Estimating dengue vector abundance in the wet and dry season: implications for targeted vector control in urban and peri-urban Asia.

BACKGROUND: Research has shown that the classical Stegomyia indices (or "larval indices") of the dengue vector Aedes aegypti reflect the absence or presence of the vector but do not provide accurate measures of adult mosquito density. In contrast, pupal indices as collected in pupal productivity surveys are a much better proxy indicator for adult vector abundance. However, it is unknown when it is most optimal to conduct pupal productivity surveys, in the wet or in the dry season or in both, to inform control services about the most productive water container types and if this pattern varies among different ecological settings. METHODS: A multi-country study in randomly selected twelve to twenty urban and peri-urban neighborhoods ("clusters") of six Asian countries, in which all water holding containers were examined for larvae and pupae of Aedes aegypti during the dry season and the wet season and their productivity was characterized by water container types. In addition, meteorological data and information on reported dengue cases were collected. FINDINGS: The study reconfirmed the association between rainfall and dengue cases ("dengue season") and underlined the importance of determining through pupal productivity surveys the "most productive containers types", responsible for the majority (>70%) of adult dengue vectors. The variety of productive container types was greater during the wet than during the dry season, but included practically all container types productive in the dry season. Container types producing pupae were usually different from those infested by larvae indicating that containers with larval infestations do not necessarily foster pupal development and thus the production of adult Aedes mosquitoes. CONCLUSION: Pupal productivity surveys conducted during the wet season will identify almost all of the most productive container types for both the dry and wet seasons and will therefore facilitate cost-effective targeted interventions.

Building and analyzing an innovative community-centered dengue-ecosystem management intervention in Yogyakarta, Indonesia.

BACKGROUND AND OBJECTIVES: Dengue is an important public health problem in Yogyakarta city, Indonesia. The aim of this study was to build an innovative community-centered dengue-ecosystem management intervention in the city and to assess the process and results. METHODS: For describing the baseline situation, entomological surveys and household surveys were carried out in six randomly selected neighborhoods in Yogyakarta city, documents were analyzed and different stakeholders involved in dengue control and environmental management were interviewed. Then a community-centered dengue-ecosystem management intervention was built up in two of the neighborhoods (Demangan and Giwangan) whereas two neighborhoods served as controls with no intervention (Tahunan and Bener). Six months after the intervention follow up surveys (household interviews and entomological) were conducted as well as focus group discussions and key informant interviews. FIindings: The intervention results included: better community knowledge, attitude and practices in dengue prevention; increased household and community participation; improved partnership including a variety of stakeholders with prospects for sustainability; vector control efforts refocused on environmental and health issues; increased community ownership of dengue vector management including broader community development activities such as solid waste management and recycling. CONCLUSION: The community-centred approach needs a lot of effort at the beginning but has better prospects for sustainability than the vertical "top-down" approach.

Promoting equity to achieve maternal and child health.

Maternal and child mortality rates, the targets for two of the eight Millennium Development Goals, remain unacceptably high in many countries. Some countries have made significant advances in reducing deaths in pregnancy, childbirth, and childhood at the national level. However, on a sub-national basis most countries show wide disparities in health indices which are not necessarily reflected in national figures. This is a sign of inequitable access to and provision of health services. Yet there has been little attention to health equity in relation to the Millennium Development Goals. Instead, countries have focused on achieving national targets. This has led to an emphasis on utilitarian, as opposed to universalist, approaches to public health, which we discuss here. We recommend a policy of "proportionate universalism". In this approach, universal health care and a universal social policy are the ultimate goal, but in the interim actions are carried out with intensities proportionate to disadvantage. We also briefly describe an initiative that aims to promote evidence-based policy and interventions that will reduce inequity in access to maternal and child health care in China, India, Indonesia and Viet Nam.

Eco-bio-social determinants of dengue vector breeding: a multicountry study in urban and periurban Asia.

OBJECTIVE: To study dengue vector breeding patterns under a variety of conditions in public and private spaces; to explore the ecological, biological and social (eco-bio-social) factors involved in vector breeding and viral transmission, and to define the main implications for vector control. METHODS: In each of six Asian cities or periurban areas, a team randomly selected urban clusters for conducting standardized household surveys, neighbourhood background surveys and entomological surveys. They collected information on vector breeding sites, people's knowledge, attitudes and practices surrounding dengue, and the characteristics of the study areas. All premises were inspected; larval indices were used to quantify vector breeding sites, and pupal counts were used to identify productive water container types and as a proxy measure for adult vector abundance. FINDINGS: The most productive vector breeding sites were outdoor water containers, particularly if uncovered, beneath shrubbery and unused for at least one week. Peridomestic and intradomestic areas were much more important for pupal production than commercial and public spaces other than schools and religious facilities. A complex but non-significant association was found between water supply and pupal counts, and lack of waste disposal services was associated with higher vector abundance in only one site. Greater knowledge about dengue and its transmission was associated with lower mosquito breeding and production. Vector control measures (mainly larviciding in one site) substantially reduced larval and pupal counts and "pushed" mosquito breeding to alternative containers. CONCLUSION: Vector breeding and the production of adult Aedes aegypti are influenced by a complex interplay of factors. Thus, to achieve effective vector management, a public health response beyond routine larviciding or focal spraying is essential.