Larval ecology and infestation indices of two major arbovirus vectors, Aedes aegypti and Aedes albopictus (Diptera: Culicidae), in Brazzaville, the capital city of the Republic of the Congo

Abstract

Background Invasive mosquito species, such as Aedes albopictus in Congo can affect the distribution of native species, changing the vector composition and pattern of disease transmission. Here, we comparatively establish the geographical distribution and larval habitat preference of Ae. aegypti and Ae. albopictus and the risk of arbovirus disease outbreaks using Stegomyia indices in the city of Brazzaville, the capital of the Republic of the Congo. Methods Human dwelling surveys of water-holding containers for immature stages of Aedes was carried out in December 2017 in Brazzaville through a random cluster sampling method. A total of 268 human dwellings distributed in 9 boroughs and 27 neighbourhoods were surveyed across the city. Results Overall, 455 potential larval habitats were surveyed. Both Ae. aegypti and Ae. albopictus were collected across the city with an overall high prevalence of Ae. aegypti (53.1%) compared to Ae. albopictus (46.9%). Geographical distribution analysis showed that Ae. aegypti was more abundant (mean = 6.6 ± 1.4) in neighbourhoods located in downtown, while the abundance of Ae. albopictus was low (mean = 3.5 ± 0.6) in suburbs. Peridomestic containers, especially discarded tanks, were the most strongly colonized productive larval habitat for both mosquito species with the prevalence of 56.4% and 53.1% for Ae. aegypti and Ae. albopictus, respectively. Globally, the house index (HI), Breteau index (BI) and container index (CI) were high for Ae. aegypti (26.6%, 38.4% and 22.6%) and Ae. albopictus (33.3%, 49.6% and 26.6%) compared to the transmission risk threshold (5%, 5% and 20%) established by the WHO/PAHO. Overall, pupae-based indices (the pupae index and the pupae per person index) were not significantly different between Ae. aegypti (273.4% and 23.2%) and Ae. albopictus (228.8% and 19.5%). Conclusions The findings of this study suggest a high risk for transmission of arbovirus diseases in Brazzaville and call for an urgent need to implement vector control strategies against these vectors in the Republic of the Congo.

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

“…albopictus was highly prevalent in discarded tires, empty cans and containers. These findings were in accordance with previous studies in Cameroon [ 41 , 42 ] and elsewhere in central Africa [ 43 , 44 , 45 ]. Used vehicle tires have been reported as the main larval habitats and presumably one of the most productive for Ae.…”

Entomological Risk Assessment for Dengue Virus Transmission during 2016–2020 in Kamphaeng Phet, Thailand

“…Our current findings are consistent with those of a previous study conducted in 2016 in KPP, Thailand, which found a small number of discarded coconut shells around houses and most of them were infested with Aedes larvae [26]. This observation is also in agreement with previous studies in other regions of the Central African Republic and the Republic of the Congo, where the lack of pipe water promotes the storage of water in households and there is a lack of waste management [27,28]. Tires, which were the discarded containers that were most commonly infested with larvae, are one of the most important sources of adult vector populations, since they generated 59.6% of the Aedes larval presence in our study.…”

“…albopictus adults were trapped inside houses, which is consistent with an earlier study that demonstrated larvae of both species coexisting in the same natural containers (coconut shells, husks, and bracts) [30]. Colonization of both vector species was reported to be especially high in trash and discarded containers [27,28,31]. Sharing the same vectors as other arboviruses, e.g., Zika and Chikungunya viruses, may explain this.…”

Meta-Analysis of the Relative Abundance of Nuisance and Vector Mosquitoes in Urban and Blue-Green Spaces

“…Blue-Green Space Urban Space [12,19,23] Parks and cemeteries Suburban neighborhood [24] Highly vegetated suburban neighborhoods Scarcely vegetated urban neighborhoods [25] Farm and park Urban and suburban neighborhoods [22,25] Parks Urban and suburban neighborhoods [26][27][28] Vegetated suburban areas Scarcely vegetated urban areas [29] Urban forest Peri-urban neighborhood [30] Urban green space Densely urban area Unrelated results were eliminated during the screening process. The abundance, mean, and standard deviation for individual mosquito species were extracted from the studies and categorized by treatment.…”