Prevalência de anticorpos anti-Rickettsia spp. em cães da cidade de Belo Horizonte, MG

Ixodid diversity and detection of spotted fever group Rickettsia spp. in ticks collected on birds in the Brazilian Atlantic Forest

The Brazilian Atlantic Forest helds one of the most diverse and unique avifauna in the world. Many vertebrate species are reservoirs of tick-borne pathogens, and birds are an important group among them due to their mobility which facilitates the dispersion of ticks and the infectious agents they carry. This study brings data on the tick diversity parasitizing birds and the molecular detection of Rickettsia spp. in these arthropods. Birds (n = 773) were captured, identified, and banded at Mata do Paraíso Research, Training, and Environmental Education Center located in Viçosa, Minas Gerais, Brazil. Birds were checked for the presence of ticks, which were individually collected, identified, and molecularly processed through Polymerase Chain Reaction (PCR) for the detection of Rickettsia spp. A total of 130 individuals were infested by ticks, and 479 tick specimens were collected, showing a seasonal distribution of the life stages throughout the year. Ticks were identified as Amblyomma longirostre (59/479); Amblyomma calcaratum (20/479); Amblyomma varium (3/479); Amblyomma sculptum (2/479) and Amblyomma spp. larvae (395/479). Seasonal distribution of the life stages of ticks was observed along the year and significant negative correlations were found between temperature and collected ticks and temperature and infested birds. From the evaluated samples of ticks, 25.44% (n= 43/169) scored positive for Rickettsia spp., and sequence analysis indicated high nucleotide identity with Rickettsia rhipicephali, R. massiliae, R. africae and R. honei marmionii. The potential for dispersal of ticks by birds added to the aggressiveness of species of the genus Amblyomma and the zoonotic potential of some species of Rickettsia are quite worrying when we consider that the study area is widely attended by students, researchers, people from the city and neighboring municipalities.

Research of Rickettsia spp. and Borrelia spp. in dogs in Southeast Brazil

Dogs are important in the epidemiology of tick-borne diseases, playing a significant role mainly in endemic areas of rickettsiosis and borreliosis, and serving as sentinels in epidemiological surveys. We analyzed the distribution of Rickettsia and Borrelia spp. in dogs and their ticks in the municipalities of Guaxupé, Minas Gerais, and Tapiratiba, São Paulo, Brazil, two areas non-endemic for Baggio-Yoshinari Syndrome (BYS) and rickettsiosis. Serum from 242 dogs of different ages (>12 months) and breeds were tested by the Indirect Immunofluorescence Assay (IFA) using specific antigens for Rickettsia rickettsii, Rickettsia parkeri, Rickettsia amblyommatis, Rickettsia rhipicephali, and Rickettsia bellii, and by an indirect Enzyme Linked Immunosorbent Assay (ELISA) for the detection of homologous IgG antibodies against Borrelia burgdorferi American strain G39/40. Ticks were collected from the animals and subjected to PCR and nested PCR for detection of Rickettsia spp. (synthase citrate gene) and Borrelia spp. (flagellin gene). Serological data showed that 7.85% (19/242) of the analyzed dogs were seropositive for at least one of the five Rickettsia antigens tested; one (0.41%) was considered seropositive for R. parkeri (1:64) and one (0.41%) for R. rickettsii (1:256). Nine (3.72%) were considered seropositive for R. bellii and one (0.41%) for R. amblyommatis; a seroprevalence of 13.64% (33/242) for IgG class immunoreactive antibodies against B. burgdorferi was observed. A total of 148 ticks were collected from the dogs; among these 3.40% were identified as larvae of the genus Rhipicephalus and 0.70% of the genus Amblyomma; 89.8% were identified as Rhipicephalus sanguineus, 4.70% Amblyomma sculptum and 1.40% Amblyomma ovale; all negative for PCR of Rickettsia spp. and nested PCR for Borrelia spp.. The serological findings of this study suggest the circulation of Rickettsiae associated with the spotted fever group and vector ticks, just like Borrelia spp. in a non-endemic Brazilian area, drawing attention to the possibility of a zoonotic cycle in the region.

Biodiversity of Potential Vectors of Rickettsiae and Epidemiological Mosaic of Spotted Fever in the State of Paraná, Brazil

Spotted Fever Rickettsioses (SFR) are diseases caused by bacteria of the genus Rickettsia, and are transmitted mainly by ticks. Its eco-epidemiological scenarios vary spatially, and may also vary over time due to environmental changes. It is the main disease transmitted by ticks to humans in Brazil, with the state of Paraná (PR) having the sixth highest number of notified incidences in the country. However, information is lacking regarding the SFR disease cycles at likely infection sites within PR. During case investigations or environmental surveillance in PR for SFR, 28,517 arthropods were collected, including species known or potentially involved in the SFR cycles, such as Amblyomma sculptum, Amblyomma aureolatum, Amblyomma ovale, Amblyomma dubitatum, Amblyomma parkeri, Ctenocephalides felis felis, and Rhipicephalus sanguineus sensu lato. From these Rickettsia asembonensis, Rickettsia bellii, Rickettsia felis, Rickettsia parkeri strain Atlantic Rainforest and Candidatus Rickettsia paranaensis were detected. Ectoparasite abundance was found to be related with specific hosts and collection environments. Rickettsiae circulation was observed for 48 municipalities, encompassing 16 Health Regions (HR). As for socio-demographic and assistance indicators, circulation occurred largely in the most urbanized HR, with a higher per capita Gross Domestic Product, lower Family Health Strategy coverage, and with a higher ratio of beds in the Unified Health System per thousand inhabitants. For environmental variables, circulation occurred predominantly in HR with a climatic classified as “subtropical with hot summers” (Cfa), and with forest type phytogeographic formations. In terms of land use, circulation was commonest in areas with agriculture, pasture and fields and forest cover. Rickettsiae were circulating in almost all hydrographic basins of PR state. The results of this study provide the first descriptive recognition of SFR in PR, as well as outlining its eco-epidemiological dynamics. These proved to be quite heterogeneous, and analyzed scenarios showed characteristics strongly-associated with the outbreaks, with cases presenting clinical variation in space, so illustrating the complexity of scenarios in PR state. Due to the diversity of the circumstances surrounding SFR infections in PR, public health initiatives are necessary to foster a better understanding of the dynamics and factors effecting vulnerability to SFR in this Brazilian state.

First report of a Rickettsia asembonensis related infecting fleas in Brazil

The present study was performed in a non-endemic area for spotted fever (SF) in Imperatriz microregion, state of Maranhão, Brazil. Blood samples and ectoparasites were collected from 300 dogs of the Imperatriz microregion. Canine serum samples were tested individually by indirect immunofluorescence assay (IFA), using five Rickettsia isolates from Brazil. Antibodies reactive to at least one of the five species of Rickettsia were detected in 1.6% of the dogs (5/300). These sera were considered reactive to Rickettsia rickettsii and Rickettsia amblyommatis or very closely related species. The ticks (Acari: Ixodidae), identified as Rhipicephalus sanguineus sensu lato (Latreille), and the fleas, identified as Ctenocephalides felis, were tested by polymerase chain reaction (PCR) for detection of rickettsial DNA. More than 78% (83/106) of the C. felis fleas were found to be infected with Rickettsia species using gltA as rickettsial PCR targets, whereas no evidence of Rickettsia spp. was found in R. sanguineus s. l. Genetic analysis based on genes gltA, htrA and ompB showed that the detected strain, is most closely related to Rickettsia asembonensis (formerly Candidatus Rickettsia asemboensis). The present study is the first report of a R. asembonensis related infecting C. felis fleas in Brazil.

A serological and molecular survey of Babesia vogeli, Ehrlichia canis and Rickettsia spp. among dogs in the state of Maranhão, northeastern Brazil

This study evaluated exposure and infection by tick-borne agents (Babesia vogeli, Ehrlichia canis and Rickettsia spp.) in 172 dogs in rural areas and 150 dogs in urban areas of the municipality of Chapadinha, state of Maranhão, northeastern Brazil, using molecular and serological methods. Overall, 16.1% of the sampled dogs (52/322) were seroreactive to B. vogeli, with endpoint titers ranging from 40 to 640. For E. canis, 14.6% of the dogs (47/322) were seroreactive, with endpoint titers from 80 to 163,840. Antibodies reactive to at least one of the five species of Rickettsia were detected in 18.9% of the dogs (61/322), with endpoint titers ranging from 64 to 4,096. High endpoint titers were observed for Rickettsia amblyommii. Three (0.9%) and nine (2.8%) canine blood samples were PCR-positive for Babesia spp. and E. canis. The ticks collected from urban dogs were all Rhipicephalus sanguineus sensu lato, whereas the rural dogs were infested by R. sanguineus s.l, Amblyomma cajennense sensu lato and Amblyomma ovale. One A. ovale tick was found to be infected by Rickettsia bellii. This study provides an epidemiological background for controlling and preventing canine tick-borne diseases in a neglected region of Brazil.

INQUÉRITO EPIDEMIOLÓGICO DE SUPOSTO FOCO DE FEBRE MACULOSA

Resumo O presente estudo objetivou avaliar a suspeita de ocorrência da febre maculosa (FM) em Quirinópolis - GO, por meio de inquérito sorológico em amostras de humanos, cães e equinos e identificação de carrapatos vetores. Em 2007, foram realizadas reações de imunofluorescência indireta (RIFI) para Rickettsia spp. em amostras de sangue colhidas de 28 pessoas do grupo de convívio de um caso suspeito (uma criança de três anos que apresentou sinais de riquetsiose, após exposição a carrapatos). Também foram colhidas amostras de sangue em cinco cães e 42 equinos, havendo soro reagentes somente entre os equinos (28,6%). Não foi constatada a presença do carrapato Amblyomma cajennense. Sete indivíduos foram reagentes para Rickettsia spp., a maioria desses eram parentes paternos do caso suspeito. Em 2008, na mesma região, foram realizadas RIFI em amostras de 30 humanos sem sinais clínicos de FM e constatou-se 50% de soro reagentes para Rickettsia spp. Adicionalmente, colheram-se amostras de sangue de 24 cães errantes, havendo um cão soropositivo. A evidência sorológica do contato entre bactérias do gênero Rickettsia com habitantes humanos e animais de Quirinópolis indica que a FM ou outra riquetsiose possa estar ocorrendo no Estado de Goiás.