Browsing by Author "Labruna, Marcelo Bahia"

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    Caracterização de Rickettsia spp. circulante em foco silencioso de febre maculosa brasileira no Município de Caratinga, Minas Gerais, Brasil.
    (2006) Cardoso, Luciane Daniele; Freitas, Renata Nascimento de; Mafra, Cláudio Lísias; Neves, Cristiane Vilas Boas; Figueira, Fátima Cristina Bacellar; Labruna, Marcelo Bahia; Gennari, Solange Maria; Walker, David Hughes; Galvão, Márcio Antônio Moreira
    The present study was intended to characterize Rickettsia spp. circulating in arthropod vectors in Caratinga,Minas Gerais, Brazil, by PCR and to investigate the presence of antibodies against the spotted fever Rickettsiae group (SFRG) in dogs and horses. 2,610 arthropods were collected and taxonomically identified. DNA samples obtained from these vectors were submitted to PCR and cycle-sequenced. Ctenocephalides and Amblyomma cajennense showed sequences presenting 100.0% homology with R. felis. A sequence obtained from Rhipicephalus sanguineus showed 99.0% homology with R. felis, and a sequence from A. cajennense showed 97.0% homology with R. honei and R. rickettsii. Canine (73) and equine (18) serum samples were tested by indirect fluorescent antibody (IFA) using R. rickettsii antigen. Only three of the equine sera tested (17.0%) had positive antibody titers. Molecular detection of rickettsiae species potentially pathogenic to humans in arthropod vectors and the presence of seroreactivity to SFRG in horses show the risk of transmission of rickettsiosis in this area and the need to maintain continuous epidemiological surveillance for rickettsial diseases.
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    Prevalence of antibodies to spotted fever group rickettsiae in humans and domestic animals in a brazilian spotted fever−endemic area in the state of São Paulo, Brazil : serologic evidence for infection by Rickettsia rickettsii and another spotted fever group rickettsia.
    (2004) Horta, Maurício Cláudio; Labruna, Marcelo Bahia; Sangioni, Luis Antônio; Vianna, Manoella Campostrini Barreto; Gennari, Solange Maria; Galvão, Márcio Antônio Moreira; Mafra, Cláudio Lísias; Vidotto, Odilon; Schumaker, Teresinha T. S.; Walker, David Hughes
    In serum samples obtained from all the healthy humans, horses, dogs, and donkeys present on three farms in the Pedreira Municipality, an endemic area for Brazilian spotted fever, an indirect immunofluorescence assay (IFA) detected antibodies against Rickettsia rickettsii in 17 (77.3%) horses, 5 (31.3%) dogs (titers ranging from 64 to 4,048), and none of 4 donkeys or 50 humans. Five canine and eight equine sera with high antibody titers to R. rickettsii were also tested by IFA against R. bellii, R. akari, and R. africae antigens. Sera from two horses and two dogs that showed similar high antibody titers against two rickettsial antigens were evaluated after cross-absorption. Sera from seven horses and two dogs contained antibodies specific for R. rickettsii, and one dog serum had antibodies against a Rickettsia species very closely related to R. africae. The latter may have been caused by infection with the recently identified COOPERI strain.
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    Rickettsia in synanthropic and domestic animals and in their host from two areas of low endemicity for Brazilian spotted fever, in the eastern region of Minas Gerais state, Brazil.
    (2010) Milagres, Bruno Silva; Padilha, Amanda de Freitas; Gabriel G. Gomes; Montandon, Carlos Emmanuel; Pena, Dárlen Crísthiê Hermelinda; Bastos, Fernanda Aparecida Nieri; Silveira, Iara; Pacheco, Richard de Campos; Labruna, Marcelo Bahia; Bouyer, Donald H.; Freitas, Renata Nascimento de; Walker, David Hughes; Mafra, Cláudio Lísias; Galvão, Márcio Antônio Moreira
    The aim of this study was to understand the current epidemiology of rickettsial diseases in two rickettsialendemic regions in Brazil. In the municipalities of Pingo D’Agua and Santa Cruz do Escalvado, among serum samples obtained from horses and dogs, reactivity by immunofluorescent assay against spotted fever group rickettsiae was verified. In some serum samples from opossums ( Didelphis aurita ) captured in Santa Cruz do Escalvado, serologic response against rickettsiae was also verified. Polymerase chain reaction identified rickettsiae only in ticks and fleas obtained in Santa Cruz do Escalvado. Rickettsiae in samples had 100% sequence homology with Rickettsia felis . These results highlight the importance of marsupials in maintenance of the sylvatic cycle of rickettsial disease and potential integration with the domestic cycle. Our data also support the importance of horses and dogs as sentinels in monitoring circulation of rickettsiae in an urban area.
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    Rickettsial infection in animals and brazilian spotted fever endemicity.
    (2005) Sangioni, Luis Antônio; Horta, Maurício Cláudio; Vianna, Manoella Campostrini Barreto; Gennari, Solange Maria; Soares, Rodrigo Martins; Galvão, Márcio Antônio Moreira; Schumaker, Teresinha T. S.; Ferreira, Fernando; Vidotto, Odilon; Labruna, Marcelo Bahia
    We compared the rickettsial infection status of Amblyomma cajennense ticks, humans, dogs, and horses in both Brazilian spotted fever (BSF)–endemic and –nonendemic areas in the state of São Paulo, Brazil. Most of the horses and few dogs from BSF-endemic areas had serologic titers against Rickettsia rickettsii antigens. In contrast, no dogs or horses from BSF-nonendemic areas had serologic titers against R. rickettsii antigens, although they were continually exposed to A. cajennense ticks. All human serum samples and ticks from both areas were negative by serologic assay and polymerase chain reaction, respectively. Our results indicate that surveys of horse serum are a useful method of BSF surveillance in areas where humans are exposed to A. cajennense ticks. In addition, we successfully performed experimental infection of A. cajennense ticks with R. parkeri.
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    Rickettsial spotted fever in Capoeirão Village, Itabira, Minas Gerais, Brazil.
    (2008) Vianna, Manoella Campostrini Barreto; Horta, Maurício Cláudio; Sangioni, Luis Antônio; Cortez, Adriana; Soares, Rodrigo Martins; Mafra, Cláudio Lísias; Galvão, Márcio Antônio Moreira; Labruna, Marcelo Bahia; Gennari, Solange Maria
    The present study investigated the infection by spotted fever rickettsia in an endemic area for Brazilian spotted fever (BSF; caused by Rickettsia rickettsii) in Minas Gerais State, Brazil. Human, canine and equine sera samples, and Amblyomma cajennense adult ticks collected in a rural area of Itabira City, Minas Gerais State were tested for rickettsial infection. Through Immunofluorescence Assay (IFA) we demonstrated the presence of antibodies anti-R. rickettsii in 8.2%, 81.3% and 100% of the human, canine and equine sera, respectively. None of the 356 tick specimens analyzed were positive for Rickettsia by the hemolymph test or Polymerase Chain Reaction technique (PCR) for the htrA and the gltA genes. Our serological results on horses and dogs (sentinels for BSF) appoint for the circulation of a SFG Rickettsia in the study area, however in a very low infection rate among the A. cajennense tick population.
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    Spotted fever group rickettsia in small rodents from areas of low endemicity for brazilian spotted fever in the eastern region of Minas Gerais state, Brazil.
    (2013) Milagres, Bruno Silva; Padilha, Amanda de Freitas; Montandon, Carlos Emmanuel; Freitas, Renata Nascimento de; Pacheco, Richard de Campos; Walker, David Hughes; Labruna, Marcelo Bahia; Mafra, Cláudio Lísias; Galvão, Márcio Antônio Moreira
    We investigated the humoral immune response against different species of Rickettsia in serum samples from small rodents collected in two areas of a silent focus for Brazilian spotted fever in the eastern region of Minas Gerais State, Brazil. Sera samples were analyzed by indirect immunofluorescence assay using antigens from Rickettsia species of the spotted fever, ancestral, and transition groups. Titers ³ 1:64 were considered positive. In Santa Cruz do Escalvado, 94% (30 of 32) of the samples collected from Rattus rattus, 22% (5 of 23) from Nectomys squamipes, and 80% (4 of 5) from Akodon sp., reacted by indirect immunofluorescence assay with Rickettsia antigens of the spotted fever group. In the municipality of Pingo D’A´ gua, 84% (26 of 31) of the samples collected from R. rattus, 86% (6 of 7) of the samples from Oryzomys subflavus, 86% (6 of 7) from N. squamipes, and 100% (1 of 1) from Bolomys sp. contained antibodies that reacted with rickettsial antigens of the spotted fever group. These results demonstrated the previous exposure of small rodents to spotted fever group Rickettsia, suggesting the participation of these animals in the natural history of these rickettsiae in this region.