Correlation between Dengue Hemorrhagic Fever Cases, Vector Indices, and Climatic Factors in Khanh Hoa Province from 2000 to 2019

This cross-sectional study aimed to describe the state of Dengue Hemorrhagic Fever (DHF) and examined the correlation between DHF cases and vector and climatic factors in Khanh Hoa over a 20-year period (2000–2019). The results revealed that dengue fever was a highly endemic disease in Khanh Hoa, with an increasing trend annually and a clear seasonal cycle. Aedes aegypti was identified as the primary mosquito vector in the area. The Breteau index and mosquito density index increased from May to December each year, and vector indices peaked about one month before the epidemic reached its height. Cases with a one-month delay were more strongly correlated with vector and climatic factors than cases without a lag. The Breteau index was moderately positively correlated with dengue cases. Specifically, an increase of 1 in the average monthly BI resulted in a 16-case increase with a one-month lag and a probability of 13%. However, a weak correlation was found between dengue cases and the mosquito density index, average temperature, and average rainfall. Cohort studies are deemed necessary to provide a more comprehensive understanding of the relationship between vector and environmental factors and the increase and transmission of dengue cases.