 2019, and 2023. Health region explained 31.5% of the variation in temporal incidence profiles (p = 0.001), whereas Paraopeba basin status explained no significant variation (p = 0.998). No temporal cluster was enriched for municipalities in the Paraopeba basin. PCA identified 2023, 2019, and 2016 as the main years driving variability. In the mixed model, year was significant (p < 0.001), but Paraopeba basin status and its interaction with time were not. Incidence increased significantly after 2019 in non-exposed municipalities (p < 0.001), but not in basin municipalities (p = 0.088). Conclusions: Dengue dynamics in Minas Gerais were driven mainly by regional and state-wide epidemic processes, with no significant independent effect of the Brumadinho dam collapse on notified dengue patterns.

Dengue transmission is strongly influenced by climatic conditions that affect mosquito population dynamics and virus circulation. In Southern Brazil, where dengue historically occurred at low levels, recent climatic anomalies may be contributing to the expansion of Aedes vectors and an increase in local dengue incidence. This study investigated the spatiotemporal association between climatic variables, Aedes mosquito infestation and dengue cases in Porto Alegre (Southern Brazil, 2018 to 2025). Entomological, surveillance and climatic data were analyzed using Morans I and LISA for spatial association, Kendall correlation, polynomial regression and LASSO to identify relevant drivers and develop predictive models of mosquito infestation and dengue incidence. A strong spatial association between Aedes aegypti and Aedes albopictus was observed, with persistent local clusters detected across all years. Annual climatic variables were associated with mosquito abundance in several districts. Overall, rainfall frequency had a stronger effect on Aedes aegypti abundance than accumulated rainfall. Temperature and lagged infestation indices showed strong association with both species and dengue incidence, with effects observed up to four weeks prior. Predictive models demonstrated good agreement between observed and predicted values, particularly within low to moderate infestation levels. Lagged variables were consistently retained in both mosquito infestation abundance and dengue incidence models, highlighting the importance of temporal predictors for anticipating vector dynamics and dengue risk. This approach is generally applicable for predicting Aedes infestation and disease incidence and emphasizes the importance of integrating entomological and climatic surveillance data to improve anticipation and detection of dengue risk periods and support more effective public health interventions.

Some Anopheles species that act as malaria vectors are members of species complexes, a concept whereby sibling species cannot be differentiated solely on the basis of morphological characters. Therefore, species complexes represent a major problem in malaria vector control, because within an Anopheles complex, vectors cannot be differentiated from non-vector species, unless molecular techniques are used to identify them. The Anopheles tessellatus species complex is an important potential vector in South, East, and Southeast Asia, including certain regions of Indonesia. However, no in-depth studies have been conducted on this species complex in that country. Therefore, this study investigated the taxonomic status of An. tessellatus from diverse populations across five Indonesian islands (Sumatra, Java, West Nusa Tenggara, East Nusa Tenggara, and Sulawesi) and identified interpopulation genetic variation based on molecular data of the ITS2, COI, and COII genes. Phylogenetic relationships were constructed using the Maximum Likelihood method. Haplotype and network analysis were also conducted. The results indicate that An. tessellatus constitutes a monophyletic group comprising three well-defined lineages that exhibit clear intraspecific genetic differentiation. Cluster 1 corresponds to the population of Sumatra, Cluster 2 represents population from Sulawesi, and Cluster 3 encompasses populations from Java, West Nusa Tenggara, and East Nusa Tenggara. These findings demonstrate high haplotype diversity and low nucleotide diversity within the species. Populations from West Sumatra, Manado, Tojo Una - Una, and North Morowali (Sulawesi) have the potential for speciation with a genetic distance of 0.61 - 0.94% for COI, between 0.81 - 0.95% for ITS2, and between 0.62 - 0.71% for COII. These findings underscore the need for further integrative studies to obtain a more comprehensive understanding of the An. tessellatus complex in Indonesia and its role in malaria transmission.

Urbanization in the 21st century has given rise to complex socio-environmental landscapes that contribute to spatial inequalities in health, particularly in the context of emerging infectious diseases, such as dengue fever. This study employs an urban systems framework to explore the multi-dimensional drivers of dengue risk in Ibague, Colombia, where Aedes mosquitoes thrive in diverse urban environments. We characterized the biophysical, socio-economic, and institutional properties of the urban landscape and employed hierarchical cluster analysis to define urban typologies at both census block and urban section levels. Our findings reveal significant differences in dengue incidence across these typologies, with higher rates associated with areas of high population density and commercial activity. Additionally, we examined the landscape configuration and its role in shaping dengue risk, identifying that diversity and intermixing of typologies had protective effects against dengue incidence. This research underscores the importance of considering multi-scale, socio-ecological factors in dengue risk assessments and highlights the need for targeted public health interventions that address the complex interactions within urban landscapes.

Anopheles albimanus (Nyssorhynchus) is featured as the main malaria vector on Hispaniola. However, five other Anopheles species have been reported circulating in the area; four of them belonging to the subgenus Anopheles (An. crucians, An. grabhamii, An. pseudopunctipennis, and An. vestitipennis) and another one to the Nyssorhynchus subgenus (An. argyritarsis). Previous studies on mosquitoes in the genus Anopheles have identified and characterized peptides from immunogenic salivary proteins, with several of these peptides being unique to the Nyssorhynchus and Anopheles subgenera. This underscores their potential use as biomarkers for differentiating exposure to Anopheles mosquitoes in both the Old World and New World. Since both Nyssorhynchus and Anopheles subgenera have been reported in Haiti, a series of ELISAs were conducted to quantify IgG antibody titers against three published antigenic anopheline salivary peptides (gSG6-P1, Peroxi-P3, and Apy-2) in 348 participants registered in Haitis multi-partner/multidisciplinary Malaria Zero Program. This study aimed to evaluate the intensity of human-vector contact with Anopheles from both subgenera in Grand Anse, Haiti. In addition, the study measured antibodies against a panel of Plasmodium falciparum antigens to determine any association between anti-parasite and anti-peptide antibodies. Significantly elevated IgG responses to Peroxi-P3 in comparison to Apy2 and gSG6-P1 in the total study population (p < 0.001) were observed. Additionally, immune responses to Peroxi-P3 and gSG6-P1 differed significantly between [&le;]18-year-olds and >18-year-olds (p = 0.004 and p = 0.002), whereas no sex-based differences were observed for any peptide. Correlation analyses observed a greater number of significant positive associations in immune response between gSG6-P1 and Plasmodium antigens than any other salivary peptide, an occurrence which was more pronounced in [&le;]18-year-olds than >18-year-olds. A marked reduction in IgG responses to Apy2 and Peroxi-P3, but not gSG6-P1, among participants who kept a single household animal species compared with those who owned two or more species or those who did not have household animals was also demonstrated. Spatial analysis revealed heterogenous geographic overlap of high antibody responses among Peroxi-P3, Apy2, and gSG6-P1, alongside geographically overlapping clusters of low antibody responses to Peroxi-P3 and Apy2. These results provide additional data on the utility of anopheline salivary peptides to characterize human-vector-parasite exposure dynamics in low-transmission areas, such as Haiti.

BackgroundAnimal bites represent a significant public health concern due to the risk of injuries and transmission of zoonotic diseases such as Rabies, particularly in low and lower- middle-income countries (LMICs). Understanding the epidemiological characteristics of animal bite incidents is essential for improving the prevention and control strategies. This study aimed to characterize the epidemiological patterns and characteristics of animal bite cases in Sylhet, Bangladesh. Methodology/Principal findingsWe conducted a retrospective analysis of 6,565 animal bite cases reported between January 1 and December 31, 2024, in Sylhet, Bangladesh. Data on demographic characteristics, type of biting animal, site of bite, and exposure category were collected and analyzed to determine associations using correlation analyses and chi-square tests. Among the victims, 3,917 (60%) were male and 2,648 (40%) were female and young adults aged 20-39 years comprised the largest group (39% of cases). The majority of cases (88.1%) originated from urban areas within Sylhet City Corporation. Cats were the leading cause of bites (56.6%), followed by dogs (35.0%) and monkeys (7.5%), suggesting a shift from the traditional dog-dominated pattern. The most frequently affected anatomical sites were the legs (50.3%) and hands (40.9%). Most exposures were classified as World Health Organization (WHO) Category II (98.2%). Bite incidents showed moderate seasonal variation, with peaks in spring and early autumn. A significant declining temporal trend was observed for monkey bites (R = -0.59, p = 0.044), whereas cat and dog bite patterns remained relatively stable throughout the year. Significant associations were identified between bite site and age group, as well as between biting animal and demographic characteristics (p < 0.05). Conclusion/SignificanceThese findings highlight the epidemiological patterns of animal bites in Sylhet and emphasize the need for strengthened public awareness, surveillance, and preventive strategies to reduce animal bite incidents and associated zoonotic disease risks. SynnopsisO_LIA large-scale retrospective analysis of 6,565 animal bite cases revealed a cat-dominant bite pattern (56.6%), contrasting with the traditional dog-dominant paradigm in South Asia. C_LIO_LIYoung adults (20-39 years) and males (60%) were disproportionately affected, reflecting occupational and behavioral exposure risks. C_LIO_LIUrban residents (88.1%) accounted for the majority of cases, highlighting the growing public health burden of animal bites in rapidly urbanizing settings. C_LIO_LIThe most frequently affected anatomical sites were the legs (50.3%) and hands (40.9%). Bite incidents showed moderate seasonal variation, with peaks in spring and early autumn. C_LIO_LICategory II exposures (98.2%) predominated, indicating a high burden of seemingly minor injuries that may be underestimated in rabies prevention strategies. C_LI

BackgroundThe Hump-nosed pit viper is a recognized but neglected medically significant species causing morbidity and mortality, with non-availability of a specific antivenom. There are many gaps in our understanding of its envenomation, including burden, clinical syndrome, complications and management. MethodologyThe study is a retrospective sub analysis of the Prospective VENOMS registry and hospital records of Hump Nosed Pit Viper envenomation from a single tertiary care center in coastal Karnataka from May 2018 to March 2024. Epidemiology, syndrome, complications and treatment strategies have been described. A linear mixed model analysis was conducted to study the effect of different therapeutic interventions in combating venom induced consumptive coagulopathy (VICC) Principal FindingsOf 46 cases, 24 patients had VICC. The most common complications were AKI (21.7%), TMA (10.9%) and stroke (4.4%). Anaphylaxis to ASV (23.9%) was the most common therapeutic complication. Therapeutic interventions included ASV, administration of blood products and therapeutic plasma exchange along with supportive care. The linear mixed model revealed that administration of blood products (p=<0.001) had the strongest influence on the INR value, however, often resulting in a transient decline in INR value. ASV (p=0.052) caused only marginally significant change in INR. The role of TPE could not be statistically inferred, however, individual cases with severe VICC improved without complications, therefore it required further study but can be considered in critical cases. Conclusions/SignificanceThis study describes the syndrome of hump-nosed pit viper envenomation, while highlighting the urgent need for a species-specific antivenom, recommends treatment strategies that can be used in the interim. Additionally, geo-spatial mapping draws attention to hotspots and the hypothesis that HNPV in coastal Karnataka have regionally distinct toxicity trends. Author SummaryIndia is often known as the snakebite capital of the world, with recent literature suggesting that not all death and disability is attributable to the "Big four" and highlighting regionally significant species of snake. In the Western Ghat region of India, envenomation by the Hump-nosed pit viper is increasingly being reported. In coastal Karnataka, it has been reported as the second most common cause of envenomation following the Russells Viper, causing systemic envenomation and death. However, little is known about why envenomation is common in this region, is it increasing, how to diagnose envenomation, its clinical syndrome, the anticipated complications, and most importantly, an effective treatment strategy. This study reports envenomation in 46 patients, resulting in 3 deaths, and 24 patients developing derangement in coagulation parameters.

Accurate species identification is crucial to assess the medical and veterinary relevance of a mosquito specimen, but it requires high experience of the observers and well-equipped laboratories. This study aimed to evaluate whether low-cost imaging in combination with geometric wing morphometrics can provide accurate identification of invasive, morphologically similar Aedes species. The right wings of 670 female specimens covering 184 Ae. aegypti, 156 Ae. albopictus, 166 Ae. j. japonicus and 164 Ae. koreicus, were removed, mounted and photographed with a professional stereomicroscope (Olympus SZ61, Olympus, Tokyo, Japan) and a macro lens (Apexel-24XMH, Apexel, Shenzhen, China) attached to a smartphone. The coordinates of 18 landmarks on the vein crosses were digitalized by a single observer for each image. In addition, the landmarks of 20 specimens per species and imaging device were digitalized by six different observers to assess the degree of the observer error. The superimposed shape variables were used to compare the species classification accuracy of linear discriminant analysis (LDA), support vector machine (SVM), Random Forest (RF), and XGBoost. In the single-observer landmark data, the LDA achieved the best classification results with a mean accuracy of 95 % for landmarks from microscope images and 92 % for those obtained from smartphone images. In the multi-observer landmark data, LDA consistently performed worse than the other three classifiers, and the reduction in the accuracy was more pronounced for smartphone images than for microscope images. This pattern was associated with a higher degree of observer error for smartphone images, as confirmed by a landmark-wise comparison across all landmarks. Geometric wing morphometrics provides a reliable method to distinguish the most common invasive Aedes species in Europe. Thereby, the image quality obtained by smartphones equipped with a macro lens is sufficient and represents a cost-effective alternative to professional microscopes. However, due to the greater degree of observer variation for smartphone images, landmark coordinates for such images should ideally be collected by a single observer.

BackgroundMosquito-borne arboviruses present persistent public health threats in Mexico. Multiple vector species are often considered to influence the local transmission of arboviral diseases; however, the structure and spatial dynamics of mosquito-arbovirus associations are unknown. MethodsWe conducted a systematic review to synthesize research investigating natural arboviral infections across mosquito taxa. PRISMA-guided search was done in PubMed, Scopus, Web of Science and Google Scholar, resulting in 46 included articles from 2007 to 2025. To delineate mosquito-arbovirus associations, spatial autocorrelation, bipartite network analysis, generalized linear mixed models (GLMMs) and comparative analysis of infection across sex and life stages were used to resolve spatial dynamics, species-specific viral detection and maintenance profiles. ResultsMinimum Infection Rate (MIR) revealed significant positive spatial autocorrelation (Global Morans I = 0.139; p = 0.016), indicating structured but diffuse spatial patterns (Local Morans I = 0.092; p = 0.045). Sampling intensity negatively correlated with the MIR (Spearman {rho} = -0.680, p < 0.001), indicating that sampling effort did not obscure the spatial structure. Elevated values were observed in a few municipalities across south-central and southeastern Mexico, where vegetation and land use interface. Network analysis (connectance = 0.40) and GLMM characterized an Aedes-centered network with broader taxonomic patterns driven by ZIKV; detection was significantly higher in Culex quinquefasciatus (OR = 1.88, p < 0.001) relative to Aedes aegypti. DENV detection patterns contrasted with other key viruses; no significant differences in transmission modes ({chi}{superscript 2} = 1.01, p = 0.315), suggesting a distinct maintenance profile. ConclusionsThis review unveils spatially diffuse and virus-specific detection patterns across heterogeneous communities in Mexico, findings that transcend Aedes-centric frameworks. These resolutions provide an evidence-based baseline that encourages an integrated, community-scale approach in regional surveillance programs. AUTHOR SUMMARYMosquito-borne arboviruses continue to threaten human and animal health across Mexico. Previous research has investigated arboviral infections and mosquito fauna as separate entities, but not their associations. This systematic review aims to resolve the spatial structure and multi-species dynamics of mosquito-arbovirus associations. We synthesized a long-term dataset of mosquito-borne virus surveillance from academic articles. Spatial models determined if localized detections were random and/or clustered with hotspots. Network and mixed models estimated the likelihood of positive arbovirus detection in mosquito species and a comparison test quantified the influence of vertical transmission on viral maintenance. Arboviral infection rates showed a diffuse spatial pattern with elevated values across urban and interface settings. Aedes aegypti shaped the mosquito-arbovirus network as expected; however, Culex quinquefasciatus showed significantly higher odds of ZIKV detection, supporting broader surveillance. These findings clarify species-specific detection and maintenance profiles across mosquito taxa, informing improved and targeted control strategies for arboviral diseases in Mexico.

Astyanax Baird & Girard, 1854 is a widely distributed and species-rich genus of Acestrorhamphidae, whose abundant populations in Neotropical basins play a crucial ecological role at the trophic level. Taxonomic uncertainties persist within the genus, as seen in Astyanax sp. (formerly designated as A. fasciatus) from the Magdalena basin in Colombia. Concerns about its genetic status are heightened due to ecological threats posed by hydroelectric dams, from habitat loss to river connectivity. We isolated and characterized 17 microsatellite loci to assess the population genetics of this species in a broad sample from the middle and lower sections of the Cauca River, now interrupted by the Ituango dam. Furthermore, a multidisciplinary approach integrating phylogenetic analyses of mitochondrial (COI) and nuclear (rag2) markers with geometric morphometric analyses was employed to evaluate potential cryptic diversity within Astyanax sp. Microsatellites revealed two genetic groups in the studied area, strongly supported as distinct lineages by phylogenetic analyses. Unexpectedly, one of these lineages of Astyanax sp. was recovered in an unresolved clade with samples of A. microlepis and allopatric samples of A. viejita from the Maracaibo Lake basin. Each genetic group showed high genetic diversity, but also evidence of recent bottleneck events and significant-high values of inbreeding. Morphometric analyses provided evidence of significant phenotypic differentiation among A. microlepis, Astyanax sp. 1 (Asp1), and Astyanax sp. 2 (Asp2). Morphological patterns ranged from the robust profile of A. microlepis to the streamlined shape of Astyanax sp. 2 (Asp2), with Astyanax sp. 1 (Asp1) displaying intermediate traits and localized differences in head length and fin placement. Statistical support from permutation tests and a high overall classification accuracy (95.65%) underscore the existence of distinct morphospecies, suggesting that phenotypic differentiation is well-established, despite the complex evolutionary history of the group. This study suggests the presence of cryptic diversity within Astyanax sp. and provides valuable genetic information for the conservation and management of their populations in the Magdalena basin.

Despite the relevance of spatial mapping in analyzing the health situation and understanding the risk factors and determinants of leptospirosis, peripheral urban communities often remain invisible on maps, which tend to use data and methods that do not express community contribution nor promote local participation. Furthermore, in the implementation of sanitation interventions, the same happens: there is limited user participation, and a lack of identification of intervention needs based on the perception of community residents, failing the interventions. We conducted a cross-sectional study through collaborative mapping from February to October 2022 with 213 residents and self-declared heads-of-household in two peripheral urban communities. We analyzed the perception of sanitation needs indicated by residents and their relationship with the risk of leptospirosis in these communities. Based on community perception, sewage (NS: 87.1%; JSI/ME: 84.9%) and urban cleaning and solid waste management (NS: 25.9%; JSI/ME: 32.6%) were the sanitation needs. In NS, most participants indicated that the necessary interventions for sewage improvement were actions of sewer cleaning and sealing (26.5%), sewer cleaning and piping (23.5%), and implementation/installation/construction of a sanitary sewage network (41.4%). In JSI/ME, interventions included sewage sealing (48.7%) and piping (25.6%), in addition to actions to maintain sewage cleaning (93.3%). The removal of solid waste (trash) in the square (NS: 22.2%) and on the streets (JSI/ME: 69.2%), as well as community awareness (JSI/ME: 15.4%), were indicated as interventions to meet the needs of urban cleaning and solid waste management. Respondents agreed on where interventions should occur, which congregated around the local river. We found a negative correlation between the predicted leptospirosis seropositivity and perceived intervention needs in both study areas. The prevention of diseases such as leptospirosis in peripheral urban communities requires integrated basic sanitation interventions, encompassing different components and aligned with the local needs perceived by residents.

In wildlife forensic practice, species identification and estimation of the Minimum Number of Individuals (MNI) for highly processed specimens have long relied on weight-based conversion methods, which may result in underestimation of the number of individuals involved in a case. Focusing on confiscated casque products of the helmeted hornbill (Rhinoplax vigil), this study combines macroscopic morphological examination with mitochondrial DNA barcoding (16S rRNA, COI, and Cytb) to explore a more robust approach for individual quantification. The results demonstrate that the conventional "weight-based" approach overlooks critical biological information contained in anatomical structures and cannot accurately reflect the actual number of individuals involved. Based on this, we propose an anatomy-based criterion centered on the principle of structural uniqueness: specimens retaining biologically unique beak or casque structures should be directly assigned to a single individual, whereas weight-based estimation should only be applied when original anatomical features are entirely absent. In addition, considering material loss during processing, we propose approximately 85 g as a reference threshold for estimating the number of individuals in heavily processed solid casque products. This approach improves the scientific rigor and accuracy of forensic identification and provides reliable technical support for the conviction, sentencing, and law enforcement of wildlife trafficking cases involving helmeted hornbill and other endangered species.

Progress towards elimination of onchocerciasis transmission is evaluated using entomological and serological indicators. The latter assesses anti-Ov16 IgG4 seroprevalence in children aged <10 years. A seroprevalence of <0.1% suggests that ivermectin Mass Drug Administration (MDA) can be stopped and post-treatment surveillance initiated, according to World Health Organization (WHO) guidelines. Surveillance of populations living in close proximity to vector breeding sites and first-line villages may mask spatial transmission heterogeneity. We mapped anti-Ov16 seroprevalence within a 25-km radius around a known Simulium damnosum s.l. breeding site in Asubende, Ghana, to assess its spatial patterns and their implications for serosurveillance. A cross-sectional survey was conducted in September-November 2024 in 30 settlements. Individuals aged [&ge;]3 years were recruited through convenience sampling. The Ov16 rapid diagnostic test (RDT) using dry blood spots was used to estimate overall and site-level seroprevalence. Generalized additive models were used to assess seroprevalence trends versus distance from the breeding site. Among 2,479 participants with valid RDT results, overall seroprevalence was 10.0% (95% CI: 8.9%, 11.3%) and increased with age. Seroprevalence varied across sites (0-24.4%) and declined with increasing distance from the breeding site. Among 584 children <10 years old, seroprevalence was 1.5% (95% CI: 0.7%, 2.9%). Adjusting for RDT sensitivity and specificity, seroprevalence in this age-group was 0.7%, (95% CI: 0%, 2.4%). Seropositive children were detected up to 18 km from the breeding site, but none were identified at it. The distance-related decrease in overall seroprevalence is consistent with spatial patterns in vector abundance at Asubende and implies higher cumulative exposure near the breeding site. The small number of children tested limited inference in this WHO target age-group. Detection of seropositive children away from, but not at, the breeding site highlights limitations of surveillance focused on first-line villages and supports broader spatial sampling to strengthen evidence for stop-MDA decisions. Author summaryAfter decades of onchocerciasis control using ivermectin, many countries hope to demonstrate that they have interrupted transmission of this vector-borne parasitic disease using serological surveys. It is unclear whether exposure to infection is spatially clustered around the riverine breeding sites of the blackfly vectors and therefore whether this is where serosurveillance should focus. To address this, we collected dried blood spots from 2,480 consenting participants aged 3-96 years old from 29 communities within a 25-km radius of a known blackfly breeding site in Asubende, Ghana. A rapid diagnostic test was used to test the blood spots for antibodies to the Onchocerca volvulus parasite. We found that overall seropositivity declined with increasing distance from the breeding site, which suggests that cumulative exposure is higher near the breeding site, where vector population is also high. However, seropositivity in children (3-10-year-olds, n= 584), which is indicative of recent transmission, was spatially distributed across the study area and found up to 18 km from the breeding site. These findings are relevant to serosurveillance sampling strategies intended to detect low levels of transmission, which could miss peripheral evidence of ongoing transmission if they are focussed at breeding sites and those villages closest to them.

Human leptospirosis is a disease of public health importance in Thailand, but the animal species involved in the transmission cycle have not been fully uncovered. This study investigated Leptospira infection in dogs and terrestrial micromammals in rural Nan Province, Thailand, and the pathogen diversity. Sera from 95 seemingly healthy dogs and kidney samples from 399 micromammals were analyzed using real-time PCR for Leptospira detection, followed by conventional PCR and sequencing of infecting Leptospira. We investigated environmental factors associated with Leptospira infection in micromammals, using data collected during trapping. Real-time PCR revealed ongoing infection in 8.4% (8/95) of dogs and 10.0% (40/399) of terrestrial micromammals, with 12 infected species including Bandicota indica, Berylmys berdmorei, Berylmys bowersi, Mus cervicolor, Mus cookii, and Hylomys suillus. In this qPCR-positive micromammals, three pathogenic Leptospira species were identified: L. interrogans, L. weilii, and L. borgpetersenii. This represents the first confirmed detection of L. weilii in rodents in Thailand. Infected micromammals were found in agricultural and forest habitats but not in human settlements. Our study demonstrates potential complex leptospirosis epidemiology in rural Thailand, with multiple species serving as pathogenic Leptospira reservoirs across diverse habitats, and some shared pathogen diversity with human leptospirosis cases in Thailand. Free-roaming dogs may serve as bridge hosts, transmitting zoonotic Leptospira from micromammals to humans by visiting both animal habitats and human settlements. These findings emphasize the need for integrated One Health surveillance approaches to control leptospirosis in rural communities.

Introduction: Rickettsial infections are vector borne diseases and seroprevalence shows regional and population based variation. This prospective study assesses the seroprevalence and factors associated with rickettsial infections in different geographical regions of Northern Tamil Nadu, India. Methods: A community based cross sectional study was performed among 2565 individuals in five districts in Tamil Nadu who consented and provided 4 ml blood samples. A semistructured questionnaire was administered to gather information on sociodemographic and environmental parameters. The serum IgG antibodies to scrub typhus (ST), spotted fever (SF), murine typhus (MT) and Q fever (QF) were detected by ELISA and the optical density (OD) recorded. EpiData was used for data entry and SPSS for analysis. Results: The seroprevalence of ST, SF, MT and QF was 14%, 9.1%, 3.7%, and 5.7%, among the study population. For ST, age >35, people living in rural and <1000 MSL, farmers, sleeping on the floor, lack of toilet at home, and grass near the home were associated with higher risk. For SF, people living at 501 to 1000 MSL elevation, no toilet at home and having pet animal were associated with higher odds. Females, 46 to 55 and >65 years, people residing in urban areas and elevation upto 500 MSL, those who sleep on the floor, not changing clothes daily and with pet at home were associated with higher odds of MT. Whereas Q fever was more likely to affect who sleep directly on the floor, residing in urban and do not have pets. Conclusion: Scrub typhus is the most common rickettsial infection followed by spotted fever in Northern Tamil Nadu. Factors associated with prevalence vary for different rickettsial diseases and include personal and lifestyle behaviors. The findings of this study need to be verified by multicentre cohort studies.

There is an ongoing Oropouche Fever (OF) outbreak in Brazil since 2024. There are dengue and chikungunya prediction models available, but none to help discriminate dengue, chikungunya, and OF. ObjectiveThis study aims to develop and validate clinical prediction models for dengue, chikungunya, OF. MethodsThis study uses surveillance data from Espirito Santo state / Brazil, from 2023-2025. Epidemiological investigations and biological samples were used to conclude cases as either (a) clinical-epidemiologically confirmed, (b) laboratory confirmed, or (c) "discarded". The predictors were all data related to signs, symptoms, and comorbidities available in the notification forms. The analysis was performed using random forest regression models, one for each outcome, in development and validation datasets. ResultsA total of 465,280 observations were analyzed, 261,691 dengue cases (56.6%), 18,676 chikungunya cases (4.0%), 12,174 OF cases (2.6%), and 179,115 discarded cases (38.6%). All three models had good discrimination and moderate to good calibration after scaling prediction. The models retained from 26 to 16 predictors each. Leukopenia and vomiting were the most discriminatory predictors for dengue, arthritis, arthralgia, and rash were the most discriminatory for chikungunya, and epidemiological features were the most relevant for OF. The dengue, chikungunya, and OF models had ROC AUC of 0.726, 0.851, and 0.896 in the validation set, respectively. ConclusionThis research identified predictors most discriminative between dengue, chikungunya, and OF. We developed and validated predictive models, one for each condition, with moderate to very good performance available at https://pedrobrasil.shinyapps.io/INDWELL/. One may use them in diagnostic work-up and arbovirus surveillance. LAY SUMMARYO_LIDengue fever was by far the most common confirmed infection in the surveillance system (56.6%), followed by chikungunya cases (4.0%), oropouche cases (2.6%), zika cases (0.2%), with different seasonality. C_LIO_LIAlthough suspected dengue cases were more laboratory tested, laboratory confirmation was more frequent among oropouche fever cases. It was possible to develop and validate models for dengue, chikungunya, and oropouche diagnostic investigation, and their performance was from moderate to very good, with suggested decision limits to aid the users. All attempts to develop Zika models returned models with unacceptable performance. C_LIO_LIWe developed an instrument to predict the three conditions with the same predictors and made it available for users at https://pedrobrasil.shinyapps.io/INDWELL/. C_LI

O_LIRapid and ongoing anthropogenic habitat modification has the potential to alter the species composition, abundance and activity of biting insect communities, which are important disease vectors. The resulting changes in the network of interactions between biting insects and their hosts have implications for the transmission of vector-borne pathogens. C_LIO_LIWe used DNA metabarcoding of Diptera blood meals to document bipartite networks of interactions between biting flies (Diptera) and their hosts (including humans, domesticated and wild animals) across a gradient of anthropogenic habitat modification (village, agricultural and near-natural habitat) surrounding two rural villages in Ghana. C_LIO_LIWe collected 7,095 biting Diptera (of 42 species) from 30 collection sites, and generated sequencing data from 75 blood meals (from 29 species). These blood meals contained DNA from 18 vertebrate host species, dominated by humans and their livestock. C_LIO_LIHabitats with lower levels of anthropogenic modification had higher richness of biting Diptera and their host species. Species diversity and evenness did not differ significantly among habitats. Less modified habitats had higher network specificity, but connectance was highest in heavily modified habitats. C_LIO_LIHumans were highly embedded within biting Diptera-host networks, detected in 68% of blood meals. The networks reveal several potential disease transmission pathways linking competent vectors with susceptible hosts. The presence of mixed blood meals containing DNA of both human and wild animal origin highlights the potential for transmission of established and emerging zoonotic disease via bridge vectors. The high betweenness-centrality within interaction networks of the important disease vector Culex watti, combined with its high abundance across all levels of anthropogenic landscape modification, suggest that it may be a connector species, linking and facilitating disease transmission between spatially distinct communities. C_LIO_LISynthesis and applications: Our results are of epidemiological interest, as they identify the exposure of humans to pathogen transmission cycles across a gradient of anthropogenic habitat modification through the movement of opportunistic bridge vectors. We discuss the implications for the transmission of emerging and established zoonotic disease and for the targeting and implementation of initiatives to reduce disease exposure and transmission. C_LI

Successive dengue virus (DENV) outbreaks can progressively reshape population immunity influencing disease expression and diagnostic performance. Objectives The aim was to evaluate the impact of secondary infections across sequential outbreaks on clinical severity, serotype dynamics and diagnostic concordance. Methods This retrospective study analyzed 976 febrile-stage samples from three sequential outbreaks in Misiones, Argentina. For serotyping and clinical analyses, 869 viremic samples confirmed by at least one direct method were included (2016: n=512; 2019: n=148; 2024: n=209). Additionally, 318 samples, including 107 non-viremic cases, were used to compare NS1 rapid diagnostic tests (NS1 Ag) and RT-PCR. Viral serotyping and clinical and laboratory markers of disease severity were evaluated. Results Secondary infections increased from 31.05% (2016) to 43.24% (2019) and 53.87% (2024) (p<0.0010). Serotype distribution shifted from DENV-1 predominance in 2016 (95.12%), DENV-1/DENV-4 co-circulation in 2019 (60.71%/39.29%), and DENV-2 predominance in 2024 (97.60%). Secondary infections were associated with more severe disease manifestations, particularly in 2024, with higher hematocrit (p=0.0120) and hemoglobin (p=0.0080), lower white blood cells (p=0.020) and platelet counts (p=0.0030), and elevated AST (p=0.0007) and ALT (p=0.0130). Concordance between NS1 Ag and RT-PCR was lower in secondary infections (k=0.457 vs k=0.759, p=0.0013). Conclusions The rising frequency of secondary infections may affect both clinical severity and diagnostic performance during outbreaks. The clinical impact was more evident in 2024, likely associated with the introduction of a new serotype. These findings highlight the need for optimized surveillance and diagnostic strategies to improve case detection and patient management during epidemics.

In recent years, detection of local dengue cases in Florida have increased in both frequency and geographical extent. From 2022 to 2024, consecutive outbreaks in Miami-Dade County were mainly caused by a single lineage of dengue virus (DENV) serotype 3, prompting questions about changing epidemiology and a transition towards endemicity. In this study, we used mathematical modeling and genomic epidemiology to reveal the spatiotemporal dynamics and drivers of local dengue cases in Florida. We found that annual clusters and outbreaks were caused by frequent short-lived DENV introductions, primarily from the Caribbean, and did not find evidence for local trans-seasonal DENV lineage persistence. Further, we show that the climate-driven increases in local suitability for Aedes aegypti transmission and travel-associated cases were the greatest risk factors for outbreaks in Miami-Dade and the geographic expansion of dengue in Florida. Overall, while we do not yet find evidence for endemicity, we demonstrate how climatic trends are enhancing the local public health risk caused by dengue in Florida.