Amblyomma imitator ticks as vectors of Rickettsia rickettsii, Mexico.

Real-time PCR of Amblyomma imitator tick egg masses obtained in Nuevo Leon State, Mexico, identified a Rickettsia species. Sequence analyses of 17-kD common antigen and outer membrane protein A and B gene fragments showed to it to be R. rickettsii, which suggested a potential new vector for this bacterium.

Rickettsiosis of the genus Rickettsia in South America.

In South America, human cases of infection by the genus Rickettsia have been described in several countries in the last twenty years. The role of international organizations, such as the Centers for Disease Control and Prevention in Atlanta, Georgia, USA and the World Health Organization Collaborating Center for Tropical Diseases at the University of Texas Medical Branch at Galveston, Texas, USA, was very important in the last twenty years for the development of surveillance systems and for the increase in notification of rickettsial diseases by the countries of South America. We hope that the next goal will be prevention and control of rickettsial diseases in the countries of South America, as well as maintaining the programs developed during the last twenty years, so that a good health system and improved social conditions will be possible.

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.

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.

Human ehrlichioses in Brazil: first suspect cases.

Brazilian spotted fever (BSF) rickettsiosis is the most common and recognized of the human rickettsioses in Brazil. It is difficult to establish the diagnosis of human rickettsiosis infection by routine microbiologic methods, creating a false idea that Rickettsia and Ehrlichia infections are rare and without importance. New tick-borne diseases, like human granulocytic anaplasmosis (HGA) and human monocytic ehrlichiosis (HME), have been described in many countries. These diseases can present symptoms similar to rickettsioses of the spotted fever group, and they are transmitted by ixodid ticks. The first two suspected cases of human ehrlichiosis in Brazil were first considered to be cases of BSF. The differential diagnosis was made at the Minas Gerais Rickettsiosis Public Health Laboratory. The clinical and laboratory findings, with positive serology for the HME agent, indicated suspected cases of human ehrlichioses in Brazil.

[Emerging and reemerging rickettsiosis in an endemic area of Minas Gerais State, Brazil]. / Rickettsioses emergentes e reemergentes numa região endêmica do Estado de Minas Gerais, Brasil.

This article describes a serological survey for rickettsiosis in the county of Novo Cruzeiro, Minas Gerais State, Brazil, in 1998, testing schoolchildren and dogs. Sera included 331 samples from schoolchildren from an endemic area and 142 samples from schoolchildren from a non-endemic area in the county. All children examined were healthy and had not reported clinical symptoms of Brazilian spotted fever prior to the serological survey. Some 35 children in the endemic area were reactive to Rickettsia rickettsiiby indirect fluorescent antibody (IFA) with a titer of 1:64, corresponding to 10.6%. Sera from 73 dogs were tested, showing seroreactivity (IFA 1:64) to Rickettsia rickettsi, Ehrlichia chaffeensis, and Ehrlichia canisin 3 (4.11%), 11 (15.07%), and 13 (17.81%), respectively. The results in schoolchildren and the presence of canine seroreactivity to Ehrlichiaspecies that are potentially pathogenic to humans suggests the risk of transmission of other Rickettsiaein the study area.

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.

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 ≥ 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'Água, 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.

Rickettsia in synanthropic and domestic animals and their hosts from two areas of low endemicity for Brazilian spotted fever in the eastern region of Minas Gerais, Brazil.

The aim of this study was to understand the current epidemiology of rickettsial diseases in two rickettsial-endemic 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.

Rickettsial infection in animals and Brazilian spotted fever endemicity.

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 Sao 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.

Rickettsia felis in Ctenocephalides spp. fleas, Brazil.

In June 2000, suspected cases of Brazilian spotted fever (BSF) occurred in Coronel Fabriciano Municipality, Minas Gerais State, Brazil. Pooled fleas collected near two fatal cases contained rickettsial DNA. The nucleotide sequence alignment of the 391-bp segment of the 17-kDa protein gene showed that the products were identical to each other and to the R. felis 17-kDa gene, confirming circulation of R. felis in Brazil.

Human ehrlichioses in Brazil: first suspect cases

Brazilian spotted fever (BSF) rickettsiosis is the most common and recognized of the human rickettsioses in Brazil. It is difficult to establish the diagnosis of human rickettsiosis infection by routine microbiologic methods, creating a false idea that Rickettsia and Ehrlichia infections are rare and without importance. New tick-borne diseases, like Human Granulocytic Anaplasmosis (HGA) and Human Monocytic Ehrlichiosis (HME), have been described in many countries. These diseases can present symptoms similar to rickettsioses of the spotted fever group, and they are transmitted by ixodid ticks. The first two suspected cases of human ehrlichiosis in Brazil were first considered to be cases of BSF. The differential diagnosis was made at the Minas Gerais Rickettsiosis Public Health Laboratory. The clinical and laboratory findings, with positive serology for the HME agent, indicated suspected cases of human ehrlichioses in Brazil.

Rickettsioses emergentes e reemergentes numa regiäo endêmica do Estado de Minas Gerais, Brasil / Emerging and reemerging rickettsiosis in an endemic area of Minas Gerais State, Brazil

O trabalho descreve um inquérito sorológico para rickettsioses em escolares e cäes de Novo Cruzeiro, Minas Gerais, Brasil, em 1998. Trezentos e trinta e um escolares pertenciam a uma área endêmica e 142 a uma área näo endêmica do município. Trinta e nove (10,1 por cento) soros foram reativos à Reaçäo de Imunofluorescência Indireta (RIFI) para Rickettsia rickettsiino título de 1:64, sendo que dentre esses reativos, 35 eram de estudantes de escolas de área endêmica. Dentre os 73 cäes analisados quanto à presença de anticorpos anti R. rickettsii, anti Ehrlichia chaffeensise anti Ehrlichia canisà RIFI no título de 1:64, 3 (4,11 por cento), 11 (15,07 por cento) e 13 (17,81 por cento) desses animais foram reativos respectivamente aos antígenos testados. Conclui-se que, a sororeatividade para R. rickettsiiem indivíduos sadios sem história prévia de febre maculosa brasileira, uma doença marcante por sua alta letalidade, e a presença de sororeatividade para Ehrlichiacom potencial patogênico para o homem em cäes, nos leva a indagar sobre a transmissäo ao homem de outras espécies da família Rickettsiae na área estudada

Ingestäo de broto de samambaia e risco de câncer de esôfago e estômago na regiäo de Ouro Preto, MG / Ingestion of bracken and risk of oesophageal and stomach cancer in the region of Ouro Preto, Minas Gerais, Brazil

A populaçäo da regiäo de Ouro Preto, MG, tem o hábito de consumir as folhas jovens de uma planta (Pteridium aquilinum), chamada popularmente de broto de samambaia (BS). A alta incidência de câncer de esôfago e estômago na regiäo, em relaçÝo a outras áreas do estado onde o consumo de BS näo se verifica, levou-nos a investigar a possível influênciada da ingestäo do vegetal na ocorrência daquelas patologias. Foi desenvolvido um estudo retrospectivo de casos e controles baseado em esquema de vigilância epidemiológica estabelecido nos dois únicos serviços de endoscopia da regiäo. Quarenta e seis casos confirmados histologicamente foram pareados com 40 controles que näo apresentavam alteraçöes ao exame endoscópico. O consumo de BS foi identificado através de entrevista com os pacientes próximos, em caso de morte. Os hábitos de fumar e de consumir bebida alcoólica foram também considerados. A medida de associaçäo utilizada foi a "Razäo das Chances" ("Odds Ratio", OR). Pacientes que ingeriam BS apresentaram aumento de 5,47 vezes na "Razäo de Chances" para câncer de trato digestivo alto (esôfago e estômago), em comparaçäo com os controles. Na análise multivariada, controlando-se os fatores de confusäo como álcool, fumo, sexo e idade, encontrou-se ainda OR de 3,63 vezes para os dois tipos de câncer citados. Calcularam-se ainda os riscos separadamente para cada tipo de câncer, sendo os resultados ainda significativos, ou seja, OR de 3,40 para câncer de asôfago e de 3,45 para câncer de estômago, valores esses que passam para 3,93 e 3,51 respectivamente quando controlados os fatores de confusäo acima mencionados.