Aedes aegypti entomological indices in an endemic area for dengue in Sao Paulo State, Brazil

Abstract

OBJECTIVE:To evaluate the most productive types of properties and containers for Aedes aegypti and the spatial distribution of entomological indices. METHODS:Between December 2006 and February 2007, the vector's immature forms were collected to obtain entomological indices in 9,875 properties in the Jaguare neighborhood of Sao Jose do Rio Preto, SP, Southeastern Brazil. In March and April 2007, a questionnaire about the conditions and characteristics of properties was administered. Logistic regression was used to identify variables associated with the presence of pupae at the properties. Indices calculated per block were combined with a geo-referenced map, and thematic maps of these indices were obtained using statistical interpolation. RESULTS:The properties inspected had the following Ae. aegypti indices: Breteau Index = 18.9, 3.7 larvae and 0.42 pupae per property, 5.2 containers harboring Ae. aegypti per hectare, 100.0 larvae and 11.6 pupae per hectare, and 1.3 larvae and 0.15 pupae per inhabitant. The presence of yards, gardens and animals was associated with the presence of pupae. CONCLUSIONS:Specific types of properties and containers that simultaneously had low frequencies among those positive for the vector and high participation in the productivity of larvae and pupae were not identifi ed. The use of indices including larval and pupal counts does not provide further information beyond that obtained from the traditional Stegomyia indices in locations with characteristics similar to those of São José do Rio Preto. The indices calculated per area were found to be more accurate for the spatial assessment of infestation. The Ae. aegypti infestation levels exhibited extensive spatial variation, indicating that the assessment of infestation in micro areas is needed.

Complex relationships between Aedes vectors, socio-economics and dengue transmission—Lessons learned from a case-control study in northeastern Thailand

“…The Malaysian study included two sets of controls: one test-negative and the other being hospitalized (inpatient) with no suspicion of dengue ("traditional" control). In their analysis, no risk factors were identified in the test-negative controls, although the number of them was small (28). The authors suggest that test-negative studies could be subject to bias resulting from misclassification of dengue status due to imperfect diagnostic tests.…”

“…Indeed, the larval stages (four successive instars) typically suffer high mortality during development to pupal stage, thus indices based only on their presence are generally poor indicators of the eventual adult vector density. Pupal indices (a stage with very low mortality) were proposed as a more accurate determination of actual adult production; however, pupal collections are far more challenging and time consuming to carry out [ 26 , 28 ]. Adult collections can be performed via several devices such as gravitraps, sticky traps, baited mechanical traps, and mouth or mechanical aspirators, but they only provide an imprecise estimation of the true vector density and do not reflect human-vector exposure.…”

Identification of Aedes albopictus larval index thresholds in the transmission of dengue in Guangzhou, China

“…Many indices were used to evaluate larval density, such as pupae per person index (PPI) (Wai et al Banerjee et al Favaro et al and Mosq‐ovitrap index (MOI) (Qiaoli et al Because these indices were not convenient or need time to get feedback, we adopted and suggested the use of BI and CI as evaluation indices because of their convenient and quick evaluation. Additionally, we have already confirmed the relationship between larval density and dengue transmission.…”

Arbovirus Vectors of Epidemiological Concern in the Americas: A Scoping Review of Entomological Studies on Zika, Dengue and Chikungunya Virus Vectors

“…Five studies examined the occurrence and correlates of domiciliary and peri-domicilliary mosquito density, including sociodemographic characteristics, container types, and meteorological correlates [73–77]. Specifically, Rodrigues et al [73] and Serpa et al [77] studied Aedes aegypti and Aedes albopictus , and Favaro et al [74], Morales-Pérez et al [75] and Schafrick et al [76] studied Aedes aegypti . Covered containers [75–77], low education of the household head [75] and higher densities of residents per household [73] were found to be associated with higher risk of infestation.…”