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Ilha Grande, Rio de Janeiro State, is an important island remnant of Atlantic Forest and presents four conservation units. Although dogs are forbidden inside conservation units, in Ilha Grande they...

The bacterium Rickettsia rickettsii causes Brazilian spotted fever (BSF), a highly lethal disease that is transmitted by Amblyomma sculptum ticks in areas where capybaras (Hydrochoerus hydrochaeris) are the tick's major hosts. In this study, we evaluated the expansion of a capybara population in a residential park in Sao Paulo state, and the implications of such expansion to the occurrence of ticks and BSF. The capybara population was quantified during 2004-2013. In 2012, there was a BSF human case in the area, culminating in the complete fencing of the residential park and the official culling of all capybaras. Quantification of ticks in the environment was performed by dry ice traps from 2005 to 2018. Domestic dogs in 2006-2011 and capybaras in 2012 were serologically tested for the presence of anti-R. rickettsii antibodies. Our results show that capybara numbers increased ≈5 times from 2004 (41 capybaras) to 2012 (230 capybaras). Dry ice traps collected A. sculptum and Amblyomma dubitatum. The number of A. dubitatum adult ticks was generally higher than A. sculptum adults during 2005-2006; however, during 2012-2013, A. sculptum outnumbered A. dubitatum by a large difference. During 2016-2018 (after capybara culling), the number of both species fell close to zero. The low numbers of A. sculptum adult ticks during 2005-2006 coincided with relatively low capybara numbers (

The study of the ixodofauna in fragments of woods in an urban area is important to the knowledge of species of tick and the dynamic among wild and domestic hosts, allowing to subsidize proposals for the conservation of the fauna and the control of zoonoses such as Brazilian spotted fever. To accomplish the survey, CO2 traps were built up in six different sites of the forest, during a oneyear period, totalizing 12 collections. The ixodids were collected by monitoring the traps and the adjacent vegetation during two hours and put in ethanol 70° GL. At the laboratory they were identified under the stereoscopic optics. At the end of a one-year period of study 2.122 ixodids were colleted, being 793 larvae (37,3%) and 1.277 nymphs (57,8%) of the genus Amblyomma and 102 were adults (4,9%) of the Amblyomma species. The most constant species was Amblyomma cajennense, present in 83,33% of the collections (71 specimen) followed by Amblyomma dubitatum, present in 50% (30 specimen), and Amblyomma calcaratum, 8,33% (one specimen). The observations showed that in the observed environment the populations of Ixodidae have an aggregate distribution, possibly because of the aggregate distribution of the resource, in the case wild hosts. RESUMO O estudo da ixodofauna de fragmentos de mata em área urbana é fundamental para o conhecimento das espécies de carrapatos e para a dinâmica de transmissão entre hospedeiros silvestres e domésticos, gerando subsídios para propostas de conservação da fauna e controle de zoonoses como a Febre Maculosa Brasileira. Para o levantamento, quatro armadilhas de CO2 foram montadas em seis localidades na mata do Morro do Imperador, Juiz de Fora, MG, durante um ano, totalizando 12 coletas. Os ixodídeos foram coletados por monitoramento das armadilhas e vegetação adjacente durante o período de duas horas e acondicionados em etanol 70° GL. No laboratório, os carrapatos foram identificados sob esterioscopia. Ao final de um ano de estudo, foram coletados 2.122 ixodídeos, sendo 793 larvas (37,3%) e 1.277 ninfas (57, 8%) do gênero Amblyomma, além de 102 adultos (4,9%) do gênero Amblyomma. A espécie mais constante foiAmblyomma cajennense, presente em 83,33% das coletas (71 espécimes), seguido de Amblyomma dubitatum presente em 50% (30 espécimes) e Amblyomma calcaratum em 8,33% (um espécime). As observações mostram que, no ambiente estudado, os ixodídeos têm um padrão de distribuição agregado, possivelmente em função da distribuição agregada do recurso, no caso hospedeiros silvestres.

Spotted fever is an acute febrile illness, which is considered severely underreported and misdiagnosed in the Brazilian Pampa, caused by tick-borne Rickettsiae. Here, we report an eco-epidemiological investigation of Rickettsia spp. in ticks from a spotted fever focus in Toropi, southern Brazil. Ticks were collected from capybara carcasses and processed individually to obtain genomic DNA. Rickettsia was investigated using PCR that amplified the rickettsial fragments of the gltA, ompA and htrA genes. DNA from Rickettsia parkeri was found in four of 14 Amblyomma dubitatum ticks collected from capybara carcasses in Toropi and the nearby municipality of Quevedos. We also tested 210A. dubitatum ticks obtained from road-killed capybaras of other localities from the Pampa biome; none of them were positive for Rickettsiae. Thus, in Rio Grande do Sul, two Rickettsia species can be potentially associated to spotted fever: Rickettsia sp. strain Atlantic Rainforest, associated with Amblyomma ovale ticks in the Atlantic Rainforest biome, and R. parkeri, associated both with Amblyomma tigrinum and A. dubitatum ticks in the Pampa biome. Our results reinforce that R. parkeri may be the agent associated with spotted fever in the Brazilian Pampa.

Anaplasma marginale, a well-known cattle pathogen of tropical and subtropical world regions, has been previously molecularly characterized in a giant anteater (Myrmecophaga tridactyla) from Corrientes, Argentina. Ticks or other hematophagous arthropod involved in the wild transmission cycle remained unknown. The aim of the present study was to analyze the simultaneous occurrence of A. marginale in blood samples and ticks from giant anteaters from Corrientes in order to investigate if ticks could be relevant in the transmission among these mammals. Blood samples from 50 giant anteaters collected in different years and 26 ticks Amblyomma dubitatum and A. sculptum were studied through the molecular amplification of two unequivocal species-specific genes from A. marginale: msp5 and msp1&beta, Twenty five giant anteaters and tick organs (salivary glands, gut and oviduct) from 11 ticks tested positive to the A. marginale DNA amplification. The further molecular characterization through MSP1a tandem repeats analysis revealed the presence of genotypes circulating among giant anteaters that had been previously identified in cattle blood samples from the same geographical region. These results confirm the presence of A. marginale in giant anteaters in Corrientes and suggests that A. dubitatum and A. sculptum ticks could be involved in the transmission among giant anteaters. Future studies will determine the role of these tick species in the wild transmission cycle in the study area and the eventual connection with the domestic cycle.

Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is transmitted to humans mainly by the tick Amblyomma sculptum in southeastern Brazil. In most BSF-endemic areas A. sculptum populations are sustained chiefly by capybaras (Hydrochoerus hydrochaeris), which are also the host of another tick species, Amblyomma dubitatum, not implicated in R. rickettsii transmission. Herein, we evaluated the effects of relative humidity (RH), temperature, and water immersion on the successful development of the engorged stages of A. dubitatum and compared them with recently published data under the same experimental conditions for A. sculptum. We showed that free-living developmental stages (engorged larvae, nymphs and females, and eggs) of A. dubitatum had higher survival rates when these stages were submerged in water for different periods of times (24–72 h). On the other hand, higher survival rates were observed for A. sculptum when ticks were incubated at lower RH values, 65 or 78 %, regardless of summer or winter mean temperatures. These results suggest that A. dubitatum is more adapted to humid habitats and seasonally flooding soils than A. sculptum, whereas this latter species should be more adapted than A. dubitatum to drier habitats. The implications of these results for the spatial distribution of A. dubitatum and A. sculptum, in relation to BSF epidemiology, are discussed.

The study aimed to identify species of ticks present in the environment and among captive animals, in Mangaratiba, Rio de Janeiro, Brazil. Ticks were isolated from captive animals by manual examination and free-living ticks in the environment were captured using the flannel drag technique. A total of 91 ticks were obtained (51 adults, 25 nymphs and 15 larvae). The specimens were identified morphologically as Amblyomma sp., Amblyomma dubitatum, Amblyomma ovale and Amblyomma sculptum , and were distributed among five species of native mammals and an exotic bird. This study also reports the first case of infestation of the Australian emu (Dromaius novaehollandiae) by A. sculptum.

Aim: The vulnerability of tropical developing countries to the emerging disease constitutes a critical phenomenon in which the invasion of wild niches by human hosts, contributes to expansion of zoonotic diseases, such as the Brazilian spotted fever (BSF). This study performed a diagnosis of species occurrence of their hosts (Hydrochoerus hydrochaeris) and vectors (Amblyomma sculptum and Amblyomma dubitatum) on the warning area for this reemerging disease in Brazil. Materials and Methods: The study was conducted in a warning area for BSF in the city of Americana, São Paulo state. The occurrence of capybaras was registered by use of binoculars and GPS equipment and 24 acarological researches were performed through 180 CO2 traps. Samples of adult ticks were dissected for salivary glands removal, DNA extraction, and evaluation by polymerase chain reaction (PCR) being tested by initial gltA-PCR, ompA-PCR, and Rickettsia bellii-specific PCR, with the positive samples subjected to sequencing. Results: Eleven clusters of capybaras (total of 71 individuals), were observed along the riparian of Ribeirão Quilombo and 7,114 specimens of A. sculptum and 7,198 specimens of A. dubitatum were collected in this same area. About 568 samples of adult ticks were dissected for salivary glands removal, DNA extraction and evaluation by gltA-PCR, with results of 1.94% (11/568) of positive samples. Results for the initial gltA-PCR indicated none positive sample to Rickettsia species into A. sculptum and 11 positive samples to A. dubitatum. These samples were negative to the ompA-PCR and positive to the Rickettsia bellii-specific PCR protocol and subjected to DNA sequencing, whose result indicated 100% similarity to Rickettsia bellii. The distribution of tick species A. sculptum and A. dubitatum was configured regarding to the biotic potential of the riparian areas, measuring the risks for BSF in peri-urban areas of Americana. Conclusion: These results confirmed a status of epidemiological warning with a strong association of the amplifiers hosts of Rickettsia and tick vectors for the transmission of BSF to humans in this region.

Rickettsia infection of each tick was evaluated by the hemolymph test and polymerase chain reaction (PCR) targeting gltA and ompA genes. All hemolymph tests were negative and PCR of one A. dubitatum detected both Rickettsia genes. Sequence of ompA exhibited a 99% identity with Rickettsia parkeri and R. africae and a 98% identity with R. sibirica. Rickettsia of the spotted fever group in A. dubitatum is described for the first time in an urban area within the municipality of Campo Grande in the state of Mato Grosso do Sul (MS), Brazil. This finding reinforces the importance of more detailed studies to determine the role of A. dubitatum in the transmission of spotted fever agents.

Brazilian spotted fever (BSF) is a potentially lethal human disease caused by Rickettsia rickettsii transmitted by ticks, including Amblyomma sculptum. However, in Southeast Brazil, where most BSF cases occur, capybaras are key hosts for both A. sculptum and Amblyomma dubitatum. We therefore compared the risk of human exposure to these ticks at a non-endemic anthropogenic site in Southeast Brazil where both tick species are maintained by capybaras and occur at high abundance. Cloth dragging, human baits and CO2 traps were used to assess tick abundance and risk for human exposure. The two tick species displayed profound differences in behavior and microhabitat use. Notably, A. sculptum but not A. dubitatum quested for hosts openly from vegetation (ambush behavior) and infested human baits. Furthermore, A. dubitatum was more aggregated at a specific site whereas A. sculptum was more widespread along differing and drier microhabitats. Adults and nymphs of both species were infected with Rickettsia bellii. Overall, the results indicate that even though both species co-existed in the same area, A. sculptum posed a greater risk for biting humans and thus also for transmitting tick-borne pathogens.

Rickettsia parkei is the etiological agent of spotted fever in Uruguay, where is transmitted to humans by the tick Amblyomma triste. In the present study, ticks were collected from capybaras (Hydrochoerus hydrochaeris) and domestic dogs during 2011-2012 in different parts of Uruguay. Three out of 11 (27.3%) Amblyomma dubitatum ticks collected from capybaras, and 4 out of 6 (66.7%) Amblyomma tigrinum ticks collected from dogs were shown by molecular analyses to be infected by Rickettsia parkeri strain Maculatum 20. Until the present work, A. triste was the only tick species that was found infected by R. parkeri in Uruguay. This is the first report of R. parkeri infecting these two tick species in Uruguay, expanding the current distribution of this rickettsial pathogen in the country.

Amblyomma yucumense was recently described from specimens collected in the Turvo State Park, southern Brazil. In search of this tick species, free-living ticks were collected at the Mocona Provincial Park and the Yaboti Biosphere Reserve in Misiones province, Argentina. A total of 594 ticks were collected, of which 448 were Amblyomma brasiliense, 90 Amblyomma incisum , one Amblyomma ovale , 48 Haemaphysalis juxtakochi and seven A. yucumense. The latter was confirmed by the presence of certain morphological characters and the analysis of sequences of a 410-bp fragment of the mitochondrial 16S rDNA performed to representative specimens. The sequences showed 100% identity with that of A. yucumense from Turvo State Park in Brazil. Amblyomma yucumense , Amblyomma dubitatum and Amblyomma coelebs phylogenetically group together and are morphologically similar, though they seem to have distinct ecological preferences. Amblyomma coelebs has only been found in northern Misiones province, while the most numerous records of A. dubitatum come from the central area of the province. Until now, the distribution of A. yucumense in Argentina is restricted to Mocona and Yaboti. The findings in this study expand A. brasiliense , A. incisum , A. ovale and H. juxtakochi distribution ranges to the south, and we report for the first time the presence of A. yucumense in Argentina.

We supply information about hosts and distribution of Amblyomma dubitatum. In addition, we carry out an analysis of genetic divergence among specimens of A. dubitatum from different localities and with respect to other Neotropical Amblyomma species, using sequences of 16S rDNA gene. Although specimens of A. dubitatum were collected on several mammal species as cattle, horse, Tapirus terrestris, Mazama gouazoubira, Tayassu pecari, Sus scrofa, Cerdocyon thous, Myocastor coypus, Allouata caraya, Glossophaga soricina and man, most records of immature and adult stages of A. dubitatum were made on Hydrochoerus hydrochaeris, making this rodent the principal host for all parasitic stages of this ticks. Cricetidae rodents (Lundomys molitor, Scapteromys tumidus), opossums (Didelphis albiventris) and vizcacha (Lagostomus maximus) also were recorded as hosts for immature stages. All findings of A. dubitatum correspond to localities of Argentina, Brazil, Paraguay and Uruguay, and they were concentrated in the Biogeographical provinces of Pampa, Chaco, Cerrado, Brazilian Atlantic Forest, Parana Forest and Araucaria angustifolia Forest. The distribution of A. dubitatum is narrower than that of its principal host, therefore environmental variables rather than hosts determine the distributional ranges of this tick. The intraspecific genetic divergence among 16S rDNA sequences of A. dubitatum ticks collected in different localities from Argentina, Brazil and Uruguay was in all cases lower than 0.8%, whereas the differences with the remaining Amblyomma species included in the analysis were always bigger than 6.8%. Thus, the taxonomic status of A. dubitatum along its distribution appears to be certain at the specific level. Fil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; Argentina Fil: Venzal, José M.. Universidad de la Republica, Salto; Uruguay Fil: Labruna, Marcelo B.. Universidade de Sao Paulo; Brasil Fil: Mastropaolo, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; Argentina Fil: González, Enrique M.. Museo Nacional de Historia Natural Uruguay; Uruguay Fil: Mangold, Atilio Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; Argentina Fil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

During two field trips in the state of Sao Paulo, two of us became infested by two adults, three nymphs, and one larva of the capybara tick, Amblyomma dubitatum Neumann, 1899 (= Amblyomma cooperi Nuttall and Warbuton, 1908). Previously, there has been only a single report of an A. dubitatum adult tick from humans. Our observations on human infestation by all parasitic stages of A. dubitatum suggest that this behavior may be more frequent than previously thought, especially in the case of immatures, which are herein reported from humans for the first time.

En octubre de 2015, una ninfa de garrapata fue colectada sobre un ejemplar macho de Procyon cancrivorus hallado muerto a la vera de la Ruta Nacional 119 en las cercanías de la ciudad de Mercedes, provincia de Corrientes, Argentina. La ninfa colectada fue identificada morfológica y molecularmente como Amblyomma dubitatum, y la misma se encontró infectada con la alfaproteobacteria Rickettsia bellii. Este reporte constituye el primer registro de la asociación A. dubitatum P. cancrivorus In October 2015, a tick nymph was collected from a male Procyon cancrivorus found dead at the roadside of the National Road 119 near Mercedes city, Corrientes province, Argentina. The nymph collected was morphologically and molecularly identified as Amblyomma dubitatum and it was found infected with the alpha-proteobacterium Rickettsia bellii. To the best of our knowledge, this report constitutes the first record of the A. dubitatum - P. cancrivorus association. Fil: Eberhardt, María Ayelen Teresita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina Fil: Fernandez Basile, Camilo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina Fil: Zurvera, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina Fil: Monje, Lucas Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina

The present study evaluated rickettsial infection in Amblyomma spp. ticks collected in a farm in Coronel Pacheco, a Brazilian spotted fever (BSF) endemic area. A total of 78 A. cajennense and 78 A. dubitatum free-living adult ticks were collected and tested by polymerase chain reaction (PCR) targeting a fragment of the rickettsial gene gltA. Only one pool of three A. cajennense ticks showed the expected product by PCR. This pool was further tested by PCR using sets of primers targeting the rickettsial genes gltA, ompA, and ompB. All reactions yielded the expected bands that by sequencing, showed 100% identity to the corresponding sequences of the Rickettsia rickettsii gene fragments gltA (1063-bp), ompA (457-bp), and ompB (720-bp). The minimal infection rate of R. rickettii in the A. cajennense population was 1.28% (at least one infected tick within 78 ticks). The present study showed molecular evidence for the presence of R. rickettsii in A. cajennense from a BSF-endemic area in Coronel Pacheco, state of Minas Gerais. Although R. rickettsii has been previously reported infecting A. cajennense ticks in Brazil and other Latin American countries, the present study performed the first molecular characterization of R. rickettsii from the tick A. cajennense.

The life cycle of Amblyomma dubitatum was described based on the seasonal distribution of all parasitic stages and the development periods of engorged ticks under different conditions of photoperiod and temperature. All stages were found active along the entire year in the study area. Larvae peaked from May to July, nymphs peaked from July to October, and females peaked from November to March. This pattern represents a life cycle with one generation per year with most of the ticks reaching adulthood during the warmest months. The analysis of the effect of the photoperiod on the development of A.dubitatum showed no indication of morphogenetic diapause. Exposure of ticks to field conditions indicates a delay in metamorphosis of immature stages, in the oviposition of females and in the incubation of eggs, which were associated with low winter temperatures. The results indicate that though A. dubitatum has a one year life cycle, more than one cohort can co-exist within the same population in a certain interval of time. Finally, the potential role of small rodents as hosts for larvae and nymphs of A. dubitatum is confirmed. Fil: Debárbora, Valeria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Oscherov, Elena Beatriz. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología. Laboratorio Biología de los Parásitos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Hydrochoerus hydrochaeris serves as a host for a number of tick species that play an important role as vectors of emergent zoonotic diseases. This is the first report of the occurrence of Amblyomma cajennense adults and Amblyomma dubitatum nymphs retrieved from capybaras run over on two highways in the state of Santa Catarina, southern Brazil. Key words: Ticks, ixodidae, biology, morphology, nymphs

Entre janeiro de 1997 e dezembro de 2007 foi realizada uma investigação epidemiológica objetivando identificar casos de parasitismo por carrapatos em humanos na comunidade que invadiu e está ocupando Área de Proteção Ambiental – (APA), entre o “Parque Estadual do Maciço da Pedra Branca” e o “Parque Nacional da Floresta da Tijuca” na cidade do Rio de Janeiro, RJ. Foram comprovados 6.072 casos de ixodidose, relacionados às espécies: Amblyomma aureolatum (Pallas), Amblyomma cajennense (Fabricius), Amblyomma dubitatum Neumann, Amblyomma ovale Kock, Amblyomma varium Kock, Ixodes loricatus Neumann e Rhipicephalus sanguineus (Latreille) em relação parasitária com moradores do espaço trabalhado. Foram calculados indicadores de saúde relacionados ao coeficiente de prevalência, índice de abundância, coeficiente de dominância, intensidade média de parasitismo, e coeficiente de correlação entre o parasitismo e o sexo, faixa etária, atividade social dos infectados, o risco relativo, e o risco atribuível para o parasitismo, e desenvolvida estatística descritiva para visualização do fenômeno, e estatística analítica dos dados para dar suporte às conclusões. Foi salientada a importância destas espécies de ixodídeos na transmissão de patógenos, bioagentes de doenças infecciosas reincidentes, ou de recém introdução no espaço geopolítico brasileiro. Human Parasitism for Ticks in the Atlantic Forest, Rio de Janeiro, RJ, Brazil Abstract. From January 1997 to December 2007 was carried out a epidemiologic investigation to identify a cases of parasitism in the human community that is invaded and occupied area of Environmental Protection - (BB), between the “State Park of the Pedra Branca” and “National Park of Tijuca Forest” located in Rio de Janeiro, RJ, Brazil. These work comprouved 6,072 cases of ixodidosis in relation with species: Amblyomma aureolatum (Pallas), Amblyomma cajennense (Fabricius), Amblyomma dubitatum Neumann, Amblyomma ovale Kock, Amblyomma varium Kock, Ixodes loricatus Neumann and Rhipicephalus sanguineus (Latreille) infected local human living into the space worked. Through an analysis of statistical data demonstrating transcribes the importance of transmission of pathogens and serves as a model for understanding of the human X tick.

INTRODUCTION: Spotted fevers are emerging zoonoses caused by Rickettsia species in the spotted fever group (SFG). Rickettsia rickettsii is the main etiologic agent of Brazilian spotted fever (BSF) and it is transmitted by Amblyomma spp. ticks. METHODS: The study aimed to investigate SFG rickettsiae in the Arthur Thomas Municipal Park in Londrina, PR, by collecting free-living ticks and ticks from capybaras and blood samples from personnel working in these areas. Samples from A. dubitatum and A. cajennense were submitted for PCR in pools to analyze the Rickettsia spp. gltA (citrate synthase gene). RESULTS: All the pools analyzed were negative. Human sera were tested by indirect immunofluorescence assay with R. rickettsii and R. parkeri as antigens. Among the 34 sera analyzed, seven (20.6%) were reactive for R. rickettsii: four of these had endpoint titers equal to 64, 2 titers were 128 and 1 titer was 256. None of the samples were reactive for R. parkeri. An epidemiological questionnaire was applied to the park staff, but no statistically significant associations were identified. CONCLUSIONS: The serological studies suggest the presence of Rickettsiae related to SFG that could be infecting the human population studied; however, analysis of the ticks collected was unable to determine which species may be involved in transmission to humans. INTRODUÇÃO: A febre maculosa é uma zoonose emergente causada por espécies de Rickettsia do grupo febre maculosa (GFM). Rickettsia rickettsii é o principal agente etiológico da febre maculosa brasileira (FMB) e é transmitida por Amblyomma spp. MÉTODOS: Com o objetivo de obter informações sobre GFM Rickettsiae no Parque Municipal Arthur Thomas em Londrina, PR, carrapatos de vida livre e de capivaras foram coletados, assim como amostras de sangue das pessoas que trabalham no parque. A. dubitatum e A. cajennense foram submetidos à PCR em pools para analises de Rickettsia spp. gltA (citrate synthase gene). RESULTADOS: Todos os pools de carrapatos analizados foram negativos. Soros de humanos foram testados pela imunofluorescência indireta com antigenos de R. rickettsii e R. parkeri. Entre os 34 soros analisados, 7 (20,6%) foram positivos para R. rickettsii. Destes, quatro apresentaram títulos iguais a 64, dois iguais a 128 e um, igual a 256, mas nenhum soro reagiu com R. parkeri. Não houve nenhuma associação, estatisticamente significante, entre as variáveis analisadas no questionário epidemiológico fornecido às pessoas que participaram da pesquisa. CONCLUSÕES: Os estudos sorológicos sugerem a presença de alguma Rickettsiae relacionada ao GFM que poderiam estar infectando a população humana estudada. Entretanto, as análises dos carrapatos foram inconclusivas para determinar qual espécie poderia estar envolvida na transmissão para os humanos.

Foi pesquisada a presença de riquétsias em 3.545 carrapatos Amblyomma cajennense e 2.666 Amblyomma dubitatum. Através do teste de hemolinfa, reação em cadeia pela polimerase e isolamento de rickettsia em cultivo celular, todos os Amblyomma cajennense foram negativos, sendo que 634 (23,8%) Amblyomma dubitatum mostraram-se infectados com Rickettsia bellii. The 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.

O ciclo biologico do Amblyomma dubitatum, que se alimentava experimentalmente em coelhos domesticos, foi avaliado em condicoes laboratoriais e comparado com dados recentemente obtidos de infestacoes experimentais em capivaras (Hydrochaeris hydrochaeris), hospedeiros naturais para essa especie. Os coelhos foram considerados hospedeiros experimentais adequados para larvas e ninfas porque quatro dos cinco parâmetros avaliados (numero de carrapatos que ingurgitaram, periodo de alimentacao, percentagem de carrapatos que realizaram muda e periodo de pre-muda) foram semelhantes aos resultados obtidos com capivaras. As percentagens diarias de desprendimento e de muda das larvas e ninfas confirmam os coelhos como hospedeiros experimentais adequados para esses estagios de A. dubitatum. Os resultados do experimento indicam que os coelhos sao hospedeiros inadequados para os adultos.