Early biting of the Anopheles gambiae s.s. and its challenges to vector control using insecticide treated nets in western Kenya highlands

Wamae, Peter; Githeko, Andrew K.; Otieno, G.; Kabiru, Ephantus W.; Duombia, S. O.

doi:10.1016/j.actatropica.2015.07.008

Cited by 47 publications

(43 citation statements)

References 57 publications

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“…gambiae were found to be highly anthropophilic, but surprisingly a few mixed human/goat and goat only blood meals were identified in both vectors, which has been infrequently reported. 40,[44][45][46] In Nchelenge District, goats are occasionally kept indoors at night and may serve as an incidental host to indoor foraging An. funestus and An.…”

Section: Discussionmentioning

confidence: 99%

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Das

Muleba

Stevenson

et al. 2016

The American Society of Tropical Medicine and Hygiene

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Abstract. Nchelenge District in Luapula Province, northern Zambia, experiences holoendemic malaria despite implementation of vector control programs. The major Anopheles vectors that contribute to Plasmodium falciparum transmission in this area had not previously been well defined. Three collections performed during the 2012 wet and dry seasons and the 2013 wet season revealed Anopheles funestus sensu stricto and Anopheles gambiae sensu stricto as the main vectors, where 80-85% of each collection was composed of An. funestus. Both vectors were found to be highly anthropophilic, and An. funestus has higher sporozoite infection rates (SIRs) and entomological inoculation rates (EIRs) year-round compared with An. gambiae: SIRs of 1.8-3.0% and 0-2.5%, respectively, and EIRs of 3.7-41.5 infectious bites per 6-month period (ib/p/6mo) and 0-5.9 ib/p/6mo, respectively. Spatial and temporal changes in each vector's dynamics and bionomics were also observed. Anopheles funestus was the predominant vector in the villages near Kenani Stream in both wet and dry seasons, whereas An. gambiae was found to be the main vector in areas near Lake Mweru during the wet season. The vector data illustrate the need for broader temporal and spatial sampling in Nchelenge and present unique opportunities to further our understanding of malarial transmission and implications for malarial control in high-risk areas.

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Section: Discussionmentioning

confidence: 99%

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Das

Muleba

Stevenson

et al. 2016

The American Society of Tropical Medicine and Hygiene

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“…On the other hand, Anopheles mosquitoes have a speci c circadian rhythm in which blood-feeding activities are preferentially performed during the night [21]. Thus, this daytime biting activity may imply a change in Anopheles circadian rhythms, despite the fact that experimental exposure to light can alter their biting ability [22] [19]. Further investigations are needed to assess the basis of this diurnal biting behaviour, as it is now becoming widespread in Dielmo.…”

Section: Discussionmentioning

confidence: 99%

Anopheles arabiensis and Anopheles funestus biting patterns in Dielmo, an area of low level exposure to malaria vectors

Doucouré¹,

Thiaw

Wotodjo

et al. 2020

Preprint

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Background In Dielmo, Senegal, the widespread use of long-lasting insecticidal nets has decreased both the incidence of malaria and the density of the Anopheles population. However, persistent low-level malaria transmission may hamper efforts to eliminate the disease. Therefore, continuous monitoring of the vector population is needed in order to improve knowledge of Anopheles biting behaviour and to readjust control interventions.Methods In 2015, Anopheles were collected every month for a whole year and each specimen was identified using morphological and molecular techniques. The biting pattern of each species was analysed according to night (7pm–7am) and morning (7am–11am) periods, the place of biting and the season. The ELISA CSP technique was used to assess the Plasmodium falciparum sporozoite rate to evaluate the entomological inoculation rate (EIR).Results Anopheles arabiensis and Anopheles funestus sensu stricto were found to be the main vectors biting humans. Overall, the biting rate was low, at 3.84bites per night (bpn) and 1.27 bites per morning (bpm), respectively (IRR =3.04, CI = [1.84-5.00], p<0.001). The EIR was 2.51 and 5.03 infectious bites per year during the night and morning, respectively. During the night, the An. arabiensis and An. funestus biting rate was 1.81 bpn and 1.71 bpn, respectively (IRR=0.95, CI= [0.46-1.92], p=0.88). During the morning, their density decreased to 0.51 bpm and 0.73 bpm for An. arabiensis and An. funestus, respectively (IRR=1.47, CI= [0.58-3.71], p=0.41). During the night and the morning, no specific trend of indoor or outdoor biting was observed in the dry and rainy season for both vectors. Conclusion This study highlighted low level Anopheles nocturnal and diurnal biting and the associated risk of malaria transmission. It showed also the influence of the season on the indoor and outdoor biting pattern, indicating that the human population could be exposed all year round to a low level of Anopheles bites. Control programmes should increase awareness of the use of bed nets throughout the year and promote the development and implementation of complimentary tools to target Anopheles biting shortly after dawn when people are still indoors.

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“…We limited assessment of spatial structure to inter-household distance owing to: 1) prior mapping of larval sites around a subset of these households, which indicate that larval sites are numerous, small, and transient 2 ; 2) vector behavior in western Kenya, which occurs after 9pm 51 and thus renders the household as epicenter of parasite transmission; and 3) the absence in the very circumscribed study site (∼100 km 2 ) of other candidate features (e.g. rivers, lakes, mountain ranges).…”

Section: Methodsmentioning

confidence: 99%

High-resolution micro-epidemiology of parasite spatial and temporal dynamics in a high malaria transmission setting in Kenya

Nelson

Sumner

Freedman

et al. 2019

Preprint

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1 2 3 High-resolution micro-epidemiology of parasite spatial and temporal dynamics in a high 4 malaria transmission setting in Kenya 5 6 7 Cody S. Abstract WC: 149 (150 max) 24Main Text WC: 4,830 (5,000 max) 25Methods WC: 2,450 (3,000 max) 26 ABSTRACT 27Novel interventions that leverage the heterogeneity of parasite transmission are needed to push 28 malaria further towards elimination. To better understand spatial and temporal dynamics of 29 transmission, we applied amplicon NGS of two polymorphic gene regions (csp and ama1) to a 30 cohort identified via reactive case detection in a high-transmission setting in western Kenya. From 31 4/2013-6/2014, we enrolled 442 symptomatic children with malaria, 442 matched controls, and 32 all household members of both groups. We evaluated genetic similarity between infected 33 individuals using three novel indices: sharing of parasite haplotypes on binary and proportional 34 scales and the L1 norm. Symptomatic children more commonly shared haplotypes with their own 35 household members. Furthermore, we identified robust temporal structuring of parasite genetic 36 similarity that we exploited to identify the molecular signature of an outbreak. These findings of 37 both micro-and macro-scale organization of parasite populations might be harnessed to inform 38 next-generation malaria control measures. 39 RESULTS 94Haplotype metrics and read coverage. 95Of 5,353 total study participants from across the study area (Fig. 1), 1,050 were RDT+ for 96 P. falciparum. A total of 966 RDT+ infections were submitted for amplicon NGS of csp and ama1 97 loci (Fig. 1). After haplotype assignment 17 and quality filtering of reads, we identified 120 unique 98 csp haplotypes across 655 participants and 180 ama1 haplotypes across 667 participants ( Fig. 99

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Early biting of the Anopheles gambiae s.s. and its challenges to vector control using insecticide treated nets in western Kenya highlands

Cited by 47 publications

References 57 publications

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Anopheles arabiensis and Anopheles funestus biting patterns in Dielmo, an area of low level exposure to malaria vectors

High-resolution micro-epidemiology of parasite spatial and temporal dynamics in a high malaria transmission setting in Kenya

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