Mesa Track: Larval Source Management

Source: https://mesamalaria.org/mesa-track/deep-dives/larval-source-management

Cross-sectional surveys will be carried out in order to identify risk factors for residual malaria infection and disease at both the individual and household level, to supply parasite samples for detailed population-level molecular analyses and to supply epidemiological data for parameterization of new mathematical models of malaria transmission.

SPECIFIC AIMS:


Aim 1: Longitudinally determine malaria dynamics in a major residual malaria hotspot in Brazil.
Aim 2: Identify and quantify population changes in P. vivax and P. falciparum to detect reintroductions, and to estimate parasite population complexity at baseline and potentially after interventions.
Aim 3: Develop and apply mathematical models to describe changing dynamics of malaria incidence and parasitemia prevalence over time, and to assess potential effects of combinations of interventions on malaria control and elimination (e.g., insecticide-treated bednet distribution, larviciding or improved antirelapse therapy for vivax malaria).

The central hypothesis is that an adaptive approach based on local malaria risk and changing vector ecology will lead to significant reductions in malaria incidence and transmission risk. To accomplish this objective, the following three specific aims are proposed:

1. Measure malaria incidence and predict risk using environmental, biological, social, and climatic features with machine learning approaches.
Hypothesis: Malaria risk prediction can be improved through the use of machine learning techniques that include environmental, biological, socio-economic, and climatic features.
Approach: Each site will measure malaria incidence, prevalence and social economic factors through community surveys. Classification-based and regression-based approaches will be used to develop malaria risk predictive models, and model performance will be validated.
Outcome: This Aim will establish improved malaria risk prediction models and lay an important foundation for developing intervention strategies adaptive to local vector ecology and future malaria risks using reinforced machine learning approaches.


2. Use a cluster-randomized sequential, multiple assignment randomized trial (SMART) design to develop an optimal adaptive intervention strategy.


Hypothesis: Malaria control interventions that are adapted to local malaria risk and vector ecology and are cost effective can be identified using a cluster-randomized SMART design.
Approach: Cluster-randomized SMART design will be used in two high transmission areas to evaluate the impact of adaptive interventions that involve sequential and combinational use of next-generation nets, indoor spraying of non-pyrethroid insecticides, and larval source management for malaria control.


3. Evaluate the cost-effectiveness and impact of an adaptive intervention approach on secondary endpoints related to malaria risk and transmission.


Hypothesis: Intervention strategies adapted to local malaria risk and vector ecology will be more cost-effective in reducing malaria incidence and transmission risk than the currently-used LLIN intervention.
Approach: The economic costs of individual interventions or combinations thereof will be assessed from both a provider and societal perspective using standard economic evaluation methodologies. Cost-effectiveness will be measured in terms of cost per person protected. The study will examine changes in drug and insecticide resistance and infection prevalence attributable to the adaptive interventions.


Malaria interventions adapted to rapidly changing malaria risk and vector ecologies are critically needed to improve the effectiveness of malaria control measures. This study will use new techniques, including machine learning and a novel cluster-randomized SMART design, to develop optimal adaptive malaria intervention strategies.

This project aims to:


establish the accuracy and efficiency of Geographic profiling (GP) to identify Anopheles breeding sites in comparison to field-based Larval surveillance;
demonstrate the benefit of adding the spatial distribution of adult mosquito densities to the GP model; and
evaluate the effect of using a novel, high-throughput sequencing method to exclude imported malaria cases to improve the accuracy of the GP model.

Main objective
To demonstrate that trained community members can identify, characterize and target aquatic habitats of An. funestus mosquitoes with effective larvicides, to reduce malaria transmission in rural south-eastern Tanzania villages, where ongoing malaria transmission is overwhelmingly mediated by this vector species.
 

Specific objectives


Identify and characterize aquatic habitats of An. funestus mosquitoes in four villages in Ulanga and Kilombero districts, south-eastern Tanzania. This will be achieved by working with trained community volunteers.
Demonstrate that preferentially targeting these An. funestus habitats with the microbial larvicide, Bacillus thuringiensis israelensis (Bti) can dramatically disrupt vector densities and overall malaria transmission in the villages.
Assess the cost-effectiveness of this species-specific approach that preferentially targets the dominant An. funestus mosquitoes, for improved malaria prevention.

To evaluate the feasibility and impact of community-based winter larviciding using biological agent Bacillus thuringiensis var. israelensis (Bti; VectoBac®) on malaria transmission in southern African countries aiming for malaria elimination.

Specific objectives:

• To assess whether winter larviciding combined with IRS prior to the rainy season reduces vector adult density inside and outside houses when compared with IRS alone

• To assess whether winter larviciding combined with IRS prior to the rainy season provides added protection against clinical malaria when compared with areas that receive IRS alone

• To determine whether the combined interventions reduce the proportion of aquatic habitats containing Anopheles larvae not only during the intervention but also when larviciding is not implemented (spill-over effect, synergistic effect with IRS)

This project aims to assess the impact of larviciding for reducing malaria transmission in the city of Yaoundé using a new larvicide VectomaxTM combining both Bacillus thurigiensis israelensis and Bacillus sphaericus in single microparticles displaying longer residual effect. Specifically, the aims are:


Map the spatial and temporal distribution and abundance of mosquitoes,
Assess larviciding impact on malaria transmission intensity and malaria vectors bio-ecology,
Assess larviciding impact in reducing the prevalence of pyrethroid resistance in An. gambiae s.l. populations.

This project will strengthen the management and technical capacity of the primary health care unit (PHCU) to maintain high coverage and the use of high impact malaria control interventions. In addition, it will build the health system’s ability to detect and respond to outbreaks, monitor malaria and use data for decision making.

Programme implementation that aimed at contributing to a significant reduction in the burden of malaria, other vector-borne and diarrhoeal diseases among the Internally Displaced Person (IDP) population in Bentiu PoC and in the adjacent host community.

Two rounds of larviciding and one round of fly control were conducted in the PoC while one round of larviciding and two rounds of fly control were carried out in the host community. All the mosquito breeding sites like drainage/trenches, water surrounding the tap stands, and accumulated in water cisterns and used tyres were treated with liquid Abate. MENTOR hired and trained daily workers from both PoC and host community. This included twenty-eight (28) larviciding workers (14 in the PoC and 14 in the host community).

These activities were understood to have reduced mosquito and fly populations density in both locations. The community in both locations also reported reduction in the presence of mosquitoes and flies after the campaigns were carried out.

To estimate the incremental costs of implementing house improvement and larval source management, alone or in combination, in addition to standard national malaria control interventions, as implemented with the Majete Malaria Project LSM/HI trial.

This project aims to assess whether drone imagery can feasibly be used by the national malaria control programme (NMCP) in Malawi to target activities such as LSM.

Specific objectives are to:


conduct field studies within the UNICEF humanitarian drone testing corridor in Kasungu district, Central Malawi to determine if the mosquito breeding sites can be pragmatically identified using drones, and to establish a framework by which the NMCP could adopt this technology;
compare the capabilities of multiple drones and a range of open source and commercial image processing approaches in order to establish a balance between habitat identification accuracy and usability; and 
collect data including larval samples, adult mosquito catches and clinical malaria case in order to explore whether breeding site location can be used to identify malaria transmission hotspots within the area.

This is a six-month health project with the overall objective to contribute to a significant reduction in the burden of malaria and diarrheal diseases in Bentiu PoC. 

5 rounds of larviciding and 3 rounds of fly control campaigns were conducted. The larviciding was carried out using liquid Abate where the systematic water drainages/trenches, water from tap stands and open stagnant waters were targeted as they serve as key breeding sites for Anopheles and Culex mosquitoes. For the 5 rounds of larviciding, MENTOR hired daily workers: Eighteen (18) larvicide applicators with four (4) supervisors for larviciding campaigns. The application was done on a campaign basis every 3 weeks after breeding site assessments and upon observations of mosquito larvae, especially Anopheles and Culex. The common breeding sites identified and treated included: Stagnant waters, water in trenches/drainages and water from taps / tap stands.

The combination of interventions (Indoor Residual Spraying (IRS) (funded by another donor), Information Education Communication (IEC) and Behaviour Change Communication (BCC) and larviciding) has resulted in a significant reduction of malaria incidence/cases in this year (2019) when compared with the same period during 2018. 

Rising insecticide resistance and increased outdoor transmission have greatly hampered the effectiveness of insecticide-treated nets (ITN) and indoor residual spraying (IRS) because the current indoor-based interventions do not target the outdoor-biting mosquitoes. Therefore, new supplemental interventions that can tackle outdoor transmission and pyrethroid insecticide resistance are urgently needed.

The central objective of this study is to determine the efficacy and cost-effectiveness of EPA-approved long-lasting microbial larvicides in reducing malaria transmission and clinical malaria incidence in western Kenya highlands.

To reduce morbidity and mortality caused by malaria and other VBD by ensuring that the refugee camps and surrounding vulnerable communities in Flood Affected Areas of Upper Nile State and Unity State are protected through a targeted and integrated vector management (IVM). Larviciding campaigns were done to protect people from Anopheles and Aedes mosquito borne diseases such as malaria, Dengue, Chikungunya, Rift Valley Fever and Yellow Fever.

There was active participation and integration of target community leaders, camp management NGOs, and local government bodies in the planning and implementation stages as well as a workforce composed of the communities targeted. All potential breeding sites were regularly surveyed on a biweekly basis for the presence or absence of mosquito larvae/pupae. These surveys helped the MENTOR team in deciding on the implementation of larviciding rounds.

The data strongly suggest that the IRS/larviciding campaign in conjunction with LLIN distributions and targeted IEC had a significant impact on the burden of malaria. Sudden and sharp decrease in malaria incidence, community acceptance of the IVM interventions was extremely high, enabling remarkable coverage rates for the IRS/larviciding throughout all of the camps and the surrounding host communities.

The main objective of this study was to ensure reduced risk of infection from vector-borne diseases in Malakal PoC and Bentiu PoC by providing protection through the implementation of integrated vector management. Larviciding activities included larval assessment, recruitment and training of staff in larvicide application and treatment of surface and container water.

Larval assessments were done on a bi-weekly basis during the dry periods when the breeding sites are few and easy to locate in order to identify surface water mosquito (Anopheles) breeding sites. Confirmed mosquito breeding sites were treated with the WHO-recommended larvicide Abate. Large water containers were also assessed and treated with larvicide upon identification of Aedes and Anopheles mosquito larvae.

The outcomes were reduction of mosquito larvae and malaria incidence. The integrated vector management (IVM) strategy showed positive impact especially on the malaria cases, significant reduction was registered when compared with the same period in 2018.

The central objective of this project is to determine the efficacy and cost-effectiveness of EPA-approved long-lasting microbial larvicides in reducing malaria transmission and clinical malaria incidence in western Kenya highlands.

The three specific aims are:


to examine mechanisms regulating larval habitat productivity,
to determine the efficacy of long-lasting microbial larvicides on the reduction of malaria transmission and clinical malaria incidence using a cluster randomized study, and
to determine the cost-effectiveness of the long-lasting microbial larviciding program as compared to other malaria control interventions and evaluate its impact on non-target organisms.


Through comprehensive evaluation of potentially cost-effective long-lasting microbial larvicides, this project will provide critically needed data on whether long-lasting microbial larvicides can be scaled up as a supplemental malaria control tool to further reduce malaria incidence in African highlands. Malaria outdoor transmission control is presently a highly significant and urgent issue in malaria control across Africa, and thus, our results will have broad implications on malaria prevention and control in endemic and epidemic regions of Africa.

The objectives of this project are:


To perform a Phase III randomized controlled trial of new vector control tools in combination with Long Lasting Insecticidal Nets (LLINs). The study will evaluate the benefit to use 1) insecticidal paints, 2) larvicides, 3) Ivermectin for both human and domestic animals and 4) a strengthened information, education and communication strategy to complement the universal coverage with LLINs through a cluster randomized trial.
To assess the efficacy of each combination against malaria transmission, prevalence, and incidence.
To assess the efficacy of each combination to manage insecticide resistance.
To characterize the residual transmission and to assess its determinants.
To study the behaviour of old, infectious and resistant Anopheles.

Surface water was treated with larvicide Abate (temephos) to prevent the proliferation of dengue fever, yellow fever and malaria mosquito vectors among other disease vectors. The larviciding activities were guided daily by larval assessments and delivery was done by MENTOR larviciders.

The project overall goal is an 80% reduction in the incidence of clinical malaria and 50% reduction in the prevalence of malaria in epicentre zones in the Majete Perimeter within 4 years of interventions. The project purpose is that through improved health and socio-economic conditions, the community will become a better partner in natural resource management.

Specific Objectives:


To build capacity for implementation and evaluation of malaria control through the epicentre approach;
To increase community participation in malaria control;
To implement locally-appropriate malaria vector control strategies;
To measure impact on malaria;
To study the efficacy and economic feasibility of various combinations of three anti-malaria techniques; and
To introduce the best combination of techniques into the region within the final years of the project.


Community-based Larval Source Management and housing improvement will be implemented as additional interventions to the current national malaria control strategies, using a randomised block, 2 × 2 factorial, cluster-randomised design in rural, southern Malawi.

The research was conducted with two objectives:


To demonstrate the applicability of mosquito larviciding in a large-scale mode for malaria control.
To guide the integration of larviciding and Larval Source Management (LSM) in general, into the malaria control strategy of Uganda.

The project’s objective is to support the Rwandan government’s ambition to achieve malaria pre-elimination by 2018, by connecting community mobilisation and participation to the national and district malaria control programme and to (inter)national expert knowledge bases, and by supporting the development of area-specific strategies for malaria elimination.

Organizational change management systems will be applied, as well as facilitating techniques proven within the field of organizational change and community building that (1) connect knowledge and ownership in the local community to the national and district malaria control program and that (2) will lead to design of health systems interventions towards malaria elimination. This process of expeditionary action and learning will be implemented with repeated participatory works.

Annual household surveys into malaria, entomology, sociology, economy and indicators of ownership and willingness to invest will be conducted as well as a continuous monitoring of health service coverage and preventive measures. The process of intervention design and the interventions and their impact itself are topics of study for 4 PhD students.

Specific objective: To assess community awareness, acceptance and participation in a study that incorporated the socio-economic and entomological impact of LSM using Bacillus thuringiensis var. israelensis (Bti) in eastern Rwanda, and identified challenges and recommendations for future scale-up.

This experimental study was conducted to assess the field effectiveness of winter larviciding on the larval stages of the mosquito in Botswana and Zimbabwe.

Water bodies in the intervention villages were treated using the commercial product VectoBac® WG (Valent BioSciences Corporation, IL, USA) containing the active ingredient Bacillus thuringiensis var. israelensis (Bti) applied at a rate of 300 g per hectare every 2 weeks. In both countries, the study arms were characterized by few larval habitats as all of the temporary habitats had dried up by the time of implementation of the intervention.

Application of biolarvicide was conducted in intervention areas/villages at two week intervals for eight time periods. In both Botswana and Zimbabwe, larviciding was conducted by community volunteers who were identified with the help of the local community leadership and through the local health facilities.

To perform a high-throughput screen to identify small interfering (si)RNAs that cause death when ingested by mosquito larvae as a method for reducing malaria transmission. Malaria vector mosquitoes are developing resistance to current larval insecticides, which are used to complement other control strategies such as insecticide-treated nets. Small RNAs are ingested by mosquito larvae and can silence their gene targets. The team will perform a screen of siRNAs targeting 1000 candidate larval essential genes in the malaria vector mosquito Anopheles gambiae at different developmental stages. Identified lethal siRNAs will be tested in multiple Anopheline species to target malaria spread by other species.

This project aims to introduce biolarvicides in rice farming practices in rural Tanzania, as an innovative approach in malaria control. By offering larvicides in the form of pellets that can be mixed with fertilizers, local skills are put to use, creating a double impact: the reduction of malaria transmission and increased rice yields.

The integrated application of biolarvicides is a safe, effective and environmentally sustainable component of a successfully integrated vector management strategy.

The project is aimed at applying pastoralists’ knowledge to find water bodies during the dry season and accurately identify aquatic habitats that can be treated with larvicide pyriproxyfen (PPF) to render the sites unproductive to mosquitoes in rural communities of Tanzania, where malaria is mostly endemic.

The specific objectives of the project were to:


recruit pastoralists with knowledge of local dry-season water bodies into the study;
educate the selected pastoralists on the safety of PPF to human and animal health;
assess the impact of the intervention on mosquito populations at aquatic habitat and household levels,
conduct educational sessions with pastoralists and non-pastoralists communities on better animal keeping practices, with help from District Veterinary Officers.

To assess the effect of supplementing LLINs with either larviciding with Bacillus thuringiensis israelensis (Bti) or community education and mobilization (CEM), or with both interventions in the context of integrated vector management (IVM).

The study specifically aimed at verifying under field conditions if adding larviciding and CEM either individually or combined can further reduce indoor malaria vector density and malaria prevalence in the community compared to when LLINs alone are used.

To analyze the ecologic and health impacts as well as the cost-effectiveness of larval source management under different larviciding scenarios in a health district in Burkina Faso.

The central objective of this proposal is to improve malaria control outcomes through an implementation science approach that integrates health delivery experiments and decision support modeling to promote joint optimization of vector control and disease management strategies.

We propose three specific aims: (1) perform randomized experiments of vector control and disease management strategies in Tanzania to elucidate which intervention strategy combinations are most effective in real world settings, using an implementation science approach; (2) use analytical insights from the health delivery experiments to refine an existing decision support model that includes both vector control and disease management; and (3) develop approaches for replicating the decision support tool in other parts of Tanzania and other countries in sub-Saharan Africa.

Accomplishing these combined specific aims will provide a framework for designing and implementing multi-pronged malaria control strategies that have the best chances for sustained effectiveness in an operational setting. We will test the effectiveness of different combinations of vector and disease management interventions over time based on field experiments. We will then use the experimental results in conjunction with decision support modeling to improve a new tool that will allow decision-makers to jointly optimize vector and disease management strategies. The tool is flexible enough to incorporate new therapies and interventions as they are developed.

This project bioprospected plants for novel anti-mosquito blends or compounds that show promise in integrated management of malaria vectors.Specifically, the team carried out the following activities:Determined molecular diversity, and developed molecular barcodes and spatial distribution maps of selected mosquitocidal M. koenigii from various regions of KenyaDetermined bioactivity, and the impact of M. koenigii phytochemical blends on biological fitness of An. gambiae s.sIdentified phytochemical components in M. koenigii plant extracts mosquitocidal or growth, disrupting to An. gambiae s.s (larvae and adults)Determined molecular responses in the mosquito to the phytochemical blends.

To investigate whether larviciding, if implemented in addition to other vector control interventions, would contribute to a reduction in the malaria burden in a selected district in Botswana.

Specific objective: To evaluate the susceptibility of local Anopheles to commonly used larvicides.

This study aims to determine the value of rolling out four targeted malaria control efforts in reducing overall malaria transmission. These targeted control efforts include:


Distribution of LLINs in all households in malaria hotspots; instruction about correct use.
6-monthly IRS with deltamethrin in all households malaria hotspots.
Larviciding (Bacillus thuringiensis) to target malaria vectors, particularly those that are less susceptible to IRS and ITNs as a consequence of outdoor feeding and resting. Treatment of all waterbodies within hotspots will be carried out on a weekly basis
Focal screening and treatment (FSAT) in all households in malaria hotspots prior to the peak transmission season. Screening of a sentinel age group by rapid diagnostic tests; all parasitaemic individuals and household members of parasitaemic individuals will be treated (focal MDA).


The impact of these interventions will be evaluated based on changes in parasite prevalence measured in community surveys inside and outside hotspots of malaria transmission. Parasite prevalence will be compared before and after the intervention in intervention clusters and between intervention and control clusters.

To assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands.

Aquatic habitats were searched thoroughly by a team of technicians accompanied by field assistants from local villages. Bti granules (CG formulation, VectoMax, Valent BioSciences Corp, Illinois, USA) were applied, following guidelines provided by manufacturer, in all aquatic habitats in all intervention clusters, regardless of habitat type, size, and presence/absence of mosquito larvae.

% of projects where funding unknown

Total funding known