First comprehensive analysis of Aedes aegypti bionomics during an arbovirus outbreak in west Africa: Dengue in Ouagadougou, Burkina Faso, 2016–2017

Abstract

Background Dengue’s emergence in West Africa was typified by the Burkina Faso outbreaks in 2016 and 2017, the nation’s largest to date. In both years, we undertook three-month surveys of Aedes populations in or near the capital city Ouagadougou, where the outbreaks were centered. Methodology In 1200LG (urban), Tabtenga (peri-urban) and Goundry (rural) localities, we collected indoor and outdoor resting mosquito adults, characterized larval habitats and containers producing pupae and reared immature stages to adulthood in the laboratory for identification. All mosquito adults were identified morphologically. Host species (from which bloodmeals were taken) were identified by PCR. Generalized mixed models were used to investigate relationships between adult or larval densities and multiple explanatory variables. Results From samples in 1,780 houses, adult Ae. aegypti was significantly more abundant in the two urban localities (Tabtenga and 1200 LG) in both years than in the rural site (Goundry), where Anopheles spp. were far more common. Results from adult collections indicated a highly exophilic and anthropophilic (>90% bloodmeals of human origin) vector population, but with a relatively high proportion of bloodfed females caught inside houses. Habitats producing most pupae were waste tires (37% of total pupae), animal troughs (44%) and large water barrels (30%). While Stegomyia indices were not reliable indicators of adult mosquito abundance, shared influences on adult and immature stage densities included rainfall and container water level, collection month and container type/purpose. Spatial analysis showed autocorrelation of densities, with a partial overlap in adult and immature stage hotspots. Conclusion Results provide an evidence base for the selection of appropriate vector control methods to minimize the risk, frequency and magnitude of future outbreaks in Ouagadougou. An integrated strategy combining community-driven practices, waste disposal and insecticide-based interventions is proposed. The prospects for developing a regional approach to arbovirus control in West Africa or across Africa are discussed.

Impact of Aedes aegypti breeding containers physicochemical parameters on their productivity and adult mosquito body size in Ouagadougou city, Burkina Faso

“…The results are also consistent with ndings from other African countries, Côte d'Ivoire, Kenya, Mozambique, Tanzania, and Ethiopia, where tires were the most predominant water-holding containers and were found to have the highest positivity ratio and the highest abundance of immatures, compared to the rest of the container types [13,54,[57][58][59]. When classifying the breeding sites according to the container material, tire, plastic, and ceramic containers had the highest numbers and positivity rates consistent with previous studies in Ouagadougou [17,50] found that the type of breeding site affects Aedes aegypti mosquito body size. Indeed, we observed that adults of Aedes aegypti mosquito emerging from the BCP containers had an average bigger body size than those from tires and drums and barrels (DB).…”

“…Indeed, our study period corresponded with the peak of dengue cases in Ouagadougou in 2018 [49]. A similar trend of higher Stegomyia indices compared to WHO Thresholds were reported in and around Ouagadougou during the two consecutives and important outbreaks of 2016 and 2017 [17], even with lower Stegomyia indices compared to the current study ones. Despite these high Stegomyia indices and a total number of 4,386 dengue cases and 25 deaths, a dengue outbreak was not o cially declared in 2018, in contrast to 2016 and 2017 [50,51].…”

“…Aedes aegypti breeding sites pro le Aedes aegypti immature stages were found colonizing different type of water-holding containers, with the most predominant being used tyres, followed by drums/barrels (DB), and buckets/cans/boxes (BCP). A study in Ouagadougou and neighbourhoods in 2016 and 2017 recorded similar results, where tires were found to be among the most common and most productive breeding sites in urban and semi-urban localities while in the rural sites, DB were more important [17]. Previous studies which include other localities in Ouagadougou reported importance of discarded containers mainly tires [25,53].…”

“…The typology and the productivity of these containers can vary between countries and between localities in the same country [13][14][15][16]]. A recent study in Burkina Faso showed that tires and small containers are the most abundant breeding containers in the urban locality while drums are the most abundant in the peri-urban and rural localities due to water storage, a consequence of an absence of piped water in these localities [17]. Productivity measured by the number of pupae varied also across containers, and localities.…”

Association of 410L, 1016I and 1534C kdr mutations with pyrethroid resistance in Aedes aegypti from Ouagadougou, Burkina Faso, and development of a one-step multiplex PCR method for the simultaneous detection of 1534C and 1016I kdr mutations

“…Ae. aegypti is closely associated with urban environments and in West Africa, where they breed preferentially in man-made breeding sites such as plastic containers, drums, used tires, ower pots [4]. Insecticide-based vector control and breeding site reduction are the only effective dengue prevention methods [5][6][7] in the absence of an effective dengue vaccine which can protect against all dengue virus serotypes [5].…”