ABSTRACT
Ticks of the Amblyomma cajennense species complex are important vectors of spotted fever in Latin America. Environmental conditions determine the geographic distribution of ticks, such that climate change could influence the distribution of tick-borne diseases. This study aimed to analyze the potential geographic distribution of A. cajennense complex ticks in a Brazil region under present-day and future climate models, assuming dispersal limitations and non-evolutionary adaptation of these tick populations to climate warming. Records of A. cajennense sensu stricto (s.s.) and Amblyomma sculptum were analyzed. Niche models were calibrated using Maxent considering climate variables for 1950-2000 and projecting models to conditions anticipated for 2050 and 2070 under two models of future climate (CCSM4 and HadGEM2-AO). Broad suitable areas for A. cajennense s.s. and A. sculptum were found in present-day climate models, but suitability was reduced when models were projected to future conditions. Our exploration of future climates showed that broad areas had novel climates not existing currently in the study region, including novel extremely high temperatures. Indeed, predicted suitability in these novel conditions would lead to biologically unrealistic results and therefore incorrect forecasts of future tick-distribution. Previous studies anticipating expansions of vectors populations due to climate change should be considered with caution as they assume that model extrapolation anticipates that species would evolve rapidly for adaptation to novel climatic conditions.
Subject(s)
Animal Distribution , Climate Change , Ixodidae/growth & development , Spotted Fever Group Rickettsiosis/parasitology , Tick-Borne Diseases/parasitology , Ticks/growth & development , Animals , Brazil , GeographyABSTRACT
INTRODUCTION: Triatoma sordida Stål, 1859 populations were investigated for susceptibility to deltamethrin. METHODS: This study aimed to analyze the resistance of 11 populations of insects from the States of Goiás, Mato Grosso and Mato Grosso do Sul by topical application bioassays. RESULTS: The estimated LD50 and RR50 showed high levels of susceptibility (LD50 < 1 and RR50 < 2). However, analysis of the slope of the dose response curve showed that the populations of insects in the towns of Firminópolis/GO, Posse/GO, Poxoréu/MT, Douradina/MS and Aparecida do Taboado/MS present great probability of evolving resistance and, thus, are more likely to tolerate treatment with deltamethrin. CONCLUSIONS: Small changes in susceptibility and low levels of resistance were detected, but the temporal changes of susceptibility should be continuously monitored to adequately guide the actions of vector-control of DC.
Subject(s)
Insect Vectors , Insecticide Resistance , Insecticides , Nitriles , Pyrethrins , Triatoma , Animals , BrazilABSTRACT
INTRODUÇÃO: Populações de Triatoma sordida Stål, 1859 foram investigadas quanto à suscetibilidade à deltametrina. MÉTODOS: Análise por meio de bioensaios por aplicação tópica em 11 populações de T. sordida procedentes dos Estados de Goiás, Mato Grosso e Mato Grosso do Sul. RESULTADOS: As estimativas de DL50 e RR50 demonstraram elevados níveis de suscetibilidade (DL50 < 1 e RR50 < 2). Entretanto, as análises do coeficiente angular da curva dose resposta revelaram que as populações de triatomíneos dos municípios de Firminópolis/GO, Posse/GO, Poxoréu/MT, Douradina/MS e Aparecida do Taboado/MS apresentam maiores probabilidades de evolução de resistência, portanto, mais propícias a tolerar o tratamento com deltametrina. CONCLUSÕES: Detectaram-se pequenas alterações de suscetibilidade e baixos níveis de resistência, porém as alterações temporais de suscetibilidade deverão ser continuamente monitoradas, a fim de nortear adequadamente as ações de controle dos vetores da DC.
INTRODUCTION: Triatoma sordida Stål, 1859 populations were investigated for susceptibility to deltamethrin. METHODS: This study aimed to analyze the resistance of 11 populations of insects from the States of Goiás, Mato Grosso and Mato Grosso do Sul by topical application bioassays. RESULTS: The estimated LD50 and RR50 showed high levels of susceptibility (LD50 < 1 and RR50 < 2). However, analysis of the slope of the dose response curve showed that the populations of insects in the towns of Firminópolis/GO, Posse/GO, Poxoréu/MT, Douradina/MS and Aparecida do Taboado/MS present great probability of evolving resistance and, thus, are more likely to tolerate treatment with deltamethrin. CONCLUSIONS: Small changes in susceptibility and low levels of resistance were detected, but the temporal changes of susceptibility should be continuously monitored to adequately guide the actions of vector-control of DC.
Subject(s)
Animals , Insect Vectors , Insecticide Resistance , Insecticides , Nitriles , Pyrethrins , Triatoma , BrazilABSTRACT
INTRODUCTION: Hantavirosis has worldwide distribution and is an important public health problem. The epidemiology of hantavirosis in Brazil shows that the number of cases notified and the number of variants discovered in several states and the Federal District have been increasing year by year. Within this context, the main objective of this study was to examine land use and occupation in relation to the spread of hantavirosis in the Federal District, between 2004 and 2008. METHODS: To carry out this investigation, epidemiological and land use data were used to drafting tables and cartograms in order to detail the special spread of hantavirosis in this area. RESULTS: Out of the 40 likely infection sites plotted on the coverage and land use map, 19 (47%) were in pasture areas, 10 (25%) in urban areas (periurban), 6 (15%) in areas used for agriculture and 5 (12%) in savanna areas. CONCLUSIONS: It can thus be seen that agricultural activities and urban expansion towards the savanna areas have favored the spread of hantavirosis in the Federal District and especially in São Sebastião.
Subject(s)
Hemorrhagic Fever with Renal Syndrome/epidemiology , Topography, Medical , Agriculture , Animals , Brazil/epidemiology , Disease Reservoirs/virology , Hemorrhagic Fever with Renal Syndrome/transmission , Humans , Rodentia/virologyABSTRACT
INTRODUÇÃO: As hantaviroses apresentam distribuição mundial e constituem importante problema de saúde pública. A epidemiologia da hantavirose no Brasil mostra que vem aumentando a cada ano o número de casos que são notificados e de variantes que têm sido descobertas em diversos estados e no Distrito Federal. Neste contexto, o estudo tem como objetivo principal analisar o uso e da ocupação do solo na disseminação da hantavirose no Distrito Federal, no período de 2004 a 2008. MÉTODOS: Para a realização desta pesquisa, foram utilizados dados epidemiológicos e do uso da terra com fins de elaborar tabelas e cartogramas para detalhar a espacialização da hantavirose no território. RESULTADOS: Dos 40 locais prováveis de infecção (LPIs) plotados no Mapa de Cobertura e Uso da Terra, 19 (47 por cento) ocorreram em áreas de pastagens, 10 (25 por cento) em área urbana (periurbana), 6 (15 por cento) em áreas utilizadas para a agricultura e 5 (12 por cento) em espaços de cerrado. CONCLUSÕES: Sendo assim, as atividades agrícolas e a expansão urbana em direção às áreas de cerrado vêm favorecendo a disseminação da hantavirose no Distrito Federal e em especialmente em São Sebastião.
INTRODUCTION: Hantavirosis has worldwide distribution and is an important public health problem. The epidemiology of hantavirosis in Brazil shows that the number of cases notified and the number of variants discovered in several states and the Federal District have been increasing year by year. Within this context, the main objective of this study was to examine land use and occupation in relation to the spread of hantavirosis in the Federal District, between 2004 and 2008. METHODS: To carry out this investigation, epidemiological and land use data were used to drafting tables and cartograms in order to detail the special spread of hantavirosis in this area. RESULTS: Out of the 40 likely infection sites plotted on the coverage and land use map, 19 (47 percent) were in pasture areas, 10 (25 percent) in urban areas (periurban), 6 (15 percent) in areas used for agriculture and 5 (12 percent) in savanna areas. CONCLUSIONS: It can thus be seen that agricultural activities and urban expansion towards the savanna areas have favored the spread of hantavirosis in the Federal District and especially in São Sebastião.
