Dengue and dengue hemorrhagic fever epidemics in Brazil: what research is needed based on trends, surveillance, and control experiences?

Abstract

Dengue epidemics account annually for several million cases and deaths worldwide. The high endemic level of dengue fever and its hemorrhagic form correlates to extensive domiciliary infestation by Aedes aegypti and multiple viral serotype human infection. This study analyzed serial case reports registered in Brazil since 1981, describing incidence evolutionary patterns and spatial distribution. Epidemic waves followed the introduction of every serotype (DEN 1 to 3), and reduction in susceptible individuals possibly accounted for decreasing case frequency. An incremental expansion of affected areas and increasing occurrence of dengue fever and its hemorrhagic form with high case fatality were noted in recent years. In contrast, efforts based solely on chemical vector control have been insufficient. Moreover, some evidence demonstrates that educational measures do not permanently modify population habits. Thus, as long as a vaccine is not available, further dengue control depends on potential results from basic interdisciplinary research and intervention evaluation studies, integrating environmental changes, community participation and education, epidemiological and virological surveillance, and strategic technological innovations aimed to stop transmission.

Spatial Vulnerability to Dengue in a Brazilian Urban Area During a 7-Year Surveillance

“…What remains to be understood are the higher incidence rates observed among young adults in Belo Horizonte, and in Brazil, contrary to what were described in Southeast Asia. 23 A critical level of vector infestation may not exist as a single measure to characterize a metropolitan area as a whole. As pointed out by Gó mez-Dantés, in 1995, 6 a combination of factors is related to the transmission of dengue.…”

“…This issue was revised recently by some Brazilian authors. 23 Regarding the possible bias, besides the ones related to ecological studies, the first refers to the use of secondary data from the official surveillance system, regarding misclassification and underreporting cases. The increased availability of laboratory testing for diagnostic confirmation along the years might have reduced the misclassification in the last waves.…”

“…aegypti breeding sites. Moreover, considering that the traditional indicator of mosquito infestation, based on larval survey, was not accurate enough to estimate dengue risk, 23 this study may provide one way to overlap this limitation as introducing other variables to classify risk areas, especially for surveillance purposes.…”

Análise espacial da dengue e o contexto socioeconômico no município do Rio de Janeiro, RJ

“…19,26 Between 2001 and 2002 there was in the state of Rio de Janeiro the largest epidemic since the 1980s, coinciding with the isolation of serotype 3 (DEN 3): 17 of 368,460 notifi ed cases in the state, 177,919 were from the municipality of Rio de Janeiro. a Dengue control is one of the health services' most diffi cult tasks due to the vector's broad capacity for dispersion, to populations' mobility, to the size of the cities' population and to the complexity of the social and political problems that affect the quality of life and the environment.…”

Dinâmica intra-urbana das epidemias de dengue em Belo Horizonte, Minas Gerais, Brasil, 1996-2002

“…É causado por um arbovírus com quatro sorotipos antigenicamente relacionados: DEN-1, DEN-2, DEN-3 e DEN-4. A infecção por um determinado sorotipo de vírus do dengue confere imunidade homóloga, que é duradoura, enquanto a imunidade para os outros sorotipos é apenas parcial e temporária 2 .O principal vetor do dengue é o mosquito Aedes aegypti, um culicídeo que apresenta alta capacidade de adaptação nos ambientes urbanos atuais 3,4 . O desenvolvimento e viabilidade do vetor são bastante sensíveis às condições ambientais, porém, seus ovos podem resistir a longos períodos de dessecação.…”