Dengue is present in 128 countries worldwide and is still expanding. There is currently no treatment or universally approved vaccine available. Therefore, prevention and control of mosquito vectors remain the most efficient ways of managing the risk of dengue outbreaks. The Stegomyia indices have been developed as quantitative indicators of the risk of dengue outbreaks. However, conflictual data are circulating about their reliability. We report in this article the first extensive study on Stegomyia indices, covering 78 locations of differing environmental and socioeconomic conditions, climate, and population density across Indonesia, from West Sumatra to Papua. A total of 65,876 mosquito larvae and pupae were collected for the study. A correlation was found between incidence and human population density. No correlation was found between the incidence of dengue and the Stegomyia indices.

Chikungunya is repeatedly affecting Indonesia through successive outbreaks. The Asian genotype has been present in Asia since the late 1950s while the ECSA-IOL (East/Central/South Africa - Indian Ocean Lineage) genotype invaded Asia in 2005. In order to determine the extension of the circulation of the chikungunya virus (CHIKV) in Indonesia, mosquitoes were collected in 28 different sites from 12 Indonesian provinces in 2016-2017. The E1 subunit of the CHIKV envelope gene was sequenced while mosquitoes were genotyped using the mitochondrial cox1 (cytochrome C oxidase subunit 1) gene to determine whether a specific population was involved in the vectoring of CHIKV. A total of 37 CHIKV samples were found in 28 Aedes aegypti, 8 Aedes albopictus and 1 Aedes butleri out of 15,362 samples collected and tested. These viruses, like all Indonesian CHIKV since 2000, belonged to a genotype we propose to call the Asian-Pacific genotype. It also comprises the Yap isolates and viruses having emerged in Polynesia, the Caribbean and South America. They differ from the CHIKV of the Asian genotype found earlier in Indonesia indicating a replacement. These results raise the question of the mechanisms behind this fast and massive replacement.

Currently, Aedes aegypti, the principal vector of dengue virus in Indonesia, has spread throughout the archipelago. Aedes albopictus is also present. Invasion and high adaptability of the Aedes mosquitoes to all of these areas are closely related to their ecology and biology. Between June 2016 and July 2017, larval and adult mosquito collections were conducted in 43 locations in 25 provinces of Indonesia using standardized sampling methods for dengue vector surveillance. The samples collected were analyzed for polymorphism and phylogenetic relationship using the mitochondrial cox1 gene and the nuclear ribosomal internal transcribed spacer 2 (ITS2). Almost all Ae. aegypti samples collected in this study (89%) belonged to the same haplotype. A similar situation is observed with the nuclear ITS2 marker. Populations of Ae. aegypti characterized few years ago were genetically different. A closely related observation was made with Aedes albopictus for which the current populations are different from those described earlier. Ae. aegypti populations were found to be highly homogenous all over Indonesia with all samples belonging to the same maternal lineage. Although difficult to demonstrate formally, there is a possibility of population replacement. Although to a lower extent, a similar conclusion was reached with Ae. albopictus.

Currently, dengue has became a major public health problem in Indonesia. Aedes aegypti is confirmed as the main dengue vector. The organophosphate and phyretroid have been used in vector control program for more than 3 decades. Insecticide resistance evidences and mechanisms are essential to find the current status of insecticide susceptibility of dengue vectors. In this study, we analyzed the molecular principles of resistance to phyrethroid and organophosphate insecticides on mosquitoes collected from Palu, Central Sulawesi, and Belu and Ende, East Nusa Tenggara. Single-step polymerase chain reaction (PCR) method was conducted to detect amino acid mutations in paratype voltage-gated sodium channel (VGSC) gene and Achetylcoline esterase-1 (AChE) gene of Ae. Aegypti mosquitoes. The result showed that V1016G mutations of VGSC gene were detected from the wild-caught Ae. Aegypti mosquito from Palu, Belu and Ende. In contrast, G119 wild type allele of AChE gene was found from all Ae. Aegypti of all study sites. These evidences suggest that Ae. aegypti from Palu, Belu and Ende have developed multiple resistance towards phyrethroid insecticides. Based on prior susceptibility test, Ae. aegypti from all study sites were possibly developing resistance to organophosphate in other mechanisms. New strategies are needed, especially insecticide rotation in this area to achieve efficient vector control.