Transmitted by day biting, invasive Aedes mosquitoes who prefer human targets, dengue is a life-threatening disease that continues to be neglected, although its presence has increased over six folds since 2000. In sub-Saharan Africa Aedes control programmes are either inexistent or mainly follow a top down approach with sporadic insecticide spray campaigns targeting adult mosquitoes. These interventions have only a very limited, short-term impact and are environmentally not sustainable since Aedes mosquitoes breed in small water containers that are ubiquitous in urban areas. Therefore, targeting the juvenile stages of their development is more promising, while requiring the active support of the affected communities.
The current project aims to mobilise and engage local residents in the sustainable control of Aedes mosquitoes by removal of potential larval breeding sites and trapping egg-laying females.
It seeks to answer two main research questions
The research methods include collecting baseline data to assess the association between housing, human behaviour and mosquito habitat suitability through surveys and mosquito collections in Abidjan, the largest city of Côte d’Ivoire, which has recently experienced multiple dengue outbreaks. In consultation with local residents, the researchers will design a community-based intervention to reduce Aedes breeding sites. To test whether the intervention in this African context reduces mosquito densities, the process involves implementing a cluster randomised trial over the course of a whole year. The trial will also test whether mass trapping with simple traps targeting egg-laying females adds to the effectiveness of the larval source management.
The key outcome of this project are clear policy recommendations for the control of Aedes-borne arboviruses with community mobilisation in urban sub-Saharan Africa.
Transmitted by day biting, highly anthropophilic invasive Aedes mosquitoes, dengue is a life-threatening disease that has dramatically increased in incidence globally in recent years. While vector control interventions are the mainstay in dengue control programmes, in sub-Saharan Africa such programmes are largely inexistent or mainly follow a top down approach with sporadic insecticide spray campaigns targeting adult mosquitoes. However, these interventions have only a very limited, short-term impact and are environmentally not sustainable, since invasive Aedes mosquitoes breed in small water containers that are ubiquitous in urban areas. Together with local residents, we co-designed a community-based intervention to reduce Aedes breeding sites in Abidjan, the largest city in Côte d’Ivoire. A key suggestion that came from the community was to involve volunteers as supervisors to empower residents in eliminating Aedes breeding sites. To measure the intervention’s efficacy, we implemented a cluster-randomised control trial. In the trial, we also tested whether adult mass trapping (AMT) with simple traps targeting egg-laying females reduces mosquito densities, either alone or in combination with the community-based larval source management (LSM). The trial consisted of four study arms, including LSM, AMT, the combination of LSM and AMT, and a control arm without any of the two interventions. While the CRT has been completed, the entomological data is still being analysed. The social science analysis showed that the interventions significantly enhanced community knowledge about dengue across all treatment groups, including control clusters, indicating that broader community sensitisation efforts boosted awareness beyond targeted areas. However, changes in attitudes and practices were less consistent, highlighting the challenge of translating knowledge into behaviour change. These findings underscore the need for integrated approaches that not only improve knowledge but also address attitudes and barriers to adopting preventive measures for more effective dengue prevention. Integrating the lessons learnt so far combined with the feedback from policy makers and key stakeholder, we compiled a policy brief. Key recommendations include establishing protocols for engaging communities, aligning national and local vector control strategies and involving influential local leaders to bridge policy and action gaps.
Most sub-Saharan African countries, including Côte d’Ivoire (West Africa), have increasingly faced multiple outbreaks of Aedes mosquito-borne arboviruses (e.g., dengue, yellow fever, Zika and chikungunya). In sub-Saharan Africa, over 831 million (~70%) people live in arboviral risk areas(1). West Africa is highly vulnerable (27,000 arboviral cases in 2017-2020(2,3)), and projected to be the next front for arboviruses(2,3). From 1899 to the present, Côte d’Ivoire has faced major outbreaks of yellow fever and dengue, with significant increases in disease incidence in the two last decades (2001-2019) due to accelerated urbanization and poor sanitation. This creates large numbers of unmanaged waste and discarded containers that serve as Aedes larval breeding sites. There is a high risk of a global spread of the main vector Aedes aegypti and arboviruses from their tropical foci due to international trade and climate change(4,5). When this project was written in 2021 there were no licensed vaccines or specific drugs available for most arboviruses, Aedes vector control is key to effective arboviral prevention and control. However, Aedes vector control in Africa is strongly hindered by limited scientific capacities, poor technical resources, restricted financial investment, and a lack of an effective sanitation measure for an integrated management of solid waste and Aedes mosquito risks (e.g., management of millions of non-biodegradable and plastic containers widely dispersed in African cities)(1). Abidjan, the largest city and the economic capital of Côte d’Ivoire, is characterized by unplanned urbanization, and inadequate health and hygiene services. When this project was designed, Abidjan, with an estimated population of 6 million inhabitants (2021), in 422 km2 was and remains a hotspot of dengue and yellow fever (80-100% cases) and Ae. aegypti (~100% Aedes), as there were no routine Aedes vector control programs there(6,7,8-11). Local Aedes larvae breed abundantly in unmanaged containers (e.g., tires, cans) discarded in private and public spaces, leading to multiple arboviral outbreaks and illnesses(6,7,8-11). The governmental outbreak responses led by the National Institute of Public Hygiene (NIPH) of the Ministry of Health and Hygiene (MoHH) have always followed a top-down approach (removal of Aedes breeding sites and insecticide space spraying) and operate in public spaces (roadsides), but not in households due to limited access(10,11). These vertical actions, without community participation have resulted in very little and short-term impacts(6,7): Aedes populations rapidly recover and arboviruses re-emerge once the campaigns are over(10,11). Abidjan is currently facing an ongoing dengue outbreak- in July 2024 the 2 Ministry of Health announced that there were 2,621 suspected cases of dengue reported, with 383 of those confirmed by rapid test and testing of thousands of suspected or new cases ongoing. Professor Ekra Kouadio Daniel, Director General of the National Institute of Public Hygiene (INHP), said that 80% of cases are concentrated in districts within Abidjan. It is timely to consider policy guidelines that can support more comprehensive and wide-reaching strategies to reduce the impacts of dengue and prevent future outbreaks. This is the context within which the “Citizen Action for Sustainable Dengue Control in Sub-Saharan Africa” project emerged. As the project wraps up the research team, informed by community participatory workshops and key stakeholder meetings, and based on research team observations and findings, has developed a set of policy recommendations. These recommendations are intended first for the context of Côte d’Ivoire, however the secondary audience is intended to be other large African cities in the region facing similar challenges.
Pie Müller
Coordinator
Swiss Tropical and Public Health Institute
Giovanfrancesco Ferrari
Co-Coordinator
Swiss Tropical and Public Health Institute
Sarah Ruel-Bergeron
Principal Member
ARCHIVE Global
Julien Zahouli
Principal Member
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire
Véronique Koffi
Principal Member
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire
Pélagie E.B. Aboa
Principal Member
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire
Larissa Angouan
Principal Member
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire
Claver Adjobi
Principal Member
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire
Swiss Network for
International Studies