Dengue in Thailand and Cambodia: An Assessment of the Degree of Underrecognized Disease Burden Based on Reported Cases

Dengue is a major public health problem especially in tropical and subtropical countries of Asia and Latin-America. An effective dengue vaccine is not yet available, but several vaccine candidates are currently being evaluated in clinical trials. Accurate country-level incidence data are crucial to assess the cost-effectiveness of such vaccines and will assist policy-makers in making vaccine introduction decisions. Existing national surveillance systems are often passive and are designed to monitor trends and to detect disease outbreaks. Our analyses of data from prospectively followed cohorts with laboratory confirmation of dengue cases show that, in Thailand and Cambodia, dengue incidence is underrecognized by more than 8-fold. The magnitude of the outpatient burden caused by dengue is not assessed or reflected by the national surveillance data. We estimate that a median of more than 340,000 symptomatic dengue virus infections occurred annually in children less than 15 years of age in Thailand in Cambodia between 2003 and 2007

Effectiveness of dengue control practices in household water containers in Northeast Thailand

OBJECTIVE: To investigate the influence of larval control methods (using temephos, keeping fish and covering containers with lids), water use and weekly cleaning of containers on the presence of Aedes aegypti larvae in water-storage containers in rural and urban households in Khon Kaen province. METHOD: Cross-sectional questionnaire survey and larval survey covered 966 households and 5821 containers were inspected. RESULT: In rural and urban areas larval control was patchy and often ineffective. Consequently, the mosquito indices exceed the target indices for dengue control with the Breteau Indices of 201 and 113, and Container Indices of 25 and 28 in rural and urban areas, respectively. The containers most frequently infested with larvae were rectangular cement containers storing water for bathing (rural: 37.2%; urban: 35%) and flushing the toilets (rural: 35.7%; urban: 34.3%). Keeping fish [adjusted odds ratio (AOR): 0.08-0.16] was the most effective methods of control. Correctly covering containers with lids was similarly effective (AOR: 0.10-0.25) when used on jars for storing drinking water. However, frequent use of containers reduced the effectiveness of lids. Temephos was effective only in dragon jars in urban areas (AOR: 0.46) where a standard package of temephos were available. Weekly cleaning of containers was an effective method for larval control in most types of containers. A combination of control methods increased effectiveness. CONCLUSION: This study highlights the complex interaction of household water use and larval control practices as well as the importance of determining the most effective control measures compatible with water practices for implementing control promotion