**Abstract**

The recent introduction of chikungunya and Zika virus and their subsequent dispersion in the Americas have encouraged the use of novel technologies for adult *Aedes* surveillance to improve vector control. In Brazil, two platforms for surveillance of eggs and gravid *Aedes aegypti* have been developed. First, it consists of using data of sampling of eggs in ovitraps associated with GIS technologies to monitor *Aedes* spp. populations. Although effective, it is not realistic to use in a largescale epidemic scenario as it requires a large amount of human resources for field and laboratory activities. Second, it consists of trapping female *Ae. aegypti* citywide at fine spatial and temporal scales for vector surveillance (MI-*Aedes*) to detect high *Aedes* infestation areas using a GIS environment and the identification of arbovirusinfected trapped mosquitoes by RT-PCR (MI-Virus platforms). Such integration of continuous vector surveillance and targeting vector control in hotspot areas is cost-effective (less than US\$ 1.00/person/year), and it has been shown to reduce mosquito population and prevent dengue transmission. The main advantage of the MI-*Aedes* platform over traditional mosquito surveillance is the integration of continuous vector monitoring coupled with an information technology platform for near real-time data collection, analysis, and decision-making. The technologies also provide data to model the role of climate on the vector population dynamics.

**Keywords:** surveillance, vector control, novel technologies, adult trap, MI-*Aedes*, MI-Virus

### **1. Introduction**

The public health impact of arthropod-borne viruses (arboviruses) has increased dramatically over the last 50 years with diseases such dengue and chikungunya spreading to new geographic locations and increasing in incidence [1]. Most of the known arboviruses were initially isolated in tropical areas such as Africa, South America, and some Asian countries [2]. In fact, many of the diseases transmitted by arthropods encountered today not only existed but were widespread in their distribution before written records began and are among the major causes of illness and death in many countries. In recent years, and despite efforts to control vectors, the prevalence of viral infections transmitted by arthropods worldwide has increased. However, changes in viral genetics, host, and vector population as well

as the global climate facilitated, among other factors, the expansion and spread of arboviruses in the world. The expansion of global human population, migratory movements of people and animals, and rapid disordered urbanization led to a closer contact between man and animal reservoirs, thereby increasing exposure to infection with arboviruses [2].

Various arboviruses including the important public health concern dengue virus (DENV) [3], yellow fever virus [4], chikungunya virus (CHIKV) [5], and Zika virus (ZIKV) [6] have *Aedes aegypti* (**Figure 1**) and *Aedes albopictus* as vectors. The most prevalent human arboviral infection is caused by DENV that accounts for approximately 100 million annual infections worldwide with almost half of the world's population at risk of infection [7, 8]. Since CHIKV was firstly detected in the Americas in December 2013, it has caused more than 1.7 million of confirmed or suspected cases. At least 48 countries and territories of the Americas confirmed the autochthonous circulation of ZIKV [9].

Historically, surveillance of vectors that transmit arboviruses was focused on immature stages (eggs, larvae, and pupae) with little emphasis given to the adult mosquito. The oviposition trap (ovitrap) developed in the 1960s [10] is still being used to detect *Aedes* spp., especially when vector population is low (**Figure 2a**). However, surveillance of adult female population is necessary to evaluate the impact of vector control interventions, to detect arboviruses, and to look for insecticide resistance alleles. Interventions that also require surveillance of adult mosquito population include evaluations on the efficacy of insecticide-treated materials, the release of sterile or genetically modified insects, and the dispersion of spatial repellents.

In light of the requirements listed above, various traps have been developed to monitor the populations of *Aedes* spp. and other arthropods by sampling eggs and host-seeking or gravid females. Traps devised to catch adult *Ae. aegypti* are divided into two major classes: active and passive. Passive traps are low cost and capture gravid *Ae. aegypti* without electricity using funnels, sticky cards, or insecticides. In these traps, water or an infusion of hay is used to attract the insects. Examples of sticky traps for adult vectors are MosquiTRAP, Gravid *Aedes* Trap (GAT), and Autocidal Gravid Ovitrap (CDC-AGO) (**Figure 2b**–**d**) [11]. The catch rates of passive traps depend on factors such as size, color, and type of attractant, among others. In contrast, active traps use an electrical device—for instance, a batteryoperated fan that sucks the insects into the trap. BG-Sentinel (**Figure 2e**) is an example of active trap used to capture adult mosquitoes.

#### **Figure 1.**

*Global map of forecasted probability of occurrence of Aedes aegypti at a spatial resolution of 5 × 5 km (Kraemer et al. [1], https://doi.org/10.7554/eLife.08347.004).*

**125**

health authorities.

**2. Gravid mosquito traps**

*New Cost-Benefit of Brazilian Technology for Vector Surveillance Using Trapping System*

Health authorities are increasingly employing new technologies in order to achieve integrated *Aedes* management. In this context, predictive mathematical modeling has the potential to help authorities to act preemptively by rapidly preparing vector alerts and mobilizing the resources needed for an integrated vector management whenever an imminent surge of mosquitoes and, therefore, a higher risk of infection with arboviruses are likely to take place. Also, by assessing the data collected by surveillance traps for adult mosquitoes using spatial statistics, it is possible to present data correlating the infestation index with other variables such as the vector control method used, epidemiological data, virus-infected mosquito data, and climatic data, among others [12]. The automated presentation of the results obtained directly from the field allows the integrated analysis of entomological data with geographic information system (GIS), thereby enabling the deliverance of immediate vector control responses to the precise localities presenting the

*Passive mosquito traps used for surveillance: (a) ovitrap, (b) MosquiTRAP, (c) Aedes Gravid Traps (GAT),* 

*(d) Autocidal Gravid Ovitrap (CDC-AGO), and (e) the active trap BG-Sentinel.*

Climate is an important factor in the geographic and temporal distribution of arthropods. It is also relevant for the patterns of dispersion and efficiency in the transmission of arboviruses by arthropods to their hosts [13]. Considering the perspectives regarding global climate changes, it is likely that arboviruses will continue to colonize new regions of the planet. Thus, research regarding the role of climate in the population dynamics of vectors and predictions of future scenarios depend on the ability of climate-based models to describe associations with arboviruses. Monitoring the effect of climatic variations on vector surveillance and control can be achieved by technological platforms with adequate space-time resolution.

This chapter presents two study cases of vector surveillance by sampling egg and adult *Aedes* spp. mosquitoes in Brazilian municipalities. It also provides a comprehensive description of innovative web platforms that process, in near real time, data regarding adult vector abundance and arbovirus identification from mosquitoes caught in sticky traps strategically positioned in urban areas. The information gathered can be used to rapidly activate vector control actions making these platforms successful and cost-effective tools to deal with arboviral disease threats by public

The ovitrap has been used for many decades as a sensitive, inexpensive, passive surveillance tool for detecting the presence of gravid mosquitoes [10, 14]. The addition of a larvicide or autocidal mechanism allows long-term use of ovitraps with minimal risk of the device becoming a productive source of adult mosquitoes [15]. In spite of these positive attributes, ovitraps only provide information on the number of collected eggs and cannot produce accurate information about the

*DOI: http://dx.doi.org/10.5772/intechopen.78781*

**Figure 2.**

highest levels of mosquito infestation.

*New Cost-Benefit of Brazilian Technology for Vector Surveillance Using Trapping System DOI: http://dx.doi.org/10.5772/intechopen.78781*

**Figure 2.**

*Malaria*

repellents.

tion with arboviruses [2].

autochthonous circulation of ZIKV [9].

as the global climate facilitated, among other factors, the expansion and spread of arboviruses in the world. The expansion of global human population, migratory movements of people and animals, and rapid disordered urbanization led to a closer contact between man and animal reservoirs, thereby increasing exposure to infec-

Various arboviruses including the important public health concern dengue virus (DENV) [3], yellow fever virus [4], chikungunya virus (CHIKV) [5], and Zika virus (ZIKV) [6] have *Aedes aegypti* (**Figure 1**) and *Aedes albopictus* as vectors. The most prevalent human arboviral infection is caused by DENV that accounts for approximately 100 million annual infections worldwide with almost half of the world's population at risk of infection [7, 8]. Since CHIKV was firstly detected in the Americas in December 2013, it has caused more than 1.7 million of confirmed or suspected cases. At least 48 countries and territories of the Americas confirmed the

Historically, surveillance of vectors that transmit arboviruses was focused on immature stages (eggs, larvae, and pupae) with little emphasis given to the adult mosquito. The oviposition trap (ovitrap) developed in the 1960s [10] is still being used to detect *Aedes* spp., especially when vector population is low (**Figure 2a**). However, surveillance of adult female population is necessary to evaluate the impact of vector control interventions, to detect arboviruses, and to look for insecticide resistance alleles. Interventions that also require surveillance of adult mosquito population include evaluations on the efficacy of insecticide-treated materials, the release of sterile or genetically modified insects, and the dispersion of spatial

In light of the requirements listed above, various traps have been developed to monitor the populations of *Aedes* spp. and other arthropods by sampling eggs and host-seeking or gravid females. Traps devised to catch adult *Ae. aegypti* are divided into two major classes: active and passive. Passive traps are low cost and capture gravid *Ae. aegypti* without electricity using funnels, sticky cards, or insecticides. In these traps, water or an infusion of hay is used to attract the insects. Examples of sticky traps for adult vectors are MosquiTRAP, Gravid *Aedes* Trap (GAT), and Autocidal Gravid Ovitrap (CDC-AGO) (**Figure 2b**–**d**) [11]. The catch rates of passive traps depend on factors such as size, color, and type of attractant, among others. In contrast, active traps use an electrical device—for instance, a batteryoperated fan that sucks the insects into the trap. BG-Sentinel (**Figure 2e**) is an

*Global map of forecasted probability of occurrence of Aedes aegypti at a spatial resolution of 5 × 5 km* 

example of active trap used to capture adult mosquitoes.

*(Kraemer et al. [1], https://doi.org/10.7554/eLife.08347.004).*

**124**

**Figure 1.**

*Passive mosquito traps used for surveillance: (a) ovitrap, (b) MosquiTRAP, (c) Aedes Gravid Traps (GAT), (d) Autocidal Gravid Ovitrap (CDC-AGO), and (e) the active trap BG-Sentinel.*

Health authorities are increasingly employing new technologies in order to achieve integrated *Aedes* management. In this context, predictive mathematical modeling has the potential to help authorities to act preemptively by rapidly preparing vector alerts and mobilizing the resources needed for an integrated vector management whenever an imminent surge of mosquitoes and, therefore, a higher risk of infection with arboviruses are likely to take place. Also, by assessing the data collected by surveillance traps for adult mosquitoes using spatial statistics, it is possible to present data correlating the infestation index with other variables such as the vector control method used, epidemiological data, virus-infected mosquito data, and climatic data, among others [12]. The automated presentation of the results obtained directly from the field allows the integrated analysis of entomological data with geographic information system (GIS), thereby enabling the deliverance of immediate vector control responses to the precise localities presenting the highest levels of mosquito infestation.

Climate is an important factor in the geographic and temporal distribution of arthropods. It is also relevant for the patterns of dispersion and efficiency in the transmission of arboviruses by arthropods to their hosts [13]. Considering the perspectives regarding global climate changes, it is likely that arboviruses will continue to colonize new regions of the planet. Thus, research regarding the role of climate in the population dynamics of vectors and predictions of future scenarios depend on the ability of climate-based models to describe associations with arboviruses. Monitoring the effect of climatic variations on vector surveillance and control can be achieved by technological platforms with adequate space-time resolution.

This chapter presents two study cases of vector surveillance by sampling egg and adult *Aedes* spp. mosquitoes in Brazilian municipalities. It also provides a comprehensive description of innovative web platforms that process, in near real time, data regarding adult vector abundance and arbovirus identification from mosquitoes caught in sticky traps strategically positioned in urban areas. The information gathered can be used to rapidly activate vector control actions making these platforms successful and cost-effective tools to deal with arboviral disease threats by public health authorities.

### **2. Gravid mosquito traps**

The ovitrap has been used for many decades as a sensitive, inexpensive, passive surveillance tool for detecting the presence of gravid mosquitoes [10, 14]. The addition of a larvicide or autocidal mechanism allows long-term use of ovitraps with minimal risk of the device becoming a productive source of adult mosquitoes [15]. In spite of these positive attributes, ovitraps only provide information on the number of collected eggs and cannot produce accurate information about the

number of gravid *Aedes* mosquitoes. This is because a single female can lay different numbers of eggs in a single ovitrap [16], and therefore, information on the presence of eggs alone does not produce enough information about the levels of infestation of a particular area. Another shortcoming of the ovitrap is that it requires laboratory logistics for egg counting, hatching, and identification of the larvae. Consequently, information about the vector population is delayed by at least 1 or 2 weeks [17].

Ovitraps can be modified to collect gravid females by incorporating an adhesive capture surface (sticky ovitraps). Adult female mosquitoes collected in sticky ovitraps provide a direct measure of adult abundance, and those can also be morphologically identified in the field and processed to detect arboviruses [18, 19]. Sampling with sticky ovitraps is a more sensitive method to detect and estimate adult mosquitoes in comparison with sampling of immatures [20–22].

A major advantage of using sticky traps is that the captured mosquitoes can be readily identified in the field at the time of trap inspection. This avoids the need for additional specialized human labor and the delay imposed when samples have to be delivered to laboratories to identify the mosquito [20]. The abundance of adult mosquitoes was successfully estimated in three areas of Rio de Janeiro, Brazil, by using sticky traps [23]. Obviously, these kinds of field-ready results are only possible if field agents are well-trained to identify the mosquito species of *Ae. aegypti*. Indeed, well-trained agents have been shown to accurately (95–100%) identify *Ae. aegypti* captured using the sticky trap MosquiTRAP [24]. However, a later study found that mosquito identification in the laboratory was superior to that performed in locus by trained field agents [25]; divergent results presented by these studies may be due to differences in the way the field agents were trained and qualified.

Several sticky trap models have been developed to capture gravid *Ae. aegypti* in Brazil [20, 26], Australia [18], Italy [27], Porto Rico [28], and Malaysia [29]. All rely on a combination of visual and olfactory stimuli for the oviposition behavior of gravid *Aedes* spp. Typically, a sticky trap consists of a black matte plastic container of any size, an entrance port, water, an oviposition attractant, and a sticky card using an odorless entomological glue to retain the gravid mosquito. Once stuck, the mosquito remains in resting position. Those that escape usually loose one or more legs remain adhered to the sticky card. Identification of collected mosquitoes is still possible with their thoraces since they usually remain somewhat visible [18, 20]. Sticky traps do not require electricity or batteries and are, therefore, lowcost devices.

The oviposition attractants include infusions of organic materials such as hay [15], grass infusions [30], or synthetic lures [31]. The chemical composition of synthetic oviposition attractants was derived from research that identified volatiles of grass infusions that were behaviorally active in laboratory, semi-field, and field studies. The synthetic oviposition attractant Atr*Aedes*™ used in the MosquiTRAP consists of a mixture of nonanal, decanal, and 3-methylphenol, which is released from a sealed-tube reservoir system for approximately 45 days at a constant rate to continually attract the target species [31]. The main advantage of using synthetic attractants is that the synthetic lure has a constant attractiveness over time and has a pleasant smell, whereas grass infusions need to be transported and rest for 5–7 days to be active and are smelly.

The place where the sticky trap is positioned in the investigated premises is important to increase the mosquito catch rate. Studies in Brazil revealed that when the sticky trap MosquiTRAP was placed outdoor, it captured five times more females than indoor traps [26]. This is probably because host-seeking *Ae. aegypti* feed on human blood indoors but lay eggs outdoors after a few days of digesting

**127**

**Figure 3.**

*New Cost-Benefit of Brazilian Technology for Vector Surveillance Using Trapping System*

the blood meal. Moreover, outdoor traps allow vector control workers to sample the mosquitoes without inconveniencing homeowners and are notably well-accepted by

The potential of the MosquiTRAP for trapping gravid *Ae. aegypti* has been compared with the Nasci aspirator [33] and backpack aspirator [34]. Sticky traps collected a higher number of mosquitoes and are more cost-effective and operationally easier, besides being less inconvenient to householders than active traps. MosquiTRAP has ben also compared with BG-Sentinel trap and Adultrap and

Altogether, sticky traps are perhaps the most appropriate tools for *Ae. aegypti* surveillance and the development of new entomological indices for the detection of epidemic outbreaks in urban areas. Interestingly, a study comparing the ability to detect *Ae. aegypti* by the different surveillance methods (larval survey, ovitrap, and the sticky trap MosquiTRAP) showed that ovitrap and the sticky trap predicted dengue occurrence better than larval survey, both spatially and temporally. However, ovitrap clusters showed less accuracy in pinpointing the dengue risk areas, and the sticky trap presented better results for signaling dengue transmission

*Cluster reliability maps of (A) dengue cases, (B) larval survey, (C) ovitrap, and (D) MosquiTRAP catches in Belo Horizonte (Minas Gerais, Brazil) from January 2007 to June 2008. Darker colors represent higher reliability values (Belo Horizonte city, Minas Gerais State, Brazil, Adapted from De Melo et al. [36]).*

*DOI: http://dx.doi.org/10.5772/intechopen.78781*

local communities [17, 18, 27, 32].

ovitrap with favorable results [35].

risk both geographically and temporally (**Figure 3**) [36].

*New Cost-Benefit of Brazilian Technology for Vector Surveillance Using Trapping System DOI: http://dx.doi.org/10.5772/intechopen.78781*

the blood meal. Moreover, outdoor traps allow vector control workers to sample the mosquitoes without inconveniencing homeowners and are notably well-accepted by local communities [17, 18, 27, 32].

The potential of the MosquiTRAP for trapping gravid *Ae. aegypti* has been compared with the Nasci aspirator [33] and backpack aspirator [34]. Sticky traps collected a higher number of mosquitoes and are more cost-effective and operationally easier, besides being less inconvenient to householders than active traps. MosquiTRAP has ben also compared with BG-Sentinel trap and Adultrap and ovitrap with favorable results [35].

Altogether, sticky traps are perhaps the most appropriate tools for *Ae. aegypti* surveillance and the development of new entomological indices for the detection of epidemic outbreaks in urban areas. Interestingly, a study comparing the ability to detect *Ae. aegypti* by the different surveillance methods (larval survey, ovitrap, and the sticky trap MosquiTRAP) showed that ovitrap and the sticky trap predicted dengue occurrence better than larval survey, both spatially and temporally. However, ovitrap clusters showed less accuracy in pinpointing the dengue risk areas, and the sticky trap presented better results for signaling dengue transmission risk both geographically and temporally (**Figure 3**) [36].

#### **Figure 3.**

*Malaria*

qualified.

cost devices.

to be active and are smelly.

number of gravid *Aedes* mosquitoes. This is because a single female can lay different numbers of eggs in a single ovitrap [16], and therefore, information on the presence of eggs alone does not produce enough information about the levels of infestation of a particular area. Another shortcoming of the ovitrap is that it requires laboratory logistics for egg counting, hatching, and identification of the larvae. Consequently, information about the vector population is delayed by at least 1 or 2 weeks [17].

Ovitraps can be modified to collect gravid females by incorporating an adhesive

A major advantage of using sticky traps is that the captured mosquitoes can be readily identified in the field at the time of trap inspection. This avoids the need for additional specialized human labor and the delay imposed when samples have to be delivered to laboratories to identify the mosquito [20]. The abundance of adult mosquitoes was successfully estimated in three areas of Rio de Janeiro, Brazil, by using sticky traps [23]. Obviously, these kinds of field-ready results are only possible if field agents are well-trained to identify the mosquito species of *Ae. aegypti*. Indeed, well-trained agents have been shown to accurately (95–100%) identify *Ae. aegypti* captured using the sticky trap MosquiTRAP [24]. However, a later study found that mosquito identification in the laboratory was superior to that performed in locus by trained field agents [25]; divergent results presented by these studies may be due to differences in the way the field agents were trained and

Several sticky trap models have been developed to capture gravid *Ae. aegypti* in Brazil [20, 26], Australia [18], Italy [27], Porto Rico [28], and Malaysia [29]. All rely on a combination of visual and olfactory stimuli for the oviposition behavior of gravid *Aedes* spp. Typically, a sticky trap consists of a black matte plastic container of any size, an entrance port, water, an oviposition attractant, and a sticky card using an odorless entomological glue to retain the gravid mosquito. Once stuck, the mosquito remains in resting position. Those that escape usually loose one or more legs remain adhered to the sticky card. Identification of collected mosquitoes is still

[18, 20]. Sticky traps do not require electricity or batteries and are, therefore, low-

The oviposition attractants include infusions of organic materials such as hay [15], grass infusions [30], or synthetic lures [31]. The chemical composition of synthetic oviposition attractants was derived from research that identified volatiles of grass infusions that were behaviorally active in laboratory, semi-field, and field studies. The synthetic oviposition attractant Atr*Aedes*™ used in the MosquiTRAP consists of a mixture of nonanal, decanal, and 3-methylphenol, which is released from a sealed-tube reservoir system for approximately 45 days at a constant rate to continually attract the target species [31]. The main advantage of using synthetic attractants is that the synthetic lure has a constant attractiveness over time and has a pleasant smell, whereas grass infusions need to be transported and rest for 5–7 days

The place where the sticky trap is positioned in the investigated premises is important to increase the mosquito catch rate. Studies in Brazil revealed that when the sticky trap MosquiTRAP was placed outdoor, it captured five times more females than indoor traps [26]. This is probably because host-seeking *Ae. aegypti* feed on human blood indoors but lay eggs outdoors after a few days of digesting

possible with their thoraces since they usually remain somewhat visible

capture surface (sticky ovitraps). Adult female mosquitoes collected in sticky ovitraps provide a direct measure of adult abundance, and those can also be morphologically identified in the field and processed to detect arboviruses [18, 19]. Sampling with sticky ovitraps is a more sensitive method to detect and estimate

adult mosquitoes in comparison with sampling of immatures [20–22].

**126**

*Cluster reliability maps of (A) dengue cases, (B) larval survey, (C) ovitrap, and (D) MosquiTRAP catches in Belo Horizonte (Minas Gerais, Brazil) from January 2007 to June 2008. Darker colors represent higher reliability values (Belo Horizonte city, Minas Gerais State, Brazil, Adapted from De Melo et al. [36]).*
