Serotype-Specific Dengue Virus Circulation And Dengue Disease In Bangkok, Thailand From 1973 To 2010

Background: Since 1962, the Queen Sirikit National Institute of Child Health (former Bangkok Children Hospital) and AFRIMS have engaged in a long termed collaborative study of clinical epidemiology, virology and serology of dengue. hospitalized dengue cases This is an update of a previous report spanning the period between 1973 to 1999. (Nisalak A, et al, 2003).This update contains data from 1973 to 2010. Methods: Study sites. Queen Sirikit National Institute of Child Health, Ministry of Public Health is located in Bangkok, Thailand with 429beds. There is a hemorrhagic fever unit with 25 beds and ICU unit with 8 beds. This is also a WHO collaborating centre for case management of Dengue, DHF and DSS. Clinical Diagnosis.The attending physicians assigned dengue clinical diagnosis and severity grading at the time of discharge according to the 1997 WHO case definitions. Laboratory methodology.Serology diagnoses were determined using on dengue/JE IgM/IgG capture enzyme immunoassay developed at AFRIMS (Innis BL, Nisalak A., et al, 1989).Determination of infecting viral serotypes was based on viral isolation (prior to 1994) and molecular technique (1994-2010). Statistical analysis.Stastistical analysis was performed using SPSS for Windows version 12.0(SPSS Inc.) Results: The updated findings are consistent with our previous findings: 1) primary cases are increasing relative to secondary cases, 2) symptomatic primary cases are still most likely to be DENV-1 and DENV- 3) primary non-infant hospitalized cases are still less severe than secondary non-infant hospitalized cases. 4) DENV-2 is still most associated with DHF. Higher case fatality rates were found in non-infant cases and cases with a secondary infection. Among non-infant cases, the fatality rates were higher in cases with a secondary infection compared to cases with a primary infection. This is different from our previous analysis which showed similar case fatality rates between primary and secondary non-infant infections. During 2000-2010, DENV-4 were found more frequently compared to previous years and the mean age of DHF cases increased to 8.14 years. Conclusion: These findings highlight unique information of a longitudinal epidemiological study of dengue. Further spatial analysis is planned to elucidate transmission dynamics.