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BackgroundBrazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, has been associated with the transmission by the tick Amblyomma sculptum, and one of its main hosts, the capybara (Hydrochoerus hydrochaeris).MethodsDuring 2015–2019, we captured capybaras and ticks in seven highly anthropic areas of São Paulo state (three endemic and four nonendemic for BSF) and in two natural areas of the Pantanal biome, all with established populations of capybaras.ResultsThe BSF-endemic areas were characterized by much higher tick burdens on both capybaras and in the environment, when compared to the BSF-nonendemic areas. Only two tick species (A. sculptum and Amblyomma dubitatum) were found in the anthropic areas; however, with a great predominance of A. sculptum (≈90% of all ticks) in the endemic areas, in contrast to a slight predominance of A. dubitatum (≈60%) in the nonendemic areas. Tick species richness was higher in the natural areas, where six species were found, albeit with a predominance of A. sculptum (≈95% of all ticks) and environmental tick burdens much lower than in the anthropic areas. The BSF-endemic areas were characterized by overgrowth populations of A. sculptum that were sustained chiefly by capybaras, and decreased populations of A. dubitatum. In contrast, the BSF-nonendemic areas with landscape similar to the endemic areas differed by having lower tick burdens and a slight predominance of A. dubitatum over A.sculptum, both sustained chiefly by capybaras. While multiple medium- to large-sized mammals have been incriminated as important hosts for A. sculptum in the natural areas, the capybara was the only important host for this tick in the anthropic areas.ConclusionsThe uneven distribution of R. rickettsii infection among A. sculptum populations in highly anthropic areas of São Paulo state could be related to the tick population size and its proportion to sympatric A. dubitatum populations.

A febre maculosa brasileira (FMB), doença causada pela bactéria Rickettsia rickettsii, é o principal agravo em conseqüência da infecção por riquétsias do grupo da febre maculosa (GFM) em humanos no Brasil. Casos confirmados de FMB têm sido relatados em determinadas áreas dos Estados da região Sudeste 18 . O carrapato Amblyomma cajennense é incriminado como o principal vetor da doença 5 e, embora não haja comprovação do papel do Amblyomma dubitatum na transmissão da FMB, suspeita-se de sua possível participação na transmissão de riquétsias do GFM para humanos 11 12 . Os eqüinos, capivaras e antas estão entre os principais hospedeiros para todos os estágios parasitários de Amblyomma cajennense 7 , enquanto as capivaras são também hospedeiros primários para o Amblyomma dubitatum 9 . Desta forma, este trabalho buscou avaliar a infecção ABSTRACTThe presence of rickettsial infection was surveyed in 3,545 Amblyomma cajennense ticks and 2,666 Amblyomma dubitatum ticks. Using the hemolymph test, polymerase chain reaction and isolation of Rickettsia in cell cultures, all of the Amblyomma cajennense were negative, whereas 634 (23.8%) of the Amblyomma dubitatum ticks were shown to be infected with Rickettsia bellii.

Introduction: Brazilian spotted fever (BSF) is a disease transmitted by ticks for which the etiological agent is Rickettsia rickettsii. The present essay evaluates the risk factors associated with the transmission of cases of BSF in the time period between 2003 and 2013 in the Piracicaba river basin, state of São Paulo. Methods: This essay presents a retrospective study to identify the factors associated with the transmission of cases of BSF among all suspected cases identifi ed by the System for Epidemiological Surveillance of São Paulo (CVE). After the description of temporal distribution (onset of symptoms) and the environmental and demographic variations of the confi rmed and discarded cases, a multiple logistic regression model was applied. Results: We searched 569 probable locations of infection (PLI) with 210 (37%) confi rmed cases of BSF and 359 (63%) discarded cases. The associated variables for the confi rmation of BSF in the multiple logistic model using a confi dence interval (CI) of 95% were age (OR = 1.025 CI: 1.015-1.035), the presence of Amblyomma sculptum in the environment (OR = 1.629 CI: 1.097-2.439), the collection of ticks from horses (OR = 1.939 CI: 0.999-3.764), the presence of capybaras (OR = 1.467 CI: 1.009-2.138), an urban environment (OR = 1.515 CI: 1.036-2.231), and the existence of a dirty pasture (OR = 1.759 CI: 1.028-3.003). Conclusions: The factors associated with the confi rmation of BSF cases included an urban environment, age, presence of the A. sculptum vector, the collection of ticks from horses, the presence of a capybara population, and a dirty pasture environment.

RESUMO O objetivo deste estudo foi determinar os valores 6 /μl ± 0.2; hemoglobin: 13.5g/dl ± 0.7; hematocrit: 40.4% ± 2; MCV: 90.2fl ± 0.9; MCH: 30.1pg ± 0.7; MCHC: 33.3g/dl ± 1. In the leukocytes series: 5.3 x10 3 /μl ± 2; band neutrophil:1 % ± 2.1; segmenter: 36.6 %± 19.9; eosinophils: 3.5% ± 11.7; basophiles: 0%; lymphocytes: 58.8% ± 19.6; monocytes: 1.5% ± 2.1. Myelocytes and metamyelocytes were not found.

Equines play a role in the epidemiology of Brazilian spotted fever (BSF) since they are a primary host for the tick Amblyomma sculptum. We studied the seroprevalence for three species of Rickettsia in equines in four endemic (with human cases) and in four non-endemic areas (no human cases) in the Piracicaba River Basin, São Paulo, Brazil. A serological survey of 504 equines was performed: around 63 animals were sampled in each area and tested through indirect immunofluorescence assay for R. rickettsii, R. parkeri, and R. bellii in 2012–2013. Blood samples were seropositive for 183 equines (36.3%) in which 73 (39.9%) were from non-endemic areas. In the studied sites equines were highly exposed to Rickettsia infection ranging from 6.1% to 54.7%, with Geometric Mean Titers greater in endemic area (p = 0.012). Results suggest that Rickettsia may be more widespread than the surveillance of BSF has detected. These results highlight the need to include data on the seroprevalence of sentinel animals to improve human diagnoses and surveillance in areas with no reported human cases.

A febre maculosa é mundialmente reconhecida como um problema reemergente de saúde pública. Na região de Campinas-SP, observam-se uma ampliação da área de transmissão do agente da doença e a ocorrência de um maior número de casos confirmados nos últimos anos. Nesta região, a maioria dos casos desta doença está quase sempre relacionada com o aumento populacional de capivaras, que são um dos principais hospedeiros primários do estádio adulto do carrapato Amblyomma cajennense. O principal objetivo deste estudo foi determinar o comportamento populacional de larvas, ninfas e adultos de Amblyomma spp no habitat de mata ciliar de uma área endêmica. De novembro de 2000 a outubro de 2002, carrapatos de vida livre foram coletados com armadilhas de CO2. Picos populacionais de larvas do gênero Amblyomma se estenderam por praticamente todos os meses do ano. Ninfas do gênero Amblyomma ocorreram o ano todo na mata ciliar, sendo mais abundantes de julho a dezembro. Adultos de A. cajennense foram mais abundantes na estação de primavera e verão. Adultos de A. dubitatum (=Amblyomma cooperi) apresentaram um padrão sazonal diferenciado, com os maiores picos populacionais ocorrendo de agosto a fevereiro.

Diseases transmitted by ticks have been an important health problem all over the world. Brazilian Spotted Fever (BSF) stands for a serious epidemiological concern