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Brazilian spotted fever (BSF) is a highly lethal disease in southeastern Brazil. BSF is caused by the bacterium Rickettsia rickettsii and is transmitted by the bites of the tick of the genus Amblyomma. The spatial distribution of BSF risk areas is not well known in the country given the complexity of the transmission cycle. This study used the ecological niche modeling (ENM) approach to anticipate the potential distribution of the etiological agent (Rickettsia rickettsii), vectors (Amblyomma sculptum and A. dubitatum), and hosts (Hydrochoerus hydrochaeris, Didelphis aurita, and D. marsupialis) of BSF in Brazil. We compiled occurrence records for all vectors, hosts, and BSF from our own field surveillance, online repositories, and literature. ENM identified BSF risk areas in southeastern and southern Brazil, and anticipated other dispersed suitable areas in the western, central, and northeastern coast regions of Brazil. Tick vectors and mammalian hosts were confined to these same areas; however, host species showed broader suitability in northern Brazil. All species ENMs performed significantly better than random expectations. We also tested the BSF prediction based on 253 additional independent cases identified in our surveillance; the model anticipated 251 out of 253 of these independent cases. Background similarity tests comparing the ENMs of R. rickettsii, tick vectors, and mammalian hosts were unable to reject null hypotheses of niche similarity. Finally, we observed close coincidence between independent BSF cases, and areas suitable for combinations of vectors and hosts, reflecting the ability of these model pairs to anticipate the distribution of BSF cases across Brazil., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In Brazil, Spotted Fever (SF) is caused by Rickettsia rickettsii and Rickettsia parkeri strain Atlantic Forest. In recent years, several human cases of a milder SF have been reported from the Maciço de Baturité region of Ceará State. Previous studies in this region found R. parkeri strain Atlantic Forest to be present in Rhipicephalus sanguineus sensu lato and Amblyomma ovale ticks. The present study isolated and identified the Rickettsia spp. present in this new endemic area in Brazil. In March 2015, R. sanguineus s.l. and A. ovale were collected in rural areas of the Maciço de Baturité region, and subjected to the isolation technique. A bacterium was isolated from one R. sanguineus s.l., which phylogenetic analysis clustered to the R. rickettsii group. In conclusion, R. rickettsii bacteria is circulating in the studied area and may in future have an impact on the clinical diagnoses and consequently cause changes in the profile of the disease in the region. In addition, we suggest the increase of epidemiological and environmental surveillance in the area, in order to prevent Brazilian Spotted Fever cases., (Copyright © 2017. Published by Elsevier B.V.)

Brazilian Spotted Fever (BSF) is a zoonotic disease caused by the bacterium Rickettsia rickettsii. In the São Paulo Metropolitan Region (SPMR) it is transmitted by Amblyomma aureolatum ticks. In this region, annual lethality of the disease can reach 80% and spatial occurrence depends on environmental factors and more particularly on the presence and interaction of domestic and wild carnivores as well as the presence and characteristics of the remnant Atlantic Rain Forest patches. This study analyzed the association between forest fragmentation and its influence on the risk of occurrence of the disease in the human population. Domestic dogs tested for R. rickettsii antibodies in nine different areas under the influence of different patterns of Rain Forest fragmented landscapes and human occupancy. Landscape metrics were obtained by analyzing satellite images and high-resolution orthophotos. Principal component analysis (PCA) was used to determine among the different landscape variables the one that could best explain the data variance, and the results were tested against canine seroprevalence in order to address disease occurrence risk levels. From 270 canine samples, the seroprevalence ranged from 0 to 37%. PCA showed an inverse correlation between functionally connected large forest patches and the canine seroprevalence for R. rickettsii (p=0.030; Spearman's R=-0.683), while there was a positive correlation between forest border effect and canine seroprevalence (p=0.037; Spearman's R=- 0.909). The further attributed disease occurrence risk level supported the real spatial prevalence of the disease reported for the last eight years (p=0.023; Spearman's R=0.63). The results suggest an important relation of deforestation and fragmentation with the occurrence of BSF in the SPMR., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The historical, clinical, ecological, and epidemiological features of Rocky Mountain spotted fever and Colorado tick fever, the two important tick-borne diseases in the United States, are reviewed. Rocky Mountain spotted fever, once considered a disease of the past, has again become a measurable public health problem. Its nationwide incidence has steadily increased since 1960 and has reached record proportions in 1976. The various factors responsible for this trend as well as for the mortality rates, which in spite of availability of effective antibiotics ranges from 5 to 10%, are discussed. Education of the public about ticks and their potential role as vectors of Rickettsia rickettsii and/or Colorado tick fever virus, and about the clinical manifestations of Rocky Mountain spotted fever, is considered the best means for preventing high incidence and mortality from these diseases.