RESUMO
BACKGROUND: The distribution of parasite load across hosts may modify the transmission dynamics of infectious diseases. Chagas disease is caused by a multi-host protozoan, Trypanosoma cruzi, but the association between host parasitemia and infectiousness to the vector has not been studied in sylvatic mammalian hosts. We quantified T. cruzi parasite load in sylvatic mammals, modeled the association of the parasite load with infectiousness to the vector and compared these results with previous ones for local domestic hosts. METHODS: The bloodstream parasite load in each of 28 naturally infected sylvatic mammals from six species captured in northern Argentina was assessed by quantitative PCR, and its association with infectiousness to the triatomine Triatoma infestans was evaluated, as determined by natural or artificial xenodiagnosis. These results were compared with our previous results for 88 humans, 70 dogs and 13 cats, and the degree of parasite over-dispersion was quantified and non-linear models fitted to data on host infectiousness and bloodstream parasite load. RESULTS: The parasite loads of Didelphis albiventris (white-eared opossum) and Dasypus novemcinctus (nine-banded armadillo) were directly and significantly associated with infectiousness of the host and were up to 190-fold higher than those in domestic hosts. Parasite load was aggregated across host species, as measured by the negative binomial parameter, k, and found to be substantially higher in white-eared opossums, cats, dogs and nine-banded armadillos (range: k = 0.3-0.5) than in humans (k = 5.1). The distribution of bloodstream parasite load closely followed the "80-20 rule" in every host species examined. However, the 20% of human hosts, domestic mammals or sylvatic mammals exhibiting the highest parasite load accounted for 49, 25 and 33% of the infected triatomines, respectively. CONCLUSIONS: Our results support the use of bloodstream parasite load as a proxy of reservoir host competence and individual transmissibility. The over-dispersed distribution of T. cruzi bloodstream load implies the existence of a fraction of highly infectious hosts that could be targeted to improve vector-borne transmission control efforts toward interruption transmission. Combined strategies that decrease the parasitemia and/or host-vector contact with these hosts would disproportionally contribute to T. cruzi transmission control.
Assuntos
Doença de Chagas/transmissão , Mamíferos/parasitologia , Triatoma/parasitologia , Trypanosoma cruzi , Animais , Animais Selvagens/parasitologia , Argentina/epidemiologia , Tatus/parasitologia , Gatos , Doença de Chagas/diagnóstico , Doença de Chagas/prevenção & controle , Didelphis/parasitologia , Reservatórios de Doenças/parasitologia , Vetores de Doenças , Cães , Florestas , Genes de Protozoários , Humanos , Insetos Vetores/parasitologia , Carga Parasitária/estatística & dados numéricos , Parasitemia/parasitologia , Reação em Cadeia da Polimerase em Tempo Real , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificação , Doenças Transmitidas por Vetores/diagnóstico , Doenças Transmitidas por Vetores/prevenção & controle , Doenças Transmitidas por Vetores/transmissão , XenodiagnósticoRESUMO
Bartonellosis is a vector-borne zoonotic disease with worldwide distribution that infect a broad spectrum of mammalian species. Despite the recent studies carried out in Brazil, information regarding Bartonella in dogs are scarce. Therefore, we performed a retrospective study to investigate the exposure to Bartonella sp. in dogs by indirect immunofluorescence assay (IFA). Three hundred and thirty-five archived serum samples from dogs previously tested for vector-borne pathogens, Toxoplasma gondii, and Neospora caninum were screened for the presence of IgG antibodies to Bartonella sp. All dogs originated from the Metropolitan region of Ribeirão Preto, northeast of the State of São Paulo. Twenty-eight samples (8.3%) were positive for Bartonella sp. at the cut-off of 64. Among the 28 seropositive samples for Bartonella sp., 16 (57.1%) were also seropositive for Ehrlichia canis, 12 (42.8%) for Babesia vogeli, five (17.8%) for T. gondii and three (10.7%) for L. infantum and N. caninum. Our results demonstrated that dogs sampled were exposed to Bartonella sp. Since all the animals sampled in the present study were from private owners, our findings demonstrate that these people may also be exposed to Bartonella sp. Further studies designed to assess whether the infection by other arthropod-borne pathogens such as B. vogeli and E. canis are risk factors for Bartonella infection are needed.(AU)
A bartonelose é uma zoonose transmitida por vetores, com distribuição mundial, que infecta várias espécies de mamíferos. Apesar dos estudos conduzidos no Brasil, informações sobre Bartonella em cães são escassas. Portanto, foi realizado um estudo retrospectivo para investigar a exposição a Bartonella sp. em cães cães, utilizando-se o ensaio de imunofluorescência indireta (IFA). Trezentas e trinta e cinco amostras de soro de cães, previamente testadas para patógenos transmitidos pelos vetores, Toxoplasma gondii e Neospora caninum foram avaliadas quanto à presença de anticorpos IgG contra Bartonella sp. Todos os cães eram oriundos da região metropolitana de Ribeirão Preto, Nordeste do Estado de São Paulo. Vinte e oito amostras (8,3%) foram positivas para Bartonella sp. no ponto de corte de 64. Entre as 28 amostras positivas, 16 (57,1%) também foram positivas para Ehrlichia canis, 12 (42,8%) para Babesia vogeli, cinco (17,8%) para T. gondii e três (10,7%) para L. infantum e N. caninum. Os resultados demonstraram que os cães amostrados foram expostos a Bartonella sp. Como os animais eram de proprietários particulares, nossos achados demonstram que as pessoas também podem ter sido expostas a Bartonella sp. São necessários estudos para avaliar se a infecção por B. canis ou E. canis constitui fator de risco para infecção por Bartonella em cães.(AU)
Assuntos
Animais , Infecções por Bartonella/diagnóstico , Coccidiose/diagnóstico , Cães , Doenças Transmitidas por Vetores/diagnóstico , Bartonella/imunologia , Toxoplasmose Animal/diagnóstico , NeosporaRESUMO
BACKGROUND: Vector-borne diseases are a public health problem in Colombia, where dengue virus infection is hyperendemic. The introduction of other arboviruses, such as chikungunya and Zika in the last three years, has aggravated the situation. Mobile health (mHealth) offers new strategies for strengthening health care and surveillance systems promoting the collection, delivery, and access of health information to professionals, researchers, and patients. Assessing mobile application performance has been a challenge in low- and middle-income countries due to the difficulty of implementing these technologies in different clinical settings. In this study, we evaluate the usability and acceptability of a mobile application, FeverDX, as a support tool in the management of patients with febrile syndrome and suspected arboviruses infection by general practitioners from Colombia. METHODS: A pilot implementation study was conducted to evaluate the usability and acceptability of FeverDX using the modified version of the Mobile Application Rating Scale (uMARS). The evaluation form included 25 questions regarding quantity and quality of information, engagement, functionality, aesthetics, impact, and acceptability by healthcare workers. Each item uses a 5-point scale (1-Inadequate, 2-Poor, 3-Acceptable, 4-Good, 5-Excellent). A global score was obtained for the evaluation form test by determining the median scores of each subsection. A descriptive statistical analysis of the data obtained was performed. RESULTS: Between December 2016 and January 2017, a total of 20 general practitioners from the Emergency room and hospitalization areas evaluated FeverDX. Less than half (9/20) of the evaluators had a comprehensive knowledge of the Colombian Ministry of Health's guidelines for the diagnosis and management of arboviruses, and evaluators partially (4/9) or completely (5/9) agreed that the content of the application follows the management guidelines. On uMARS scale, FeverDX excelled regarding impact (median 5; IQR = 5-5), functionality (median 5; IQR = 4.8-5), and information and scientific basis (median 4; IQR = 4-4). FeverDX scored well regarding user feedback (median 4; IQR = 4-4.5), design and aesthetics (median 4; IQR = 4-4.3), and subjective assessment of quality (median 4.5; IQR = 4.3-4.8). CONCLUSIONS: FeverDX, a mobile application, is a novel mHealth strategy to strengthen care processes and facilitate the detection and reporting of notifiable surveillance diseases. It could improve adherence to clinical practice guidelines for the management and prevention of prevalent diseases as arboviruses in healthcare settings. Although this pilot study used a small sample size, FeverDx performed adequately in a simulated emergency consultation. Further implementation studies are needed to increase the reliability of mHealth technologies in different scenarios.