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We report finding Rickettsia parkeri in Brazil in 9.7% of Amblyomma triste ticks examined. An R. parkeri isolate was successfully established in Vero cell culture. Molecular characterization of the agent was performed by DNA sequencing of portions of the rickettsial genes gltA, htrA, ompA, and ompB.

In the present study, attempts to isolate Rickettsia in cell culture were performed individually in seven specimens of Haemaphysalis juxtakochi ticks collected in the state of São Paulo (southeastern Brazil). Rickettsia was successfully isolated by the shell vial technique and established in Vero cell culture from six ticks (six isolates). DNA extracted from infected cells of these isolates was tested by PCR and DNA sequencing, using genus-specific Rickettsia primers targeting the genes gltA, htrA, ompA, and ompB. After the generated sequences were compared with available sequences in GenBank, five out of the six isolates were identified as Rickettsia bellii (isolates HJ#1, HJ#2, HJ#3, HJ#4, and HJ#7). The sixth isolate (HJ#5) was closest to Rickettsia sp. strain R300, previously detected in H. juxtakochi in northern Brazil, and to Rickettsia rhipicephali, isolated from ticks in the United States. Following recent gene sequence-based criteria proposed for the identification of Rickettsia isolates, both isolate HJ#5 and strain R300 were identified as South American strains of R. rhipicephali, which was confirmed in this continent for the first time. Isolation of R. bellii from H. juxtakochi ticks, added to eight other tick species that have been reported to be infected with this bacterium in Brazil, indicates that R. bellii is indeed the most frequent Rickettsia species infecting ticks in Brazil. Currently, the role of both R. rhipicephali and R. bellii as human pathogens is regarded as unknown.

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BackgroundThe goal of this study was to reassess the taxonomic status of A. maculatum, A. triste and A. tigrinum by phylogenetic analysis of five molecular markers [four mitochondrial: 12S rDNA, 16S rDNA, the control region (DL) and cytochrome c oxidase 1 (cox1), and one nuclear: ribosomal intergenic transcribed spacer 2 (ITS2)]. In addition, the phenotypic diversity of adult ticks identified as A. maculatum and A. triste from geographically distinct populations was thoroughly re-examined.ResultsMicroscopic examination identified four putative morphotypes distinguishable by disjunct geographical ranges, but very scant fixed characters. Analysis of the separated mitochondrial datasets mostly resulted in conflicting tree topologies. Nuclear gene sequences were almost identical throughout the geographical ranges of the two species, suggesting a very recent, almost explosive radiation of the terminal operational taxonomic units. Analysis of concatenated molecular datasets was more informative and indicated that, although genetically very close to the A. maculatum - A. triste lineage, A. tigrinum was a monophyletic separate entity. Within the A. maculatum - A. triste cluster, three main clades were supported. The two morphotypes, corresponding to the western North American and eastern North American populations, consistently grouped in a single monophyletic clade with many shared mitochondrial sequences among ticks of the two areas. Ticks from the two remaining morphotypes, south-eastern South America and Peruvian, corresponded to two distinct clades.ConclusionsGiven the paucity of morphological characters, the minimal genetic distance separating morphotypes, and more importantly the fact that two morphotypes are genetically indistinguishable, our data suggest that A. maculatum and A. triste should be synonymized and that morphological differences merely reflect very recent local adaptation to distinct environments in taxa that might be undergoing the first steps of speciation but have yet to complete lineage sorting. Nonetheless, future investigations using more sensitive nuclear markers and/or crossbreeding experiments might reveal the occurrence of very rapid speciation events in this group of taxa. Tentative node dating revealed that the A. tigrinum and A. maculatum - A. triste clades split about 2 Mya, while the A. maculatum - A.triste cluster radiated no earlier than 700,000 years ago.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3186-9) contains supplementary material, which is available to authorized users.

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.

RESUMO:Foram analisados os arquivos do laboratório de Patologia Animal do Hospital Veterinário da UFU de janeiro de 2000 a dezembro de 2010, selecionando protocolos referentes a biopsias cutâneas de cães coletando-se as seguintes informações: diagnóstico morfológico, localização anatômica, idade, sexo e raça dos cães, com o objetivo de realizar um estudo epidemiológico. Foram diagnosticados 549 tumores cutâneos em 543 cães, sendo que 281 cães eram machos e 247 fêmeas. Cães adultos e idosos foram os mais acometidos, assim como os cães sem raça definida, Poodle, Boxer, Pit Bull e Dashchund. Os tumores malignos prevaleceram com 65,39% dos casos, sendo os de origem epitelial os mais frequentes. O carcinoma de células escamosas foi a neoplasia predominante, seguido pelo mastocitoma e histiocitoma. Com relação á localização anatômica prevaleceu as regiões do abdômen (19,49%), cabeça (16,40%) e membros (15,30%). Não houve diferença na probabilidade de apresentar tumor cutâneo com relação ao sexo, porém considerando-se os tipos de tumores há maior probabilidade da população canina apresentar carcinoma de células escamosas e mastocitomas em detrimento dos outros tipos de tumores cutâneos.