Surveillance of malaria vector population density and biting behaviour in western Kenya

Ototo, Ednah N; Mbugi, J.P.; Wanjala, Christine; Zhou, Guofa; Githeko, Andrew K.; Yan, Guiyun

doi:10.1186/s12936-015-0763-7

Cited by 86 publications

(123 citation statements)

References 26 publications

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“…However, in the case of mosquito-monitoring field studies, collection sites may be far from the laboratories where samples will be analyzed. As such, mosquito samples are generally preserved in a variety of different buffers and temperatures [45][46][47]. Among the mosquito storage modes tested here, the highest levels of MS mosquito species identification at both developmental stages were obtained for samples preserved frozen at -20ЊC (97.5% identification) or in liquid nitrogen (95.8% identification) for up to 6 months.…”

Section: Discussionmentioning

confidence: 98%

Standardization of sample homogenization for mosquito identification using an innovative proteomic tool based on protein profiling

et al. 2016

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The rapid spread of vector-borne diseases demands the development of an innovative strategy for arthropod monitoring. The emergence of MALDI-TOF MS as a rapid, low-cost, and accurate tool for arthropod identification is revolutionizing medical entomology. However, as MS spectra from an arthropod can vary according to the body part selected, the sample homogenization method used and the mode and duration of sample storage, standardization of protocols is indispensable prior to the creation and sharing of an MS reference spectra database. In the present study, manual grinding of Anopheles gambiae Giles and Aedes albopictus mosquitoes at the adult and larval (L3) developmental stages was compared to automated homogenization. Settings for each homogenizer were optimized, and glass powder was found to be the best sample disruptor based on its ability to create reproducible and intense MS spectra. In addition, the suitability of common arthropod storage conditions for further MALDI-TOF MS analysis was kinetically evaluated. The conditions that best preserved samples for accurate species identification by MALDI-TOF MS were freezing at -20°C or in liquid nitrogen for up to 6 months. The optimized conditions were objectified based on the reproducibility and stability of species-specific MS profiles. The automation and standardization of mosquito sample preparation methods for MALDI-TOF MS analyses will popularize the use of this innovative tool for the rapid identification of arthropods with medical interest.

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Section: Discussionmentioning

confidence: 98%

Standardization of sample homogenization for mosquito identification using an innovative proteomic tool based on protein profiling

et al. 2016

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“…Of the five malaria transmission zones in Kenya, Western Kenya currently experiences the highest transmission intensity 24, 26 , despite efforts to scale up various control interventions, such as long lasting insecticide nets, indoor residual spraying and artemisinin combination therapy, in this region 45– 47 .…”

Section: Discussionmentioning

confidence: 99%

Geographic-genetic analysis of Plasmodium falciparum parasite populations from surveys of primary school children in Western Kenya

Omedo¹,

Mogeni²,

Rockett³

et al. 2017

Wellcome Open Res

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Background. Malaria control, and finally malaria elimination, requires the identification and targeting of residual foci or hotspots of transmission. However, the level of parasite mixing within and between geographical locations is likely to impact the effectiveness and durability of control interventions and thus should be taken into consideration when developing control programs. Methods. In order to determine the geographic-genetic patterns of Plasmodium falciparum parasite populations at a sub-national level in Kenya, we used the Sequenom platform to genotype 111 genome-wide distributed single nucleotide polymorphic (SNP) positions in 2486 isolates collected from children in 95 primary schools in western Kenya. We analysed these parasite genotypes for genetic structure using principal component analysis and assessed local and global clustering using statistical measures of spatial autocorrelation. We further examined the region for spatial barriers to parasite movement as well as directionality in the patterns of parasite movement. Results. We found no evidence of population structure and little evidence of spatial autocorrelation of parasite genotypes (correlation coefficients <0.03 among parasite pairs in distance classes of 1km, 2km and 5km; p value<0.01). An analysis of the geographical distribution of allele frequencies showed weak evidence of variation in distribution of alleles, with clusters representing a higher than expected number of samples with the major allele being identified for 5 SNPs. Furthermore, we found no evidence of the existence of spatial barriers to parasite movement within the region, but observed directional movement of parasites among schools in two separate sections of the region studied. Conclusions. Our findings illustrate a pattern of high parasite mixing within the study region. If this mixing is due to rapid gene flow, then “one-off” targeted interventions may not be currently effective at the sub-national scale in Western Kenya, due to the high parasite movement that is likely to lead to re-introduction of infection from surrounding regions. However repeated targeted interventions may reduce transmission in the surrounding regions.

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“…In Kenya, the government rolled out the universal bed net programme where every two persons in a household were provided with a free ITN. The ITN ownership rose from 12.8% in 2004 to over 80% in 2015[8, 9] The increased use of indoor interventions may pose stress on the indoor feeding and resting of malaria vectors leading to either behavioural defense [10] or physiological defense [5].…”

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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Surveillance of malaria vector population density and biting behaviour in western Kenya

Cited by 86 publications

References 26 publications

Standardization of sample homogenization for mosquito identification using an innovative proteomic tool based on protein profiling

Standardization of sample homogenization for mosquito identification using an innovative proteomic tool based on protein profiling

Geographic-genetic analysis of Plasmodium falciparum parasite populations from surveys of primary school children in Western Kenya

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

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