Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities

Abstract

BackgroundDengue and chikungunya are global re-emerging mosquito-borne diseases. In Singapore, sustained vector control coupled with household improvements reduced domestic mosquito populations for the past 45 years, particularly the primary vector Aedes aegypti. However, while disease incidence was low for the first 30 years following vector control implementation, outbreaks have re-emerged in the past 15 years. Epidemiological observations point to the importance of peridomestic infection in areas not targeted by control programs. We investigated the role of vectors in peri-domestic areas.MethodsWe carried out entomological surveys to identify the Aedes species present in vegetated sites in highly populated areas and determine whether mosquitoes were present in open-air areas frequented by people. We compared vector competence of Aedes albopictus and Aedes malayensis with Ae. aegypti after oral infection with sympatric dengue serotype 2 and chikungunya viruses. Mosquito saliva was tested for the presence of infectious virus particles as a surrogate for transmission following oral infection.ResultsWe identified Aedes albopictus and Aedes malayensis throughout Singapore and quantified their presence in forested and opened grassy areas. Both Ae. albopictus and Ae. malayensis can occupy sylvatic niches and were highly susceptible to both arboviruses. A majority of saliva of infected Ae. malayensis contained infectious particles for both viruses.ConclusionsOur study reveals the prevalence of competent vectors in peri-domestic areas, including Ae. malayensis for which we established the vector status. Epidemics can be driven by infection foci, which are epidemiologically enhanced in the context of low herd immunity, selective pressure on arbovirus transmission and the presence of infectious asymptomatic persons, all these conditions being present in Singapore. Learning from Singapore’s vector control success that reduced domestic vector populations, but has not sustainably reduced arboviral incidence, we suggest including peri-domestic vectors in the scope of vector management.

Risk of arbovirus emergence via bridge vectors: case study of the sylvatic mosquito Aedes malayensis in the Nakai district, Laos

“…The mosquito Ae. malayensis is widely distributed across South-East Asia with documented occurrence in Vietnam, Cambodia, Peninsular Malaysia and Singapore, Taiwan, the Andaman and Nicobar Islands, Laos, and Thailand [8][9][10][11]13 . Recently, a peridomestic population of Ae.…”

“…Recently, a peridomestic population of Ae. malayensis in Singapore was shown to be competent for diverse arboviruses such as DENV, YFV and chikungunya virus 11,12 .…”

“…The mosquito Aedes malayensis in the Stegomyia sub-genus is widely distributed in South-East Asia with records in Thailand, Cambodia, Vietnam, Peninsular Malaysia, the Andaman and Nicobar Islands, and Taiwan [8][9][10] . It was also identified in peridomestic habitats of Singapore as a putative vector of YFV, DENV and chikungunya virus 11,12 . Recently, our mosquito surveys in the Nakai National Biodiversity Conservation Area indicated the presence of Ae.…”

Mosquitoes (Diptera: Culicidae) of Singapore: Updated Checklist and New Records

“…Both species are also involved in the local transmission of chikungunya and Zika viruses (Ng et al 2009, Tan et al 2017, Ho et al 2017). Mendenhall et al (2017) reported that Ae. malayensis showed high susceptibility to dengue and chikungunya viruses and should be considered a potential vector.…”

Population genetics of Aedes albopictus (Diptera: Culicidae) in its native range in Lao People’s Democratic Republic

“…albopictus can be more competent at transmitting DENV and CHIKV than Ae. aegypti [22–24]. Furthermore, Ae.…”