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The intensifying expansion of arboviruses highlights the need for effective invasive Aedes control. While mass-trapping interventions have long been discredited as inefficient compared to insecticide applications, increasing levels of insecticide resistance, and the development of simple affordable traps that target and kill gravid female mosquitoes, show great promise. We summarize the methodologies and outcomes of recent lethal oviposition trap-based mass interventions for suppression of urban Aedes and their associated diseases. The evidence supports the recommendation of mass deployments of oviposition traps to suppress populations of invasive Aedes, although better measures of the effects on disease control are needed. Strategies associated with successful mass-trap deployments include: (1) high coverage (>80%) of the residential areas; (2) pre-intervention and/or parallel source reduction campaigns; (3) direct involvement of community members for economic long-term sustainability; and (4) use of new-generation larger traps (Autocidal Gravid Ovitrap, AGO; Gravid Aedes Trap, GAT) to outcompete remaining water-holding containers. While to the best of our knowledge all published studies so far have been on Ae. aegypti in resource-poor or tropical settings, we propose that mass deployment of lethal oviposition traps can be used for focused cost-effective control of temperate Ae. albopictus preempting arboviral epidemics and increasing participation of residents in urban mosquito control.
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Insects 2017, 8, 5; doi:10.3390/insects8010005
The State of the Art of Lethal Oviposition Trap-Based
Mass Interventions for Arboviral Control
Brian J. Johnson 1,2,*, Scott A. Ritchie 1,2 and Dina M. Fonseca 3
1 College of Public Health, Medical and Veterinary Sciences, James Cook University, McGregor Rd.,
Cairns, QLD 4878, Australia;
2 Australian Institute of Tropical Health and Medicine, James Cook University, P.O. Box 6811,
Cairns, QLD 4870, Australia
3 Center for Vector Biology, Rutgers University, 180 Jones Ave., New Brunswick, NJ 08901, USA;
* Correspondence:; Tel.: +61-7-4232-1202
Academic Editor: Walter J. Tabachnick
Received: 2 November 2016; Accepted: 19 December 2016; Published: 8 January 2017
Abstract: The intensifying expansion of arboviruses highlights the need for
effective invasive
control. While mass-trapping interventions have long been discredited as inefficient compared
to insecticide applications, increasing levels of insecticide resistance, and the development of
simple affordable traps that target and kill gravid female mosquitoes, show great promise. We
summarize the methodologies and outcomes of recent lethal oviposition trap-based mass
interventions for suppression of urban
and their associated diseases. The evidence
supports the recommendation of
mass deployments of oviposition traps to suppress populations
of invasive Aedes, although better measures of the effects on disease control are needed. Strategies
associated with successful mass-trap deployments include: (1) high coverage (>80%) of the
residential areas; (2) pre-intervention and/or parallel source reduction campaigns; (3) direct
involvement of community members for economic long-term sustainability; and (4) use of new-
generation larger traps (Autocidal Gravid Ovitrap, AGO; Gravid Aedes Trap, GAT) to outcompete
remaining water-holding containers. While to the best of our knowledge all published studies so far
have been on Ae. aegypti in resource-poor or tropical settings, we propose that mass deployment of
lethal oviposition traps can be used for focused cost-effective control of temperate Ae. albopictus pre-
empting arboviral epidemics and increasing participation of residents in urban mosquito control.
Keywords: urban; invasive; Aedes; ovitrap; vector control; dengue; Zika; community engagement
1. Introduction
continued global scourge of mosquito-borne dengue fever [1],
the recent emergence and
explosive spread of chikungunya around the world [2], of Zika fever in South and Central
America and, most importantly, its association with fetal microcephaly [3],
have provided
renewed impetus for the development of effective urban mosquito control. The primary vectors
of emerging arboviruses are invasive
Aedes aegypti
Aedes albopictus
that thrive in private
backyards and/or inside the residence [4,5]
, limiting
the efficacy of area-wide mosquito control
approaches [6]
. Rising insecticide resistance in Aedes [7] often leads to failed control and the short-
lived efficacy of adulticides (often only a couple of days) requires frequent applications [8,9].
Therefore, although models often support the use of peri-domestic insecticide space spraying to
control dengue, and now Zika, there has been little to no epidemiological evidence that such costly
and time consuming control strategies are effective [10].
Insects 2017, 8, 5 2 of 15
The evidence is strong for the need for novel control methods, ideally those circumventing the
use of insecticides, and that are cheap, allowing for deployment in resource-poor areas and/or at the
large scale needed for eradication, a viable aim when addressing invasive species limited by their
association to humans and human-modified environments [11,12]. A standard approach in pest
control is to exploit “weak links”, critical needs of the pest that may be targeted for control [13], such
as the characteristic behavior of urban Aedes females to lay eggs
in artificial (man-made) water-
holding containers [1416]
. Of note, in temperate regions, where with some exceptions [17,18] Aedes-
vectored viruses are still a worry and not a panic, public health campaigns employ
residents to
empty or remove any water-holding containers from their yards [19]
. Even when such advice is
supported by information campaigns, however, there has been a lack of entomological data showing
that residents on their own can significantly reduce Aedes habitat from their properties [20], but see
[21]. More importantly, however, there has been scarce evidence that targeting just immature stages
has a real impact on adult populations [22], possibly because there is such high baseline immature
mortality due to the transient nature of the small containers exploited by invasive Aedes [23] and
density-dependent regulation due to limited food in containers [24].
With the goal of developing new interventions aimed at reducing both adult female mosquitoes
and their future offspring, researchers have developed lethal oviposition traps, which are lure and
kill traps that lure ovipositing females with an attractive infusion and kill them when they attempt
to lay eggs (Figure 1). Importantly, these traps target a critical epidemiological stage: gravid female
mosquitoes that are more likely to be infected with a vector-borne pathogen than the general adult
population, since they have had contact with blood. Females are usually killed quickly, thus killing
their progeny, leading to population reductionslarvae or adults that may develop from dropped
eggs are killed by residual insecticide or trapped and drowned. Of note, likely a consequence of the
high container turnover rate, as well as the need to avoid high-competition environments for the
immature, female Ae. aegypti and Ae. albopictus are “bet-hedgers” that employ strategies to minimize
the risk of total reproductive failure, or the loss of all eggs, over space and time by laying their eggs
among several oviposition sources [25,26]. This “skip-oviposition” strategy [27,28] means the
attractiveness of the trap relative to alternative water-holding containers is critical for control
effectiveness. Of note, temperate populations of Ae. albopictus allow diapausing eggs to accumulate
in the fall [26], possibly to maximize the chance of successful emergence in the spring, a strategy that
can be easily exploited for control.
The first modern example of a lethal trap for mosquito control can be credited to Lok et al. [29]
and consisted of a black, water-filled cylindrical container with a flotation device made up of a wire
mesh and two wooden paddles. Although ovipositing females were not killed, after eggs laid on the
wooden paddles hatched, larvae developed in the water under the wire mesh and emerging adults
trapped under the wire mesh drowned. While the trap was largely successful at eliminating Ae.
aegypti from the Singapore International Airport in the late 1970s [29], it was prone to mechanical
failure and, as mentioned, did not kill adult females. Thus, the next step in trap evolution was the
development of the lethal ovitrap (LO, Figure 1a), the first lethal oviposition trap. LOs are commonly
comprised of a small black plastic cup (400700 mL) containing an insecticide treated ovistrip that
kills ovipositing females attracted by the hay and water infusion [3032]. LOs can be very cheap
(<US$1) and therefore hundreds of traps can be deployed simultaneously across many individual
residences to achieve high coverage. A drawback of LOs, however, is that they are ineffective against
insecticide-resistant individuals [30,3234]. To overcome the problem imposed by insecticide
resistance, several researchers developed a sticky ovitrap (SO; Figure 1b,c) [3538]. SOs use the same
lure and kill strategy of LOs, but instead of insecticide treated ovistrips, they contain an adhesive
strip that captures and kills ovipositing females. The added benefit of SOs is that they can be used for
mosquito surveillance or to determine viral infection rates in local mosquito populations.
But a trade-off of the low price of the original LOs and SOs is their small size and consequently
high evaporation rates, which mandates short maintenance intervals (at least once a week depending
on rainfall). A larger trap, besides holding more attractive infusion [39], allows for longer
maintenance intervals and also provides a more conspicuous visual target for gravid females
Insects 2017, 8, 5 3 of 15
searching for suitable oviposition sites by a greater release of infusion and olfactory attraction. When
dealing with females that “skip-oviposit” and the almost impossible task of removing all other
sources of standing water where a female may choose to lay eggs [14,16], it makes sense to stack the
odds towards deploying the most attractive lethal oviposition trap and kill the ovipositing females
at their first try. While urban Aedes will enter small openings to gain access to water in hard-to-find
(cryptic) areas [26,40], they typically will first lay eggs in open containers of easy access, if those are
present [26]. Of note, one of the foreseeable drawbacks of source reduction without providing
alternative oviposition substrates (such as the traps) is that cryptic habitats, which are harder to find,
may become the primary larval production sources, further complicating Aedes control [16,41].
To harness the potential benefits derived from a larger ovitrap, researchers have recently
developed the Centers for Disease Control and Prevention Autocidal Gravid Ovitrap (AGO; Figure
1e; [39]) and the Gravid Aedes Trap (GAT; Figure 1d; [42]). The AGO is a large (19 L) black bucket
with a relatively large opening (3.8 L black cylindrical entrance) in which an adhesive panel is placed
and is baited with 10 L of water-hay infusion. In contrast to the solid black design of the AGO, the
GAT employs a compartmentalized design with a black bottom bucket with 3 L of water-hay infusion
(or other types as needed) and a translucent middle collection chamber with a black entry funnel. The
translucent collection chamber helps retain captured mosquitoes by exploiting their “fly to the light”
behavior once they enter the trap. While the recommended killing agent in the GAT is the application
of a long-lasting surface spray to inside of the collection chamber, it has recently been demonstrated
that using a hanging adhesive panel or applying edible canola oil to the inside of the collection
chamber are effective non-insecticide killing agents [43].
Figure 1. Common ovitraps used in recent mass-trapping campaigns: (A) standard (500 mL) lethal
ovitrap (LO); (B) National Environmental Agency Singapore sticky ovitrap (SO); (C) MosquiTRAP
sticky ovitrap (SO); (D) Biogents Gravid Aedes Trap (GAT); and (E) Centers for Disease Control (CDC)
Autocidal Gravid Ovitrap (AGO).
Although the traps differ in design, both the AGO and GAT have achieved the desired effect of
outperforming standard ovitraps and other lethal autocidal ovitraps in attractiveness to Aedes. Field
trials in Puerto Rico have demonstrated that the AGO captured more gravid females and provided
greater sensitivity (number of traps positive for Ae. aegypti) than conventional ovitraps [39], whereas
in field trials in Northern Australia, GATs collected 24 times more female Ae. aegypti than two
variations of SOs, the MosquiTRAP and the double sticky ovitrap [44]. Results from the AGO and
GAT trials support the notion that a larger size and greater amount of infusion increases trap efficacy.
The flexibility of the GAT allowing the use of a variety of killing agentsincluding edible canola
oilmakes it customizable and acceptable by residents that want to develop community-based Aedes
control [45].
Insects 2017, 8, 5 4 of 15
Because LOs, SOs and large AGOs and GATs all satisfy many of the requirements for sustainable
vector control (i.e., simple, cheap, target adult females), they make ideal candidates for mass-trapping
interventions. Here we summarize recent (20002016) mass-deployments of lethal oviposition traps.
We then provide a summary/discussion of best operating procedures and discuss limitations,
opportunities and future directions.
2. Mass Lethal Ovitrapping Interventions
2.1. LO Mass-Trapping in Brazil and Thailand
Two of the earliest attempts to reduce female Ae. aegypti populations using simple LOs were
conducted by Perich et al. [30] in Brazil, and Sithiprasasna et al. [33] in Thailand. Both studies
involved the placement of 10 LOs/residence for 12 weeks [30] or 30 weeks [33], and the sampling of
30 houses per intervention neighbourhood. Both studies used the same LOs comprised of a small,
473 mL black plastic cup baited with 10% hay (w/v) infusion and containing a 11 × 2.5 cm ovistrip
treated with deltamethrin, a pyrethroid. Neither study provided information on the proportion of
houses with LOs in the intervention areas or implemented any concurrent vector control (no space
spraying, source reduction, or larviciding). Despite the lack of additional control, these wide-scale
deployments of LOs resulted in a >40% reduction in adult female abundance in at least one site, a
49%80% reduction in containers positive for Ae. aegypti larvae, and a 56%97% reduction in the mean
number of pupae per house. Despite these successes, the observed impact on viral transmission risk,
particularly in the Sithiprasasna et al. [33] study, was lower than desired. The failure was attributed
to immigration of Ae. aegypti from adjacent areas, reduced lethality of the ovistrip after field exposure,
and competition from alternative breeding sites. However, particularly because no source reduction
or other complementary interventions were implemented, these standalone LO results provide
compelling support for multi-trap per residence LO-based interventions.
2.2. LO Mass-Trapping in Australia
Despite the relative success of the early LO mass-trapping interventionsor maybe because of
itthere was a lack of adoption of LO-based control interventions (at least published in the peer-
reviewed literature) until those conducted by Rapley et al. [46] in Cairns, Australia. In two studies in
separate areas of Cairns, 1.2 L LOs were deployed four per residence with 71%93% coverage within
the intervention areas and both were preceded by area-wide larval control interventions. In the first
deployment, the trap buckets were made of durable plastic, while in a second deployment they were
made of biodegradable material. The hay infusion was 0.5 g alfalfa/1 L water and each LO contained
a 13.5 × 5 cm flannel ovistrip treated with bifenthrin, another pyrethroid. Larval control interventions
included a source reduction campaign and the treatment of non-removable containers with S-
methoprene pellets, a long-lasting insect growth regulator [47,48]. The primary results were an 87%
reduction in female collections during the mass trap deployment in concurrently monitored SOs
during the wet season, but, unfortunately, there were no observed reductions during the following
dry season. Likewise, the biodegradable LO intervention achieved only an unspecified reduction in
adult female collections in concurrently monitored SOs in one of three sites. Despite the generally
low efficacy of both LO interventions, the study achieved high public acceptability [49] and the lack
of significant adult control was attributed to the relatively short duration of the interventions (four
weeks). Of note, despite pre-intervention, large-scale source reductions and additional larval control
efforts before both experiments, they were not as effective as those reported by Perich et al. [30] or
Sithiprasasna et al. [33]. Based on their results, the authors concluded that LOs could be an effective
component of a dengue control strategy, particularly when coupled with pre-intervention larval
control interventions. While not formally quantified, this conclusion has been largely supported by
the absence of an explosive dengue outbreak on Thursday Island in the Torres Strait, Australia, where
intervention strategies involving source reduction, limited indoor residual spraying, larviciding, and
the widespread use of LOs and SOs to suppress local Ae. aegypti populations have been implemented
Insects 2017, 8, 5 5 of 15
2.3. Mass Deployment of SOs in Brazil
As mentioned, the small SOs were developed to circumvent the problems of insecticide
resistance and to allow the simultaneous surveillance of adult gravid mosquitoes by capturing them
on a sticky panel as they enter the trap. Interestingly, although SOs were developed over 10 years
ago [35], only one study to date has assessed their utility in a mass-trapping intervention. The study
was conducted by Degener et al. [51] in Manaus, state of Amazonas, Brazil, and used the
commercially available MosquiTRAP (Ecovec Ltd., Belo Horizonte, MG, Brazil; Figure 1c) [52]. The
MosquiTRAP consists of a matte black container (16 cm high × 11 cm diameter) containing
approximately 280 mL of water, a synthetic AtrAedes® (Ecovec Ltd.) oviposition attractant and a
removable sticky card. Importantly, Degener et al. [51] monitored epidemiological outcomes by
monitoring dengue virus (DENV) IgM-seropositivity of residents in the intervention and control
clusters during the last two months of the intervention. The study involved a matched pair cluster
design (three treatment and three control areas) during which three MosquiTRAPs were placed at
each participating residence in the treatment clusters. Traps in the same household were positioned
at least 5 m apart from each other, preferentially in different environments (e.g., veranda, yard,
laundry area). In total, 51.1% of available households participated in the mass-trapping effort in the
intervention clusters and the intervention lasted 17 months.
Unfortunately, despite high household participation and the deployment of multiple traps at
individual residences, mass-deployment of MosquiTRAPs failed to reduce adult Ae. aegypti
abundance and serological data indicated that recent dengue infections were equally frequent in the
intervention and control areas. The failure of the MosquiTRAP mass-trapping intervention may have
resulted from its previously quantified poor performance relative to standard ovitraps (78.3%
ovitraps positive for eggs vs. 46.4% MosquiTRAPs positive for adult females, p < 005, [53]) and the
relatively low number of traps deployed per residence (three/house). More importantly, however, it
is likely that the lack of pre-intervention source reduction campaigns also contributed to the poor
performance of the relatively small MosquiTRAP due to competition from other water sources.
3. Large-Scale Mass-Trapping Interventions
3.1. Multi-Year Trapping Intervention in Brazil
Although the above studies provided evidence supporting mass-trapping intervention
strategies targeting ovipositing females, the studies were relatively small in scale (<200 houses)
making it hard to assess the sustainability of large-scale interventions. This was first addressed in a
study performed by Regis et al. [54] during which 8400 small (2 L) ovitraps were deployed over a
two-year intervention period, during which five ovitraps were placed at each participating residence.
Unlike the mechanical suppression of adults in Lok et al. [29], control in the Regis et al. [54] trap
intervention relied on the physical collection and destruction of eggs or treatment of containers with
Bacillus thuringiensis israelensis (Bti) to kill any larvae that developed. The decision not to rely on
insecticide treated ovistrips was most likely based on the presence of insecticide resistance in local
Ae. aegypti populations in the state of Pernambuco, Brazil, in which the study was conducted [55]. To
make such a large-scale effort affordable, the LOs were made from recycled 2 L bottles that were
painted black, allowing traps to be produced at a cost of US$0.6 each. To overcome the problem of
keeping track of thousands of ovitraps, the research team coordinated their efforts with municipal
health departments, which were allowed to design their own intervention plans according to the local
characteristics and resources available, and operated a network of georeferenced sentinel ovitraps to
monitor the impact of the interventions. Altogether, control activities centered around: (1) mechanical
mass destruction through incineration of eggs laid on ovistrips; (2) indoor systematic removal of
adults using aspirators, targeting places considered highly important for virus transmission, such as
health units, schools and premises located within hotspots of mosquito density; (3) the addition of
larvivorous “piabas” fish added to nearly 7000 cisterns, the primary local water reservoirs; and (4)
educating the public about the importance of source reduction through public exhibition, radio,
television, banners, posters and leaflets. This stratified strategy resulted in decreases of 90% and 77%
Insects 2017, 8, 5 6 of 15
in egg density in sentinel ovitraps in the intervention areas relative to paired controls after two years
of sustained pressure. Overall, control efforts destroyed more than 8,000,000 eggs between the two
sites and at least 3200 adult females by aspiration. These results demonstrate that wide-scale
interventions can be successful if enough traps can be deployed, which is only likely if expertise and
resources are shared between researchers and municipal public health agencies, and effective public
engagement campaigns can be implemented. Unfortunately, because of the diversity of approaches
(source reduction, ovitraps, adult aspiration, and use of larvivorous fish), the authors were unable to
determine the level of impact of each individual intervention. Most regrettably, however, the impact
of such a wide-scale mass-trapping intervention on disease transmission remains unknown since the
authors did not measure epidemiological variables such as mosquito infection rate or seropositivity
rates in local residents.
3.2. Large Autocidal Gravid Ovitrap-Based success in Puerto Rico
Encouraged by the potential impact of large-scale trapping, a series of interventions using mass
deployments of large AGOs were conducted in Puerto Rico from 2011 to 2014 [56,57] to exploit the
greater visual and olfactory attraction afforded by large AGOs (Figure 1e) in a mass-trapping
intervention. The studies included two intervention zones, La Margarita (20112014) and Villodas
(20132014), each with a paired control area. The experimental design for both studies involved
placing three AGOs per house at 81% [56] and 85% [57] of the houses in each intervention area. The
researchers implemented a two-month service interval to take advantage of the extended activity of
the large AGOs (long-lasting stickiness of the glue panel and large water volume and closed design
reduces likelihood the traps will dry) to limit the amount of staff and resources required to service
the large number of traps deployed (>700 traps). Because of the long service interval, adult
populations were monitored using a combination of BG-Sentinel (BGS) traps and sentinel AGO traps
distributed throughout the intervention and control areas. In addition to the trap intervention, pre-
intervention source reduction, larviciding, and oviciding campaigns were conducted in both the
intervention and control areas. Source reduction consisted of the removal of all containers as allowed
by residents. The larvicide Natular (spinosad) was applied to containers that could not be removed
and which water was not for animal or human consumption. The inner walls of containers that could
not be removed were also brushed and rinsed to remove Ae. aegypti eggs.
The pre-intervention source reduction and larviciding campaigns combined with the wide-scale
distribution of large AGOs proved highly successful. Over the course of the first study (20112012),
the La Margarita (8121050 traps) intervention area experienced a 53% and 70% reduction in weekly
BGS and sentinel AGO collections, respectively, relative to the control area. During the second study,
the La Margarita (20122014; 793 traps) and Villodas (20132014; 570 traps) intervention areas
experienced a 79% and 88% reduction in weekly sentinel AGO collections, respectively, relative to
their paired control areas. To date, these two studies provide the greatest support for large-scale
mass-trapping interventions as a means of controlling urban Aedes. The success of these interventions
is most likely due to the careful large-scale pre-intervention source reduction effort coupled with the
greater visual and olfactory attraction of the large AGO compared to smaller LOs and SOs, with the
added benefit of the long service intervals of large AGOs enabling greater deployment scale and
3.3. Epidemiological Support for Mass-Trapping Interventions in Puerto Rico
Although the large AGO interventions were highly successful, the lack of epidemiological
impact continued to impede the true assessment of the effectiveness of large-scale AGO mass-
trapping interventions for control Aedes-borne viruses. However, the chikungunya virus (CHIKV)
epidemic in the Caribbean from 2014 to 2015 allowed the quantification of the efficacy of a large AGO-
based mass-deployment for arboviral control. From early 2014 to the end of 2015, there were
approximately 29,000 confirmed chikungunya cases in Puerto Rico, which by fortunate happenstance,
overlapped with the AGO mass-trapping interventions in Puerto Rico. As mentioned, the
Insects 2017, 8, 5 7 of 15
interventions resulted in a ten-fold reduction in Ae. aegypti female densities (~1 per trap/week in
intervention sites vs. ~10 per trap/week in control sites) during the 20142015 chikungunya epidemic.
To assess the effect of the areawide deployment of AGO traps on chikungunya prevalence,
Lorenzi et al. [58] conducted a stratified random serosurvey of 620 households from intervention and
non-intervention communities, representing 28.5% of the residents of the communities participating
in the AGO field trial sites of Barrera et al. [57]. Serum specimens were tested by immunoglobulin G
(IgG) enzyme-linked immunosorbent assay to detect evidence of recent chikungunya virus infection.
The authors reasoned that the prevalence of CHIKV IgG antibody after the introduction of
chikungunya in a population without previous chikungunya virus exposure provided a valid
estimate of chikungunya virus incidence in residents of these communities. After adjustment for
sample design, the serosurvey revealed that the proportion of CHIKV IgG antibody among
participants from the two intervention communities was one-half that of the participants from the
two non-intervention (no AGO traps) communities (22.9% vs. 45.4%; risk ratio = 0.52, 95% CI = 0.38
0.71). To date, this is the only evidence of a significant epidemiological impact by a mass-trapping
The Lorenzi et al. [58] report was preliminary, but the findings are centered on a multi-year
mass-trapping intervention that significantly reduced adult female Ae. aegypti populations in the
intervention areas. However, while these results are promising, the cost of the AGOs, which like the
GAT are commercially available, is relatively high, likely dampening prospects for very large
deployments. Of note, efforts to reduce costs by decreasing the number of traps deployed per house
appear to result in decreased efficacy. A recent study in Clovis, CA, by Cornel et al. [59] using a single
AGO trap per house (144 houses in total) failed to significantly reduce adult Ae. aegypti populations
compared to the reductions experienced in the three traps/house interventions performed in Puerto
Rico. However, no intensive source reduction was performed and the study’s scale was relatively
small. One is hopeful that economies of scale as mass deployment of these larger lethal oviposition
traps become more common will lead to significant reductions in trap prices.
4. The Need for Community Engagement and Participation
Reliance on vertically structured government programs (topdown) standard in yellow fever
control in the early 20th century, and still common to dengue control programs in the 1980s, has since
shifted to community-based (bottomup) programs [60]. This practice started from the realization
that disease control programs needed community engagement for long-term sustainability as well as
due to diminishing government funds [61]. Although community-based interventions have generally
failed to prevent epidemic dengue, there have been successes in mosquito control [62,63] and those
willing to implement a mass-trapping intervention should consider adopting a community-based
At its most basic, this requirement is due to the colossal task of monitoring and servicing 100’s
to 1000’s of traps, all of which, if neglected, can become productive larval habitats. Furthermore, for
mass-trapping interventions to be a success, operators need continued access to the homes and yards
of participants, as well as engaged and informed homeowners who recognize and alert operators to
trap malfunctions. Ultimately, success through sustainability will rely on interagency cooperation
and coordinated involvement of local health services, trained vector control personnel, and the
Source Reduction Campaigns Minimize Competition from Alternative Oviposition Sites
Destruction or removal of alternative water-holding containers is particularly important for
mass-trapping interventions targeting gravid Aedes females because they maximise the likelihood
that the females will try to lay eggs first in the trap, killing them and all their progeny. However,
source reduction for control of invasive Ae. aegypti and Ae. albopictus poses one of the greatest
challenges for dengue and Zika control. The difficulties arise from the ability of both species to exploit
small pockets of water, often inaccessible because they are located in private areas within the
peridomestic environment [14,64,65]. These sources are also often ephemeral and their abundance
Insects 2017, 8, 5 8 of 15
increases and decreases on a continual basis [6]. Combined, these factors, as well as inadequate
engagement of the local communities, likely accounted for the historical failures of traditional source
reduction campaigns [66]. However, recent community-based control initiatives, emphasising source
reduction and other non-insecticide methods of control, have been successful in Cuba [67], Singapore
[68], Nicaragua and Mexico [69], as well as India [70]. The success of these programs can be largely
attributed to extensive communication and cooperation among agencies, as well as the use of wide-
scale education efforts (e.g., school visits, use of community volunteers, door-to-door demonstrations
[21]). Of note, because they exploit and expose specific mosquito behavior, lethal oviposition traps
can be useful tools for active learning, providing “teachable moments” and indelible hands-on
experience that are worth thousands of written words (Fonseca, D.M., personal experience).
5. Recommendations, Conclusions and Future Directions
Based on the few available studies summarized and our own experience, we propose several
recommendations to help achieve the greatest entomological and epidemiological impact. These
recommendations are:
1. Conduct source reduction campaigns before implementing mass-trapping intervention to
remove competing containers. These efforts should involve collaboration and coordination
among all groups involved, especially the residents.
2. Involve homeowners in the maintenance/servicing of traps to achieve short-term success and
long-term sustainability. Motivating homeowners to purchase their own traps, particularly in
developed countries, and possibly at subsidized rates, may enhance participation in community-
based mosquito control, including source reduction (step 1).
3. Aim for a minimum of >80% coverage (i.e., number of houses with traps) within intervention
areas. Due to the limited data available, this is a “best guess” estimate based on the success of
the AGO interventions (81%85% coverage) in Puerto Rico [56,57], which resulted in a positive
epidemiological outcome [58]. However, this value will likely depend on variables such as the
type and size of the trap deployed and the density and type of housing in the intervention
location. As such, further field trials are needed to determine the optimal coverage percentage
across trap and location types.
4. Optimize the number of traps per yard based on the size of the property, trap size and placement,
and number of competing water-holding containers. Again, undertaking source reduction
campaigns, while unlikely to overcome the spatial variability in target populations created by
cryptic breeding sites, will reduce and, to an extent, even out competition from secondary
breeding sources across residences. This will help operators optimise trap interventions based
on easy-to-assess metrics such as property and trap size, all the while helping to reduce the target
population prior to the intervention.
5. Use large autocidal gravid traps, such as the AGO and the GAT, to maximise visual and olfactory
attraction to achieve optimal suppression, while limiting the number of traps deployed.
Economies of scale will inexorably bring the price of the traps down as more programs start
buying them in bulk. To this point, initial investments and ongoing operational costs will need
to match or reduce operational costs relative to traditional vector control strategies such as space
spraying to be attractive to public health programs. The annual per-household costs of various
dengue vector control interventions have been estimated to cost between $1.89 and $31.75 [71
73]. Although there is no available costing data for mass-trapping interventions, the long service
intervals (24 weeks or longer) and ability to reuse the traps for multiple seasons, combined with
emphasis on community involvement to reduce staffing, will likely help trap-based
interventions to match or reduce these costs. However, further research is needed involving
long-term interventions before cost estimates can be provided.
6. Avoid the use of organophosphate and synthetic pyrethroid insecticides, as insecticide
resistance is increasing in urban Aedes. The use of edible canola oil makes GATs appealing to the
public who find them “safe” to use (Fonseca, D.M., unpublished data [41]).
Insects 2017, 8, 5 9 of 15
7. While the design of most lethal oviposition traps prevents adult emergence from dropped eggs
from escaping, treat infusions with S-methoprene or long-release Bti formulations to further
minimize the likelihood that traps may become productive larval habitats. Bti is particularly well
suited for community-based interventions as many formulations are commercially available and
do not require specialized applicator licenses or permits. These products can also be provided
by a local public health agency and simply added to trap infusions at each service interval to
maintain efficacy.
8. Use natural grass or hay infusions as the olfactory lure to attract gravid Ae. aegypti. The infusions
can last for up to 2 months or longer (see Mackay [39] or Barrera [56]). This can be tasked to
residents who can simply change water and add hay or other organic material provided by the
control program. The infusion material can also be sourced locally from their own yards (e.g.,
dead leaves, grass clippings) at no cost. Of note, field surveys by Johnson et al. [74] suggest that
aromatic infusions may be unnecessary as they found no difference in the number of gravid Ae.
albopictus females captured in GATs baited with (hay or fish food) and without (water or empty)
aromatic infusions. This finding is supported by Trexler et al. [75], who found that the initial
female attraction to the trap may be overwhelmingly associated with the water rather than an
olfactory attractant produced by the infusion. If extendable to other species and locations, the
omission of aromatic infusions would greatly extend and simplify trap servicing, reducing costs
and reliance on homeowners to maintain infusions, and possibly increasing participation by
homeowners opposed to having “smelly” traps around the house. These observations
undoubtedly warrant further investigation, but until more data is available, the
recommendation remains for the inclusion of aromatic infusions.
9. Use a mapping strategy (e.g., GIS) during trap placement so traps can be easily found. This will
be a useful tool to ensure that traps are accounted for even if a bottomup approach is used in
which residents are encouraged to purchase their own traps. For example, a serial number or
barcode could be assigned to individual traps and reported to the corresponding public health
program overseeing the intervention. This identifier could then be linked to the residential
address, allowing the agency to periodically check to ensure that the traps are being properly
maintained, as well as track missing traps.
Of the eight studies summarised involving mass deployment of lethal oviposition traps (Table
1), seven resulted in a significant reduction in adult female Ae. aegypti abundance in at least one
intervention site, whereas five of these resulted in significant reductions across all sites. However,
only two studies attempted to assess the epidemiological impact of the intervention and only one
showed a significant reduction in disease prevalence. Based on these results, further large-scale
randomised controlled trials in disease endemic countries are needed before mass-trapping
interventions of lethal oviposition traps can be recommended as a means of suppressing disease.
However, there seems to be sufficient supporting evidence to recommend their use as a means of
suppressing female Ae. aegypti populations.
Furthermore, while to the best of our knowledge all mass deployments of lethal oviposition traps
so far have been on Ae. aegypti in resource-poor or tropical settings (Table 1), we propose that mass
deployment of lethal oviposition traps can be developed as a pre-emptive strategy for control of
temperate Ae. albopictus in resource-rich communities, because: (1) mass deployments can be focused
in a relatively short period of time in late spring to prevent exponential population growth to levels
that allow disease transmission; (2) as mentioned, these traps are a gateway strategy to involve
residents in local mosquito control, especially if they become directly “invested” by purchasing the
traps themselves (a relatively small investment in medium- and high-income neighbourhoods); (3)
by their simplicity and direct association to an understandable mosquito behaviour (oviposition) and
control outcome (i.e., observable dead mosquitoes), lethal ovitraps are an excellent “teaching tool”
that easily feeds back to community-level source reduction as residents understand the need to
reduce competing water-holding containers. A win-win.
Insects 2017, 8, 5 10 of 15
Table 1. Summary of lethal oviposition trap mass-trapping interventions to control female Aedes aegypti populations.
Standard Lethal Ovitraps
Killing Agent
Length of
of Traps
Reduction Achieved
% Residences
Perich et al.
11 × 2.5 cm
treated with
3 months; Areia
Branca and
Nilopolis, Rio de
Janeiro, Brazil
Female adult abundance
reduced 47% at one site;
% containers positive for Ae.
aegypti larvae reduced 49%
and 80%;
Mean pupae per house
reduced 97% and 91%
Not specified
Did not measure
et al. [33]
11 × 2.5 cm
treated with
Two studies; each 12
months in length;
Ratchaburi Province,
First study (1999): No
Second study (2000): 47%
reduction in female adult
49% reduction in containers
with Ae. aegypti larvae;
56% reduction in containers
with Ae. aegypti pupae
Not specified
Did not measure
Rapley et al.
13.5 × 5 cm
treated with
4 weeks/site; Cairns,
Wet season: 87% reduction in
sticky ovitrap collections;
reductions in BG-Sentinel
(BGS) collections not
75% Dry season;
71% Wet season
Larval control:
source reduction
and treatment of
potential breeding
sites with S-
Did not measure
Rapley et al.
13.5 × 5 cm
treated with
4 weeks/site; Cairns,
Reduction observed in 1 out
of 3 sites;
% reduction not specified
93% Wet season
Larval control:
source reduction
and treatment of
potential breeding
sites with S-
Did not measure
Regis et al.
water; egg
24 months; Ipojuca
and Santa Cruz do
Pernambuco, Brazil
90% and 77% in egg density
in two separate study sites
Not specified;
8400 ovitraps
installed during
larvivorous fish
and adult
Did not measure
Sticky Ovitraps (adhesive sticky cards/panels)
Insects 2017, 8, 5 11 of 15
Degener et
al. [51]
card. Card
17 months: Manaus,
Amazonas, Brazil
No, observed an increase in
trap counts in intervention
No difference in
dengue virus
intervention and
control sites
Large (>5 L) Autocidal Gravid Ovitraps
Barrera et al.
adhesive card
placed on
inside of trap
12 months; La
Margarita, Puerto
53% reduction in BGS
70% reduction in sentinel
AGO traps
Source reduction,
larviciding and
oviciding (physical
destruction of eggs)
prior to trap
Did not measure
Barrera et al.
adhesive card
placed on
inside of trap
24 months; La
Margarita, Puerto
12 months; Villodas,
Puerto Rico
La Margarita: 79% reduction
in sentinel AGO collections;
Villodas: 88% reduction in
sentinel AGO collections
Source reduction,
larviciding and
oviciding (physical
destruction of eggs)
prior to trap
Did not measure
Lorenzi et al.
adhesive card
placed on
inside of trap
Continuation of
study by Barrera et
al. [57]: 1 year prior
to introduction of
chikungunya and
Not specified, but same study
areas as Barrera 2014a,b
Same as Barrera et al.
Yes, 52%
reduction in
chikungunya virus
prevalence in
intervention areas
(risk ratio = 0.52,
95% CI = 0.38
0.71). 62% of
households and
64% of eligible
Cornel et al.
adhesive card
placed on
inside of trap
6 weeks; Clovis, CA,
No, % reduction not
specified. Small slopes of
regression in weeks 38 in
intervention site (BGS =
0.0047 and AGO = 0.0035)
indicate reduction due to
AGOs was minimal
Not specified;
residences in
a single
Did not measure
Insects 2017, 8, 5 12 of 15
Acknowledgments: Dina M. Fonseca would like to acknowledge the residents of the community of University
Park, MD, especially David Brosch and Arlene Christiansen for being strong community leaders willing to learn
new tricks. Funding for the University Park project mentioned as “Fonseca et al. unpublished data” was
provided by Multistate USDA-NE 1043.
Conflicts of Interest: Scott A. Ritchie receives a small royalty from sales of the BG-GAT. The other authors
declare no conflict of interest.
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... Recently, there is entomological evidence for mass deployment of lethal oviposition traps to reduce Aedes [mosquito density]. Our work complements and updates fhe review by Johnson et al. [12] and differs from it in two aspects. Firstly, from a methodological point of view, we have chosen a systematic review, which facilitates the updating of evidence as new results are available. ...
... Next, the traps were used to evaluate their efficacy as a vector control method [14]. Indeed, over the past decade, some of these traps have been evaluated as vector control tools, mainly targeting adult females [12]. Depending on the physiological stage targeted, two categories can be distinguished: (i) host-seeking female traps and (ii) lethal ovitraps targeting gravid females. ...
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Background Over the past decades, several viral diseases transmitted by Aedes mosquitoes-dengue, chikungunya, Zika-have spread outside of tropical areas. To limit the transmission of these viruses and preserve human health, the use of mosquito traps has been developed as a complement or alternative to other vector control techniques. The objective of this work was to perform a systematic review of the existing scientific literature to assess the efficacy of interventions based on adult mosquito trap to control Aedes population densities and the diseases they transmit worldwide.Methods and findingsFollowing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review was conducted using the PubMed and Scopus databases. Among the 19 selected papers, lethal ovitraps were used in 16 studies, host-seeking female traps in 3 studies. Furthermore, 16 studies focused on the control of Ae. aegypti. Our review showed great heterogeneity in the indicators used to assess trap efficacy: e.g., the number of host-seeking females, the number of gravid females, the proportion of positive containers, the viral infection rate in female mosquitoes or serological studies in residents. Regardless of the type of studied traps, the results of various studies support the efficacy of mass trapping in combination with classical integrated vector control in reducing Aedes density. More studies with standardized methodology, and indicators are urgently needed to provide more accurate estimates of their efficacy.Conclusions This review highlights gaps in the demonstration of the efficacy of mass trapping of mosquitoes in reducing viral transmission and disease. Thus, further large-scale cluster randomized controlled trials conducted in endemic areas and including epidemiological outcomes are needed to establish scientific evidence for the reduction of viral transmission risk by mass trapping targeting gravid and/or host-seeking female mosquitoes.
... albopictus) is a competent vector for at least 22 arboviruses such as dengue, Zika, yellow fever, and so on. [5][6][7][8] At present, many Aedes-borne diseases have neither vaccines nor special therapeutic drugs. It has been proved that vector control is the most effective measure to prevent transmission of these diseases. ...
... albopictus. 6,7,45 Field trials in Puerto Rico demonstrated that AGO captured more Ae. aegypti gravid females and provided higher sensitivity than conventional ovitraps. ...
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Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae) transmits a variety of arboviruses (arthropod-borne viruses) and acts as one of the most dangerous mosquito species in the world. Mosquito surveillance is the main means of evaluating vector density, vector-borne disease risk, and the efficacy of vector-control operations. The larval density of Ae. albopictus can be reflected by means of Breteau index and Route index, and egg density can be monitored by ovitrap and mosq-ovitrap, whereas mosquito surveillance methods mainly include human landing catch, human-baited double net trap, BG-Sentinel trap, autocidal gravid ovitrap, gravid Aedes trap, and mosquito magnet. This article describes different methods of Ae. albopictus surveillance and offers suggestions to improve surveillance.
... The attractive properties for oviposition of organic infusions have been used widely for monitoring mosquito vector densities, for targeted interventions, and to achieve area-wide mosquito population control by leveraging the use of lethal traps (Barrera et al. 2014a(Barrera et al. , 2014bJohnson et al. 2017). In this exploratory study where highly locally available organic materials were assessed as oviposition attractants for Ae. ...
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Aedes aegypti is the primary vector of dengue fever virus (DENV) worldwide. Infusions made from organic materials have been shown to act as oviposition attractants for Ae. aegypti; however, studies on locally suitable infusion materials are lacking. The current study assessed the suitability of 4 locally available materials as oviposition infusions for use in surveillance and control of Ae. aegypti in Kwale County, Kenya. Oviposition infusion preferences were assessed in laboratory, semifield, and field conditions, using 4 infusions made from banana, grass, neem, and coconut. In addition, ovitrapping in wall, grass, bush, and banana microhabitats was done in 10 houses each in urban and rural coastal households to determine suitable oviposition microhabitats. Overall, the highest oviposition responses were observed for banana infusion, followed by neem and grass infusions, which were comparable. Coconut infusion resulted in the lowest oviposition response. Although female Ae. aegypti did not show preference for any microhabitat, the oviposition activity across all the microhabitats was highly enhanced by use of the organic infusions. Banana, neem, and grass infusions could be used to attract gravid mosquitoes to oviposition sites laced with insecticide to kill eggs. Additionally, banana plantings could be important targets for integrated vector control programs.
... Due to a lack of specific drugs and effective vaccines against dengue, vector control remains to be the mainstay of control measures towards the prevention of disease. 7,8 Pyrethroids and organophosphates are the major classes of insecticides recommended for vector control under the National Centre for Vector Borne Diseases Control (NCVBDC) of the Government of India. Thus, the same are being used in the state of Punjab for the control of the vector of Dengue. ...
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Background: As the state of Punjab has become endemic for dengue, this study was planned to determine the susceptibility status for two different classes of adulticides and the VGSC gene polymorphism in domain II of Aedes aegypti. Methodology: Adult bioassays were performed with pyrethrum, deltamethrin and malathion as per the WHO protocol. AS-PCR and sequencing of VGSC gene were carried out to detect V1016G and Kdr (Knockdown resistance) mutations. Results:Ae. aegypti from the districts of Ludhiana and Patiala were found to be resistant to pyrethrum. The V/ V genotype frequency was found to be higher in all districts. Three known polymorphisms in VGSC gene were not recorded but one synonymous and non-synonymous mutation was found. Group B intron was found in domain II of the VGSC gene. For deltamethrin and malathion, 100% susceptibility was recorded for all four districts. Conclusion: Thus, the present findings indicate 100% susceptibility towards deltamethrin and malathion whereas, moderate resistance towards pyrethrum was recorded. Therefore, more studies should be planned to study polymorphisms in the various domains of the VGSC gene.
... As part of current entomological surveillance campaigns, the reliable and proven ovitrap method is used [7] (Fig. 1, right) for detecting and quantifying Ae. aegypti eggs. This method is extremely sensitive and efficient in generating early alerts [8], [9], [10], [11], [12], [13]. Entomological surveillance campaigns are planned and executed by government agencies. ...
Millions of people around the world are infected with mosquito-borne diseases each year. One of the most dangerous species is Aedes aegypti, the main vector of viruses such as dengue, yellow fever, chikungunya, and Zika, among others. Mosquito prevention and eradication campaigns are essential to avoid major public health consequences. In this respect, entomological surveillance is an important tool. At present, this traditional monitoring tool is executed manually and requires digital transformation to help authorities make better decisions, improve their planning efforts, speed up execution, and better manage available resources. Therefore, new technological tools based on proven techniques need to be designed and developed. However, such tools should also be cost-effective, autonomous, reliable, and easy to implement, and should be enabled by connectivity and multi-platform software applications. This paper presents the design, development, and testing of an innovative system named “MosquIoT”. It is based on traditional ovitraps with embedded Internet of Things (IoT) and Tiny Machine Learning (TinyML) technologies, which enable the detection and quantification of Ae. aegypti eggs. This innovative and promising solution may help dynamically understand the behavior of Ae. aegypti populations in cities, shifting from the current reactive entomological monitoring model to a proactive and predictive digital one.
... It is customary to add oviposition attractants to enhance productivity 16,21 . Other resources have been added to ovitraps, such as insecticides, microbial larvicides, pheromones, entomopathogenic fungi, and yeast ribonucleic acid (RNA) interference, to hinder the development of immature stages of vector mosquitoes 10,[22][23][24][25][26][27][28][29] . ...
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Background: Egg collection traps have been studied to assist in the integrated control of arbovirus vectors. Many enhancements have been made over the years. Methods: This study evaluated the use of a hydrated superabsorbent polymer (SAP) in the egg collection of Aedes aegypti and Aedes albopictus in ovitraps. An experiment was conducted in the laboratory to determine the minimum concentration of the product to be used in traps in the field to prevent the development of larvae into adults. In the field, the use of polymers has been evaluated using a traditional model of ovitraps. The positive ovitrap index and mean number of eggs per trap indicator were calculated. Results: In the laboratory, the larvae did not successfully develop to the adult stage, even at the lowest SAP concentration. In the field, the results showed that ovitraps with SAP proved to be effective for egg collection from both species. It was possible to identify sites with the highest concentration of species and expose the ovitraps for a longer period without larval development. Conclusions: There is a need for studies on the adequacy of this technology for control programs. However, the results showed that ovitraps with hydrogel were potentiated to capture eggs, configuring themselves as another tool for vector control.
... In addition to traditional gels, new hydrogels are among the formulations that already have or are finding new applications for mosquito control. In addition to attractant or repellent formulations, they may be employed as carriers of larvicide formulations [85] or in mosquito ovitraps [86][87][88]. Friuli et al. [88] validated a new recipe of hydrogels to imitate the natural oviposition site's conditions in order to incorporate them inside "lure-and-kill" ovitraps as a biomimetic oviposition substrate. The study compared oviposition between standard substrates (absorbing paper/masonite) and a hydrogel composition panel under labor field conditions. ...
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Insecticides and rodenticides form the basis of integrated pest management systems worldwide. As pest resistance continues to increase and entire groups of chemical active ingredients are restricted or banned, manufacturers are looking for new options for more effective formulations and safer application methods for the remaining pesticide ingredients. In addition to new technological adaptations of mainstream formulations in the form of sprays, fumigants, and dusts, the use of gel formulations is becoming increasingly explored and employed. This article summarizes information on the current and potential use of gel (including hydrogel) and paste formulations against harmful arthropods or rodents in specific branches of pest management in the agricultural, food, stored product, structural wood, urban, medical, and public health areas. Due to the worldwide high interest in natural substances, part of the review was devoted to the use of gels for the formulation of pesticide substances of botanical origin, such as essential or edible oils. Gels as emerging formulation of so called “smart insecticides” based on molecular iRNA disruptors are discussed.
... The combination of vector control interventions targets both adult and immature stages of the mosquito aiming at reducing oviposition through container covers and clean up campaigns, increasing immature predation by larvivorous fish, and trapping adult mosquitoes using mass trapping designs. Much research is currently ongoing to develop sustainable mosquito mass trapping designs as viable options for vector control 73 . ...
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Background. Dengue is the most common and widespread mosquito-borne arboviral disease globally estimated to cause >390 million infections and >20,000 deaths annually. There are no effective vaccines or preventive drugs. Control of dengue transmission relies primarily on mosquito vector control. Although most vector control methods currently used by national dengue control programs may temporarily reduce mosquito populations, there is little evidence that they affect transmission. There is an urgent need for innovative, participatory, effective, and locally adapted approaches for sustainable vector control and monitoring in which students can be particularly relevant contributors and to demonstrate a clear link between vector reduction and dengue transmission reduction, using tools that are inexpensive and easy to use by local communities in a sustainable manner. Methods. Here we describe a cluster randomized controlled trial to be conducted in 46 school catchment areas in two townships in Yangon, Myanmar. The outcome measures are dengue cases confirmed by rapid diagnostic test in the townships, dengue incidence in schools, entomological indices, knowledge, attitudes and practice, behavior, and engagement. Conclusions. The trial involves middle school students that positions them to become actors in dengue knowledge transfer to their communities and take a leadership role in the delivery of vector control interventions and monitoring methods. Following this rationale, we believe that students can become change agents of decentralized vector surveillance and sustainable disease control in line with recent new paradigms in integrated and participatory vector surveillance and control. This provides an opportunity to operationalize transdisciplinary research towards sustainable health development. Due to the COVID-19 pandemic and political instability in Myanmar the project has been terminated by the donor, but the protocol will be helpful for potential future implementation of the project in Myanmar and/or elsewhere. Registration: This trial was registered in the ISRCTN Registry on 31 May 2022 ( ).
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Current trends in clinical & medical sciences is a highly interdisciplinary research field is dedicated to disseminating in-depth information and insights into all areas of current medical and clinical sciences including neurology, cardiology, anaesthesia, gynecology, dentistry, nursing, gastroenterology, ophthalmology, orthopaedics, cancer, medical imaging, dermatology, anatomy, genomic medicine etc. Clinical research is that component of medical and health research intended to produce knowledge valuable for understanding human disease, preventing and treating illness, and promoting health. The importance of clinical research is that it brings basic biomedical discoveries to the bedside to address patient care from the physical, behavioral, and social perspectives. The present volume is based on the contributions made by various authors on different important topic of “Advance Research Trends in Medical and Clinical Sciences Volume-1” and introduces the subject along the following topics: Role of Physiotherapy Interventions in Diabetes Peripheral Neuropathy; A SWOC Analysis of Health Politics in Globalized World; Impact of COVID-19 on perioperative management and outcomes of critically ill pregnant patients; Role of High Flow Nasal Cannula for Respiratory Support during Oral Feeding for COVID-19 Patients on Non-invasive Ventilation; Introduction to Spinal Cord Injury; Pharmacotherapy for Diabetic Neuropathy; Alzheimer"s Disease - Paths for Treatment; Dengue Prevention; and Cancer and Smartphones: Fact or Fiction?
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Vaginal myiasis is one of the most serious parasitic diseases in Bactrian camels. At present, there are no reports on biological control measures of the disease. In this paper, the metabolomic analysis of vaginal secretions from susceptible and non-susceptible camels was performed by ACQUITY UPLC H-Class Ultra Performance Liquid Chromatograph. The results matched in 140 vaginal compounds. Methylheptenone, 1-octen-3-ol, and propyl butyrate and their mixtures were selected for gas chromatography-electroantennography (GC-EAD), electroantennography (EAG), behavioral experiments and trapping experiments of Wohlfahrtia magnifica (W. magnifica). Results showed that the W. magnifica had EAG responses to the three compounds, respectively. The EAG responses of female flies to different concentrations of methylheptenone were significantly different, but to the others had no significant difference, and there was no significant difference in the same compounds between the different sexes. Behavioral and trapping experiments showed that methylheptenone and 1-octen-3-ol have significant attraction to W. magnifica, but there was no significant difference to propyl butyrate. When methylheptenone and 1-octen-3-ol were mixed in different proportions, it was found that a mixture at the ratio of 1:1 and 0.5:1 had extremely significant and significant attraction, respectively, to both male and female W. magnifica. The study showed that, except for propyl butyrate, the higher the concentrations of the other two compounds, the stronger the attractivity to the W. magnifica, and a mixture at the ratio of 1:1 could enhance the attractivity to the W. magnifica.
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We report on the use of the Gravid Aedes Trap (GAT) as a surveillance device for Aedes albopictus (Skuse) relative to the BG-Sentinel (BGS) trap in field studies conducted in Trenton, NJ, and on Hammond Island, Queensland, Australia. A parallel study conducted in Nha Trang, Vietnam, assessed the use of the GAT as an indoor surveillance device as well as the use of canola oil as a noninsecticide killing agent. In Trenton and Hammond Island, the GAT collected fewer male (0.40 ± 0.12 and 0.43 ± 0.30, respectively) and female (3.05 ± 0.67 and 2.7 ± 2.3, respectively) Ae. albopictus than the BGS trap (males: 3.54 ± 1.26 and 3.75 ± 0.83; females: 4.66 ± 1.18 and 3.9 ± 0.23) over their respective sampling periods (i.e., 24 h for the BGS and 1 wk for the GAT). Despite differences in capture rates, the percentage of traps positive for female Ae. albopictus was similar between the BGS and GAT (Trenton: 60.1 ± 6.3% and 64.4 ± 4.1%; Hammond: 87.5 ± 6.9% and 80.0 ± 8.2%). In Nha Trang, the GAT was equally effective indoors and outdoors with (10 g hay or 3 g fish food) and without (water or empty) infusion. Additionally, no significant decrease in collections was observed between GATs set with canola oil or long-lasting insecticidal net. In summary, both traps were successful in monitoring female Ae. albopictus over their respective trapping intervals, but would be best used to complement each other to monitor both sexes and all physiological stages of female Ae. albopictus. However, the versatility and low-cost of the GAT makes it an attractive alternative to the more expensive BGS trap.
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The invasion and subsequent establishment in California of Aedes aegypti in 2013 has created new challenges for local mosquito abatement and vector control districts. Studies were undertaken to identify effective and economical strategies to monitor the abundance and spread of this mosquito species as well as for its control. Overall, BG Sentinel (BGS) traps were found to be the most sensitive trap type to measure abundance and spread into new locations. Autocidal-Gravid-Ovitraps (AGO-B), when placed at a site for a week, performed equally to BGS in detecting the presence of female Ae. aegypti. Considering operational cost and our findings, we recommend use of BGS traps for surveillance in response to service requests especially in locations outside the known infestation area. We recommend AGO-Bs be placed at fixed sites, cleared and processed once a week to monitor mosquito abundance within a known infestation area. Long-term high density placements of AGO-Bs were found to show promise as an environmentally friendly trap-kill control strategy. California Ae. aegypti were found to be homozygous for the V1016I mutation in the voltage gated sodium channel gene, which is implicated to be involved in insecticide resistance. This strain originating from Clovis, California was resistant to some pyrethroids but not to deltamethrin in bottle bio-assays. Sentinel cage ultra-low-volume (ULV) trials using a new formulation of deltamethrin (DeltaGard®) demonstrated that it provided some control (average of 56% death in sentinel cages in a 91.4 m spray swath) after a single truck mounted aerial ULV application in residential areas.
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The Gravid Aedes Trap (GAT) uses visual and olfactory cues to attract gravid Aedes aegypti (L.) that are then captured when knocked down by a residual pyrethroid surface spray. However, the use of surface sprays can be compromised by poor availability of the spray and pesticide resistance in the target mosquito. We investigated several “alternative” insecticide and insecticide-free killing agents for use in the GAT. This included long-lasting insecticide-impregnated nets (LLINs), vapor-active synthetic pyrethroids (metofluthrin), canola oil, and two types of dry adhesive sticky card. During bench top assays LLINs, metofluthrin, and dry sticky cards had 24-h knockdown (KD) percentages >80% (91.2 ± 7.2%, 84.2 ± 6.8%, and 83.4 ± 6.1%, respectively), whereas the 24-h KD for canola oil was 70 ± 7.7%, which improved to 90.0 ± 3.7% over 48 h. Importantly, there were no significant differences in the number of Ae. aegypti collected per week or the number of traps positive for Ae. aegypti between the sticky card and canola oil treatments compared with the surface spray and LLIN treatments in semifield and field trials. These results demonstrate that the use of inexpensive and widely available insecticide-free agents such as those described in this study are effective alternatives to pyrethroids in regions with insecticide-resistant populations. The use of such environmentally friendly insecticide-free alternatives will also be attractive in areas where there is substantial resistance to insecticide use due to environmental and public health concerns.
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Improving resident-based management and knowledge of mosquitoes is often an integral component of integrated mosquito management, especially in urban landscapes with considerable mosquito habitat on privately owned lands. This study tested the effectiveness of print education materials at reducing urban mosquito exposure through improving resident knowledge of, and attitudes towards, mosquitoes and mosquito management in Washington DC, USA. There was a specific focus on the removal of water-filled containers that are utilized by the developmental stages of the two most common vector species in the region, Aedes albopictus and Culex pipiens. Households in six neighborhoods that varied in socio-economic status were administered knowledge, attitude, and practice (KAP) surveys in 2010 and 2012, and had their yards surveyed for container habitats and immature mosquitoes (larvae and pupae) in 2010, 2011, and 2012. Half the households (intervention, n = 120) received education materials in 2011 and 2012 to yield a before-after control-intervention (BACI) design. Unexpectedly, residents in intervention households were more likely to show decreased concern for mosquito-borne illnesses than residents in control households, which did not receive materials. Moreover, there was a greater probability that control households reduced containers in 2012 than intervention households, particularly when they had low numbers of baseline (2010) containers. Irrespective of control, reductions in containers were associated with decreased abundances of immature mosquitoes. Overall, our findings suggest that print education materials may have unintended negative effects on resident attitudes and household management of mosquito production. We recommend that mosquito control agencies need to carefully consider their content of print messages and the effectiveness of strategies that passively convey information with little or no engagement with control professionals.
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Stratified random sampling targeted 620 households from intervention and nonintervention communities, representing 28.5% of residents of the communities participating in the AGO field trial. Field personnel visited the selected households up to three times each to recruit household members for participation in the study. All residents of the selected households except children aged <5 years were eligible to participate. Participating household members provided a blood specimen and completed a questionnaire on household characteristics, demographics, history of recent illnesses, and personal mosquito bite prevention practices. Serum specimens were tested by immunoglobulin G (IgG) enzyme-linked immunosorbent assay (9) to detect evidence of chikungunya virus infection. The prevalence of chikungunya virus IgG antibody after the introduction of chikungunya virus in a population without previous chikungunya virus exposure provides a valid estimate of chikungunya virus incidence in residents of these communities.
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The invasion and subsequent establishment in California of Aedes aegypti in 2013 has created new challenges for local mosquito abatement and vector control districts. Studies were undertaken to identify effective and economical strategies to monitor the abundance and spread of this mosquito species as well as for its control. Overall, BG Sentinel (BGS) traps were found to be the most sensitive trap type to measure abundance and spread into new locations. Autocidal-Gravid-Ovitraps (AGO-B), when placed at a site for a week, performed equally to BGS in detecting the presence of female Ae. aegypti. Considering operational cost and our findings, we recommend use of BGS traps for surveillance in response to service requests especially in locations outside the known infestation area. We recommend AGO-Bs be placed at fixed sites, cleared and processed once a week to monitor mosquito abundance within a known infestation area. Long-term high density placements of AGO-Bs were found to show promise as an environmentally friendly trap-kill control strategy. California Ae. aegypti were found to be homozygous for the V1016I mutation in the voltage gated sodium channel gene, which is implicated to be involved in insecticide resistance. This strain originating from Clovis, California was resistant to some pyrethroids but not to deltamethrin in bottle bio-assays. Sentinel cage ultra-low-volume (ULV) trials using a new formulation of deltamethrin (DeltaGard®) demonstrated that it provided some control (average of 56% death in sentinel cages in a 91.4 m spray swath) after a single truck mounted aerial ULV application in residential areas.
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Objective To describe the temporal and geographical distribution of Zika virus infection and associated neurological disorders, from 1947 to 1 February 2016, when Zika became a Public Health Emergency of International Concern (PHEIC). Methods We did a literature search using the terms “Zika” and “ZIKV” in PubMed, cross-checked the findings for completeness against other published reviews and added formal notifications to WHO submitted under the International Health Regulations. Findings From the discovery of Zika virus in Uganda in 1947 to the declaration of a PHEIC by the World Health Organization (WHO) on 1 February 2016, a total of 74 countries and territories had reported human Zika virus infections. The timeline in this paper charts the discovery of the virus (1947), its isolation from mosquitos (1948), the first human infection (1952), the initial spread of infection from Asia to a Pacific island (2007), the first known instance of sexual transmission (2008), reports of Guillain-Barré syndrome (2014) and microcephaly (2015) linked to Zika infections and the first appearance of Zika in the Americas (from 2015). Conclusion Zika virus infection in humans appears to have changed in character as its geographical range has expanded from equatorial Africa and Asia. The change is from an endemic, mosquito-borne infection causing mild illness to one that can cause large outbreaks linked with neurological sequelae and congenital abnormalities.
Field release of endosymbiotic Wolbachia bacteria into wild Aedes aegypti mosquito populations is a promising strategy for biocontrol of dengue. This strategy requires successful Wolbachia invasion through the mosquito vector population. Natural variation in mosquito fitness due to density‐dependent competition for limited food resources may influence Wolbachia invasion. We know little about these effects, largely because our understanding of density‐dependent dynamics in mosquito populations is limited. We developed an empirical model of A. aegypti–Wolbachia dynamics where food resources available to the developing larvae are limited. We assessed the extent of density‐dependent regulation in our A. aegypti population using a Bayesian statistical model that estimates the temporal variation in mosquito fitness components. We monitored the spread of Wolbachia and assessed the effect of the bacteria on larval fitness components. We demonstrate that mosquito population growth is regulated by strong larval density‐dependent variation in mosquito fitness components. Wolbachia spread was slowed by this heterogeneity in mosquito fitness, which reduces the capacity of the bacteria to invade. However, we found no evidence that Wolbachia affects larval fitness components. Synthesis and applications . We demonstrate that the extent and form of density‐dependent dynamics in the host population can have a major influence on Wolbachia invasion. These findings help explain slow Wolbachia invasion rates and indicate that the success of field release strategies for dengue control can depend on attaining high Wolbachia frequencies in the mosquito population.