Characterization of the spatial and temporal dynamics of the dengue vector population established in urban areas of Fernando de Noronha, a Brazilian oceanic island

Abstract

Aedes aegypti has played a major role in the dramatic expansion of dengue worldwide. The failure of control programs in reducing the rhythm of global dengue expansion through vector control suggests the need for studies to support more appropriated control strategies. We report here the results of a longitudinal study on Ae. aegypti population dynamics through continuous egg sampling aiming to characterize the infestation of urban areas of a Brazilian oceanic island, Fernando de Noronha. The spatial and temporal distribution of the dengue vector population in urban areas of the island was described using a monitoring system (SMCP-Aedes) based on a 103-trap network for Aedes egg sampling, using GIS and spatial statistics analysis tools. Mean egg densities were estimated over a 29-month period starting in 2011 and producing monthly maps of mosquito abundance. The system detected continuous Ae. aegypti oviposition in most traps. The high global positive ovitrap index (POI=83.7% of 2815 events) indicated the frequent presence of blood-fed-egg laying females at every sampling station. Egg density (eggs/ovitrap/month) reached peak values of 297.3 (0 - 2020) in May and 295 (0 - 2140) in August 2012. The presence of a stable Ae. aegypti population established throughout the inhabited areas of the island was demonstrated. A strong association between egg abundance and rainfall with a 2-month lag was observed, which combined with a first-order autocorrelation observed in the series of egg counts can provide an important forecasting tool. This first description of the characteristics of the island infestation by the dengue vector provides baseline information to analyze relationships between the spatial distribution of the vector and dengue cases, and to the development of integrated vector control strategies.

Risk factors for the presence of dengue vector mosquitoes, and determinants of their prevalence and larval site selection in Dhaka, Bangladesh

“…Thus, these “key containers” are either highly productive or highly efficient, and both drive the local abundance of vector mosquitoes and are the targets for source reduction so important to vector suppression and dengue prevention. Vector abundance varies seasonally because of local changes in temperature, humidity and rainfall that affect the availability of larval development sites [ 18 ]. In addition, the larval development sites for Aedes mosquitoes also vary spatially [ 19 ].…”

Field evaluation of sticky BR-OVT traps to collect culicids eggs and adult mosquitoes inside houses

“…The use of traps can contribute to both the monitoring and reduction in population densities of mosquitoes [18][19][20][21][22][23][24][25] . Among the traps described in the literature, some are used for the collection of eggs [26][27][28] and others are used to catch adult culicids, such as those with light attractors 29 , that target gravid females and can assist in the detection of circulating pathogens [30][31][32][33] , that involve the release of substances such as CO 2 to attract and capture mosquitoes 34,35 , and that employ sticky traps, which are based on the use of physical characteristics as a strategy to attract and imprison mosquitoes [36][37][38][39][40][41][42][43] .…”

Pyriproxyfen and the microcephaly epidemic in Brazil - an ecological approach to explore the hypothesis of their association

“…However, our findings do not invalidate the argument that improvements in environmental management to prevent and control disease may be a better choice than the widespread use of larvicide in drinking water for vector control, nor do they exclude other potential toxicities of pyriproxyfen (ABRASCO 2016). In addition, it should be noted that the mosquito vector control strategies during the past three decades, mainly based on chemical insecticides and larvicides, have proven ineffective (Regis et al 2014, Augusto et al 2016). Moreover, it is necessary to investigate other potential toxicities of pyriproxyfen.…”