Yellow fever (YF) remains a significant public health threat in tropical regions, particularly in South America and Africa. The combined forces of climate change, land-use, urbanisation, globalisation, and insufficient surveillance and health infrastructure are driving the re-emergence and expansion of YF into new areas. While mathematical models have been used to estimate transmission risk, disease burden, and the impact of vaccination, there remains a crucial gap in mechanistic models that explicitly capture how climate and environmental changes directly influence YF transmission. To address this gap, we convened a workshop in Brazil as part of the Vaccine Impact Modelling Consortium’s Climate Change programme, bringing together national and international experts. The workshop aimed to present current modelling approaches, identify key knowledge gaps, and develop strategies to improve data collection and model applicability. Discussions highlighted major uncertainties regarding vectors, non-human primates, surveillance sensitivity, vaccination, and climatic and environmental drivers. This paper synthesises the outcomes of the workshop, including priority areas for future research and recommendations for advancing mechanistic YF modelling in the context of climate change, with a focus on both Brazil and broader tropical regions.

A febre amarela, doença viral causada por um flavivírus é endêmica no Bioma Amazônico. O vírus se mantém no ambiente silvestre utilizando mosquitos como reservatório e vetor. São os mosquitos que disseminam o vírus ao voarem entre fragmentos florestais, infectando populações de primatas neotropicais (PNT). Este Guia de Vigilância de Epizootias em Primatas não Humanos e Entomologia Aplicada à Vigilância da Febre Amarela do Ministério da Saúde, considera a captação de informações, oportunamente, sobre adoecimento ou morte de PNT e a investigação adequada desses eventos, como uma importante atividade para a precoce detecção da circulação viral. Porém, um dos desafios desta investigação é a identificação do gênero e espécie de carcaças de animais encontrados. Muitas vezes, em estado avançado de decomposição. Nessa situação, é possível que as carcaças de outros animais possam ser confundidas com a de PNT sentinelas para a febre amarela. Desta forma, o Guia apresenta a distribuição territorial das diferentes espécies de primatas neotropicais e as diferenças anatômicas do crânio entre os gêneros com ocorrência no estado de São Paulo, assim como as principais diferenças anatômicas entre crânios de outros mamíferos que podem ser encontrados nos mesmo locais de ocorrência dos primatas neotropicais, todos relacionados por ordem de importância ou similaridade zoológica.

Ticks of the genus Amblyomma are of great medical and veterinary importance in Brazil, where they regularly parasitize wild and domestic animals and will bite humans that enter rural and forest areas for work and recreation purposes. This study provides morphological descriptions and redescriptions of the larval stage of 30 Amblyomma species occurring in Brazil, using morphometry, chaetotaxy and porotaxy. A dichotomous key with important characteristics illustrated by light and scanning electron microscopy was constructed for larvae of 31 species of Amblyomma from Brazil, including Amblyomma monteiroae, a recently described endemic species. The larvae of the following 11 species are described for the first time: Amblyomma aureolatum, Amblyomma cajennense, Amblyomma coelebs, Amblyomma fuscum, Amblyomma goeldii, Amblyomma humerale, Amblyomma incisum, Amblyomma latepunctatum, Amblyomma naponense, Amblyomma pseudoconcolor, and Amblyomma scalpturatum. In addition, the larvae of the following 19 species are redescribed: Amblyomma auricularium, Amblyomma brasiliense, Amblyomma calcaratum, Amblyomma dissimile, Amblyomma dubitatum, Amblyomma geayi, Amblyomma longirostre, Amblyomma nodosum, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma pacae, Amblyomma parkeri, Amblyomma parvum, Amblyomma romitii, Amblyomma rotundatum, Amblyomma sculptum, Amblyomma tigrinum, Amblyomma triste, and Amblyomma varium. Together with the recent description of A. monteiroae, these results formed the basis for the formulation of a dichotomous key encompassing 31 Amblyomma species occurring in Brazil. Undoubtedly, the results of this study will assist future fieldwork aimed at identifying Amblyomma larvae collected from hosts and the environment.

Schistosomiasis remains a significant public health concern in tropical and subtropical regions, especially in low-and-middle-income countries. In Brazil, control measures have reduced the disease's prevalence, creating low-endemic areas. However, environmental and climate dynamics, coupled with inadequate urbanization, pose risks of re-emergence. The middle Paranapanema basin, S & atilde;o Paulo state, exemplifies such a region. Here, the presence of Biomphalaria snail species (B. glabrata, B. straminea, and B. tenagophila), inadequate sanitation, and environmental changes signal potential schistosomiasis resurgence. This study aimed to develop a methodological framework to better understand schistosomiasis transmission mechanisms in low-endemic areas. It integrated demographic, environmental, malacological, and climatic data to identify transmission risk areas. The framework comprised a spatial hydrological model to assess fecal-contaminated water bodies, an exploratory spatial model for transmission hotspots, and snail dispersal analysis within drainage networks, incorporating climate projections. The methodology used geoprocessing tools to analyze hydrological, demographic, malacological, and climatic datasets. A spatial hydrological model combined sewage treatment and population density data with digital elevation models to identify potential transmission foci. Snail occurrence and schistosomiasis cases were spatially analyzed, with climate indices (1951-2022) providing rainfall trend projections. Land use datasets facilitated host habitat assessments, and outputs correlated potential foci with disease incidence. Results revealed that streams near urban areas with high concentrations of blackwater were associated with schistosomiasis cases. Streams hosting B. glabrata upstream had the strongest association with disease, while mixed-species habitats underscored hydrological connectivity's role. Urban and agricultural land-use areas overlapped with snail habitats, identifying high-risk zones. Climate projections indicated increasing extreme rainfall events, enhancing flooding and erosion, which may facilitate snail dispersal and extend schistosomiasis foci downstream. Effluent from municipalities like Ourinhos could intensify contamination, impacting neighboring areas like Salto Grande. The findings emphasize integrating hydrological, climatic, and ecological perspectives into schistosomiasis control strategies. Simple hydrological models assessing fecal-contaminated water bodies provide valuable insights for sanitation policies, and climate-related snail dispersal scenarios highlight emerging risks in connected areas. Addressing these challenges is crucial for eliminating schistosomiasis, particularly in low-endemic regions. This study's novel integrated hydrological-spatial models, based on freely available data, offer reproducible methods for identifying schistosomiasis transmission risks and guiding surveillance and control efforts in similar settings across Brazil.

RESUMO Objetivo: O objetivo deste estudo é analisar a distribuição espacial e temporal de locais prováveis de infecção (LPI) para febre maculosa brasileira (FMB) e avaliar mudanças no padrão de ocorrência em uma área endêmica do interior do estado de São Paulo. Métodos: Realizou-se estudo transversal com 40 casos confirmados de FMB (2007–2024) com LPI identificados no município de Americana/SP. Utilizaram-se dados do Sistema de Informação de Agravos de Notificação, relatórios de investigação epidemiológica e de pesquisas acarológicas. Para cada LPI georreferenciado, foram analisados dados de microclima, altimetria, declividade, Normalized Difference Vegetation Index (NDVI) e proximidade de corpos hídricos. Resultados: Os casos concentraram-se de forma atípica no primeiro semestre, diferente do que é esperado para áreas de transmissão por Amblyomma sculptum, por influência do surto registrado em 2018. Os LPI concentraram-se próximos a corpos hídricos, em áreas de mata ciliar degradada e microclima de temperaturas amenas e alta umidade, com baixo valor de NDVI, baixa altitude e declividade, apresentando agregação espacial e expansão da transmissão para áreas urbanizadas ao longo do período: inicialmente (2007–2015, nove casos) na porção norte/nordeste, em regiões limítrofes do município e, mais recentemente (2016–2024, 25 casos), avançando para áreas centrais, com formação de grandes aglomerados. Conclusão: Os achados configuram um cenário de alerta ecoepidemiológico, associado à proximidade entre alta densidade de vetores, hospedeiros amplificadores e populações humanas e reforçam a necessidade de vigilância intensificada e educação em saúde direcionada já no segundo trimestre do ano.

In southeastern Brazil, capybaras (Hydrochoerus hydrochaeris) are main hosts of the ticks Amblyomma dubitatum and Amblyomma sculptum; the latter has great medical importance for being the main vector of Rickettsia rickettsii, the agent of Brazilian spotted fever (BSF). This study aimed to quantify ticks in areas invaded and not invaded by exotic plants (Hedychium coronarium, Cenchrus purpureus or Megathyrsus maximus) within capybaras’ living areas in São Paulo state. Tick populations were quantified in 24 capybara habitats, eight in natural reserves and 16 human-modified landscapes; the latter were composed of eight BSF-endemic areas and eight BSF-nonendemic areas. In the 24 areas, ticks were sampled in plots of natural forests and plots with at least one of the three invasive plants. Both presence and density of A. sculptum were higher in human-modified landscapes, while the presence and density of A. dubitatum tended to be similar among human-modified landscapes and natural reserve areas. The two tick species were collected both in areas colonized by invasive plants (H. coronarium, M. maximus, and/or C. purpureus) and in areas of non-invaded vegetation. However, a higher density of A. dubitatum was observed in areas of H. coronarium and a lower density of A. sculptum in this type of vegetation. Within human-modified landscapes, there was a higher density of A. sculptum in BSF-endemic areas when compared to non-endemic areas, unlike A. dubitatum, which remained at an almost constant density and presence among BSF-endemic and non-endemic areas. Plant invasions may have some role in the ecology of capybara-associated ticks.

Yellow fever (YF) remains a significant public health threat in tropical regions, particularly in South America and Africa. The combined forces of climate change, land-use, urbanisation, globalisation, and insufficient surveillance and health infrastructure are driving the re-emergence and expansion of YF into new areas. While mathematical models have been used to estimate transmission risk, disease burden, and the impact of vaccination, there remains a crucial gap in mechanistic models that explicitly capture how climate and environmental changes directly influence YF transmission. To address this gap, we convened a workshop in Brazil as part of the Vaccine Impact Modelling Consortium’s Climate Change programme, bringing together national and international experts. The workshop aimed to present current modelling approaches, identify key knowledge gaps, and develop strategies to improve data collection and model applicability. Discussions highlighted major uncertainties regarding vectors, non-human primates, surveillance sensitivity, vaccination, and climatic and environmental drivers. This paper synthesises the outcomes of the workshop, including priority areas for future research and recommendations for advancing mechanistic YF modelling in the context of climate change, with a focus on both Brazil and broader tropical regions.

Brazilian spotted fever (BSF) is a tick-borne acute febrile disease that can be lethal to humans, caused by the bacterium Rickettsia rickettsii. In the State of São Paulo, transmission occurs mainly through two tick species: Amblyomma sculptum and Amblyomma aureolatum. We analyzed trends in BSF incidence and mortality in relation to the spatial distribution of these vector species in the State of São Paulo from 2007 to 2017 and evaluated clinical outcomes according to hospitalization location. In A. sculptum areas, incidence and mortality showed significant increasing trends between 2007 and 2015 (p-value < 0.05). In contrast, A. aureolatum areas exhibited a significant decrease in incidence (p-value < 0.05), while mortality remained stable throughout the study period. Lethality was substantially higher in cases associated with A. aureolatum than in those linked to A. sculptum (67.1% versus 55.0%, p-value = 0.037). Most patients received care in hospitals located near the probable site of infection. Incidence and mortality patterns differed sharply between vector-specific areas, with notably higher mortality in A. aureolatum-related cases. These findings highlight the importance of incorporating vector distribution into surveillance, prevention, and clinical management strategies to better address the distinct epidemiological contexts within the State of São Paulo.

ABSTRACT Objective: To analyze the spatial and temporal distribution of probable infection sites (PIS) for Brazilian spotted fever (BSF) and to evaluate changes in the occurrence pattern in an endemic area in the interior of the state of São Paulo. Methods: A cross-sectional study was conducted with 40 confirmed cases of BSF (2007–2024) with identified PIS in the municipality of Americana, São Paulo. Data were obtained from the Notifiable Diseases Information System (Sistema de Informação de Agravos de Notificação), epidemiological investigation reports, and acarological surveys. For each georeferenced PIS, data on microclimate, altimetry, slope, Normalized Difference Vegetation Index (NDVI), and proximity to water bodies were analyzed. Results: Cases were atypically concentrated in the first half of the year, differing from the expected pattern for areas of transmission by Amblyomma sculptum, influenced by the outbreak recorded in 2018. PIS were concentrated near water bodies, in areas of degraded riparian forest and microclimates characterized by mild temperatures and high humidity, with low NDVI values, low altitude, and low slope. Spatial clustering was observed, along with an expansion of transmission toward urbanized areas over the study period: initially (2007–2015, nine cases) in the northern/northeastern portion of the municipality, in bordering regions, and more recently (2016–2024, 25 cases) advancing toward central areas, with the formation of large clusters. Conclusion: The findings indicate an eco-epidemiological alert scenario associated with the proximity between high densities of vectors, amplifying hosts, and human populations, reinforcing the need for intensified surveillance and targeted health education starting in the second quarter of the year.

Yellow fever (YF) remains a major zoonotic disease in tropical regions of the Americas and Africa. In Brazil, surveillance of epizootics in non-human primates (NHPs) has become a cornerstone of YF prevention and control. This study provides a historical overview of NHP epizootic surveillance in Brazil from 1999 to 2025 and evaluates its role as an early warning system for human infections within a One Health framework. A retrospective descriptive epidemiological study was conducted using surveillance data from the Notifiable Diseases Information System (SINAN) and the Wildlife Health Information System (SISS-Geo). Records of YF epizootics in NHPs and confirmed human YF cases were analyzed according to geographic region, biome, seasonality, and taxonomic identification. During the study period, 35,496 epizootics involving 43,062 NHPs were reported, of which 3,203 (9.0%) were confirmed as YF. The Southeast region accounted for the most notifications, particularly in the states of São Paulo and Minas Gerais. Three major waves of viral dispersion were identified, with the largest occurring during 2016/2017 and 2017/2018. A strong positive correlation was observed between NHP epizootics and human YF cases (r = 0.72; p < 0.001), reinforcing the sentinel role of NHPs. Epizootics generally preceded human cases, especially during the pre-seasonal period. Alouatta was the genus most frequently associated with confirmed infections. Despite advances in surveillance, important regional disparities and logistical limitations persist, particularly in the Amazon region. These findings highlight the strategic importance of integrated NHP surveillance for early outbreak detection, vaccination planning, and prevention of YF transmission in Brazil.

Brazilian spotted fever is a tick-borne disease caused by the bacterium Rickettsia rickettsii, whose main vector in Brazil is the tick Amblyomma sculptum. Amplifying hosts are essential for the perpetuation of this bacterium in the tick population as they can be sources of infection during bacteremic periods. Recent studies demonstrated the ability of suids (Sus scrofa) to sustain populations of A. sculptum, one of the main tick species found parasitizing wild boars in the midwestern and southeastern regions of Brazil. In this study, wild boars were experimentally infected with R. rickettsii by tick infestation and were evaluated for their ability to transmit the infection to A. sculptum ticks, under laboratory conditions. Four wild boars were infected with R. rickettsii through infestation with R. rickettsii-infected A. sculptum adults (infected group); a fifth wild boar was infested with uninfected A. sculptum adults (control group). Simultaneously, the animals were infested with uninfected larvae and nymphs of A. sculptum. The wild boars were monitored for 28 days by clinical examination and hematological tests, real-time quantitative PCR (qPCR) of blood for the detection of Rickettsia and inoculation of blood in guinea pigs. IgG antibody titers were followed until the end of the experiment. Unfed nymphs and adults, molted from engorged larvae and nymphs that fed on wild boars, were used to infest susceptible guinea pigs and rabbits; some of these unfed ticks were tested by qPCR for rickettsial detection. The wild boars showed no clinical or hematological alterations, and bacteremia was not detected by qPCR or inoculation of wild boar blood into guinea pigs. Furthermore, wild boars showed a moderate humoral response, with anti-R. rickettsii endpoint titers up to 256 or 512. Rickettsial DNA was not detected in molted ticks after acquisition feeding on wild boars. Moreover, no disease or seroconversion was observed in guinea pigs and rabbits that were infested with ticks originated from wild boar acquisition feeding. Wild boars seroconverted to Rickettsia spp. after being infested with R. rickettsii-infected A. sculptum; however, they did not develop bacteremia and did not act as competent amplifying hosts of R. rickettsii for A. sculptum ticks.

RMSF, a tickborne infection caused by Rickettsia rickettsii, produces severe and fatal disease in humans and dogs. Since the beginning of the 21st century, cases have risen dramatically, most notably in Mexico and Brazil, where outbreaks occur in urban centers including cities with populations of > 1,000,000 persons. Reported case fatality rates can exceed 50%. Factors consistent with high case fatality include lack of awareness of disease ecology, limited capacity for diagnosis, and delay in appropriate antimicrobial treatment. The emergence of urban hyperendemic foci has been leveraged by 2 distinct but similar anthropogenic events that create disproportionately high numbers of vertebrate amplifiers of R rickettsii, as well as the tick species that transmit this pathogen in proximity with dense human populations. This often occurs in neighborhoods with a highly marginalized at-risk population that includes persons in poverty and particularly children, and health management systems that are under-resourced. We discuss strategies to reduce host dog populations, particularly in Mexico, and capybaras in Brazil. We review challenges to the control of tick populations in these settings. Robust systems are required to enhance awareness of RMSF among medical practitioners and people at risk of RMSF. Public health campaigns should incorporate innovative behavioral science (eg, diverse learning models, motivational interviews, and gamification) to increase prevention and understanding within communities. While anti-Rickettsia or anti-tick vaccines will be necessary to resolve this One Health crisis, impactful implementation will require data-driven and multiple-target innovations to address challenges with hosts, ticks, medical systems, and public welfare. The companion Currents in One Health by Foley, Backus, and L & oacute;pez-P & eacute;rez, JAVMA, March 2025, addresses helpful information for the practicing veterinarian.

Rickettsia parkeri strain Atlantic rainforest is an emerging pathogen in Brazil, but human infections remain rarely reported. We report the first confirmed case in the municipality of Caraguatatuba on the northern coast of São Paulo State, Brazil. A 37-year-old man was bitten by an Amblyomma ovale tick while visiting a forested area. Six days later, he developed a papular skin lesion with a necrotic center at the tick bite site, accompanied by regional lymphadenopathy, myalgia, and flu-like symptoms. Ticks parasitizing both the patient and his dog were collected, along with the eschar. Two ticks were analyzed for Rickettsia isolation, and R. parkeri was successfully isolated from one infected specimen. The patient’s infection was confirmed by molecular testing through the PCR amplification of the gltA and ompA genes from an eschar inoculation sample. This represents the sixth confirmed case of rickettsiosis caused by R. parkeri in Brazil, and it reinforces the need for increased epidemiological surveillance in endemic regions for spotted fever caused by this pathogen. With the increasing recognition of R. parkeri in South America, further research is needed to better understand its transmission dynamics, clinical manifestations, and potential public health impact.

The emergence and spread of zoonotic and vector-borne diseases (ZVBDs), exacerbated by environmental change, pose serious threats to global public health and the economy. Understanding the role of environmental factors in disease transmission is critical for improving risk assessments and implementing effective preventive strategies. However, current approaches often lack a comprehensive framework that integrates the three risk components (hazard, exposure, and vulnerability), limiting the reliability and actionability of assessments. Here, we reviewed studies that incorporated environmental variables into research on ZVBDs, extracting information on the three risk components. We found that 52% of studies measured only hazard, whereas only 7.4% integrated all three components. Landscape composition and temperature were the most commonly used environmental variables. Our findings highlight key gaps in disease risk assessment and offer a roadmap with targeted indicators for each component, advancing the conceptual and structural foundations of disease ecology research in the context of environmental change.

Yellow fever virus (YFV) is an arbovirus transmitted by mosquitoes that maintains sylvatic cycles in neotropical primates and mosquitoes of the genera Haemagogus and Sabethes. In Brazil, human outbreaks result from viral amplification in susceptible primate populations, especially howler monkeys (Alouatta spp.). YFV spreads in epizootic waves originating in the Amazon and extends to extra-Amazonian biomes such as the Atlantic Forest. Viral dispersion is driven by the mobility of vector mosquitoes and shows seasonal variations. Recent events show greater territorial reach, possibly linked to environmental changes, highlighting the importance of surveillance in primates and human vaccination within the One Health approach.

BACKGROUND:Yellow fever (YF) is a highly lethal arboviral disease that is transmitted to humans by the bites of infected mosquitoes. However, the drivers of epidemic episodes are not well understood. In this ecological study, we analysed spatial and temporal patterns of the largest yellow fever outbreaks in the 21st century in Brazil. METHODS:We describe the spatial and temporal patterns of 2178 human YF cases, 2911 non-human primate (NHP) cases and immunization coverage using the Global and Local Moran's Index, directional distribution and logistic regression models. RESULTS:Spatially distinct clusters were detected along heterogeneous forestland and ecological corridors. Human YF occurrence increased with a higher abundance and diverse genera of NHP YF cases along with seven other variables: lower vaccination coverage, lower elevation, moderate annual mean temperature, higher annual precipitation, increased vector abundance, low to moderate urbanization and forested land. CONCLUSIONS:Our results suggest that human YF epidemics are largely driven by vaccination coverage and environmental conditions that aid transmission in vectors and hosts. This sustains the local sylvatic cycle across administrative and political boundaries. These results reinforce the need to study YF spillover and dispersion dynamics at the human-animal-environment interface to improve disease control and devise multisectoral mitigation strategies.

(1) Background: Brazilian spotted fever (BSF) is a tick-borne disease that has occurred in several Brazilian regions, caused by Rickettsia spp. bacteria and mainly transmitted by Amblyomma ticks. Despite the high BSF lethality in several Brazilian endemic areas, predictors and associated risk factors remain to be fully established. Accordingly, the retrospective study herein aimed to assess BSF cases and associated factors in an endemic area of western São Paulo state. (2) Methods: Notified cases identified by the System for Epidemiological Surveillance of São Paulo (CVE), from January 2007 to December 2021, were gathered and analyzed by Logistic Multivariate Regression (LMR) to assess potential risk factors for BSF. (3) Results: Overall, 74/1121 (6.6%; 95% CI: 5.29–8.21) individuals were considered positive for BSF. Univariate analysis showed previous contact with capybaras (OR: 1.89; 95% CI: 1.0–3.55; p < 0.001) and raising horses (OR = 1.4; 95% CI: 0.66–2.67; p = 0.45), while LMR revealed living in rural areas (OR = 2.0; 95% CI: 1.02–3.73; p = 0.037) as an associated risk factor for BSF. (4) Conclusions: The results herein show that the geographically studied area still shows high occurrence of BSF, mostly for individuals living or visiting areas overlapping free-ranging capybaras.

Species distribution models (SDMs) are increasingly popular tools for profiling disease risk in ecology, particularly for infectious diseases of public health importance that include an obligate non-human host in their transmission cycle. SDMs can create high-resolution maps of host distribution across geographical scales, reflecting baseline risk of disease. However, as SDM computational methods have rapidly expanded, there are many outstanding methodological questions. Here we address key questions about SDM application, using schistosomiasis risk in Brazil as a case study. Schistosomiasis is transmitted to humans through contact with the free-living infectious stage of Schistosoma spp. parasites released from freshwater snails, the parasite’s obligate intermediate hosts. In this study, we compared snail SDM performance across machine learning (ML) approaches (MaxEnt, Random Forest, and Boosted Regression Trees), geographic extents (national, regional, and state), types of presence data (expert-collected and publicly-available), and snail species (Biomphalaria glabrata, B. straminea, and B. tenagophila). We used high-resolution (1km) climate, hydrology, land-use/land-cover (LULC), and soil property data to describe the snails’ ecological niche and evaluated models on multiple criteria. Although all ML approaches produced comparable spatially cross-validated performance metrics, their suitability maps showed major qualitative differences that required validation based on local expert knowledge. Additionally, our findings revealed varying importance of LULC and bioclimatic variables for different snail species at different spatial scales. Finally, we found that models using publicly-available data predicted snail distribution with comparable AUC values to models using expert-collected data. This work serves as an instructional guide to SDM methods that can be applied to a range of vector-borne and zoonotic diseases. In addition, it advances our understanding of the relevant environment and bioclimatic determinants of schistosomiasis risk in Brazil.

Abstract In Brazil, spotted fever (SF) is caused by two species of Rickettsia, both of which are transmitted by Amblyomma ticks: Rickettsia rickettsii, which results in severe and often fatal cases, and Rickettsia parkeri, which causes a mild illness. This study focused on R. parkeri in Amblyomma ovale ticks from the Maciço de Baturité region, Ceará, Northeast Brazil, an area endemic for SF with mild symptoms. We examined 60 domestic dogs with access to the forest for ticks and Rickettsia seroprevalence. A landscape analysis was conducted in all forest patches within 2–10 km from the main forest edge. In total, 125 A. ovale ticks were collected from 30 dogs (50%). DNA from 65 ticks was tested using genus-specific Rickettsia primers. Three (4.6%) tick specimens tested positive for R. parkeri while the Rickettsia seroprevalence among the dogs was 55% (33/60). A probable occurrence of Rickettsia transmission was observed in the fragmented Atlantic rainforest, which has 1,019 ha of preserved land and 50.6 km of perimeter border. The land's characteristics allow for semi-domiciled dogs to access forest fragments, where A. ovale ticks are commonly present. Infected ticks may parasitize the dogs, which then transport the ticks into homes, potentially transmitting SF-causing bacteria to humans.

The Atlantic Forest Biome (AFB) creates an ideal environment for the proliferation of vector mosquitoes, such as Haemagogus and Sabethes species, which transmit the Yellow Fever virus (YFV) to both human and non-human primates (NHP) (particularly Alouatta sp. and Callithrix sp.). From 2016 to 2020, 748 fatal cases of YF in humans and 1,763 in NHPs were reported in this biome, following several years free from the disease. This underscores the imminent risk posed by the YFV. In this study, we examined the spatiotemporal distribution patterns of YF cases in both NHPs and humans across the entire AFB during the outbreak period, using a generalized linear mixed regression model (GLMM) at the municipal level. Our analysis examined factors associated with the spread of YFV, including environmental characteristics, climate conditions, human vaccination coverage, and the presence of two additional YFV-affected NHP species. The occurrence of epizootics has been directly associated with natural forest formations and the presence of species within the Callithrix genus. Additionally, epizootics have been shown to be directly associated with human prevalence. Furthermore, human prevalence showed an inverse correlation with urban areas, temporary croplands, and savannah and grassland areas. Further analyses using Moran’s Index to incorporate the neighborhoods of municipalities with cases in each studied host revealed additional variables, such as altitude, which showed a positive correlation. Additionally, the occurrence of the disease in both hosts exhibited a spatio-temporal distribution pattern. To effectively mitigate the spread of the virus, it is necessary to proactively expand vaccination coverage, refine NHP surveillance strategies, and enhance entomological surveillance in both natural and modified environments.