It is time for a change in Aedes aegypti surveillance

Aedes aegypti is the main vector of dengue, Zika, chikungunya and yellow fever, and for centuries it has been an unwanted inhabitant of almost all Latin American countries. The early stages of monitoring and control in the 1900s were aimed at keeping yellow fever outbreaks at bay. Today, dengue is considered the most prevalent threat to public health among Dr. CAROLIN DEGEN PETRA SCHULTHEISS Researcher and Marketing Assistant, Biogents AG carolin. degener@biogents. com LATAM Sales Manager, Biogents petra. schultheiss@biogents. com vector-borne diseases in Latin America. The number of dengue cases is increasing, outbreaks seem to take longer to control and it is seen that there are an increasing number of people affected and who will be affected. Comprehensive surveillance, reliable data and effective control measures are key to keeping Aedes aegypti numbers and the number of dengue cases low. Recent years have also brought a number of challenges, for example limited financial and personnel resources in public health authorities, new health threats such as COVID-19 or increasing resistance to insecticides in mosquitoes. Therefore, rethinking established routines is crucial to finding the best tools for efficient and effective mosquito surveillance and control. This will lead to better management of Aedes aegypti in the future. TRADITIONAL STEGOMYIA INDICES: OLD, BUT HOW GOOD ARE THEY? Traditional larval indices (also known as Stegomyia indices) that were established as a tool to measure the effect of yellow fever control efforts on Ae. aegypti date back to 1923. Since then, the public health problem behind larval rates has shifted from yellow fever to dengue, chikungunya and Zika. Now, almost a hundred years after their first description, larval indices are still widely used in South America. But are they a good tool for estimating the risks of disease transmission and the effects of vector control efforts? It depends. They can give insight into the preferred breeding sites of local vector populations and something about the effect of control measures that only target such sites. However, many studies have shown that larval indices do not correlate with the risk of dengue transmission, which is due to several problems with the method itself and operational challenges: – Immature mosquitoes are often not counted and the productivity of positive containers is unknown and not taken into account. – Access to houses is often denied. – Results largely depend on the motivation and ability of healthcare workers to find breeding points. – High time consumption per household surveyed and high associated costs. – Only a limited number of larval surveys per year are possible (-> low temporal resolution, generally 3 surveys per year). Not surprisingly, over the past 25 years, larval indices have been questioned and increasingly viewed as an inappropriate measure for monitoring dengue mosquitoes. However, many countries still conduct these surveys, often following their countries' vector surveillance guidelines. TRAPS ARE THE BEST ALTERNATIVE! Mosquito traps are increasingly being used to monitor dengue vectors. A classic model, the low-cost, off-patent ovitrap, has been used to monitor Aedes aegypti since 1965. They are more detectable than larval surveys, but it remains difficult to estimate adult mosquito abundance and dengue transmission risks from ovitrap indices, since it is not known how many mosquitoes laid eggs. Additionally, to identify mosquito species from the eggs (Ae. aegypti or Ae. albopictus), they must hatch into larvae, which requires laboratory setup and time. However, ovitraps are good indicators of the presence or absence of dengue vectors. Traps for adult mosquitoes provide better information for deciding on mosquito control actions due to their advantages over larval surveys: – Direct measurement of the abundance of adult female dengue vectors and a correlation with dengue risk. – Better acceptance by homeowners, since the traps are less intrusive and avoid searching for breeding points throughout the house. – One health worker can visit the traps of many households per day. – High spatial resolution is possible (high number of monitored homes per area). – High temporal resolution. High temporal resolution, for example, weekly or biweekly monitoring leads to continuous estimation of adult Aedes infestation. This allows local health authorities to react more quickly to changes in mosquito density. Higher spatial resolution results in easier detection of Aedes infestation hotspots and direct control measures specifically to those areas that need them most. Traps for adult dengue vectors have been used successfully in some Brazilian cities for routine monitoring. In these studies, capture data for Ae. aegypti from two different types of adult traps were correlated with the risk of dengue cases (Ferreira et al. 2017, Parra et. al 2018). The study using BG-Sentinel traps showed that operating costs of using BG-Sentinel traps were 71% lower compared to conducting larval surveys. RELIABLE SURVEILLANCE – EFFECTIVE CONTROL: HOW TO DO IT? There are several mosquito traps available on the market, but only a few have been used by mosquito scientists and health authorities. Biogents' intensive research into the host-seeking behavior of mosquitoes and the goal of developing better mosquito control methods were accumulated into a highly efficient trap: the BG-Sentinel. Since its launch in 2004, it has become the gold standard for monitoring Aedes mosquitoes and is also recommended by the CDC. The BG-Sentinel has been successfully used to capture other mosquito species around the world to answer a wide variety of research questions, and has also been used for mosquito control. The new BG-GAT (Gravid Aedes Trap) trap targets egg-laying females and is increasingly used to monitor and control tiger mosquitoes. BG-SENTINEL AND BG-GAT: WHAT'S THE DIFFERENCE? The BG-Sentinel is an active suction trap that mimics humans. The upwardly directed air flows mimic the convection currents of the human body and dispense a patented artificial human scent (BG-Lure) that makes the trap more attractive. The central air currents generated by the fan attract mosquitoes. A light-dark contrast acts as a visual cue. Once captured in a catch bag, the mosquitoes are dried. ADVANTAGES OF BIOGENTS TRAPS FOR ADULT MOSQUITOES

Two types of traps for different life stages.
Reliable and patented technology.
Used by professionals around the world.
Scientifically proven effectiveness.
Easy to use and low maintenance.
Ecological and sustainable.
Without use of insecticides. BG-Sentinel
Increased mortality of two mosquito vectors.
Reduction in rates of human bites.
Reduction of disease transmission. The BG-Sentinel is very attractive to host-seeking dengue mosquitoes (Ae. aegypti and Ae. albopictus) and southern house mosquitoes (Culex quinquefasciatus). Optionally, carbon dioxide can be added, which generally increases Ae capture rates. albopictus and Cx. quinquefasciatus by approximately 5 times and also makes the trap attractive to all other mosquito species. For monitoring, the BG-Sentinel trap generally remains in position for 24 hours. For control, the trap is used 24/7 during the season. The BG-GAT (Gravid Aedes Trap) is an affordable passive trap that has all the characteristics of an ideal breeding site for Ae. aegypti and Ae. albopictus gravidas. Mosquitoes enter the transparent chamber through the black funnel. Once inside, the mosquitoes try to escape through the translucent chamber where they become trapped on the surface of the sticky card and die. Mosquitoes on sticky cards should be counted and identified weekly or every two weeks. The BG-GAT is very sensitive to detect the presence of Ae. aegypti and Ae. albopictus, and therefore a good alternative to ovitraps. Since the BG-GAT has lower capture rates than the BG-Sentinel, the trap generally remains constantly present in place. Both traps are ecological. They do not use toxic products or insecticides. AS
Scientifically proven effectiveness
Used by professionals around the world
Highly sensitive and specific giving reliable data
Reliable and patented technology
Ecological and environmentally friendly without the use of insecticides With BG-GAT traps distributed evenly in urban environments with known presence of the dengue vector, it is possible to obtain mosquito monitoring data every two weeks throughout the year. Such high temporal resolution will support early detection of mosquito hotspots that could lead to disease outbreaks and allows determination of the predominant species (Ae. aegypti or Ae. albopictus). The BG-Sentinel, with its high capture rates and operated with CO2, is a reliable ally to monitor all mosquito species and identify other possible disease vectors. Without the addition of CO2, it traps the dengue mosquito and domestic mosquitoes. This trap is especially useful in strategic locations such as airports, ports, schools or hospitals, where the introduction of mosquitoes and the circulation of viruses is likely to occur.
Patented human skin odor formulation
Visual stimuli with black and white contrast
Heat convection imitating the human body
A fan sucks in mosquitoes
Captured mosquitoes dehydrate in a capture bag. Advance your level of monitoring.
Direct measurement of adult female vector abundance
High spatial and temporal resolution
Possibility of capturing live mosquitoes, suitable for analysis
Up to 70% lower operating costs than Biogents larval studies: we know what mosquitoes want
1 team, 30 experts, 130 years of research experience
Highly competent, qualified and reliable
Scientifically established, researched and proven methods
Continuous research and field studies
The manufacturer is the world leader in mosquito traps.
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BG-GAT WHEN USED FOR CONTROL:

CAN BIOGENTS TRAPS SUPPORT PUBLIC HEALTH EFFORTS? MONITORING: ONLY AS TRAPS OR AS A COMPLEMENT TO LARVAE STUDIES Both traps are an excellent option for monitoring efforts. To obtain the best information on the local mosquito population, the best option is to use BG-GAT and BG-Sentinel in combination. Positioning BG-GAT traps in areas with low abundance of dengue mosquitoes, or in places where their presence has not yet been identified, helps detect new infestations very early. The BG-Sentinel trap: gold standard for monitoring Aedes mosquitoes New stage in vector surveillance BIOGENTS

CONTROL WITH BIOGENTS TRAPS: AN INCREASINGLY EXPLORED APPROACH Due to the often cryptic nature of spawn points, it is almost impossible to eliminate or treat them all. Therefore, targeting adult mosquitoes is important for successful control. Conventional adult mosquito control measures are inefficient due to operational limitations and insecticide resistance. The idea of using traps is to constantly eliminate adult mosquitoes from the environment. Since BG-Sentinel and BG-GAT target dengue mosquitoes at different life stages, it is best to use both traps in combination in mass trapping programs. A recent example where Biogents suction traps and BG-GAT traps were successfully used for mosquito control comes from an island in the Maldives that was heavily infested with Cx. quinquefasciatus and Ae. albopictus. Many years of extensive insecticide use made the local mosquito population resistant to insecticides. Local flora and fauna were also negatively affected. The consistent use of Biogents suction traps and BG-GAT traps, along with the elimination of breeding sites, resulted in successfully reducing the local mosquito population. Since insecticides are no longer sprayed, the local fauna and flora are also beginning to recover. https: //info. biogents. com/ en/biogents-and-soneva In the USA, several citizen science programs have been established in which Biogents traps are used for the control of Ae. albopictus. One of the results of one of these projects, which used BGGAT traps, was published in the scientific journal “nature Scientific Reports”. (https: //www. nature. com/articles/s41598018-34161-9). VECTOR MONITORING AND CONTROL: AN ENDLESS STORY History shows that public and private efforts are needed to monitor and control vectors such as Aedes aegypti in Latin America. New scientifically proven methods and products, such as adult mosquito surveys and control traps, should complement the existing toolbox. This would also support work towards a more efficient and resource-oriented approach to vector control, as suggested by the Integrated Management Strategy for the Prevention and Control of Dengue in the Region of the Americas (PAHO/WHO 2018). Imitate the human being to capture mosquitoes