Need for an efficient adult trap for the surveillance of dengue vectors

The emergence and re-emergence of arboviral diseases transmitted by Aedes aegypti and Ae. albopictus continue to be a major threat in the tropics and subtropics. Associations between currently used indices and dengue transmission have not been proven to be satisfactorily predictive of dengue epidemics. Classical larval indices in dengue surveillance have limited use in assessing transmission risk and are a poor proxy for measuring adult emergence. Besides, collection of larval indices is labour intensive and plagued by difficulties of access particularly in urban settings. The re-emergence of dengue disease in many countries despite lower immature indices has warranted the need for more effective indices in dengue vector surveillance and control. Reliable and highly useful indices could be developed with the help of efficient and appropriate entomological tools. Most current programmes emphasize reduction of immature Ae. aegypti density, but it is of little value because its relation to transmission risk is weak. More attention should be paid to methods directed toward adult rather than immature Ae. aegypti. Collection of sufficient numbers of adult mosquitoes is important to understand disease transmission dynamics and to devise an appropriate control strategy. Even though, use of certain traps such as BG-Sentinel traps has been attempted in monitoring Ae. aegypti population, their utility is limited due to various setbacks which make these insufficient for entomological and epidemiological studies. Thus, there is an urgent need for the development of an ideal trap that could be used for adult vector surveillance. The present review critically analyzes the setbacks in the existing tools of entomological surveillance of dengue vectors and highlights the importance and necessity of more improved, more sensitive and reliable adult trap that could be used for surveillance of dengue vectors.