Malaria transmission has been substantially reduced across Africa through the distribution of long-lasting insecticidal nets (LLINs). However, the emergence of insecticide resistance within mosquito vectors risks jeopardizing the future efficacy of this control strategy. The severity of this threat is uncertain because the consequences of resistance for mosquito fitness are poorly understood: while resistant mosquitoes are no longer immediately killed upon contact with LLINs, their transmission potential may be curtailed because of longer-term fitness costs that persist beyond the first 24 h after exposure. Here, we used a Bayesian state-space model to quantify the immediate (within 24 h of exposure) and delayed (>24 h after exposure) impact of insecticides on daily survival and malaria transmission potential of moderately and highly resistant laboratory populations of the major African malaria vector Anopheles gambiae. Contact with LLINs reduced the immediate survival of moderately and highly resistant An. gambiae strains by 60–100% and 3–61%, respectively, and delayed mortality impacts occurring beyond the first 24 h after exposure further reduced their overall life spans by nearly one-half. In total, insecticide exposure was predicted to reduce the lifetime malaria transmission potential of insecticide-resistant vectors by two-thirds, with delayed effects accounting for at least one-half of this reduction. The existence of substantial, previously unreported, delayed mortality effects within highly resistant malaria vectors following exposure to insecticides does not diminish the threat of growing resistance, but posits an explanation for the apparent paradox of continued LLIN effectiveness in the presence of high insecticide resistance.

Insecticide resistance in the malaria vector An. gambiae s.l. threatens insecticide-based control efforts, necessitating regular monitoring. We assessed resistance in field-collected An. gambiae s.l. from Jinja, Uganda using WHO biosassays. Only An. gambiae s.s. and An. arabiensis (≈70%) were present. Female An. gambiae exhibited extremely high pyrethroid resistance (permethrin LT50 >2h; deltamethrin LT50 >5h). Female An. arabiensis were resistant to permethrin and exhibited reduced susceptibility to deltamethrin. However, whilst An. gambiae were DDT resistant, An. arabiensis were fully susceptible. Both species were fully susceptible to bendiocarb and fenitrothion. Kdr 1014S has increased rapidly in the Jinja population of An. gambiae s.s. and now approaches fixation (≈95%), consistent with insecticide-mediated selection, but is currently at low frequency in An. arabiensis (0.07%). Kdr 1014F was also at low frequency in An. gambiae. These frequencies preclude adequately-powered tests for association with phenotypic resistance. PBO synergist bioassays resulted in near complete recovery of pyrethroid susceptibility suggesting involvement of CYP450s in resistance. A small number (0.22%) of An. gambiae s.s. x An. arabiensis hybrids were found, suggesting the possibility of introgression of resistance alleles between species. The high levels of pyrethroid resistance encountered in Jinja threaten to reduce the efficacy of vector control programmes which rely on pyrethroid impregnated bednets or indoor spraying of pyrethroids.

In the city of Bobo-Dioulasso in Burkina Faso, Anopheles arabiensis has superseded Anopheles gambiae s.s. as the major malaria vector and the larvae are found in highly polluted habitats normally considered unsuitable for Anopheles mosquitoes. Here we show that An. gambiae s.l. adults emerging from a highly polluted site in the city centre (Dioulassoba) have a high prevalence of DDT resistance (percentage mortality after exposure to diagnostic dose = 65.8% in the dry season and 70.4% in the rainy season, respectively). An investigation into the mechanisms responsible found an unexpectedly high frequency of the 1014S kdr mutation (allele frequency = 0.4), which is found at very low frequencies in An. arabiensis in the surrounding rural areas, and an increase in transcript levels of several detoxification genes, notably from the glutathione transferase and cytochrome P450 gene families. A number of ABC transporter genes were also expressed at elevated levels in the DDT resistant An. arabiensis. Unplanned urbanisation provides numerous breeding grounds for mosquitoes. The finding that Anopheles mosquitoes adapted to these urban breeding sites have a high prevalence of insecticide resistance has important implications for our understanding of the selective forces responsible for the rapid spread of insecticide resistant populations of malaria vectors in Africa.

BackgroundThere has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions.Methodology/Principal FindingsA country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s.Conclusions/SignificanceCurrently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan.

Background The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widespread. However, although mosquitoes may no longer be rapidly killed by LLIN exposure, a delayed mortality effect has been shown to reduce the transmission potential of mosquitoes exposed to nets. This has been postulated to partially explain the continued efficacy of LLINs against pyrethroid-resistant populations. Burkina Faso is one of a number of countries with very high malaria burdens and pyrethroid-resistant vectors, where progress in controlling this disease has stagnated. We measured the impact of LLIN exposure on mosquito longevity in an area of the country with intense pyrethroid resistance to establish whether pyrethroid exposure was still shortening mosquito lifespan in this setting. Methods We quantified the immediate and delayed mortality effects of LLIN exposure using standard laboratory WHO cone tests, tube bioassays and experimental hut trials on Anopheles gambiae populations originating from the Cascades region of Burkina Faso using survival analysis and a Bayesian state-space model. Results Following single and multiple exposures to a PermaNet 2.0 LLIN only one of the four mosquito populations tested showed evidence of delayed mortality. No delayed mortality was seen in experimental hut studies using LLINs. A delayed mortality effect was only observed in WHO tube bioassays when deltamethrin concentration was increased above the standard diagnostic dose. Conclusions As mosquito pyrethroid-resistance increases in intensity, delayed effects from LLIN exposure are substantially reduced or absent. Given the rapid increase in resistance occurring in malaria vectors across Africa it is important to determine whether the failure of LLINs to shorten mosquito lifespan is now a widespread phenomenon as this will have important implications for the future of this pivotal malaria control tool.

Background: Insecticide-treated nets (ITNs) are losing efficacy against pyrethroid-resistant malaria vector populations throughout Africa. Safeguarding bed net efficacy, vital for effective malaria control, requires greater knowledge of mosquito-ITN interactions and how this impacts on the mosquito. Methods: A purpose-built benchtop apparatus with a closed 10 cm cubic chamber (the 'Baited-box') was used to video record behaviour of individual free-flying female Anopheles gambiae during approach and blood-feeding on a human hand through untreated nets and ITNs at close range. Time and duration of defined behavioural events, and knockdown and mortality at 1-and 24-h post-exposure respectively, were recorded for pyrethroid susceptible and resistant mosquitoes. Results: Using three human volunteers differing in relative attractiveness to mosquitoes, 328 mosquitoes were individually tested. There were no significant differences between response rates to ITNs and untreated nets (P > 0.1) or between resistant (Tiassalé) and susceptible (Kisumu) mosquito strains, at untreated nets (P = 0.39) or PermaNet 2.0 (P = 1). The sequence of behavioural events from host-seeking to completion of blood-feeding was consistent in all tests but duration and start time of events involving net contact were reduced or delayed respectively with ITNs. Blood-feeding durations at untreated nets (means from 4.25 to 8.47 min (95% confidence interval (CI) = 3.39-9.89) at 3 human volunteers) were reduced by 37-50% at PermaNet 2.0, in susceptible (mean 2.59-4.72 min, 95% CI = 1.54-5.5, P = < 0.05) and resistant (mean 4.20 min, 95% CI = 3.42-4.97, P = 0.01) strains. Total accumulated net contact was approximately 50% lower at PermaNet and Olyset ITNs (P < 0.0001) in susceptible (two of the three volunteers) and resistant mosquitoes. Times prior to first net contact were similar at untreated nets and ITNs (P > 0.2), and neither ITN type showed detectable spatial repellency. After initial contact, blood-feeding commenced later at Olyset (mean 2.76 min, 95% CI = 1.74-3.76, P = 0.0009) and PermaNet (mean 2.4 min, 95% CI = 1.52-3.33, P = 0.0058) than untreated netting (mean 0.68 min, 95% CI = 0.42-0.94). Conclusions: The baited box offers a simple method for detailed characterization of mosquito behavioural responses to insecticidal nets, for comparing entomological modes of action between nets and for defining the behavioural

Background The WHO cone test is one of three tests currently used to evaluate the efficacy of insecticide-treated bed nets (ITNs). It generates two test outputs, knockdown and 24-h mortality, both indicative of immediate toxicity but that reveal little about the nature of mosquito and ITN interaction or how results translate to real-world settings. Methods A human arm held 5 mm behind the net surface acted as a host attractant during cone tests and a smartphone was used to capture mosquito behaviour in the cone. Post-exposure blood feeding and survival for nine days were recorded; ingested blood meal size was determined by measuring excreted haematin. Four strains of Anopheles gambiae (insecticide susceptible: Kisumu and N’gousso; insecticide resistant: Banfora and VK7) were tested with and without the host attractant using untreated, Permanet 2.0 and Olyset nets. Video recordings were scan sampled every five seconds to record mosquito positions on either the net, in flight or in contact with the cone. Generalized estimating equations were used to analyse all data except survival within nine days which was analysed using Weighted Cox Regression. Results Net contact was the most frequently recorded behaviour in all Anopheles spp. strains on all nets. Adding the human host as attractant triggered excitatory behaviours: in all strains, the magnitude of net contact was significantly decreased compared to tests without a host. ITN exposure altered the observed behaviour of the two susceptible strains, which exhibited a decreased response to the host during ITN tests. The resistant strains did not alter their behaviour during ITN tests. Significantly less net contact was observed during Olyset Net tests compared to Permanet 2.0. The host presence affected survival after exposure: Banfora and VK7 mosquitoes exposed to Permanet 2.0 with a host lived longer compared to tests performed without a host. However, mosquitoes that blood-fed and survived long enough to digest the blood meal did not exhibit significantly reduced longevity regardless of the presence of the host attractant. Conclusions Simple modifications to the WHO cone test and extension of post-test monitoring beyond the current 24 h enable detailed behavioural characterizations of individual ITNs to be compiled. The effects observed from testing with a host and including blood feeding suggest that more representative estimates of true of ITN efficacy are gained with these modifications than when using the current testing protocol.

Major developments in the use of the internet have enabled easy and widespread access to information and the ability to form virtual social networks. For parents of children with developmental disorders, who may at times feel isolated, having a forum to discuss their fears and concerns with other parents who are sharing similar experiences may provide a source of support and advice. Waiting lists for assessments, including for children with developmental co‐ordination disorder (DCD), remain in many areas; a professionally supported message centre could also add an additional level of service and empowerment for these parents. This could potentially reduce the need for unnecessary assessment in some cases and help to bridge the information gap between health and education. The Dyscovery Centre message board has been established for over four years and has seen increasing usage during that time. This paper aims to explore the range, frequency and types of concerns that parents of children with specific learning difficulties express when accessing the message board. The impact of this type of support is discussed. The paper then explores how this approach and other online strategies can effectively run alongside more traditional services in both health and education.