An Investigation of the Risk Factors of a Dengue Fever Outbreak in Sanmin District, Kaohsiung City, 1998
1999 Vol.15 NO.10
Four types of dengue viruses have appeared in Kaohsiung City since the outbreak in 1987. By December 7, 1998, the number of confirmed cases of indigenous dengue fever of the 1998 outbreak had accumulated to 52, forty (77%) of them in Sanmin District. Laboratory testing by Center for Disease Control confirmed the agent to be type Ⅱdengue virus. To understand the outbreak, to study the risk factors involved in inter-household infection of dengue fever, and thus to formulate effective control measures, a retrospective cohort epidemiological study was conducted. Of the 83 households interviewed, 11 had at least one member of the family meeting the definition of a confirmed case. Two households had at least one member meeting the definition of a suspected case. The household attack rate was then estimated at between 13.3% (=11/83) and 15.7% (13/83). In the 13 households, there were 24 cases, 13 males (54.2%) and 11 females (45.8%). Their ages ranged 5-65 years, averaging 35.6±15.6 years, with a median of 38.5 years. Major clinical symptoms were fever (24 cases, 100%), rash (22, 91.7%), and headache (20, 83.3%). 23 of them (95.8%) had been treated; two (8.3%) were hospitalized. The average period between the onset of symptoms and treatment was 0.61±1.44 days (ranging 0-5 days). In terms of risk factors, it was found that more cases clustered in households with increase in the size of household. By adjusting interfering factors with multivariate analysis, it was noted that piled junk in basement (OR=11.160, 95% confidence interval at 1.183-105.240), outdoor bonsai (OR=1.112, 95% confidence interval at 1.001-1.234), and presence of screened windows (OR=0.162, 95% confidence interval at 0.030-0.869) were statistically significant.