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Background Rickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases. While these cases were epidemiologically associated with the tick Amblyomma ovale , in none of them the tick specimens that bit the patients could be identified. Results We report a clinical case of spotted fever rickettsiosis that was acquired in an Atlantic forest area in Bahia state, northeast Brazil. The case was determined to be caused by R. parkeri strain Atlantic rainforest, based on molecular analysis of the crust removed from the tick bite site (inoculation eschar) of the patients’ skin. DNA extracted from the crust yielded partial sequences of three rickettsial genes ( gltA , ompA and ompB ), which were 99–100% identical to R. parkeri strain Atlantic rainforest. The tick specimen that was attached to patient skin was identified as a female of A. ovale. Conclusions We report the fourth confirmed case of spotted fever rickettsiosis caused by R. parkeri strain Atlantic rainforest, providing to our knowledge for the first time, direct evidence of R. parkeri strain Atlantic rainforest transmission by A. ovale .

We detected Mayaro virus (MAYV) in 3.4% (28/822) of febrile patients tested during 2018-2021 from Roraima State, Brazil. We also isolated MAYV strains and confirmed that these cases were caused by genotype D. Improved surveillance is needed to better determine the burden of MAYV in the Amazon Region.

In 2024, Brazil reached significant milestones in advancing the One Health framework, notably with the establishment of the Interinstitutional Technical Committee for One Health and the launch of the São Paulo Declaration on One Health. These developments mark a crucial step forward in Brazil’s strategy to address the interconnected challenges of human, animal, plant, and environmental health. The One Health framework underscores the need for cross-sectoral collaboration, transdisciplinary partnerships, and community-driven engagement, particularly as global issues such as climate change, ecosystem degradation, and health crises become increasingly urgent. The São Paulo Declaration advocates for integrated health surveillance, fostering intersectoral cooperation, and promoting sustainable practices to tackle emerging health threats. It calls for a unified approach to addressing climate change, biodiversity loss, and social vulnerability while prioritizing research, capacity building, and policy integration across all governance levels. This commentary highlights the importance of the São Paulo Declaration in advancing Brazil’s One Health strategy and calls for sustained action from academia, governments, and society. These collective efforts are critical to ensuring a resilient and sustainable future, safeguarding the health of humans, animals, and the environment through holistic collaboration.

We report a clinical case of African tick-bite fever in a Brazilian traveler right after his return from South Africa. Definitive diagnosis was supported by seroconversion between acute-phase and convalescent-phase serum samples, detection of rickettsial DNA in skin lesions, and in vitro culture of Rickettsia africae from the patient’s skin. Most of the previous reported cases of African tick-bite fever were confirmed solely by serological or/and molecular methods. Through this first confirmed case of African tick-bite fever in Brazil, it is quite possible that other cases are occurring unnoticed by the health authorities, requiring a greater vigilance in traveler’s medicine in South America.

A SARS-CoV-2 B.1.1.7 variant of concern (VOC) has been associated with increased transmissibility, hospitalization, and mortality. This study aimed to explore the factors associated with B.1.1.7 VOC infection in the context of vaccination. On March 2021, we detected SARS-CoV-2 RNA in nasopharyngeal samples from 14 of 22 individuals vaccinated with a single-dose of ChAdOx1 (outbreak A, n = 26), and 22 of 42 of individuals with two doses of the CoronaVac vaccine (outbreak B, n = 52) for breakthrough infection rates for ChAdOx1 of 63.6% and 52.4% for CoronaVac. The outbreaks were caused by two independent clusters of the B.1.1.7 VOC. The serum of PCR-positive symptomatic SARS-CoV-2-infected individuals had ~1.8–3.4-fold more neutralizing capacity against B.1.1.7 compared to the serum of asymptomatic individuals. These data based on exploratory analysis suggest that the B.1.1.7 variant can infect individuals partially immunized with a single dose of an adenovirus-vectored vaccine or fully immunized with two doses of an inactivated vaccine, although the vaccines were able to reduce the risk of severe disease and death caused by this VOC, even in the elderly.

Background Dengue cases have been classified according to disease severity into dengue fever (DF) and dengue hemorrhagic fever (DHF). Although DF is considered a non-severe manifestation of dengue, it has been recently demonstrated that DF represents a heterogeneous group of patients with varied clinical complications and grades of severity. Particularly, bleeding complications, commonly associated to DHF, can be detected in half of the patients with DF. Although a frequent complication, the causes of bleedings in DF have not been fully addressed. Thus, the aim of this study was to perform a comprehensive evaluation of possible pathophysiological mechanisms that could contribute to the bleeding tendency observed in patients with DF. Methods This is a case–control study that enrolled adults with DF without bleeding and adults with DF and bleeding complications during the defervescence period. Healthy controls were also included. Peripheral blood counts, inflammatory, fibrinolysis and endothelial cell activation markers, and thrombin generation were evaluated in patients and controls. Results We included 33 adults with DF without complications, 26 adults with DF and bleeding and 67 healthy controls. Bleeding episodes were mild in 15 (57.6%) and moderate in 11 (42.4%) patients, 8 (30.7%) patients had bleedings in multiple sites. Patients with DF and bleedings had lower platelet counts than DF without bleeding (median = 19,500 vs. 203,500/mm3, P < 0,0001). Levels of TNF-α, thrombomodulin and VWF were significantly increased in the two dengue groups than in healthy controls, but similar between patients with and without bleedings. Plasma levels of tPA and D-dimer were significantly increased in patients with bleedings (median tPA levels were 4.5, 5.2, 11.7 ng/ml, P < 0.0001 and median D-dimer levels were 515.5, 1028 and 1927 ng/ml, P < 0.0001). The thrombin generation test showed that patients with bleeding complications had reduced thrombin formation (total thrombin generated were 3753.4 in controls, 3367.5 in non-bleeding and 2274.5nM in bleeding patients, P < 0.002). Conclusions DF can manifest with spontaneous bleedings, which are associated with specific coagulation and fibrinolysis profiles that are not significantly present in DF without this complication. Particularly, thrombocytopenia, excessive fibrinolysis and reduced thrombin formation may contribute to the bleeding manifestations in DF.

Background Although malaria in Brazil almost exclusively occurs within the boundaries of the Amazon Region, some concerns are raised regarding imported malaria to non-endemic areas of the country, notably increased incidence of complications due to delayed diagnoses. However, although imported malaria in Brazil represents a major health problem, only a few studies have addressed this subject. Methods A retrospective case series is presented in which 263 medical charts were analysed to investigate the clinical and epidemiological characterization of malaria cases that were diagnosed and treated at Hospital & Clinics, State University of Campinas between 1998 and 2011. Results Amongst all medical charts analysed, 224 patients had a parasitological confirmed diagnosis of malaria. Plasmodium vivax and Plasmodium falciparum were responsible for 67% and 30% of the infections, respectively. The majority of patients were male (83%) of a productive age (median, 37 years old). Importantly, severe complications did not differ significantly between P. vivax (14 cases, 9%) and P. falciparum (7 cases, 10%) infections. Conclusions Severe malaria cases were frequent among imported cases in Brazil outside of the Amazon area. The findings reinforce the idea that P. vivax infections in Brazil are not benign, regardless the endemicity of the area studied. Moreover, as the hospital is located in a privileged site, it could be used for future studies of malaria relapses and primaquine resistance mechanisms. Finally, based on the volume of cases treated and the secondary complications, referral malaria services are needed in the non-endemic areas of Brazil for a rapid and efficient and treatment.

[...]a staggering case fatality rate, in a vaccine-preventable disease, not only highlights the urgency to improve coverage rates and traveler awareness but also underscores YF's standing as one of the deadliest vaccine-preventable viral infections. Agricultural activities influence this, intensifying during planting and harvesting times, especially in Brazil, and climate change during periods of high rainfall and warmer temperatures [ 31–33]. [...]entomological and disease surveillance are crucial to understanding and controlling YF and other vector-borne diseases. In addition to misinformation, pandemic fatigue—a state of demotivation and exhaustion resulting from prolonged public health crises—has emerged as a significant barrier to vaccine acceptance and risk perception following the COVID-19 pandemic.

A case of a pregnant patient with chronic hepatitis C who gave birth to monozygotic twins that were infected with HCV is reported. One of the newborns was positive for HCV-RNA in blood sample collected 12 hours after delivery. The other newborn was negative for HCV-RNA at birth, but was detected HCV viremia at three months of age. The results have led to the conclusion that one of the twins was probably contaminated in the intrauterine period, while the other acquired the infection in the perinatal period. Both were negative for HCV-RNA and for anti-HCV in the serum samples collected at nine months of age. The report describes the changes in the laboratory tests conducted in mother and twins until 29 months after delivery. É relatado o caso de paciente grávida, com hepatite C crônica que deu à luz dois gêmeos monozigóticos. Um recém-nascido apresentou positividade para o RNA do vírus da hepatite C (RNA-VHC), no sangue venoso, coletado de veia periférica doze horas após o parto. O outro recém-nascido apresentou-se negativo para o RNA-VHC logo após o nascimento, porém tornou-se RNA-VHC positivo na amostra coletada aos três meses de idade. Os resultados permitem supor que um dos gêmeos provavelmente foi contaminado no período intra-uterino, enquanto o outro adquiriu a infecção no período perinatal. Ambos foram negativos para a presença do RNA-VHC e para os anticorpos anti-HCV em todas as amostras séricas coletadas após os nove meses de idade. Os exames laboratoriais dos gêmeos não mostraram a presença de infecção crônica pelo VHC durante o acompanhamento de 29 meses .

Two recent researches described the spread of East/Central/South African (ECSA) lineage of chikungunya virus (CHIKV) in the Northeastern and Southeastern Brazil (Charlys da Costa et al. 2017, Cunha et al. 2017) . Initial studies in Northern Brazil, as observed in Caribbean, identified the Asian as the circulating lineage of the chikungunya. However, da Charlys da Costa et al. and Cunha et al. reported the exclusive occurrence of ECSA in two different Brazilian regions: Northeast as well as in Rio de Janeiro State (Charlys da Costa et al. 2017, Cunha et al. 2017) , suggesting that the ECSA is the predominant lineage in highly populated Brazilian areas. Despite the well-described vector competence of Aedes mosquitoes for CHIKV transmission, Aedes(Stegomyia)albopictus seems to have a greater competence for transmission of ECSA lineage compared to the Asian lineage (Vega-Rúa et al. 2015) , particularly when variable temperatures mimicking daily fluctuations of temperate climate (Vega-Rúa et al. 2015) . This statement is consistent with the fact that A albopictus has not been denounced as a vector of large outbreaks of chikungunya caused by the Asian genotype. This invasive species have capability of cold-tolerant diapausing eggs, it is paramount to establishment in temperate areas (Mitchell 1995) and new regions are invaded each year (Kraemer et al. 2015) . The predominance of the ECSA lineage in Brazil represents a potential risk of CHIKV dispersion to areas where Ae. albopictus has a broader distribution, particularly in temperate climates, including United States and Europe (Kraemer et al. 2015) , territories with intense commercial and touristic relationship with Brazil. Furthermore, the predominance of ECSA in Brazil can contributes to a better comprehension of the current distinct epidemiological scenarios between Caribbean - where explosive epidemics occurred with Aedes(Stegomyia) aegypti and Asian lineage predominated - and Brazil - with an apparent slower dispersion of CHIKV, where Ae.aegypti predominate but ECSA was prevalent linage. Both studies highlighted the importance of virological surveillance for analysis of current epidemiological scenarios and prediction of potential patterns of spreading of arboviral diseases, locally and worldwide.