Patterns of Ecological Adaptation of Aedes aegypti and Aedes albopictus and Stegomyia Indices Highlight the Potential Risk of Arbovirus Transmission in Yaoundé, the Capital City of Cameroon

Abstract

The dynamic of arbovirus vectors such as Aedes aegypti and Ae. albopictus remains poorly understood in large cities in central Africa. Here, we compared the larval ecology, geographical distribution and degree of infestation of Ae. aegypti and Ae. albopictus in Yaoundé, the capital city of Cameroon, and estimated their Stegomyia indices revealing a significant potential risk of arbovirus transmission. An entomological survey was conducted in April–May 2018 in a cluster of houses randomly selected. Each selected house was inspected, the number of inhabitants was recorded, and potential and positive containers for Aedes were characterized. Stegomyia and pupae-based indices were estimated. Overall, 447 houses and 954 containers were inspected comprising 10,801 immature stages of Aedes with 84.95% of Ae. albopictus and 15.05% of Ae. aegypti. Both species bred mainly in discarded tanks and used tyres, associated with turbid water and the presence of plant debris inside containers. Aedes albopictus was the most prevalent species in almost all neighbourhoods. The house index, Breteau index, and container index were higher for Ae. albopictus (38.26%, 71.81%, and 29.61%) compared to those of Ae. aegypti (25.73%, 40.93%, and 16.88%). These indices are high compared to the thresholds established by Pan American Health Organization and World Health Organization, which suggests a high potential risk of arbovirus transmission.

Aedes Mosquito Distribution along a Transect from Rural to Urban Settings in Yaoundé, Cameroon

“…aegypti is now mostly found in rural settings. Our findings are in accordance with previous studies in the city of Yaoundé and in Cameroon [ 37 , 41 , 54 , 55 ]. However, although in Brazil, Ae.…”

“…Indeed, Aedes species frequently colonize breeding and resting-habitats close to human dwellings. The high Stegomyia indexes observed in this study could result from the close proximity of both species to human dwellings as recently reported in the city of Yaoundé [55].…”

Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar

“…A great number of studies have reported strong associations between the abundance of Aedes mosquitoes and their larval habitats and poorly managed disposables as well as decorative containers [ 49 – 51 ]. These materials can hold water and organic debris for long periods, providing relatively stable micro-environmental and microclimatic conditions for proliferation of diverse mosquito species [ 24 , 25 , 51 , 52 ]. We also found high productivity of Aedes mosquitoes, particularly Ae.…”

La trampa entomológica Gravid-Aedes Trap, como una alternativa para el monitoreo del mosquito Aedes aegypti, vector del dengue, en las islas Galápagos

“…Sin embargo, estos índices han resultado muy poco eficientes en esta tarea, pues no todas las larvas o pupas sobreviven a adultos y no todas emergen a hembras de mosquito, que son las únicas transmisoras. En esta última década, los índices de adultos que cuantifican el número de mosquitos adultos por espacio físico sean por vivienda, barrio o zona geográfica determinada, han demostrado ser mejores herramientas para predecir el riesgo de transmisión [16]. Para la captura de los adultos del Ae.…”