Implementation and Evaluation of Vector Control Methods in Kinshasa: The Case of Aedes

Arboviral diseases are viral diseases transmitted by mosquitoes of the Aedes genus and are constantly spreading throughout the world, constituting a significant threat to public health. In the last 30 years, the frequency and extent of Aedes-borne epidemics have increased significantly and the main vectors, Aedes aegypti and Aedes albopictus, have expanded their geographical distribution worldwide.

In Africa, there is very little data on the epidemiological situation of Aedes-borne diseases and programs for monitoring these diseases are very limited. In the Democratic Republic of the Congo (DRC), several epidemics of yellow fever, dengue fever, chikungunya and Zika cases have been reported. In particular, in Kinshasa, the dengue and chikungunya viruses have previously been detected in patients with undifferentiated fevers and several studies have shown entomological transmission indices above the criteria and standards of the World Health Organization (WHO). However, vector control activities for Aedes are not carried out regularly outside of epidemic periods and the need for targeted strategies remains essential.

The aim of our study is to implement and evaluate different strategies to control Aedes mosquitoes at different stages of their life cycle in the city of Kinshasa. Furthermore, the integration of a serological survey on diseases transmitted by the Aedes vector will strengthen our knowledge on the circulation of these diseases in the area, for which the data in the literature remain fragmentary until now.

In particular, a before-and-after interventional study will be piloted and tested in the health zone of Mont Ngafula 1, Kinshasa, which is characterized by ecological diversity and a known history of arbovirus circulation. In this pilot study, with the aim of providing preliminary evidence of the impact of vector control tools, there are four arms: i) community-based environmental management approach, ii) community-based environmental management and vector control against immature stages of Aedes (pyriproxifen-based autodissemination stations), iii) community-based environmental management and vector control against the mature stages of Aedes aegypti (mass trapping using BG-GAT - Gravid Aedes Traps), iv) control arm without implementation of vector control interventions. These interventions will be implemented in 400 households for each arm for 12 months. Before, after and during the interventions, entomological surveys will be conducted in 160 households in each arm to define the density of the vectors. Mosquitoes will be tested for the possible presence of arbovirus RNA (dengue, chikungunya, Zika, yellow fever). During the pre-intervention period, a serological survey for the same diseases transmitted by the Aedes mosquito will be conducted on a sample of 450 people included in two health centers of reference for the health zone of Mont Ngafula 1. The knowledge, attitudes and practices of the subjects belonging to the households enrolled in the study will be collected using an electronic questionnaire before and after the intervention. The integration of the data collected within the scope of this study will provide an assessment of the feasibility and impact of the tested methods on entomological indicators, as well as determining the exposure and knowledge of Aedes-borne diseases in the Mont Ngafula 1 area, for a better definition of the next measures to be adopted in the fight against vectors, tailored to the specific context of the the DRC.

At household level:

Inclusion criteria

• Belong to a household in one of the 4 health areas selected as study arms
• From 18 years of age to consent for household enrollment and participation in the serosurvey
• Consenting

Exclusion criteria

• Not belong to a household in one of the 4 health areas selected as study arms
• Under 18 years of age
• Non-consenting

At health facility level:

Inclusion criteria

• From 18 years of age
• Resident of the health zone of Mont Ngafula 1
• Consenting

Exclusion criteria

• Under 18 years of age
• Not resident in the health zone of Mont Ngafula 1
• Seriously ill and hospitalized, requiring transfusion, presence of blood clotting disorders, allergies resulting from injections, adverse events associated with previous blood sampling, pregnancy
• Non-consenting