[Epidemiological characteristics and trends of indigenous dengue fever cases in the elderly in Guangdong Province, 2015-2023].

Objective

To analyze the epidemic characteristics and changing trends of local dengue fever among the elderly population in Guangdong Province from 2015 to 2023, in order to provide a scientific basis for improving the prevention and control strategies and measures of dengue fever.

Methods

The surveillance data of dengue fever in Guangdong Province from 2015 to 2023 were collected through the China Disease Prevention and Control Information System. The Joinpoint 4.9.1.0, SaTScan 9.6, and ArcGIS 10.7 software were used to analyze the temporal, spatial, and population characteristics of local dengue fever cases among the elderly population.

Results

From 2015 to 2023, a total of 3 092 local cases of dengue fever among the elderly population were reported in Guangdong Province. The annual incidence rate was 2.28 per 100 000, which was higher than the 1.37 per 100 000 for the entire population. The incidence of dengue fever among the elderly population exhibited a fluctuating trend, initially decreasing before increasing overall. The circular distribution results indicated that the incidence of dengue fever among the elderly population from 2015 to 2023 was strongly seasonal, with the concentration trend's γ value ranging from 0.81 to 0.95 (γ=0.88,P<0.001), and the peak days of the epidemic mainly occurred in mid-to late September to the end of October. Elderly cases were mainly concentrated in the Pearl River Delta region (58.76%, 1 817/3 092). Spatial autocorrelation analysis revealed that the incidence of the disease among the elderly exhibited apparent spatial clustering, with the high-high clustering area primarily located in the Pearl River Delta region. The spatial clustering area's spatio-temporal scanning analysis results showed that primary clusters area was mainly in Guangzhou City and Chaozhou City, and the secondary clusters area included Guangzhou City, Foshan City, and Shenzhen City in the Pearl River Delta region, Chaozhou City and Jieyang City in Eastern Guangdong, and Zhanjiang City and Yangjiang City in Western Guangdong. The scope of the clustering area exhibited a gradual expansion trend, and the clustering period was basically consistent with the seasonal distribution. The incidence rate of the elderly population was -7.11% on average, with the incidence rate of males being slightly higher than that of females.

Conclusions

From 2015 to 2023, the local dengue fever outbreaks among the elderly population in Guangdong Province showed a fluctuating trend. There was a strong seasonal pattern and obvious spatial clustering. Measures should be taken to strengthen the prevention and control of dengue fever among the elderly in the high-incidence and clustered areas.