**2. Methods of intervention for** *Aedes aegypti* **control**

Vector control is a complex task. There are a number of options available for different stages (eggs, larvae, pupae and adult) of the mosquito populations; a variety of available tools (physical/mechanical, environmental, biological, chemical and behavioral preventive measures) and different goals for each strategy (covering containers to avoid egg-laying, eliminating breeding sites in order to diminish larval densities, spraying insecticides to kill and reduce adult mosquitoes or installing barriers that diminish vector-human contact). The ultimate goal of each strategy is diminishing transmission. However, experience has shown that there is no "magic bullet" that is effective, lasting, affordable and easy to implement.

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*

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

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

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

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 incorporat-

Vector control is a complex task. There are a number of options available for different stages (eggs, larvae, pupae and adult) of the mosquito populations; a variety of available tools (physical/mechanical, environmental, biological, chemical and behavioral preventive measures) and different goals for each strategy (covering containers to avoid egg-laying, eliminating breeding sites in order to diminish larval densities, spraying insecticides to kill and reduce adult mosquitoes or installing barriers that diminish vector-human contact). The ultimate

ing these innovations into the inventory of mosquito management tools [4].

**2. Methods of intervention for** *Aedes aegypti* **control**

mosquito has become a public health priority.

96 Dengue Fever - a Resilient Threat in the Face of Innovation

the release of *Wolbachia-*infected mosquitoes.

management programs.

November of 2016.

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

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 transmission 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].

The introduction of technological innovations—such as the use of *Wolbachia*, the genetic modification of mosquito (GMM) populations, and/or the use of irradiated mosquitoes—that promise better coverage, impact and sustainability propose to improve the effectiveness and durability of control interventions. Nevertheless, the innovations also present organizational and procedural challenges that must be attended before, during and after their introduction as control measures.

that produce resistance to infection is transinfection with *Wolbachia*. Other mechanisms are effected through the incorporation of transgenes that—by way of impacting the vectors' survival, physiology (flight, feeding) or susceptibility to the infection—indirectly reduce the

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

http://dx.doi.org/10.5772/intechopen.79862

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*Self-limiting*: This strategy implicates the abundant and repeated release of mosquitoes in order to maintain the flux of the genetic change in the target population. It is reversible with

*Self-sustaining*: This strategy proposes repeated releases of modified mosquito populations sufficient to establish themselves as the dominant population (replacement), to the end of

One of the most important changes upon incorporating GMM-BCMW into the *Aedes* and ABD control programs is a *paradigm shift* in passing from emphasis on the larval stages to the direct impact on adult populations. These innovations in *Ae. aegypti* control direct efforts to the reproductive capacity or its competence as a vector, rather than the breeding sites. The theoretical assumption is based on the key elements for vector control centered on adult mosquitoes (abundance, survival, incubation periods, biting rate, etc.) [13]. However, directing control toward adult mosquitoes requires information that is not currently produced in

Traditional programs of control direct their efforts toward larval stages, reducing breeding sites abundance and the density of larvae in houses and containers, while they attack adult mosquitoes with insecticides that have limited coverage, short duration and low mortality at the population level. The focus and objective of integrated vector management (IVM) are directed to the control of mosquito populations through multi-sector interventions with a multidisciplinary and/or eco-bio-social focus based on changes to community practices,

GMM-BCMW are not technologies that can be used in case of emergency (outbreak control). Focus is directed to the reduction, suppression (elimination) or substitution of *Ae. aegypti* populations; but in all cases, they should be visualized within the IVM scheme as complimentary tools. Traditional vector control programs imposed a strong component of entomological surveillance (larval monitoring) not correlated to epidemiological surveillance (incidence of infection and disease); this favored control responses (reactive) before the increase of entomological indicators, without relating them to transmission risk (risk thresholds). This has resulted in reactive interventions based on detection of an increase in breeding sites or of the number of cases that frequently have late entomological effects but no epidemiological effect. With and IVM approach it is expected to use surveillance as a predictor of risk; the identification of priority areas for interventions and to promote actions before, during and after periods of epidemics. In the case of GMM-BCMW, surveillance should be improved so it can be a powerful (proactive) tool that permits entomological, epidemiological and viral surveillance.

their persisting in the population even while there may be unforeseen risks.

mosquito's vectorial competence (interference).

**4. Paradigm shift, focus and objective**

achieved by way of educational interventions.

the discontinuation of releases.

traditional control programs.
