Homogeneity and Possible Replacement of Populations of the Dengue Vectors Aedes aegypti and Aedes albopictus in Indonesia.

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.

Towards eradication: three years after the tsunami of 2004, has malaria transmission been eliminated from the island of Simeulue?

The island of Simeulue was the first landfall of the tsunami of December 2004. The tsunami destroyed many villages on the island, leaving one third of the population homeless. Malaria is endemic in Simeulue and an epidemic was reported to have occurred three months prior to the tsunami. Information concerning malaria was, however, not easily available. The earthquakes related to the tsunami may have created extensive potential breeding sites of Anopheles sundaicus, the probable vector, and increased vulnerability of the human population; a possibility of increased transmission made a further outbreak possible. Consequently, subsequent to the tsunami, considerable amounts of aid, including anti-malarial measures such as insecticide treated mosquito-nets, were deployed on the island. A series of island-wide cross-sectional surveys were conducted in 2005-2007 to determine whether these had had any effect on malaria prevalence. Larval sampling, and CDC light-trap and landing collections of hungry mosquitoes were also undertaken. The results indicate that despite the continuing presence of potential vectors in some places the anti-malaria measures introduced following the tsunami have controlled, and may be close to eliminating, malaria from the island.

Schistosomiasis japonica control and research needs.

Schistosomiasis japonica, a chronic and debilitating disease caused by the blood fluke Schistosoma japonicum, is still of considerable economic and public health concern in the People's Republic of China, the Philippines, and Indonesia. Despite major progress made over the past several decades with the control of schistosomiasis japonica in the aforementioned countries, the disease is emerging in some areas. We review the epidemiological status and transmission patterns of schistosomiasis japonica, placing it into a historical context, and discuss experiences and lessons with national control efforts. Our analyses reveal that an integrated control approach, implemented through intersectoral collaboration, is essential to bring down the prevalence and intensity of Schistosoma japonicum infections and disease-related morbidity, and to sustain these parameters at low levels. The need for innovation and a sufficiently flexible control approach to adapt interventions in response to the changing nature and challenges of schistosomiasis control from the initial phase of morbidity control to the final state of elimination is emphasised. The aim of the presentation and the analyses is to inspire researchers and disease control managers elsewhere in Asia, Africa, and the Americas to harness the experiences gained and the lessons presented here to improve the control and eventual elimination of schistosomiasis and parasitic diseases.

Elimination of lymphatic filariasis in Southeast Asia.

Approximately 15 million people with lymphatic filariasis (LF) live in Southeast Asia. Wuchereria bancrofti (transmitted by the Mansonia and Anopheles vectors), Brugia malayi and Brugia timori (both transmitted by Culex quinquefasciatus) are the filarial species in this region. The endemic countries are: Cambodia, Lao People's Democratic Republic, the Philippines, Indonesia, Thailand and Timor-Leste, which have all agreed to eliminate transmission of the disease by 2020. The public health interventions with respect to LF are based on the 1997 World Health Assembly resolution (WHA 50.29) which recommends elimination of the disease through mass drug administration (MDA) using diethylcarbamazine (DEC) and albendazole. The drugs are generally donated and as governments contribute 60-90% of the operational costs, MDA is deemed to be comparatively inexpensive for local administrations in relation to other public health programmes. So far, elimination has been accomplished only in the People's Republic of China (P.R. China) and this achievement is therefore described here in some detail. Resurgences have occurred but they have been successfully dealt with. Historically, the endemic areas in P.R. China covered 16,514 townships (or urban sub-districts), situated in 864 counties (or cities) in 14 provinces (or autonomous regions or municipalities). The total population at risk of infection in all endemic areas of P.R. China was originally 342 million.

Schistosomiasis in Indonesia: past and present.

Schistosomiasis is endemic in Indonesia in two isolated areas, Lindu valley and Napu valley, both located in the Province of Central Sulawesi. In 1940, a prevalence survey was initiated in Lake Lindu, which indicated a Schistosoma japonicum infection prevalence of 56% among the population of Anca, Tomado and Langko villages. Another survey was conducted in 1973 in Napu valley and very high infection prevalences of up to 72% were found among the population in Winowanga village. Since then, comprehensive studies on the epidemiology and the effects of control have been carried out in 24 endemic villages in both areas. Over the past six decades, schistosomiasis control has been implemented and the average prevalence is now much lower than before the control programme was launched. In 2006, it was 0.49% in 7 villages in Lindu valley. In Napu valley, the average infection prevalence among the population of 17 villages was 1.08% in the same year. Again in 2006, the prevalence of infection in snails ranged from 0 to 13.4% and from 0 to 9.1% in Napu and Lindu valleys, respectively. The highest prevalence among snails was found in Dodolo village. The prevalence of S. japonicum in the reservoir host Rattus spp. ranged from 0 to 20% and the highest prevalence was again found in Dodolo village. Contemporary data suggest that transmission of schistosomiasis is still ongoing in Indonesia despite regular surveillance and control activities covering the whole endemic area.