Spatial Distribution of the Risk of Dengue and the Entomological Indicators in Sumaré, State of São Paulo, Brazil

Abstract

Dengue fever is a major public health problem worldwide, caused by any of four virus (DENV-1, DENV-2, DENV-3 and DENV-4; Flaviviridae: Flavivirus), transmitted by Aedes aegypti mosquito. Reducing the levels of infestation by A. aegypti is one of the few current strategies to control dengue fever. Entomological indicators are used by dengue national control program to measure the infestation of A. aegypti, but little is known about predictive power of these indicators to measure dengue risk. In this spatial case-control study, we analyzed the spatial distribution of the risk of dengue and the influence of entomological indicators of A. aegypti in its egg, larva-pupa and adult stages occurring in a mid-size city in the state of São Paulo. The dengue cases were those confirmed by the city's epidemiological surveillance system and the controls were obtained through random selection of points within the perimeter of the inhabited area. The values of the entomological indicators were extrapolated for the entire study area through the geostatistical ordinary kriging technique. For each case and control, the respective indicator values were obtained, according with its geographical coordinates and analyzed by using a generalized additive model. Dengue incidence demonstrated a seasonal behavior, as well as the entomological indicators of all mosquito's evolutionary stages. The infestation did not present a significant variation in intensity and was not a limiting or determining factor of the occurrence of cases in the municipality. The risk maps of the disease from crude and adjusted generalized additive models did not present differences, suggesting that areas with the highest values of entomological indicators were not associated with the incidence of dengue. The inclusion of other variables in the generalized additive models may reveal the modulatory effect for the risk of the disease, which is not found in this study.

Spatial modelling of the infestation indices of Aedes aegypti: an innovative strategy for vector control actions in developing countries

“…Other studies conducted in Taiwan, Sri Lanka and Vietnam [13,14,29] have shown that larval indices may be closely related to the incidence of dengue epidemics and arboviruses. In Brazil, similar research was conducted in Rio de Janeiro, São Paulo and Maranhão [14,18,19].…”

“…The presence or absence of dengue vectors is measured using three key indices: house index (HI: the percentage of houses infested with larvae and/or pupae); Breteau index (BI: the number of positive containers per 100 houses); container index (CI: the percentage of water-holding containers infested with larvae or pupae) [12,13]. These indices may facilitate understanding of the ecology of vectors in a given control area, but they also serve as useful measures for determining the success of intervention strategies [11,14].…”

Incorporating the human-Aedes mosquito interactions into measuring the spatial risk of urban dengue fever

“…6 and 7. Past literature has discussed that mosquito indices could not comprehensively reflect the risk of dengue fever (Barbosa et al, 2014;Bowman, Runge-Ranzinger, & McCall, 2014;Sulaiman, Pawanchee, Arifin, & Wahab, 1996). Additionally, the incidence of dengue cases as a risk indicator could only reflect the risk of residence but not contain the exposure risk of daily lives, which may appear in different settings.…”

Dengue Incidence Rate Clustering by District in Selangor

“…The response variable is the observed dengue cases, dm y , where denotes the district and denotes as month, m. Due to the high variability in the monthly dengue counts, the data set, was assumed to follow the negative binomial distribution to handle the presence of overdispersion. The final model could be arranged such as in (1). The final model was referred from the previous study by [18].…”

“…Many infectious diseases are known to be carried by mosquitoes such as chikungunya, dengue, malaria and yellow fever. Dengue as the critical infectious disease since 1986 and Brazil was the first country confirmed with the outbreaks [1]. In Malaysia, DIR has grown severely and now significantly become a major public health concern to authority.…”