Malaria case in Madagascar, probable implication of a new vector, Anopheles coustani

Nepomichene, Thiery Nirina Jean Jose; Tata, Etienne; Boyer, Sébastien

doi:10.1186/s12936-015-1004-9

Cited by 47 publications

(57 citation statements)

References 20 publications

(21 reference statements)

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“…However, an increasing number of reports suggest an important role for An. coustani as a malaria vector in changing transmission settings in East Africa [51] and beyond [53, 54]. Due to its absence from the indoor environment [55], this vector will not be adequately targeted by current vector control interventions.…”

Section: Discussionmentioning

confidence: 99%

Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya

et al. 2017

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BackgroundMalaria vector mosquitoes with exophilic and zoophilic tendencies, or with a high acceptance of alternative blood meal sources when preferred human blood-hosts are unavailable, may help maintain low but constant malaria transmission in areas where indoor vector control has been scaled up. This residual transmission might be addressed by targeting vectors outside the house. Here we investigated the potential of insecticide-treated cattle, as routinely used for control of tsetse and ticks in East Africa, for mosquito control.MethodsThe malaria vector population in the study area was investigated weekly for 8 months using two different trapping tools: light traps indoors and cattle-baited traps (CBTs) outdoors. The effect of the application of the insecticide deltamethrin and the acaricide amitraz on cattle on host-seeking Anopheles arabiensis was tested experimentally in field-cages and the impact of deltamethrin-treated cattle explored under field conditions on mosquito densities on household level.ResultsCBTs collected on average 2.8 (95% CI: 1.8–4.2) primary [Anopheles gambiae (s.s.), An. arabiensis and An. funestus (s.s.)] and 6.3 (95% CI: 3.6–11.3) secondary malaria vectors [An. ivulorum and An. coustani (s.l.)] per trap night and revealed a distinct, complementary seasonality. At the same time on average only 1.4 (95% CI: 0.8–2.3) primary and 1.1 (95% CI: 0.6–2.0) secondary malaria vectors were collected per trap night with light traps indoors. Amitraz had no effect on survival of host-seeking An. arabiensis under experimental conditions but deltamethrin increased mosquito mortality (OR 19, 95% CI: 7–50), but only for 1 week. In the field, vector mortality in association with deltamethrin treatment was detected only with CBTs and only immediately after the treatment (OR 0.25, 95% CI: 0.13–0.52).ConclusionsEntomological sampling with CBTs highlights that targeting cattle for mosquito control has potential since it would not only target naturally zoophilic malaria vectors but also opportunistic feeders that lack access to human hosts as is expected in residual malaria transmission settings. However, the deltamethrin formulation tested here although used widely to treat cattle for tsetse and tick control, is not suitable for the control of malaria vectors since it causes only moderate initial mortality and has little residual activity.

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Section: Discussionmentioning

confidence: 99%

Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya

et al. 2017

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“…Indeed, An. coustani has recently been described as a potential secondary malaria vector in Madagascar [18]. Whereas An.…”

Section: Introductionmentioning

confidence: 99%

Efficient method for establishing F1 progeny from wild populations of Anopheles mosquitoes

Nepomichene

Andrianaivolambo

Boyer

et al. 2017

Malar J

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BackgroundThe changing malaria situation in Madagascar requires additional knowledge on the physiology and behaviour of local mosquito vectors. However, the absence of established colonies for several anopheline species present in Madagascar constitutes a limiting factor. To avoid labour intensive work and uncertainty for success of establishing Anopheles colonies from Malagasy species, field collections of blood-fed females and in-tube forced oviposition were combined to reliably produce large numbers of F1 progeny.MethodsBlood-fed females were captured in zebu stables or open zebu parks. Oviposition was induced by enclosing gravid females in eppendorf tubes as initially described for Anopheles funestus. The effect of cold anaesthesia on inducing in-tube forced oviposition and on egg yield was assessed for five Anopheles species, namely Anopheles coustani, An. funestus, Anopheles mascarensis, Anopheles arabiensis and Anopheles squamosus. The production of eggs from in-tube forced oviposition and standard egg laying in cages was compared.ResultsFor the five anopheline species studied, the in-tube forced oviposition method had different efficacy ranging from 35.6 to 71.1% females willing to lay eggs in tubes. Interestingly, prior anaesthesia increased significantly the proportion of ovipositing females for An. mascarensis. Prior anaesthesia has a marginal effect on the number of eggs produced. However, the overall yield in eggs collected using the in-tube forced oviposition method largely exceeds the number of eggs that can be produced by females free to oviposit in cages.ConclusionThe efficiency of the method allowed the production of F1 progeny in numbers sufficiently large for developing detailed analyses of the five species tested, including behavioural studies, insecticide resistance assessment and molecular characterization, as well as vector competence studies. It should be applicable to other anopheline species difficult to colonize.

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“…However, their abundance relative to primary vectors necessitates closer examination of their potential impact on human health. Anopheles coustani , comprising 37% of our mosquito collection, was recently implicated as a vector of malaria [10]. Despite being primarily exophagic and exophilic, overwhelming numbers could result in this species being responsible for the majority of indoor bites despite the presence of endophagic and endophilic species [10].…”

Section: Discussionmentioning

confidence: 99%

Novel Insights into Malaria Vector Surveillance in Madagascar Using a Quadrant Enabled Screen Trap (QUEST) and Bloodmeal Detection Assay for Regional Transmission (BLOODART)

Tedrow

Rakotomanga²,

Nepomichene

et al. 2019

Preprint

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31 Background: The Madagascar National Strategic Plan for Malaria Control 2018 (NSP) outlines 32 malaria control pre-elimination strategies that include detailed goals for mosquito control. 33 Primary surveillance protocols and mosquito control interventions focus on indoor vectors of 34 malaria, while many potential vectors feed and rest outdoors. Here we describe the application of 35 novel tools that advance our understanding of diversity, host choice, and Plasmodium infection 36 in the Anopheline mosquitoes of the Western Highland Fringe of Madagascar. 37 Methodology/Principal Findings: We employed a novel outdoor trap, the QUadrant Enabled 38 Screen Trap (QUEST), in conjunction with the recently developed multiplex BLOOdmeal 39 Detection Assay for Regional Transmission (BLOODART). We captured a total of 1252 female 40 Anopheles mosquitoes (10 species), all of which were subjected to BLOODART analysis. 41 QUEST collection captured a heterogenous distribution of mosquito density, diversity, host 42 choice, and Plasmodium infection. Concordance between Anopheles morphology and 43 BLOODART species identifications ranged from 93-99%. Mosquito feeding behavior in this 44 collection frequently exhibited multiple blood meal hosts (single host = 53.6%, two hosts = 45 42.1%, three hosts = 4.3%). The overall percentage of human positive bloodmeals increased 46 between the December 2017 and the April 2018 timepoints (27% to 44%). Plasmodium 47 positivity was found primarily in vectors considered to be of secondary importance, with an 48 overall prevalence of 6%.49 Conclusions/Significance: The QUEST was an efficient tool for sampling Anopheline 50 mosquitoes. Vectors considered to be of secondary importance were commonly found with 51 Plasmodium DNA in their abdomens, indicating a need to account for these species in routine 52 surveillance efforts. Mosquitoes exhibited multiple blood feeding behavior within a gonotrophic 4 53 cycle, with predominantly non-human hosts in the bloodmeal. Taken together, this complex 54 feeding behavior could enhance the role of multiple Anopheline species in malaria transmission, 55 possibly tempered by zoophilic feeding tendencies. 57 Author Summary 58Malaria continues to be a significant threat to public health in Madagascar. Elimination of 59 this disease is impeded by numerous factors, such as vector surveillance that does little to 60 account for the potential role of secondary malaria vectors, which rest and feed outdoors. In this 61 study, we designed a novel, low cost QUadrant Enabled Screen Trap (QUEST) to address the 62 lack of traps for outdoor mosquitoes. We used this in conjunction with our novel BLOOdmeal 63 Detection Assay for Regional Transmission (BLOODART) to assess mosquito feeding behavior 64 in the Western Highland Fringe of Madagascar. Our analysis revealed significant variability in 65 mosquito density, diversity, host choice, and Plasmodium infection across traps placed within 66 and between two nearby villages at two timepoints; indicating a strong, small-scale sp...

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Malaria case in Madagascar, probable implication of a new vector, Anopheles coustani

Cited by 47 publications

References 20 publications

Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya

Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya

Efficient method for establishing F1 progeny from wild populations of Anopheles mosquitoes

Novel Insights into Malaria Vector Surveillance in Madagascar Using a Quadrant Enabled Screen Trap (QUEST) and Bloodmeal Detection Assay for Regional Transmission (BLOODART)

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