Developing effective rodent control strategies to reduce disease risk in ecologically and culturally diverse rural landscapes

Diseases transmitted from rodents to humans are a serious threat to health, with the highest risk in low-income countries. The risk from rodent-borne infections (RBI) depends on the abundance of infected rodents, as well as how socio-cultural practices and beliefs influence human-rodent interactions. Many rodent species implicated in disease transmission are also pests that feed on crops and stored food, and consequently management to reduce rodent numbers could have a wide impact on health and well-being.

However, controlling rodent populations effectively is challenging. Breeding and movement from adjacent populations may rapidly cancel out the impact of control. Innovative approaches that exploit ecological understanding of where and when rodents breed have been developed in the agricultural sector, primarily in Asia, with communities working together to target control and significantly reduce crop damage. However, such techniques are poorly developed in Africa, and their potential to reduce the risk from RBI is unknown. In some circumstances, changes to rodent movements following control could increase disease transmission and prevalence in rodent populations, potentially increasing risk to humans.

Ultimately, this project aims to reduce the risk from RBI in Africa by increasing the knowledge and expertise needed to develop holistic rodent management applicable for local conditions and communities. Working with communities in Tanzania and Madagascar, in the first stage of the project we will address specific unanswered questions, whilst in the second phase we will develop and test rodent management strategies.

Two questions we will address are: how do rodent movements change after localised control, and how does control influence the prevalence of RBI in rodent populations? To make sure our approach is widely relevant, we will work with rodent species and diseases that have large impacts and contrasting ecologies. We will focus on the multi-mammate mouse, a key pest species in Africa, and the black rat, a globally important invasive pest, and consider three RBI: plague, leptospirosis and rickettsioses, which differ in key aspects of their epidemiology. We will combine field studies with sophisticated computer models to explore how control in different locations and at different times of the year impacts on rodent movement, abundance and the prevalence of RBI. The results will provide important insights into how ecological and epidemiological factors influence the impact of different control strategies on RBI and rodent damage.

We will also work with local communities using a range of approaches to address three further questions: how do communities perceive the health threat from rodents, how do communities currently interact with and manage rodents, and how feasible are different management strategies? As effective control strategies have to be accepted and sustainable for local communities, we need to understand local perceptions and practices. For example, high labour requirements during specific key periods in the agricultural cycle may mean that some rodent control strategies are not feasible.

The insights from this research during the first phase of the project will be used to inform the development of community-led trials of rodent management strategies. The impact of these trials on rodent abundance and the prevalence of RBI will be monitored, and the results used to refine and test our computer models.

We will use this comparative study to identify common features that determine the effectiveness or uptake of a strategy. To ensure our research informs policies, we will conduct workshops with service providers involved in agriculture, health and the environment. Across these sectors we will explore current attitudes, policies and communication practices, and provide training in adaptive management approaches. Our project will also build research capacity through collaboration and training.

Research is designed to answer whether sustainable community-based rodent management can reduce risks of disease transmission and improve overall human health and wellbeing. Multidisciplinary activities will be conducted in Tanzania and Madagascar, focus on three rodent-borne infections (leptospirosis, plague and rickettsiosis) and proceed in two stages. First we fill knowledge gaps, and deepening our existing collaborations with communities and stakeholders, allowing us to co-develop rodent control that will be holistically evaluated in the second stage. We will develop a spatially-realistic modelling tool to explore likely responses of rodent populations and rodent-borne infections to localised rodent control. Analyses of rich archived datasets and new experimental trials will be used to parameterise models and test output. In the first stage, we will work in 12 villages, where villages act as replicates, experimentally determining how rodent movements and the prevalence of RBI are impacted by control. We will also use a range of qualitative and quantitative social science to produce a deeper understanding of community practices, behaviour and understanding around relevant issues of health, hygiene and pest management, and work with stakeholders from health, agriculture and environment spheres to understand perceptions, policies and support services. In the second stage, we will conduct a comparative trial in 12 intervention - non-intervention village pairs (n=24), co-developing and trialling rodent management strategies over one year, and monitoring changes to human practices and attitudes, rodent damage, disease within the rodent population (i.e. leptospirosis, plague and rickettsiosis), human health indicators and time/financial inputs. Collaborative workshops will facilitate cross-country comparisons and high-level training to early career researchers.

Our project will support policy decisions on rodent management across Africa, leaving a long-term legacy for continual improvement of rodent management in African countries through (i) development of a generic modelling tool that can be used to simulate how different management strategies impact on rodent populations and disease transmission across landscapes, (ii) identification of common or, in contrast, specific factors that influence the effectiveness or sustainability of management and (iii) an increase in human capacity amongst both researchers and stakeholders.

Beneficiaries include those concerned with meeting the UN's Sustainable Development Goals. At the highest level, this includes the World Health Organisation (WHO) which increasingly recognises that endemic and outbreak diseases linked to rodents are becoming more common and in need of solutions, as demonstrated by their recent global expert meeting on "Innovative Control Approaches Of Rodent-Borne Epidemic Diseases And Other Public Health Consequences Of Rodents' Proliferation". The WHO has expressed the need to "develop targeted prevention and control strategies for rodents and improve prevention and control strategies for the rodent-borne diseases with the highest public health impact." Outcomes of the proposed project will assist the WHO in its development of global policy. As the rodents we focus on are also key pest species of crops, other global beneficiaries will include organisations such as the Food and Agriculture Organisation of the United Nations (FAO).

In the focal countries, beneficiaries will include government agencies and other organisations involved in public health, infectious disease control and pest management. In addition to the health and agricultural sectors, our research will benefit organisations in the environment sector trying to improve small-holder productivity and sustainable agriculture. Local beneficiaries will include agriculture and health support services.

The most important beneficiaries will be rural communities, who will benefit from increased awareness of the risk from rodent-borne infections and improved capacity to both reduce disease risks and sustainably manage rodent populations. We will explicitly investigate how rodent management can reduce the potential risk from rodent-borne infections through modelling and empirical studies on infection prevalence in rodent populations. Fewer rodents can result in other dramatic changes in people's livelihoods, with tangible benefits that can be recognised by rural communities and policy makers. These include improved food and nutrition security and reduced damage to costly personal possessions (e.g. mosquito nets, clothing, utensils) and infrastructure (wires, buildings).

National and local stakeholder beneficiaries and communities will be directly involved in project activities to ensure we understand their perceptions and needs, allow the co-development of solutions and build capacity within and between sectors. We will use community meetings and stakeholder workshops to actively encourage knowledge dissemination at different levels, e.g. farmer to farmer, between communities and services providers, between researchers and decision makers, such that awareness spreads though each country, increasing impact at the national level. We will also delivering a policy discussion document that is backed up by high quality peer-reviewed publications.

Ultimately the outcomes will be relevant to rural communities throughout most low- and middle-income countries facing problems with high numbers of rodent pests and disease.