Experimental infection of dogs with a brazilian strain of Rickettsia rickettsii: clinical and laboratory findings

The bacterium Rickettsia rickettsii is the etiological agent of an acute, severe disease called Rocky Mountain spotted fever in the United States or Brazilian spotted fever (BSF) in Brazil. In addition to these two countries, the disease has also been reported to affect humans in Mexico, Costa Rica, Panama, Colombia and Argentina. Like humans, dogs are also susceptible to R. rickettsii infection. However, despite the wide distribution of R. rickettsii in the Western Hemisphere, reports of R. rickettsii-induced illness in dogs has been restricted to the United States. The present study evaluated the pathogenicity for dogs of a South American strain of R. rickettsii. Three groups of dogs were evaluated: group 1 (G1) was inoculated ip with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and the control group (G3) was infested by uninfected ticks. During the study, no clinical abnormalities, Rickettsia DNA or R. rickettsii-reactive antibodies were detected in G3. In contrast, all G1 and G2 dogs developed signs of rickettsial infection, i.e., fever, lethargy, anorexia, ocular lesions, thrombocytopenia, anemia and detectable levels of Rickettsia DNA and R. rickettsii-reactive antibodies in their blood. Rickettsemia started 3-8 days after inoculation or tick infestation and lasted for 3-13 days. Our results indicate that a Brazilian strain of R. rickettsii is pathogenic for dogs, suggesting that canine clinical illness due to R. rickettsii has been unreported in Brazil and possibly in the other South American countries where BSF has been reported among human

Ticks (Acari: Ixodidae) as ectoparasites of Brazilian wild birds and their association with rickettsial diseases

Ticks (Acari: Ixodidae) are obligatory hematophagous ectoparasites of a variety of vertebrate hosts and play an important role in the transmission and ecology of infectious pathogens causing diseases in humans and animals worldwide. Sixty-eight species of ticks exist in Brazil, and at least 23 are found parasitizing wild birds. This number is increasing with the advent of new studies highlighting the underestimated role of birds in the life cycle of these arthropods. In South America, many of these ticks are involved in epidemiology of the life-threatening spotted fever diseases caused by bacteria from the genus Rickettsia (Rickettsiales: Rickettsiaceae). The aim of this paper is to present up-to-date knowledge about the bird-tick fauna of Brazil and their association with rickettsioses. The available literature concerning ticks on birds and tick-borne diseases related to these ticks in Brazil has been revised. It could be concluded that birds play a primary role in life cycles of various tick species, especially during immature stages (larvae and nymphs). The best known is a bird-tick fauna from the Atlantic Forest and from Brazilian savannah called Cerrado in southern and central Brazil, respectively. On the other hand, the knowledge about bird tick parasitism from other Brazilian biomes such as the Amazon, Caatinga, Pantanal and Pampas regions is very scarce and requires further study. Moreover, no studies about the role of birds as mobile hosts for spreading ticks to new areas exist, nor has their role in the natural life cycle of Rickettsia been thoroughly examined.Os carrapatos (Acari: Ixodoidea) são ectoparasitas obrigatórias de uma variedade de hospedeiros vertebrados e têm um papel importante na ecologia e transmissão de diversos patógenos causadores de doenças em humanos e animais no mundo todo. No Brasil existem 68 espécies de carrapatos e pelo menos 23 espécies são encontradas parasitando aves silvestres. Esse número tem crescido com o advento de novos estudos ressaltando o papel das aves nos ciclos de vida desses artrópodes. Na América do Sul alguns desses carrapatos estão envolvidos na epidemiologia de doenças graves para o ser humano, como a febre maculosa, causada por bactérias do gênero Rickettsia (Rickettsiales: Rickettsiaceae). O alvo desse artigo é apresentar o estado atual de conhecimento sobre a fauna de carrapatos encontrados em aves no Brasil e as associações estabelecidas com as riquetsioses. A literatura disponível sobre carrapatos em aves e ocorrência de riquétsias foi revisada e pôde ser concluído que aves têm um papel importante nos ciclos de vida de várias espécies de carrapatos, sendo especialmente importantes para os estágios imaturos (larvas e ninfas). A maior parte do conhecimento sabrecai na fauna de carrapatos de aves dos biomas Mata Atlântica e Cerrado no sudeste e centro-oeste do Brasil. Já o conhecimento sobre o parasitismo por carrapatos em aves dos outros biomas: Amazônia, Caatinga, Pantanal e Pampas é muito limitado. Além disso, não há estudos sobre o papel de aves como disseminadores de carrapatos entre áreas e também o papel de aves no ciclo de Rickettsia não está totalmente esclarecido.

Febre maculosa brasileira no contexto de saúde única/ Brazilian spotted fever in the context of single health/ Fiebre manchada brasileña en el contexto de la salud única

EDITORIA

Ecological aspects of Pintomyia fischeri and Migonemyia migonei in municipalities with Canine Visceral Leishmaniasis, State of São Paulo, Brazil

Abstract The objective was to study the composition of sand fly species, the seasonal activity of the dominant species and correlation with average rainfall, sex association of the dominant species with domicile habitats and analyze different landscape scenarios for the two study sites in the municipalities of Itapevi and Mogi of the Crosses. Sandflies were captured with CDC(s) traps installed in three households at each study site for a period of 24 hours, biweekly for two years. A total of 2970 specimens were collected. The dominant species were P.fischeri and M.migonei. A statistically significant difference was registered between males and females of the two species in relation to the intra and peridomicile. The seasonal activity of both species showed a weak significant positive correlation with rainfall. The species P.fischeri and M.migonei may be potential vectors of CVL in the studied sites

Seroprevalence of rickettsia spp. and a study of the tick fauna in dogs from the municipality of Seropédica, State of Rio de Janeiro

The aim of this study was to investigate the presence of anti-Rickettsia spp. antibodies, the tick fauna, and the ticks that are carriers of rickettsiae of the spotted fever group (SFG). About 68 (24%) of the 283 serum samples tested by indirect immunofluorescence (IFA) reacted against the R. rickettsii crude antigen. The titers varied between 1:64 and 1:512. At the time of collection, 189 (64.5%) of the 293 dogs included in this study, were infested with ticks. Ticks classified as Rhipicephalus sanguineus and Amblyomma sculptum were identified. None of the ticks examined for SFG rickettsiae using polymerase chain reaction (PCR) were positive. The presence of the anti-R. rickettsii antibodies detected by IFA, albeit at low titers, suggests the circulation of SFG rickettsiae, which requires permanent surveillance because there are records on human fatalities related to spotted fever and to avoid any future threats to the students moving extensively in the areas near of the Rural Federal University of Rio de Janeiro.</p

Avaliação da completitude e oportunidade dos dados no Sistema de Informação de Agravos de Notificação (Sinan) para febre maculosa no estado de São Paulo, 2007-2017

Objective: To evaluate the completeness and timeliness of notifications of cases of spotted fever (SF) in the National System of Information on Notifiable Diseases (Sinan) in the state of São Paulo, from 2007 to 2017. Methods: This is a descriptive and ecological study of confirmed human cases of SF for completeness and timeliness of ten form fields (good if ≥ 90% for most variables). Linear regression was performed to analyze trends in the time series. Results: Among essential fields, only “Discharge date” showed low completeness (68.5%). “Investigation” and “Closure” had good timeliness; other intervals were not adequate. Conclusion: In the state of São Paulo, data completeness was good for most variables, but not adequate in terms of timeliness, except for “Closing” and “Investigation”, pointing to the need for health education and communication actions on SF.Objetivo: Evaluar la integridad y oportunidad de las notificaciones de casos de fiebre maculosa (SF) en el Sistema Nacional de Información sobre Enfermedades de Declaración Obligatoria (Sinan) en el estado de São Paulo, de 2007 a 2017. Métodos: Se trata de un estudio descriptivo y ecológico. estudio de casos humanos confirmados de SF para la integridad y puntualidad de diez campos de formulario (bueno si ≥ 90% para la mayoría de las variables). Se realizó una regresión lineal para analizar las tendencias en la serie temporal. Resultados: Entre los campos esenciales, solo “Fecha de alta” mostró baja completitud (68,5%). “Investigación” y “Cierre” tuvieron buena oportunidad; otros intervalos no fueron adecuados. Conclusión: En São Paulo, la completitud fue buena para la mayoría de las variables, pero no adecuada en cuanto a la oportunidad, excepto para “Cierre” e “Investigación”, lo que apunta a la necesidad de acciones de educación y comunicación en salud sobre SF.Objetivo: avaliar completitude e oportunidade das notificações de casos de febre maculosa (FM) no Sistema de Informação de Agravos de Notificação (Sinan), no estado de São Paulo, Brasil, no período de 2007 a 2017. Métodos: estudo descritivo e ecológico dos casos humanos confirmados de FM, mediante análise dos atributos “completitude” e “oportunidade” de dez campos da ficha de notificação (boas quando ≥ 90% para a maioria das variáveis); realizou-se análise de regressão linear para avaliar as tendências das séries temporais. Resultados: foram analisados 736 registros; dos campos essenciais, apenas “Data da alta” demonstrou baixa completitude (68,5%); “Investigação” e “Encerramento” tiveram boa oportunidade; demais intervalos não foram adequados. Conclusão: no estado de São Paulo, a completitude dos dados foi boa na maioria das variáveis, porém não adequada quanto à oportunidade (exceto para “Encerramento” e “Investigação”), apontando para a necessidade de ações de educação e comunicação em saúde sobre FM

Unpacking the risks of zoonotic and vector-borne pathogen transmission to humans in the context of environmental change

The emergence and spread of zoonotic and vector-borne diseases (ZVBDs), exacerbated by environmental change, pose serious threats to global public health and the economy. Understanding the role of environmental factors in disease transmission is critical for improving risk assessments and implementing effective preventive strategies. However, current approaches often lack a comprehensive framework that integrates the three risk components (hazard, exposure, and vulnerability), limiting the reliability and actionability of assessments. Here, we reviewed studies that incorporated environmental variables into research on ZVBDs, extracting information on the three risk components. We found that 52% of studies measured only hazard, whereas only 7.4% integrated all three components. Landscape composition and temperature were the most commonly used environmental variables. Our findings highlight key gaps in disease risk assessment and offer a roadmap with targeted indicators for each component, advancing the conceptual and structural foundations of disease ecology research in the context of environmental change

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

Ticks collected on birds in the state of São Paulo, Brazil

Abstract The present study reports a collection of Amblyomma spp. ticks in birds from several areas of the state of São Paulo, Brazil. A total of 568 tick specimens (404 larvae, 164 nymphs) were collected from 261 bird specimens. From these ticks, 204 (36%) specimens (94 larvae, 110 nymphs) were reared to the adult stage, being identiWed as Amblyomma longirostre (94 larvae, 90 nymphs), Amblyomma calcaratum (13 nymphs), Amblyomma nodosum (2 nymphs), and Amblyomma cajennense (5 nymphs). Additionally, 39 larvae reared to the nymphal stage and 8 nymphs that died before reaching the adult stage were identiWed as A. longirostre according to peculiar characters inherent to the nymphal stage of this species: scutum elongate, and hypostome pointed. The remaining 271 larvae and 46 nymphs were identiWed as Amblyomma sp. Ticks were collected from 51 species of birds distributed in 22 bird families and 6 orders. The order Passeriformes constituted the vast majority of the records, comprising 253 (97%) out of the 261 infested birds. Subadults of A. longirostre were identiWed from 35 species of Passeriformes, comprising 11 families (Cardinalidae, Dendrocolaptidae, Fringillidae, Furnariidae, Parulidae, Pipridae, Thamnophilidae, Thraupidae, Turdidae, Tyrannidae, and Vireonidae), and from 1 specie

Natural blood feeding and temperature shift modulate the global transcriptional profile of Rickettsia rickettsii infecting its tick vector

Rickettsia rickettsii is an obligate intracellular tick-borne bacterium that causes Rocky Mountain Spotted Fever (RMSF), the most lethal spotted fever rickettsiosis. When an infected starving tick begins blood feeding from a vertebrate host, R. rickettsii is exposed to a temperature elevation and to components in the blood meal. These two environmental stimuli have been previously associated with the reactivation of rickettsial virulence in ticks, but the factors responsible for this phenotype conversion have not been completely elucidated. Using customized oligonucleotide microarrays and high-throughput microfluidic qRT-PCR, we analyzed the effects of a 10 degrees C temperature elevation and of a blood meal on the transcriptional profile of R. rickettsii infecting the tick Amblyomma aureolatum. This is the first study of the transcriptome of a bacterium in the genus Rickettsia infecting a natural tick vector. Although both stimuli significantly increased bacterial load, blood feeding had a greater effect, modulating five-fold more genes than the temperature upshift. Certain components of the Type IV Secretion System (T4SS) were up-regulated by blood feeding. This suggests that this important bacterial transport system may be utilized to secrete effectors during the tick vector's blood meal. Blood feeding also up-regulated the expression of antioxidant enzymes, which might correspond to an attempt by R. rickettsii to protect itself against the deleterious effects of free radicals produced by fed ticks. The modulated genes identified in this study, including those encoding hypothetical proteins, require further functional analysis and may have potential as future targets for vaccine development.São Paulo Research Foundation (FAPESP) - 2008/053570-0Coordination for the Improvement of Higher Education Personnel (CAPES)National Council for Scientific and Technological Development (CNPq)The National Institutes of Science and Technology Program in Molecular Entomology (INCT-EM