Determination of clusters and factors associated with dengue dispersion during the first epidemic related to Dengue virus serotype 4 in Vitoria, Brazil

Dengue occurrence is partially influenced by the immune status of the population. Consequently, the introduction of a new Dengue virus serotype can trigger explosive epidemics in susceptible populations. The determination of clusters in this scenario can help to identify hotspots and understand the disease dispersion regardless of the influence of the population herd immunity. The present study evaluated the pattern and factors associated with dengue dispersion during the first epidemic related to Dengue virus serotype 4 in Vitoria, Espirito Santo state, Brazil. Data on 18,861 dengue cases reported in Vitoria from September 2012 to June 2013 were included in the study. The analysis of spatial variation in temporal trend was performed to detect clusters that were compared by their respective relative risk, house index, population density, and income in an ecological study. Overall, 11 clusters were detected. The time trend increase of dengue incidence in the overall study population was 636%. The five clusters that showed a lower time trend increase than the overall population presented a higher incidence in the beginning of the epidemic and, compared to the six clusters with higher time trend increase, they presented higher relative risk for their inhabitants to acquire dengue infection (P-value = 0.02) and a lower income (P-value < 0.01). House index and population density did not differ between the clusters. Early increase of dengue incidence and higher relative risk for acquiring dengue infection were favored in low-income areas. Preventive actions and improvement of infrastructure in low-income areas should be prioritized in order to diminish the magnitude of dengue dispersion after the introduction of a new serotype

Serotype influences on dengue severity: a cross-sectional study on 485 confirmed dengue cases in Vitória, Brazil

Abstract Background Dengue is caused by a RNA virus of the family Flaviviridae, which presents four serotypes (DENV-1 to DENV-4) capable of inducing hemorrhage. The purpose of this study was to evaluate the influence of serotype on the outcome of dengue. Methods This cross-sectional study included data from dengue cases with serotyping results that occurred between 2009 and 2013 in Vitória, Espírito Santo, Brazil. Data were accessed through the Information System for Notifiable Diseases. Chi-square test, Fisher exact test, Mann–Whitney U test, and logistic regression were performed to assess associations between different serotypes and dengue severity, while considering gender and age. Results The sample consisted of 485 laboratory confirmed dengue cases, of which 46.4 % were females, with median age of 26 years. Regarding overall samples, 77.3 % were caused by DENV-1, 16.1 % by DENV-4, 6.4 % by DENV-2, and 0.2 % by DENV-3. Severe dengue affected 6.6 % of all cases, of which 32.3 % of the cases caused by DENV-2, 6.4 % of those caused by DENV-4, 4.5 % of those caused by DENV-1, and none of those caused by DENV-3. Severe dengue was found to be seven times more frequent among cases of DENV-2 than among those of the other serotypes. Conclusions The present study found that cases of DENV-2 had a higher proportion of severe dengue than among those of DENV-1 and DENV-4. Consequently, early detection of serotypes circulating in the territory could be an important approach to prevent increasing numbers of severe outcomes during dengue outbreaks by predicting the health support needed for early diagnoses and treatment of dengue cases

Serotype influences on dengue severity: a cross-sectional study on 485 confirmed dengue cases in Vitoria, Brazil

Background: Dengue is caused by a RNA virus of the family Flaviviridae, which presents four serotypes (DENV-1 to DENV-4) capable of inducing hemorrhage. The purpose of this study was to evaluate the influence of serotype on the outcome of dengue. Methods: This cross-sectional study included data from dengue cases with serotyping results that occurred between 2009 and 2013 in Vitoria, Espirito Santo, Brazil. Data were accessed through the Information System for Notifiable Diseases. Chi-square test, Fisher exact test, Mann-Whitney U test, and logistic regression were performed to assess associations between different serotypes and dengue severity, while considering gender and age. Results: The sample consisted of 485 laboratory confirmed dengue cases, of which 46.4 % were females, with median age of 26 years. Regarding overall samples, 77.3 % were caused by DENV-1, 16.1 % by DENV-4, 6.4 % by DENV-2, and 0.2 % by DENV-3. Severe dengue affected 6.6 % of all cases, of which 32.3 % of the cases caused by DENV-2, 6.4 % of those caused by DENV-4, 4.5 % of those caused by DENV-1, and none of those caused by DENV-3. Severe dengue was found to be seven times more frequent among cases of DENV-2 than among those of the other serotypes. Conclusions: The present study found that cases of DENV-2 had a higher proportion of severe dengue than among those of DENV-1 and DENV-4. Consequently, early detection of serotypes circulating in the territory could be an important approach to prevent increasing numbers of severe outcomes during dengue outbreaks by predicting the health support needed for early diagnoses and treatment of dengue cases

Comparison of clusters with lower and higher time trend increase.

<p>Comparison of clusters with lower and higher time trend increase.</p

Cases of dengue reported in Vitória per month, September 2012 to June 2013.

<p>Cases of dengue reported in Vitória per month, September 2012 to June 2013.</p

Spatial variation in temporal trends for clusters with lower (cluster 1 to 5) and higher (cluster 6 to 11) time trend increase in Vitória, from September 2012 to June 2013.

<p>Spatial variation in temporal trends for clusters with lower (cluster 1 to 5) and higher (cluster 6 to 11) time trend increase in Vitória, from September 2012 to June 2013.</p

Clusters with lower or higher time trend increase in Vitória, September 2012 to June 2013.

<p>TTI—Time trend increase: incidence increase over the time.</p

Dengue incidence in the clusters in Vitória, September 2012 to June 2013.

<p>Dengue incidence in the clusters in Vitória, September 2012 to June 2013.</p

Dengue: clinical forms and risk groups in a high incidence city in the southeastern region of Brazil Dengue: formas clínicas e grupos de risco em município de alta incidência do sudeste do Brasil

INTRODUCTION: The article describes the epidemiologic profile of dengue cases in Vitória, the capital of Espírito Santo, Brazil, from 2000 to 2009, aimed at identifying risk groups regarding the incidence and severity of the disease. METHODS: Confirmed cases of dengue among city residents during ten years were classified as dengue fever, dengue hemorrhagic fever, dengue shock syndrome and dengue with complications, and analyzed according to sex, age, race-color and education. RESULTS: The proportion of dengue cases was highest among women aged 20 to 29 years-old and similar between whites and blacks. A gradual decrease occurred in the percentage of dengue cases in the population aged 15 years-old or more, in the historical series of 10 years, and a growing increase in individuals less than 15 years-old, showing statistical significance. The fatality rate ranged from zero to 0.3% for all forms of dengue and from 0.2% to 18.2% for severe forms. CONCLUSIONS: The profile of those affected by the disease in the municipality is similar to those affected in Brazil. The increasing number of cases in individuals under 15 years-old corroborates the results of recent studies in other Brazilian municipalities.<br>INTRODUÇÃO: O artigo descreve o perfil epidemiológico dos casos de dengue ocorridos no município de Vitória, capital do Estado do Espírito Santo, no período de 2000 a 2009, procurando identificar grupos de risco para a incidência e gravidade da doença. MÉTODOS: Os casos de dengue, confirmados em residentes do município no período de dez anos, foram classificados como febre da dengue, febre hemorrágica da dengue, síndrome do choque da dengue e dengue com complicações, e analisados segundo sexo, faixa etária, raça-cor e escolaridade. RESULTADOS: A proporção de casos de dengue foi maior entre mulheres, indivíduos de 20 a 29 anos, e semelhante entre brancos e afrodescendentes. Houve uma diminuição gradual do percentual de casos de dengue na população com 15 anos ou mais, na série histórica de 10 anos, e um aumento crescente em menores de 15 anos de idade, com significância estatística. A taxa de letalidade variou de zero a 0,3% para todas as formas de dengue, e de 0,2% a 18,2% para as formas graves. CONCLUSÕES: O perfil dos acometidos pela dengue no município é semelhante ao do Brasil. O aumento crescente de casos em menores de 15 anos corrobora os resultados de estudos recentes em outros municípios brasileiros