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Dengue Control Activities (Other Than Wolbachia Release) at the Section 7 Commercial Centre, Mentari Court, and Section 7 PKNS Flats in Release and Matched Control Sites
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Dengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however the wAlbB...
Contexts in source publication
Context 1
... with a higher proportion of temporary rather than permanent breeding sites, where periodic flushing of quiescent eggs is important, are predicted to experience a higher level of population suppression following invasion. Post-release community surveys revealed that most residents did not notice any increase in mosquito biting ( Figure S6). ...
Context 2
... the 18-floor apartment buildings of Mentari Court, prior to Wolbachia releases dengue cases were high since at least 2013 ( Figure 4) despite intensive control efforts involving repeated rounds of clean-up ''source reduction'' coupled with community engagement, and repeated thermal fogging (Fig- ure 6), none of which proved effective in reducing dengue incidence. The introduction of Wolbachia wAlbB has, in contrast, reduced dengue cases to a point where insecticide fogging by the local health authorities was no longer considered necessary (Figures 4 and 5). ...
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... Reproductive disorders include parthenogenesis, cytoplasmic incompatibility, male killing, and feminization . In addition to the effects on reproduction, some Wolbachia strains introduced (trans-infected) into vector mosquitoes (wMel, wMelPop, wAlbB, wAu) are able to interfere with the replication and transmission of some viruses, such as the Yellow Fever virus (YFV), Zika virus (ZIKV), Dengue virus (DENV) and chikungunya virus (CHYKV) (Moreira et al., 2009;van den Hurk et al., 2012;Ferguson et al., 2015;Aliota et al., 2016;Tan et al., 2017;Nguyen et al., 2015;Ant and Sinkins, 2018;Nazni et al., 2019). Therefore, they constitute a potential tool that could be used in integrated programs for the control of mosquito vectors (Mousson et al., 2012;Sigle and McGraw, 2019). ...
Wolbachia is a genus of gram-negative endosymbiotic bacterium of maternal transmission, located mainly in the gonads of arthropods, including mosquitoes such as Aedes albopictus. The current distribution of Ae. albopictus in Argentina is restricted to the subtropical northeastern region of the country. Here, we studied the seasonal prevalence of Wolbachia detected in Ae. albopictus larvae and the relationship between the abiotic factors of the larval microhabitat and the infection status, in Eldorado city, Misiones province, subtropical region. The prevalence of Wolbachia infection found was 76.89% (n=312). From the total samples examined, 52.80% (n=214) showed double infection with the wAlbA/wAlbB strains, 23.84% (n=97) infection only with wAlbB, and 0.25% (n=1) only with wAlbA. The prevalence of double infection did not present statistically significant differences between the sites studied. For single infection, the lowest prevalence value of the wAlbB strain (13.33%) was found in the natural park, whereas the highest was found in the family dwellings and cemeteries. Tire repair shops showed an intermediate value. The wAlbA single infection was identified once. Our results also showed an association between temperature and slightly turbid waters with exposure to the sun in the larval habitats and the probability of infection by Wolbachia.
... Recently, Wolbachia has become one of the most promising approaches to control dengue and Zika viruses in the wild. It has been shown that the release of Wolbachia-infected Aedes aegypti mosquitoes can reduce the number of dengue cases in both areas where dengue is endemic or nonendemic (22)(23)(24)(25)(26). Although the molecular mechanisms of Wolbachia-conferred antiviral protection are not yet known, identification of factors influencing protection can contribute to understanding the association of Wolbachia and hosts in natural populations, as well as inform Wolbachia-based field interventions. ...
Wolbachia is a maternally transmitted bacterium that is widespread in arthropods and filarial nematodes and confers strong antiviral protection in Drosophila melanogaster and other arthropods. Wolbachia-transinfected Aedes aegypti mosquitoes are currently being deployed to fight transmission of dengue and Zika viruses. However, the mechanism of antiviral protection and the factors influencing are still not fully understood. Here, we show that temperature modulates Wolbachia-conferred protection in Drosophila melanogaster. Temperature after infection directly impacts Drosophila C virus (DCV) replication and modulates Wolbachia protection. At higher temperatures, viruses proliferate more and are more lethal, while Wolbachia confers lower protection. Strikingly, host developmental temperature is a determinant of Wolbachia-conferred antiviral protection. While there is strong protection when flies develop from egg to adult at 25°C, the protection is highly reduced or abolished when flies develop at 18°C. However, Wolbachia-induced changes during development are not sufficient to limit virus-induced mortality, as Wolbachia is still required to be present in adults at the time of infection. This developmental effect is general, since it was present in different host genotypes, Wolbachia variants, and upon infection with different viruses. Overall, we show that Wolbachia-conferred antiviral protection is temperature dependent, being present or absent depending on the environmental conditions. This interaction likely impacts Wolbachia-host interactions in nature and, as a result, frequencies of host and symbionts in different climates. Dependence of Wolbachia-mediated pathogen blocking on developmental temperature could be used to dissect the mechanistic bases of protection and influence the deployment of Wolbachia to prevent transmission of arboviruses.
... Thus, estimating the frequency of Wolbachia in field-caught mosquitoes during and after deployment is a critical component to evaluate whether an invasion has succeeded. Traditionally, Ae. aegypti collection during and after Wolbachia releases has been performed with BG-Sentinel traps [19][20][21]. This trap captures mostly host-seeking Ae. aegypti females since a dispenser placed inside traps releases a defined combination of lactic acid, ammonia, and caproic acid, substances that are found on human skin [22,23]. ...
Deployment of Aedes aegypti mosquitoes carrying the endosymbiont bacterium Wolbachia has been identified as a promising strategy to reduce dengue, chikungunya, and Zika transmission. We investigated whether sampling larvae from ovitraps can provide reliable estimates on Wolbachia frequency during releases, as compared to the expensive adult-based BG-Sentinel. We conducted pilot releases in a semi-field system (SFS) divided into six cages of 21 m 2 , each with five ovitraps. Five treatments were chosen to represent different points of a hypothetical invasion curve: 10%, 25%, 50%, 75%, and 90% of Wolbachia frequency. Collected eggs were counted and hatched, and the individuals from a net sample of 27% of larvae per treatment were screened for Wolbachia presence by RT-qPCR. Ovitrap positioning had no effect on egg hatching rate. Treatment strongly affected the number of eggs collected and also the hatching rate, especially when Wolbachia was at a 10% frequency. A second observation was done during the release of Wolbachia in Rio under a population replacement approach when bacterium frequency was estimated using 30 BG-Sentinel traps and 45 ovitraps simultaneously. By individually screening 35% (N = 3904) of larvae collected by RT-qPCR, we were able to produce a similar invasion curve to the one observed when all adults were individually screened. If sampling is reduced to 20%, monitoring Wolbachia frequency with 45 ovitraps would be roughly half the cost of screening all adult mosquitoes captured by 30 BG-Sentinels. Our findings support the scale-up of Wolbachia releases, especially in areas with limited resources to afford massive trapping with BG-Sentinel traps.
... Wolbachia releases are being undertaken in Aedes aegypti populations both for replacing existing populations with mosquitoes that have a reduced ability to transmit dengue [1,2] and other arboviruses, and for suppressing mosquito populations directly due to sterility generated by males infected with Wolbachia [3]. A challenge in implementing Wolbachia-based strategies is that a high level of quality control is required for release success. ...
... Malaysian samples were collected from three locations (researchers blinded as to origin) by staff from the Institute for Medical Research, Kuala Lumpur (https://www.imr.gov.my), and stored at -20˚C in absolute ethanol before extraction. Mosquitoes were collected using ovitraps from two sites in Kuala Lumpur where the release of wAlbB-infected mosquitoes with a strain described by Ant et al. [29] is currently underway [2], as well as one control site where mosquitoes with Wolbachia have not been released. Mosquitoes were reared under standard conditions and sacrificed as adults for extraction. ...
With Wolbachia-based arbovirus control programs being scaled and operationalised around the world, cost effective and reliable detection of Wolbachia in field samples and laboratory stocks is essential for quality control. Here we validate a modified loop-mediated isothermal amplification (LAMP) assay for routine scoring of Wolbachia in mosquitoes from laboratory cultures and the field, applicable to any setting. We show that this assay is a rapid and robust method for highly sensitive and specific detection of wAlbB Wolbachia infection within Aedes aegypti under a variety of conditions. We test the quantitative nature of the assay by evaluating pooled mixtures of Wolbachia-infected and uninfected mosquitoes and show that it is capable of estimating infection frequencies, potentially circumventing the need to perform large-scale individual analysis for wAlbB infection status in the course of field monitoring. These results indicate that LAMP assays are useful for routine screening particularly under field conditions away from laboratory facilities.
