Dengue is a mosquito-borne disease that has gone from isolated sylvatic spill-overs to a pathogen of global public health importance in less than a century. Surveillance and control efforts have continually lagged behind contemporary needs and this thesis investigates the pressing need to reassess the current geographic limits and case burden of dengue including how these are measured. First, the global distribution of reported dengue infections was mapped. In many areas dengue reporting is sparse as it can be asymptomatic or clinically similar to other diseases. The maps identified surveillance gaps, particularly in Africa and the Middle East, where targeted efforts are needed to reliably measure the contemporary global extent of dengue transmission. Second, the global case burden of dengue was estimated by pairing risk maps with longitudinal cohort study data. This gave the first cartographic estimate of dengue cases and at 390 million per year (95% CI: 284-528) was over three times the World Health Organization official estimate. Reconciling these estimates with reported case data allowed an assessment of existing national surveillance strategies. Third, existing methods for outbreak identification were compared. High burden dengue outbreaks are preventable if timely and appropriate measures are applied. This analysis suggested, however, that commonly used outbreak definitions are not consistent, which could have an adverse effect on outbreak response. An alternative framework for outbreak identification based on healthcare capacities is thus outlined. Fourth, an analysis was undertaken that quantified how mosquito vectors place geographic and seasonal limits on dengue transmission. This involved updating estimates of mosquito longevity which were integrated with temperature-dependent dynamic transmission models to produce global maps. These suggested that while temperature places strong limits on the distribution of dengue in some settings, mosquito ecology may be more important in others. Finally, these findings are discussed in the context of global dengue surveillance gaps, with recommendations of how these can be addressed at a time when providing an evidence base for deployment of new control strategies will be critical.

Made available in DSpace on 2016-08-10T10:53:41Z (GMT). No. of bitstreams: 1 ADRIANE FEITOSA VALADARES.pdf: 954155 bytes, checksum: a974324b3ec7a29cee64b580f03ab47f (MD5) Previous issue date: 2012-11-27 / Dengue is a growing public health issue worldwide. As a result of their environmental, climatic and social characteristics, tropical countries are those most affected. The objectives of the present study conducted in the state of Tocantins, Brazil, were: to identify the demographic characteristics of notified and confirmed cases of dengue; to calculate the incidence rate of confirmed cases of dengue; to investigate the correlation between confirmed cases and the number of hospitalizations for this disease; to correlate the number of hospitalizations and the number of severe cases; to describe the circulating serotypes identified; to investigate the correlation between the house infestation index and the incidence rate of dengue; and to investigate the correlation between environmental factors such as mean annual temperature and mean rainfall with the annual incidence rate of dengue. This was an ecological, longitudinal study conducted by evaluating secondary data for the 2000- 2010 period obtained from the Brazilian Ministry of Health s notifiable diseases database, the yellow fever and dengue database, the localities database, the hospital admissions database and from the dengue and yellow fever management unit of the Tocantins State Health Department. The mean temperatures in degrees Celsius and the mean rainfall in millimeters were supplied by the National Meteorology Institute. The data on viral isolation and serotyping were obtained from the Tocantins Central Public Health Laboratory. The inclusion criterion adopted in this study consisted of municipalities in the state of Tocantins with populations of more than 100,000 inhabitants in this case, Palmas and Araguaína. A total of 48,246 suspected cases of dengue were notified during the period and 23,614 (49%) were confirmed. Of these, 118 (0.5%) were classified as severe cases and 7 deaths occurred (5.9%). The highest prevalence of the disease occurred in females (52.9%), in individuals of 20-39 years of age (46.5%), in those living in urban areas (97.6%) and in brown-skinned individuals (51.5%). There was a statistically significant difference (p<0.05) between the variables evaluated. The highest incidence of dengue occurred in 2007; however, the greatest number of severe cases registered was in 2008, although no deaths were recorded. Of the hospitalized patients, 13% were classified as severe cases. There was a positive and significant correlation between the number of confirmed cases and the number of hospitalizations (r = 0.77; p < 0.05), as well as between hospitalizations and severe cases (r = 0.79; p < 0.05). The serotypes isolated were DENV 1, DENV 2 and DENV 3. There was a positive, albeit non-significant, correlation between the house infestation index and the incidence of the disease (r = 0.59; p > 0.05). With respect to the abiotic factors, no correlation was found between mean rainfall or mean annual temperature and the incidence rate. In conclusion, the highest incidence of dengue occurred in 2007 and the greatest number of severe cases occurred in 2008, albeit with no deaths. These findings indicate that dengue affects predominantly females, individuals of 20-39 years of age, brown-skinned individuals and those residing in urban areas. The correlation between confirmed cases and hospitalizations was significant, as was the correlation between hospitalizations and severe cases of dengue. The serotypes identified were DENV 1, DENV 2 and DENV 3. More than one serotype was circulating simultaneously. The correlations between mean rainfall and the incidence rate and between mean temperature and the incidence rate were not statistically significant. / A dengue é um problema crescente de saúde pública mundial. Os países tropicais são os mais atingidos em razão de suas características ambientais, climáticas e sociais. Os objetivos deste estudo foram: Identificar as características demográficas dos casos notificados e confirmados da dengue; Calcular o coeficiente de incidência dos casos confirmados da dengue; Investigar a associação entre os casos confirmados da dengue e o número de internações por este agravo, assim como correlacionar o número de internações por dengue e o número de casos graves; descrever os sorotipos circulantes identificados; investigar a associação entre o índice de infestação predial e o coeficiente de incidência da dengue; investigar a associação entre os fatores ambientais como temperatura anual média e precipitação pluviométrica média com o coeficiente de incidência anual da dengue. Tratase de um estudo ecológico e longitudinal com a utilização de dados secundários referentes ao período de 2000 a 2010, obtidos do Sistema de Informação de Agravos de Notificação; Sistema de Informação de Febre Amarela e Dengue, Sistema de Informação de Localidades. Sistema de Informação Hospitalar e da Gerência do Núcleo de Dengue e Febre Amarela da Secretaria de Estado da Saúde do Tocantins. As médias de temperatura em graus Celsius e de precipitação pluviométrica em milímetros foram fornecidas pelo Instituto Nacional de Meteorologia. Os dados referentes ao isolamento viral e sorotipagem foram obtidos no Laboratório Central de Saúde Pública do Tocantins. Foi adotado como critério de inclusão municípios com população acima de 100.000 habitantes, neste caso, Palmas e Araguaína. Foram notificadas 48.246 suspeitos de dengue, sendo confirmadas 23.614 (49%), destes 118 (0,5%) foram classificados como casos graves de dengue, e 07 óbitos (5,9%). A maior prevalência da doença ocorreu entre pessoas do sexo feminino (52,9%), na faixa etária de 20 a 39 anos (46,5%), que viviam na zona urbana (97,6%) e da raça parda (51,5%). Houve diferença significativa (p<0,05) entre as variáveis estudadas. A maior incidência da dengue ocorreu em 2007, porém, o maior registro de casos graves foi em 2008, sem registro de óbitos. Dos pacientes internados, 13% foram classificados como caso grave. Houve associação positiva e significativa entre os casos confirmados e número de internações (r=0,77 p<0,05), bem como entre as internações e casos graves (r=0,79 p<0,05). Os sorotipos isolados foram DENV 1, DENV 2 e DENV 3. Houve associação positiva, porém, não significativa entre o índice de infestação predial e a incidência da doença (r= 0,59 p>0,05). Em relação aos fatores abióticos não houve associação significativa entre a precipitação pluviométrica média e o coeficiente de incidência, assim como em entre a temperatura anual média e o coeficiente de incidência. Conclusão: A maior incidência de dengue ocorreu em 2007 e o maior número de casos graves em 2008, sem ocorrência de óbito. Conclui-se que a dengue acomete predominantemente pessoas do sexo feminino, com idade entre 20 39 anos, raça parda, e que residem na zona urbana. A associação foi significativa entre os casos confirmados e internações, assim como, entre internações e casos graves. Os sorotipos virais identificados foram DENV 1, DENV 2 e DENV 3. Ocorreu circulação simultânea de mais de um sorotipo. A associação não foi significativa entre a precipitação pluviométrica média e o coeficiente de incidência, assim como entre temperatura e o coeficiente de incidência