Impact of physicochemical parameters of Aedes aegypti breeding habitats on mosquito productivity and the size of emerged adult mosquitoes in Ouagadougou City, Burkina Faso

Abstract

Background Outbreaks of dengue fever caused by viruses transmitted by Aedes aegypti mosquitoes are repeated occurrences in West Africa. In recent years, Burkina Faso has experienced major dengue outbreaks, most notably in 2016 and 2017 when 80% of cases were recorded in Ouagadougou City (Central Health Region). In order to better understand the ecology of this vector and to provide information for use in developing control measures, a study on the characteristics of Aedes container breeding sites and the productivity of such sites, as measured by the abundance of immature stages and resultant adult body size, was undertaken in three health districts (Baskuy, Bogodogo and Nongremassom) of Ouagadougou. Methods Adult mosquitoes were collected indoors and outdoors in 643 households during the rainy season from August to October 2018. The presence of water containers was systematically recorded and the containers examined for the presence or absence of larvae. Characteristics of the container breeding sites, including size of the container and temperature, pH and conductivity of the water contained within, were recorded as well as the volume of water. Traditional Stegomyia indices were calculated as quantitative indicators of the risk of dengue outbreaks; generalised mixed models were fitted to larval and pupal densities, and the contribution of each covariate to the model was evaluated by the Z-value and associated P-value. Results A total of 1061 container breeding sites were inspected, of which 760 contained immature stages of Ae. aegypti (‘positive’ containers). The most frequent container breeding sites found in each health district were tyres and both medium (buckets/cans/pots) and large (bins/barrels/drums) containers; these containers were also the most productive larval habitats and the types that most frequently tested positive. Of the Stegomyia indices, the Breteau, House and Container indices exceeded WHO dengue risk thresholds. Generalised linear mixed models showed that larval and pupal abundances were associated with container type, physicochemical characteristics of the water and collection month, but there were significant differences among container types and among health districts. Aedes aegypti body size was positively associated with type and diameter of the container, as well as with electrical conductivity of the water, and negatively associated with pH and temperature of the water and with the level of exposure of the container to sunlight. Conclusion This study provides data on putative determinants of the productivity of habitats regarding Ae. aegypti immature stages. These data are useful to better understand Ae. aegypti proliferation. The results suggest that identifying and targeting the most productive container breeding sites could contribute to dengue vector control strategies in Burkina Faso. Graphical Abstract

Physico-chemical characteristics of breeding habitats in relation to larval density and relative abundance of Aedes mosquitoes from Siliguri sub-division, West Bengal, India

“…In the present study, the pH of water samples collected from positive breeding habitats varied from acidic (pH 6.61) to alkaline (pH 8.32). This pH range aligns with the findings from the previous studies (Chatterjee et al, 2015;Mbanzulu et al, 2022;Ouédraogo et al, 2022). Although Aedes spp.…”

Non-household environments make a major contribution to dengue transmission: Implications for vector control

“…Accordingly, small containers in Kisumu are much more frequent than large containers (See Supplementary Information) so slightly higher effectiveness is achieved when control is targeting only them. The situation is different in Ukunda where a higher effectiveness is observed when focusing on both types of containers, where control targeting large containers is more effective as this type of container is more productive 32,33 . These results suggest that the effectiveness of container-focused vector control depends on a trade-off between the productivity of containers and their frequency, where large containers are more productive but less frequent than small containers.…”

Biology and Behaviour of Aedes aegypti in the Human Environment: Opportunities for Vector Control of Arbovirus Transmission

“…Aedes aegypti aegypti gravid females lay eggs in natural and artificial water holding containers of a wide range of sizes and materials [ 144 , 169 ], both inside dwellings and in the peri domestic environment. Gravid females distribute eggs from a single gonotrophic cycle in several containers (skip oviposition) [ 170 , 171 , 172 , 173 , 174 ], although the latter is not always confirmed [ 175 ].…”