Citizen science for malaria vector surveillance in Rwanda

Rwanda made tremendous achievements in reducing malaria morbidity and mortality through the scale up of vector control interventions including long lasting insecticide nets (LLINs) and indoor residual spraying (IRS) from 2005 up to 2011. However, malaria remains a major public health concern in the country. With the resurgence of malaria since 2012, improving vector control is urgent. Inadequate financial resources and ecological changes which increase the risk of malaria transmission are among factors that have caused this upsurge. Hence, malaria resurgence has hindered to sustain the progress made in malaria reduction and control.

Entomological surveillance is one of the most important strategies for malaria prevention and control being undertaken in Rwanda. Although, mosquito monitoring programmes are established in 12 sentinel sites, maps of malaria risk for the whole country is needed. In this way available resources for malaria control can be deployed in an efficient way. However, there are significant costs associated with the expansion of the mosquito monitoring programmes. The implementation of a citizen science programme for (malaria) mosquito surveillance has the potential to overcome these limitations.

In this thesis biological, environmental and institutional factors have been described as contributors to the malaria resurgence in Rwanda. citizen science approach as a new and alternative strategy to contribute to the improvement of malaria mosquito surveillance in low resource settings for the vector control surveillance system in Rwanda are presented. The implementation of a sustainable citizen science programme for malaria vector surveillance requires the participation of citizens. Prior the implementation of citizen science, entomological and household surveys conducted in the studied areas demonstrate that mosquito abundance and species composition of malaria vectors collected using Centers for Disease Control and Prevention (CDC) light traps inside houses combined with demographic characteristics such as building materials of the houses (for example tiled roofs, walls made of mud and wood), as well as the number of occupants in the house, predicted the number of mosquitoes (Culicidae) in the houses. While the presence of eaves plus walls made of mud and wood predicted malaria vector abundance. The results suggest that the perception of mosquito nuisance denoted in a questionnaire could be used as a global indicator of malaria vector hotspots. Hence, involving citizens in reporting mosquito nuisance can complement malaria mosquito surveillance and control.

Results also demonstrate that prior the implementation of a citizen science programme for malaria vector surveillance , co-designing processes of a citizen science programme (CSP) with citizens who have valuable context-specific knowledge and skills is required in order a CSP in a rural area to be feasible. The results suggest that the handmade plastic bottle trap baited with CO2 and light represents an option for inclusion in mosquito surveillance activities in a citizen science context in rural areas. Additionally, the spatio-temporal distribution of mosquito nuisance and malaria vectors collected through citizen science described in this thesis provide insight into the ecology of malaria vectors and can thereby help to better understand malaria transmission patterns in Rwanda. The applicability of using remote sensing and citizen science data in determining the environmental predictors of malaria vector distribution in the studied areas are also presented. Malaria hotspots were found more in the southern part of Ruhuha, especially in Busasamana and Kibaza, the villages that also reported the highest mosquito abundance and nuisance levels.