RESUMO
Traditional indices for measuring dengue fever risk in a given area are based on the immature forms of the vector (larvae and pupae surveys). However, this is inefficient because only adult female mosquitoes actually transmit the virus. Based on these assumptions, our objective was to evaluate the association between an entomological index obtained from adult mosquito traps and the occurrence of dengue in a hyperendemic area. Additionally, we compared its cost to that of the Breteau Index (BI).Material and methods: We performed this study in São José do Rio Preto, SP, Brazil, between the epidemiological weeks of 36/2012 and 19/2013. BG-Sentinel and BG-Mosquitito traps were installed to capture adult mosquitoes. Positive and negative cases of dengue fever were computed and geocoded. We generated biweekly thematic maps of the entomological index, generated by calculating the number of adult Aedes aegypti females (NAF) per 100 households during a week by kriging, and based on the number of mosquitoes captured. The relation between the occurrence of dengue fever and the NAF was tested using a spatial case-control design and a generalized additive model and was controlled by the coordinates of the positive and negative cases of dengue fever...
Assuntos
Animais , Aedes/crescimento & desenvolvimento , Análise Espacial , Dengue/epidemiologia , Dengue/prevenção & controle , Dengue/transmissãoRESUMO
The aims of this study were to describe the occurrence of dengue in space and time and to assess the relationships between dengue incidence and entomologic indicators. We selected the dengue autochthonous cases that occurred between September 2005 and August 2007 in São José do Rio Preto to calculate incidence rates by month, year and census tracts. The monthly incidence rates of the city were compared to the monthly Breteau indices (BI) of the São José do Rio Region. Between December 2006 and February 2007, an entomological survey was conducted to collect immature forms of Aedes aegypti in Jaguaré, a São José do Rio Preto neighborhood, and to obtain entomological indices. These indices were represented using statistical interpolation. To represent the occurrence of dengue in the Jaguaré neighborhood in 2006 and 2007, we used the Kernel ratio and to evaluate the relationship between dengue and the entomological indices, we used a generalized additive model in a spatial casecontrol design. Between September 2005 and August 2007, the occurrence of dengue in São José do Rio Preto was almost entirely caused by DENV3, and the monthly incidence rates presented high correlation coefficients with the monthly BI. In Jaguaré neighborhood, the entomological indices calculated by hectare were better predictors of the spatial distribution of dengue than the indices calculated by properties, but the pupae quantification did not show better prediction qualities than the indices based on the container positivity, in relation to the risk of dengue occurrence. The fact that the municipalitys population had a high susceptibility to the serotype DENV3 before the development of this research, along with the almost total predominance ofthe occurrence of this serotype between 2005 and 2007, facilitated the analysis of the epidemiological situation of the disease and allowed us to connect it to the entomological indicators...
Assuntos
Humanos , Aedes/crescimento & desenvolvimento , Dengue/diagnóstico , Dengue/epidemiologia , Dengue/transmissãoRESUMO
Dengue virus currently causes 50-100 million infections annually. Comprehensive knowledge about the evolution of Dengue in response to selection pressure is currently unavailable, but would greatly enhance vaccine design efforts. In the current study, we sequenced 187 new dengue virus serotype 3 (DENV-3) genotype III whole genomes isolated from Asia and the Americas. We analyzed them together with previously-sequenced isolates to gain a more detailed understanding of the evolutionary adaptations existing in this prevalent American serotype. In order to analyze the phylogenetic dynamics of DENV-3 during outbreak periods; we incorporated datasets of 48 and 11 sequences spanning two major outbreaks in Venezuela during 2001 and 2007-2008, respectively. Our phylogenetic analysis of newly sequenced viruses shows that subsets of genomes cluster primarily by geographic location, and secondarily by time of virus isolation. DENV-3 genotype III sequences from Asia are significantly divergent from those from the Americas due to their geographical separation and subsequent speciation. We measured amino acid variation for the E protein by calculating the Shannon entropy at each position between Asian and American genomes. We found a cluster of seven amino acid substitutions having high variability within E protein domain III, which has previously been implicated in serotype-specific neutralization escape mutants. No novel mutations were found in the E protein of sequences isolated during either Venezuelan outbreak. Shannon entropy analysis of the NS5 polymerase mature protein revealed that a G374E mutation, in a region that contributes to interferon resistance in other flaviviruses by interfering with JAK-STAT signaling was present in both the Asian and American sequences from the 2007-2008 Venezuelan outbreak, but was absent in the sequences from the 2001 Venezuelan outbreak. In addition to E, several NS5 amino acid changes were unique to the 2007-2008 epidemic in Venezuela and may give additional insight into the adaptive response of DENV-3 at the population level.
Assuntos
Vírus da Dengue/classificação , Vírus da Dengue/genética , Dengue/epidemiologia , Dengue/virologia , Genoma Viral , Mutação , América/epidemiologia , Substituição de Aminoácidos , Animais , Sequência de Bases , Teorema de Bayes , Dengue/genética , Evolução Molecular , Genótipo , Humanos , Dados de Sequência Molecular , Filogenia , Sorotipagem , Venezuela/epidemiologiaAssuntos
Infecções por Alphavirus/epidemiologia , Alphavirus/isolamento & purificação , Infecções por Arbovirus/epidemiologia , Arbovírus/isolamento & purificação , Doadores de Sangue , Dengue/epidemiologia , Surtos de Doenças , Infecções por Flavivirus/epidemiologia , Flavivirus/isolamento & purificação , Viremia/epidemiologia , Infecções por Alphavirus/sangue , Infecções por Alphavirus/virologia , Infecções por Arbovirus/sangue , Infecções por Arbovirus/virologia , Brasil/epidemiologia , Portador Sadio/sangue , Portador Sadio/epidemiologia , Portador Sadio/virologia , Dengue/sangue , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Doenças Endêmicas , Infecções por Flavivirus/sangue , Infecções por Flavivirus/virologia , Humanos , Reação em Cadeia da Polimerase/métodos , População Urbana , Viremia/sangueRESUMO
The dengue virus has a single-stranded positive-sense RNA genome of ,10.700 nucleotides with a single open readingframe that encodes three structural (C, prM, and E) and seven nonstructural (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5)proteins. It possesses four antigenically distinct serotypes (DENV 14). Many phylogenetic studies address particularities ofthe different serotypes using convenience samples that are not conducive to a spatio-temporal analysis in a single urbansetting. We describe the pattern of spread of distinct lineages of DENV-3 circulating in Sao Jose´ do Rio Preto, Brazil, during2006. Blood samples from patients presenting dengue-like symptoms were collected for DENV testing. We performed M-NPCRusing primers based on NS5 for virus detection and identification. The fragments were purified from PCR mixtures andsequenced. The positive dengue cases were geo-coded. To type the sequenced samples, 52 reference sequences werealigned. The dataset generated was used for iterative phylogenetic reconstruction with the maximum likelihood criterion.The best demographic model, the rate of growth, rate of evolutionary change, and Time to Most Recent Common Ancestor(TMRCA) were estimated...