Spatial-temporal heterogeneity in malaria receptivity is best estimated by vector biting rates in areas nearing elimination

Burkot, Thomas R.; Bugoro, Hugo; Apairamo, Allan; Cooper, Robert D.; Echeverry, Diego F.; Odabasi, Danyal; Beebe, Nigel W.; Makuru, Victoria; Xiao, Honglin; Davidson, Jenna R.; Deason, Nicholas A.; Reuben, Hedrick; Kazura, James W.; Collins, Frank H.; Lobo, Neil F.; Russell, Tanya L.

doi:10.1186/s13071-018-3201-1

Cited by 39 publications

(61 citation statements)

References 36 publications

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“…Therefore, the EIR evaluated during this study should be interpreted with caution, as the level of exposure to Anopheles during the day and the night is very low. Nevertheless, this study shows the importance of maintaining a continues entomological surveillance during the whole year in areas dealing with low level of exposure to vector bites and residual malaria transmission [24,25]. However, incorporating a sociodemographic aspect into control strategies could help to provide better containment for residual transmission as human behaviour contributes greatly to malaria outbreaks in this situation [3,26] and malaria transmission could persist at very low level even during the dry season [27].…”

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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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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“…Also, important to highlight, is that the key vector indicators to be monitored will change as transmission intensity diminishes and the range of available recommended interventions increases. While sporozoite rates are a recommended key indicator in high transmission scenarios, the value of sporozoite and entomological inoculation rates to guide programmatic decisions wanes with the need to measure biting rates becoming an increasingly important indicator for predicting transmission risk [44].…”

Section: Algorithms For Representative Samplingmentioning

confidence: 99%

Nextgen Vector Surveillance Tools: Sensitive, Specific, Cost-effective and Epidemiologically Relevant

Farlow¹,

Russell

Burkot

2020

Preprint

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Background Vector surveillance provides critical data for decision-making to ensure that malaria control programs remain effective and responsive to any threats to effectiveness. The quality and quantity of is dependent on the sampling tools and laboratory techniques used which may lack the sensitivity required to collect relevant data for decision-making. Here, 40 vector control experts were interviewed to assess the benefits and limitations of the current vector surveillance tools and techniques. In addition, experts shared ideas on “blue sky” indicators which encompassed ideas for novel methods to monitor presently used indicators, to measure novel vector behaviours not presently measured, algorithms for deploying surveillance tools and priorities for understanding vector behaviours critical for collecting and interpreting vector data. Results. The available tools for sampling and analysing vectors are often hampered by high labour and resource requirements (human and supplies) coupled with high outlay and operating costs and variable tool performance across species and geographic regions vector. The next generation of surveillance tools needs to address the limitations of our present tools by being more sensitive, specific and less costly to deploy to enable the collection and use of epidemiologically relevant vector data to facilitate more proactive vector control guidance. Ideas and attributes for Target Product Profiles (TPPs) generated from this analysis provide targets for research and funding to develop next generation tools.Conclusions. More efficient surveillance tools and a more complete understanding of vector behaviours and populations will provide a basis for more cost effective and successful malaria control by better enabling intervention to be selected that align with vulnerabilities in vector behaviours and thus enable more effective control. Through defining the strengths and weaknesses of the current vector surveillance methods, a foundation and initial framework was provided to define the TPPS for the next generation of vector surveillance methods. The TTPs presented here aim to ensure that the next generation tools and technologies are not encumbered by the limitations of our present surveillance methods, and can be readily deployed in low resource settings.

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“…Resurgence of malaria is often associated with imported infections and/or P. vivax relapsing infections in areas that remain highly receptive to malaria [13][14][15][16]. Studies have demonstrated the usefulness of spatially referenced entomological data to characterise the heterogeneity of malaria receptivity in areas approaching elimination to prevent outbreaks in the future [17][18][19]. However, entomological surveillance can often be logistically challenging in low transmission areas due to the difficulty of catching meaningful numbers of mosquitoes.…”

Section: Introductionmentioning

confidence: 99%

Using health facility-based serological surveillance to predict receptive areas at risk of malaria outbreaks in elimination areas

Surendra

Supargiyono

Ahmad

et al. 2020

BMC Med

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Background: In order to improve malaria burden estimates in low transmission settings, more sensitive tools and efficient sampling strategies are required. This study evaluated the use of serological measures from repeated health facility-based cross-sectional surveys to investigate Plasmodium falciparum and Plasmodium vivax transmission dynamics in an area nearing elimination in Indonesia. Methods: Quarterly surveys were conducted in eight public health facilities in Kulon Progo District, Indonesia, from May 2017 to April 2018. Demographic data were collected from all clinic patients and their companions, with household coordinates collected using participatory mapping methods. In addition to standard microscopy tests, bead-based serological assays were performed on finger-prick bloodspot samples from 9453 people. Seroconversion rates (SCR, i.e. the proportion of people in the population who are expected to seroconvert per year) were estimated by fitting a simple reversible catalytic model to seroprevalence data. Mixed effects logistic regression was used to examine factors associated with malaria exposure, and spatial analysis was performed to identify areas with clustering of high antibody responses. Results: Parasite prevalence by microscopy was extremely low (0.06% (95% confidence interval 0.03-0.14, n = 6) and 0 for P. vivax and P. falciparum, respectively). However, spatial analysis of P. vivax antibody responses identified high-risk areas that were subsequently the site of a P. vivax outbreak in August 2017 (62 cases detected through passive and reactive detection systems). These areas overlapped with P. falciparum high-risk areas and were detected in each survey. General low transmission was confirmed by the SCR estimated from a pool of the four surveys in people aged 15 years old and under (0.020 (95% confidence interval 0.017-0.024) and 0.005 (95% confidence interval 0.003-0.008) for P. vivax and P. falciparum, respectively). The SCR estimates in those over 15 years old were 0.066 (95% confidence interval 0.041-0.105) and 0.032 (95% confidence interval 0.015-0.069) for P. vivax and P. falciparum, respectively. Conclusions: These findings demonstrate the potential use of health facility-based serological surveillance to better identify and target areas still receptive to malaria in an elimination setting. Further implementation research is needed to enable integration of these methods with existing surveillance systems.

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Spatial-temporal heterogeneity in malaria receptivity is best estimated by vector biting rates in areas nearing elimination

Cited by 39 publications

References 36 publications

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

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

Nextgen Vector Surveillance Tools: Sensitive, Specific, Cost-effective and Epidemiologically Relevant

Using health facility-based serological surveillance to predict receptive areas at risk of malaria outbreaks in elimination areas

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