Abstract
BackgroundInvasive 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.MethodsHuman 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.ResultsOverall, 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%).ConclusionsThe 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.
Highlights
Invasive mosquito species, such as Aedes albopictus in Congo can affect the distribution of native spe‐ cies, changing the vector composition and pattern of disease transmission
In the past decade, several outbreaks caused by these viruses have been reported in West-Central African countries [7,8,9,10,11,12,13,14] suggesting a possible change in the dynamics of these diseases
These viruses are transmitted to vertebrates including humans mainly by the bite of an infected mosquito belonging to the genus Aedes notably Ae. aegypti and Aedes albopictus (Skuse)
Summary
Invasive mosquito species, such as Aedes albopictus in Congo can affect the distribution of native spe‐ cies, changing the vector composition and pattern of disease transmission. In the past decade, several outbreaks caused by these viruses have been reported in West-Central African countries [7,8,9,10,11,12,13,14] suggesting a possible change in the dynamics of these diseases These viruses are transmitted to vertebrates including humans mainly by the bite of an infected mosquito belonging to the genus Aedes notably Ae. aegypti and Aedes albopictus (Skuse). Ae. albopictus, originated from south east Asian forest, has invaded all the continents in past 30–40 decades [22] This species was first reported in Central Africa in the early 2000s [23], and nowadays, is present in almost all countries of the region including the Republic of the Congo [24, 25]. We present an extensive analysis of the levels of infestation, detailed comparative data of larval ecology, and geographical distribution of Ae. aegypti and Ae. albopictus in Brazzaville, the capital city of the Republic of the Congo to improve the control of these vectors and help prevent other arbovirus outbreaks in this major city
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