Widespread distribution of Aedes aegypti larvae, a potential risk of arbovirus transmission in the Grand Lomé health region, Togo, West Africa.

BACKGROUND

Understanding the population dynamics and geographical range of Aedes aegypti is critically important for arbovirus vector surveillance and control. Little is known about the current distribution and seasonality of Ae. aegypti in Grand Lomé, Togo. We developed an investigation to determine whether Ae. aegypti was present across Lomé communes during a 1-year collection period.

METHODS

Mosquito ovitraps (n = 70) were deployed across the 13 communes in the Grand Lomé health region and were examined between May 2022 and April 2023. Generalized linear mixed models (GLMMs) were applied to investigate the relationship between larval collections and seasonality. The European Space Agency (ESA) WorldCover 10 m 2020 product was used to represent different land cover classes and to determine whether sites with higher larval numbers differed from sites with lower numbers.

RESULTS

A total of 52,768 Ae. aegypti larvae were collected across the 13 communes of Grand Lomé. The highest incidence of Ae. aegypti larvae was observed in the commune of Bè-Ouest (= 122.74 per 1000 population). Agoè-Nyivé was the commune with the lowest incidence over the entire study period. There was a statistically significant difference in Ae. aegypti larval counts between the rainy and dry seasons. Eight land-use classes were represented by the ESA 10 m product in Grand Lomé, with the built-up category being the most common. We found a significant relationship between larval abundance categories and land cover classes.

CONCLUSIONS

This study shows that Ae. aegypti larvae can be found across all communes of the Grand Lomé region in both the rainy and dry seasons, especially in ovitraps surrounded by built-up land cover category. The results of this study could be useful in guiding disease vector surveillance and control efforts due to the potential imminent risk of upcoming dengue outbreaks.