Reemergence of Anopheles funestus as a Vector of Plasmodium falciparum in Western Kenya after Long-Term Implementation of Insecticide-Treated Bed Nets

McCann, Robert S.; Ochomo, Eric; Bayoh, M. Nabie; Vulule, John; Hamel, Mary J.; Gimnig, John E.; Hawley, William A.; Walker, Edward D.

doi:10.4269/ajtmh.13-0614

Cited by 100 publications

(112 citation statements)

References 31 publications

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“…Despite intense intervention efforts, the estimated of morbidity and mortality levels continue to rise. Chemotherapy and vector control programs have been largely ineffective, owing to the emergence and spread of insecticide-resistant mosquito vectors and drug-resistant plasmodium strains [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Dual antiplasmodial activity of vitamin D3 and its analog, 22-oxacalcitriol, by direct and indirect mechanisms

Yamamoto

Iwagami

Seki

et al. 2017

Parasitology International

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Recent evidence suggests that 1α,25-dihydroxyvitamin D3 (calcitriol, VD3), the active form of vitamin D (VD), can inhibit the proliferation of microorganisms. In the present study, we conducted in vitro experiments and utilized in vivo murine models to investigate the antimalarial activity of VD3 and its analog, 22-oxacalcitriol (22-OCT), which was designed to cause less hypercalcemia than VD3. VD3 and 22-OCT treatments effectively resolved a Plasmodium chabaudi (Pc) infection in wild-type mice. Reduced parasitemia was observed during the acute phase of infection in the presence of VD3 and 22-OCT, followed by a delayed peak during the chronic stage of infection. Some anti-Pc activity was observed in VD receptor knockout (KO) mice. VD3 and 22-OCT also completely inhibited the proliferation of P. falciparum (Pf) in human red blood cells in vitro. Plasma levels of interferon (IFN)-γ in VD3-treated B10 and B6 mice were lower than those in vehicle-treated animals, and VD3 resolved a Pc infection in IFN-γ-KO mice, which greatly improved survival. These data suggest that the protective effects of VD3 are elicited through an IFN-γ-independent mechanism. Effective antiplasmodial doses of VD3 and 22-OCT resulted in a loss of body weight in mice. This loss in body weight occurred concomitantly with the development of hypercalcemia. Zoledronic acid partially attenuated VD3-induced hypercalcemia and abrogated the antiparasitic effects of VD3. This study highlights a potential therapeutic role for VD3 in the treatment of malarial infections and shows that hypercalcemia is excellent indicator of the antiplasmodial activity of VD3.

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Section: Introductionmentioning

confidence: 99%

Dual antiplasmodial activity of vitamin D3 and its analog, 22-oxacalcitriol, by direct and indirect mechanisms

Yamamoto

Iwagami

Seki

et al. 2017

Parasitology International

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“…gambiae complex and An. funestus group due to their anthropophilic and endophilic behaviours that makes them be more efficient in malaria transmission [17–19]. With the scale-up of indoor-based vector control tools mosquitoes have changed behaviours; some are biting and resting indoors whilst others have changed to prefer biting bite outdoors.…”

Section: Introductionmentioning

confidence: 99%

Resting behaviour of malaria vectors in a highland and a lowland site of western Kenya: Implication on malaria vector control measures

Machani

Ochomo

Amimo

et al. 2019

Preprint

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33Background: Understanding the interactions between increased insecticide resistance in field 34 malaria vector populations and the subsequent resting behaviour patterns is important for planning 35 adequate vector control measures in a specific context and sustaining the current vector 36 interventions. The aim of this study was to investigate the resting behavior, host preference and 37 infection with Plasmodium falciparum sporozoites by malaria vectors in different ecological 38 settings of western Kenya with different levels of insecticide resistance. 39 40 Methods: Indoor and outdoor resting Anopheline mosquitoes were sampled during the dry and 41 rainy seasons in Kisian (lowland site) and Bungoma (highland site), both in western Kenya. WHO 42 tube bioassay was used to determine levels of phenotypic resistance of first generation offspring 43 65 66 Conclusion: The study reports high densities of insecticide -resistant An. gambiae and An. funestus 67 resting indoors and the persistence of malaria transmission indoors with high entomological 68 inoculation rates (EIR) regardless of the use of Long-lasting insecticidal nets (LLINs). These 69 findings underline the difficulties of controlling malaria vectors resting and biting indoors using 70 the current interventions. Supplemental vector control tools and implementation of sustainable 71 insecticide resistance management strategies are needed in western Kenya.72 73 74 4 99Malaria vectors have been shown to adapt to changing environment due to either behavioural 100 avoidance or selection of mutations and recombination that favour their survival in the presence 101 of insecticides threatening the efficacy of the current indoor-based vector control tools [5,11] and 102 the resulting increase in residual transmission [12]. Insecticide resistance is common in sub- 103Saharan Africa with some regions reporting resistance to all classes of insecticides [13,14]. In 104 Kenya, the target site and metabolic resistance mechanisms play a major role in pyrethroid 105 resistance [15,16]. The primary malaria vectors in Kenya belong to An. gambiae complex and An. 106 funestus group due to their anthropophilic and endophilic behaviours that makes them be more 107 efficient in malaria transmission [17-19]. With the scale-up of indoor-based vector control tools 108 mosquitoes have changed behaviours; some are biting and resting indoors whilst others have 109 changed to prefer biting bite outdoors. Behavioral modifications including changes in biting time 110 and location [20-22], changes in host choice and shift from endophilic (i.e. resting in houses) to 111 exophilic (i.e. resting outdoors) behavior have been associated with long-term use of insecticide-112 based interventions [23,24]. Insecticide resistance could make mosquitoes respond numerically 113 and behaviorally to alter vector populations as well as resting and feeding behaviors. Knowledge 114 of the resting habits of resistant vectors and their feeding preference may predict the intensity of 115 malaria tran...

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“…arabiensis and in some areas increasing dominance of An. funestus in others [70,73,81,82,83,84,85]. It is therefore important to accurately determine the species composition to understand local malaria transmission, establish the range of resting and foraging behaviors for the species present, estimate sensitivity to insecticides for each species, and determine how their relative contributions to transmission may shift with changes in intervention coverage.…”

Section: Bionomic Traits Of Vector Speciesmentioning

confidence: 99%

Implicating Cryptic and Novel Anophelines as Malaria Vectors in Africa

Stevenson

Norris

2016

Insects

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Entomological indices and bionomic descriptions of malaria vectors are essential to accurately describe and understand malaria transmission and for the design and evaluation of appropriate control interventions. In order to correctly assign spatio-temporal distributions, behaviors and responses to interventions to particular anopheline species, identification of mosquitoes must be accurately made. This paper reviews the current methods and their limitations in correctly identifying anopheline mosquitoes in sub-Saharan Africa, and highlights the importance of molecular methods to discriminate cryptic species and identify lesser known anophelines. The increasing number of reports of Plasmodium infections in assumed “minor”, non-vector, and cryptic and novel species is reviewed. Their importance in terms of evading current control and elimination strategies and therefore maintaining malaria transmission is emphasized.

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Reemergence of Anopheles funestus as a Vector of Plasmodium falciparum in Western Kenya after Long-Term Implementation of Insecticide-Treated Bed Nets

Cited by 100 publications

References 31 publications

Dual antiplasmodial activity of vitamin D3 and its analog, 22-oxacalcitriol, by direct and indirect mechanisms

Dual antiplasmodial activity of vitamin D3 and its analog, 22-oxacalcitriol, by direct and indirect mechanisms

Resting behaviour of malaria vectors in a highland and a lowland site of western Kenya: Implication on malaria vector control measures

Implicating Cryptic and Novel Anophelines as Malaria Vectors in Africa

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