**1. Introduction**

The tools and strategies that have been implemented in recent decades to control the *Aedes aegypti* mosquito face an efficient vector of various viruses [dengue, chikungunya, Zika and yellow fever, which together are known as *Aedes-*borne diseases (ABD)] that has a great capacity for adaptation to human and urban habitats (domesticated).

Improvements in the quantification and control of this mosquito in urban environments and the transmission of ABD require a reformulation of current control strategies, as well as a

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stronger focus on reducing vector abundance, preventing human-vector contact and finally, reducing virus transmission [1, 2]. Due to the multiplicity of co-circulating viruses transmitted by the *Aedes* mosquito and the absence of effective treatment or vaccines against these infections, the development of long-term strategies for managing the populations of the *Aedes* mosquito has become a public health priority.

goal of each strategy is diminishing transmission. However, experience has shown that there

Challenges for the Introduction and Evaluation of the Impact of Innovative *Aedes aegypti*…

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The purpose of vector control is to maintain populations at "acceptable" densities, to minimize vector-human contact (to prevent mosquito bites) and to reduce the longevity of female adult mosquitoes, in order to reduce the health problem to a manageable level that does not surpass the capacities of local health systems. The ambitious campaign (1947–1970) promoted by the Pan American Health Organization (PAHO) to eliminate *Ae. aegypti* from the continent was one of the great Latin American public health events due to the extent of its achievements throughout the continent. Eradication is not plausible for *Ae. aegypti*, elimination was a goal

We are challenged by different stages of the vector's life cycle which develop in different environments (air and water) and in different types of breeding sites (natural and artificial), made of a variety of materials (plastic, metal, cement, clay, glass, etc.) and have different productivity, different uses (some may be disposable and others able to be controlled) and can be either permanent or seasonal. This variability in type of vector breeding sites imposes diverse challenges for control—whether it can be sporadic (cleaning campaigns), continuous (use of larvicides or larvivorous fish), or permanent (physical elimination)—and it is not realistic to expect that these differences require a homogenous strategy. The characteristics of the different types of breeding sites require a variety of customized strategies so that the control may be effective and sustainable. The diversity of available vector control strategies and their implementation in each operation are related to the resources available, the cultural context in which the interventions are performed and the overall capacity for applying them appropriately and with sufficient coverage. These factors can and should be included in the integrated vector management (IVM) approach promoted by the WHO [5, 6]. IVM is based on a spectrum of intervention strategies, frequently utilized in synergy and applied simultaneously, that are selected based off of knowledge of local factors influencing the vector's biology and the disease's transmis-

is no "magic bullet" that is effective, lasting, affordable and easy to implement.

sion and morbidity, with the goal of optimizing resources for vector control.

As dengue spread on the last decades, the idea of vector control replaced that of vector elimination, because the magnitude of the problem surpassed the capacity of institutional responses (vertical programs) and incorporated new approaches such as community participation; biological control of larvae (copepods, *Bacillus thuringiensis* (Bti) and fish); physical control (mosquito nets, curtains, clothing, etc., all impregnated with insecticide); chemical control (repellents, larvicides and novel insecticides); behavior change communication [7] (BCC) and communication for behavioral impact [8, 9] (COMBI); integrated management in the comprehensive control of vectors (EGI-Dengue, 2003) [10] and even the design of multidisciplinary approaches, such as an eco-bio-social emphasis [11]. The incorporation of so many different approaches is a clear sign of the complexity entailed in facing this mosquito. Despite new vector control strategies being introduced with the goal of diminishing transmission, entomological monitoring indicators were never adapted to the new demands of the programs, and the traditional indices designed to measure the presence and absence of larvae and containers, which were never linked to the risk of transmission, were maintained [12].

pursued in the past, but the desirable goal is now control.

Traditional mosquito control strategies have consisted of nonintegrated vector management of the immature (larvae) mosquito stage and of the use of insecticides that have fairly low—and temporary—mortality rates in adult female mosquitoes. Effective and sustained control by these methods and intervention is impeded by a number of obstacles: effective coverage of all breeding sources, lack of personnel needed, the need of continuous insecticide re-application, the transitory nature of their effects, the false sense of security that they generate and the dependence fomented in both the affected communities and the mosquito management programs.

On February 1, 2016, the World Health Organization (WHO) declared the Zika virus, along with microcephaly and the other associated neurological disorders, a public health emergency of international importance (public health emergency of international concern, PHEIC) [3]. The Zika outbreak rapidly reached across not only the Americas, but also 75 other countries and territories; its control continues to be a long-term challenge to public health even after the declaration of the end of the state of emergency by the WHO Emergency Committee in November of 2016.

Due to this emergency, the scientific community; entrepreneurs and international, regional, and national governmental programs in areas endemic to *Ae. aegypti* and ABD are researching on innovative alternative methods of vector control. WHO has expressed its support for developing and upscaling three novel approaches to controlling the *Ae. aegypti* mosquito: the sterile insect technique (SIT), the release of insects carrying dominant lethal genes (RIDL) and the release of *Wolbachia-*infected mosquitoes.

We find ourselves looking to the possible incorporation of various technological innovations whose application in the field of public health offers positive (theoretical) prospects of success along with new opportunities for enhancing the effectiveness of control programs; however, there are also technical and operational challenges that must be considered before incorporating these innovations into the inventory of mosquito management tools [4].
