There is an enduring disconnect between the routine surveillance of mosquitoes that transmit dengue viruses and control activities to limit disease spread. A great variety of methods used to collect vector surveillance data exists globally, with program design typically influenced by historical, socio-cultural and cost factors. Surveillance data can be expensive to collect, meaning that without demonstration of its usefulness in directing mosquito control it may be deprioritized or even abandoned. Given that universally prescribed surveillance methods are unlikely to be sustainable and successful, we propose that strategies be designed according to the local terroir of dengue transmission. Strategy design should consider not only costs, but the amenability of workers and the public to various methods, the utility of methods for directing control and reducing disease, and the underlying spatial structure of the vector populations locally. A process of evaluating each of these factors should precede strategy design and be part of on-going review processes. In the case that the usefulness of vector surveillance cannot be demonstrated, then it may be argued that resources could be allocated to other aspects of disease control.
This qualitative study aimed to describe field worker perceptions, evaluations of worth, and time costs of routine dengue vector surveillance methods in Cairns (Australia), Kuala Lumpur and Petaling District (Malaysia). In Cairns, the BG-Sentinel trap is a favored method for field workers because of its user-friendliness, but is not as cost-efficient as the sticky ovitrap. In Kuala Lumpur, the Mosquito Larvae Trapping Device is perceived as a solution for the inaccessibility of premises to larval surveys. Nonetheless, the larval survey method is retained in Malaysia for prompt detection of dengue vectors. For dengue vector surveillance to be successful, there needs to be not only technical, quantitative evaluations of method performance but also an appreciation of how amenable field workers are to using particular methods. Here, we report novel field worker perceptions of dengue vector surveillance methods in addition to time analysis for each method.
We investigated spatial autocorrelation of female Aedes aegypti L. mosquito abundance from BG-Sentinel trap and sticky ovitrap collections in Cairns, north Queensland, Australia. BG-Sentinel trap collections in 2010 show a significant spatial autocorrelation across the study site and over a smaller spatial extent, while sticky ovitrap collections only indicate a non-significant, weak spatial autocorrelation. The BG-Sentinel trap collections were suitable for spatial interpolation using ordinary kriging and cokriging techniques. The uses of Premise Condition Index and potential breeding container data have helped improve our prediction of vector abundance. Semiovariograms and prediction maps indicate that the spatial autocorrelation of mosquito abundance determined by BG-Sentinel traps extends farther compared to sticky ovitrap collections. Based on our data, fewer BG-Sentinel traps are required to represent vector abundance at a series of houses compared to sticky ovitraps. A lack of spatial structure was observed following vector control treatment in the area. This finding has implications for the design and costs of dengue vector surveillance programs.
Chikungunya virus (CHIKV) is a major threat to Australia given the distribution of competent vectors, and the large number of travellers returning from endemic regions. We describe current knowledge of CHIKV importations into Australia, and quantify reported viraemic cases, with the aim of facilitating the formulation of public health policy and ensuring maintenance of blood safety.