N Govella, Ifakara Health Institute, Integrating intervention targetable behaviours of malaria vectors to optimize interventions selection and impact

Lead Research Organisation: University of Glasgow
Department Name: College of Medical, Veterinary &Life Sci

Abstract

Malaria continues to impose a huge burden upon human health despite widespread use of insecticide-treated nets (ITNs), improved diagnosis, and treatment. The global problem this study aims to address is the lack of understanding of the mosquito and human behaviours that limit the impact of existing malaria vector control interventions like ITNs, but which also create opportunities for new ones to achieve further gains. For example, human exposure persisting outdoors could be targeted with insecticide vapour emanators and vector mosquitoes that survive by feeding on livestock could be targeted with veterinary approaches. Like most other African countries, Tanzania has achieved great success in reducing malaria with widespread use of ITNs. However, many new cases and deaths still occur, with a wide range of regional variation, from 0 up to 27 people infected per 100 tested for malaria. It is highly likely that much of this geographic variability in malaria transmission arises from the exceptional variability of climatic conditions in Tanzania and knock-on effects on relevant behaviours of mosquitoes and humans.

I therefore propose to identify, quantify and address the underlying behavioural causes of persisting malaria transmission in climatically distinct geographic strata, so that they can be optimally tackled with supplementary vector control measures. This problem has already been prioritized as an important question by the Government of Tanzania, acting through the National Malaria Control Programme (NMCP) with the aim of adjusting intervention choices according to the local context to maximize impact. Specifically, I will integrate intervention-targetable behaviours of mosquitoes (e.g. feeding early and outdoors when most people are still outside or feeding on non-human host) and humans (e.g. use or not use of ITNs, time spent outdoor in the evening) into existing nationally-representative longitudinal, community-based surveillance system that monitors vector densities and infection rates in 32 districts of Tanzania, to assess how these behaviours are shaped across wide distinct environmental conditions and provide insight on how interventions could be tailored to local conditions for maximum impact.

This study will provide insights into which additional strategies are likely to be most effective on the basis of local vector ecology. This could be a game changer in the development of locally-tailored, highly effective mosquito control packages in Africa, which accelerate progress toward malaria elimination. It will also form the basis for improved policy and practice with respect to effective targeting of supplementary vector control measures.

Technical Summary

Malaria burden in Tanzania has been reduced by more than 50% over the past 15 years. Vector control with insecticide-treated nets (ITNs) and, indoor residual spraying, account for most of these reductions. Despite these gains and sustained community-wide use of ITNs, new malaria cases continue to occur across the country, but with regional variation in prevalence ranges from 0 up to 24%. Underlying drivers for geographic heterogeneity in transmission remain unclear, and will limit Tanzania's efforts to eliminate malaria by 2030. Tanzania is climatically heterogeneous countries, and such climatic variations most likely affect the mosquito and human behaviours that allow malaria vectors to survive by attacking people outdoors or by feeding on animals. New technologies like insecticide vapour emanators and veterinary endectocides could be used to respectively target these behaviours. However, lack of information about where each of these measures may be optimal limits potential for effective geographic targeting of these complementary vector control tools.
I propose to integrate surveys of intervention-targetable behaviours of mosquitoes and humans into the existing nationally-representative vector surveillance platform in Tanzania and use this to identify what human and mosquito behaviours drive persisting malaria transmission. Specifically, I will quantify intervention-targetable behaviours of malaria vectors and characterize both environmental and anthropological determinants of how those behaviours vary across 32 locations in diverse ecological settings in mainland Tanzania. These data will be used to model and predict which supplementary vector control tools are likely to be most effective in different ecological zones, and provide NMCP with a framework for rational selection of interventions to optimize vector control impact.

Planned Impact

a) Community Impact
Based on the scope of this research which is about figuring out effective approaches to accelerate malaria elimination efforts, the people of Tanzania, who are most affected by the disease (Tanzania ranked the 5th highest number of deaths due to malaria globally) would be the immediate beneficiaries. Knowledge generated would contribute to further reduction and/or elimination of malaria and consequently reduce burden on health care infrastructure and catastrophic household expenditure in Tanzania, thus contributing to addressing global development goals (SDG 1, SDG 2, SDG 3 and SDG10). This will be achieved through partnership with government, local communities and development partners in which critical evidence for national policy may be generated and disseminated.

b) Strengthening African Institution capacity building
The proposed study would generate significant added value for the IHI's institutional priorities and capacity needs including developing senior leadership in malaria vector research which can be internationally competitive, and mentor more early career African scientists. The programme would also offer opportunities to work closely with local communities, policy-makers and policy-implementers and development partners through meetings. This will increase the visibility of the IHI and its capacity to influence both national and international health policy.

c) This programme will strengthen the ability of the ARL to independently lead large research programmes, consolidating and improve both research competence and research management. This long term funding would also allow the ARL to strengthen his newly established research group and train and supervise other African Masters and Ph.D students to create the next generation of scientists and opinion leaders in public and global health matters. Existing collaboration between the PI based in UK and other partners will be strengthened, thus promoting knowledge, skills and technological exchange over a longer period.