Impact Of Oceanic Climate Variability On The Imported Cases Of Dengue In Korea

Abstract

Background: Dengue fever is a mosquito-borne infectious disease mostly prevalent in tropical and subtropical region. In countries of temperate zone, imported cases of dengue takes a major source of introducing the disease. This study aimed to quantitatively estimate the size of the imported dengue cases using oceanic sea surface temperature variation. Methods: National database of dengue cases reported to KCDC since 2001 was collected and selected based on the geographic region of origin. Those from Southeast and South Asian countries were selected. Number of monthly imported cases was analyzed in relation to NINO3 for the estimation of the El Nino southern oscillation and dipole mode index (DMI) for the estimation of the Indian Ocean dipole and using generalized linear model. Results: Among total of 518 cases of imported cases, 506 (98.0%) were reported from Southeast and South Asia since 2001. Monthly number of cases reflected the total number of the dengue cases in the region of origin. Risk of imported cases of dengue from Southeast Asian countries and South Asian countries increased by 1.46 (95% confidence interval, CI: 1.25-1.71) and 2.44 (95% CI: 1.47-4.03) per one unit increase of NINO3 with 4 month lag and increased by 1.69 (95% CI: 1.24-2.31) and 1.33 (95% CI: 0.55-3.23), respectively, for unit increase of DMI. Prediction model had a good correlation with varying estimation of the size of the outbreak. Conclusion: Imported dengue cases reflect the level of outbreak in the region of origin. Oceanic sea surface temperature is a good predictor of the dengue cases and can be utilized for the development of early warning system.