Abstract: Objective　To provide a scientific basis for improving the prevention and control strategies of dengue fever by analyzing the epidemiological characteristics and influencing factors of reported cases in Hainan Province from 2008 to 2023. Methods　Descriptive epidemiological methods were used to analyze the temporal, spatial, and demographic distribution characteristics and influencing factors of reported dengue fever cases in Hainan Province from 2008 to 2023. Spearman correlation analysis was used to explore the correlation between local cases and imported cases. ArcGIS 10.8 and R 4.3.0 were used for graphic production, and SaTScan 10.1.3 software was used for spatiotemporal scanning analysis. Results　From 2008 to 2023, a total of 810 cases of dengue fever were reported in Hainan Province, including 164 imported cases and 646 local cases. The 646 local cases reported from June to December, showed a significant seasonal pattern, with September to October being the peak months. The cases were mainly distributed in Haikou City (41.18%) and Ledong County (39.32%). There were two large-scale outbreaks of dengue fever in 2019 and 2023, with 302 and 328 local cases reported respectively (accounting for 97.52% of the total local cases). The male-to-female ratio of local cases was 1.57∶1, and cases in the age group of 25 to under 65 accounted for 69.50% of the total. The top three occupations of local cases were housework and unemployment (17.65%), migrant workers (17.34%), and business services (13.78%). From 2008 to 2023, a total of 164 imported cases were reported, with cases reported every month. The peak months were from June to November, accounting for 82.32% of the total imported cases. A total of 66 domestically imported cases were reported, originating from Guangdong Province, Yunnan Province, and Guangxi Zhuang Autonomous Region; 98 cases were overseas imports, mainly from Thailand and Cambodia. The male-to-female ratio of imported cases was 1.65∶1, and cases in the age group of 25 to under 55 accounted for 68.29% of the total. The top three occupations of imported cases were business service (33.54%), housework and unemployment (10.37%), and farmers (9.76%). From 2008 to 2013, the years when domestic imported cases were reported in Hainan Province were 2014, 2018, 2019, and 2023, coinciding with the years local cases were reported from 2008 to 2013. There was a positive correlation between local cases and domestic imported cases (r=0.892, P<0.001), while no statistically significant correlation was found with overseas imported cases. Spatiotemporal scanning analysis detected 5 clusters, concentrated in September to October in the years 2019 and 2023. Conclusions　Dengue fever is prevalent in Hainan Province, mainly caused by imported cases leading to local outbreaks without forming local epidemics. It exhibits significant seasonal characteristics. Imported cases mainly originate from Cambodia, Thailand, and other Southeast Asian countries, as well as domestically from Guangdong Province, Yunnan Province, and Guangxi Zhuang Autonomous Region. Local cases are mainly distributed in coastal cities and counties.

Abstract： Objective　To analyze the epidemiological characteristics of scrub typhus in Hainan Province from 2008 to 2023, forecast the epidemic trend in 2024, and provide a scientific basis for the prevention and control measures of scrub typhus in Hainan Province. Methods　The data of scrub typhus cases reported in Hainan Province from 2008 to 2023 were collected. Descriptive epidemiological methods were employed to analyze the temporal, spatial, and population distribution characteristics of scrub typhus. The simple moving average, seasonal decomposition, and seasonal autoregressive moving average (SARIMA) models were used to progressively deconstruct and analyze the epidemic patterns of scrub typhus in Hainan Province from 2008 to 2023 and predict its incidence trend in 2024. Results　A total of 4 300 scrub typhus cases were reported in Hainan Province from 2008 to 2023, with an average annual reported incidence of 2.75/100 000, and the annual reported incidence showed an increasing trend (Z=0.517, P=0.006). The population distribution characteristics were mainly among individuals aged 50-<70 years and those engaged in agriculture, forestry, fishery, and animal husbandry, with statistically significant differences (all P<0.001). There was an obvious seasonality in the temporal distribution, with cases primarily occurring from April to November, and peaking in October. In terms of regional distribution, the top four cities and counties with the highest cumulative reported cases were Qionghai City (826 cases), Wenchang City (558 cases), Chengmai County (486 cases), and Haikou City (452 cases), accounting for 54.00% of the total number of cases, and there were statistically significant differences in the number of reported cases among different cities (χ2=7 755.55, P<0.001). The SARIMA (1,0,2)(0,1,1)12 model fitted the incidence of scrub typhus in Hainan Province from 2008 to 2023 and predicted 364 cases in 2024, roughly equivalent to the number of cases in 2023. Conclusions　The incidence of scrub typhus in Hainan Province shows an overall increasing trend. Individuals aged 50-<70 years and those engaged in agriculture, forestry, fishery, and animal husbandry are the high-risk populations, with a prolonged peak incidence period. The number of predicted cases for 2024 is expected to remain consistent with 2023. Therefore, scientific interventions targeting high-risk populations before the peak incidence may improve the effectiveness of scrub typhus prevention and control.

Abstract：Objective To evaluate the basic development status of public health emergencies of infectious diseases in Hainan Province from 2013 to 2022, analyze the distribution and characteristics of these emergencies, as to provide important scientific basis for the study and formulation of economic health development planning policies, for the health security policies and infectious disease prevention and control strategies in Hainan Province. Methods The relevant statistical data of public health emergencies involving infectious diseases reported in Hainan Province from 2013 to 2022 were collected, and the status quo of these emergencies was analyzed by using descriptive data statistical analysis method. The ARIMA model was used to predict the number of public health emergencies reported by infectious diseases in Hainan Province from 2023 to 2025. Results From 2013 to 2022, a total of 482 public health emergencies were reported in Hainan Province, of which 426 were infectious disease public health emergencies, accounting for 88.38%, with a total of 8 876 cases, an incidence rate of 0.61%, and eight deaths, a case fatality rate of 0.09%. The major public health emergencies of infectious diseases were unclassified events and general events, accounting for 69.25% and 29.58%, respectively. The main diseases were novel coronavirus infection, chickenpox and hand, foot and mouth disease, accounting for 45.07%, 15.49% and 11.97%, respectively; in terms of time distribution, the number of reported incidents showed an upward trend over time, with a decline in 2021, and mainly had three peak periods, April, August and December, with a total of 220 cases reported; in terms of regional distribution, the major cities and counties reported were Haikou, Wanning and Wenchang, accounting for 27.46%, 19.25% and 9.86%, respectively; in terms of location distribution, the events mainly occurred in schools, accounting for 42.02% of the total number of incidents. The ARIMA(1, 1, 0) model was used to predict infectious disease public health emergencies, and the results showed that the forecast state would be stable from 2023 to 2025, with no obvious upward trend, that is, the fluctuation range of public health emergencies related to infectious diseases in Hainan Province would be stable in the next three years. Conclusion The number of infectious disease public health emergencies reported in Hainan Province from 2013 to 2022 has increased year by year, with a decline in 2021. Although the forecast shows that public health emergencies such as infectious diseases are relatively stable with no obvious upward trend, the prevention and control of the epidemic should not be taken lightly. Hainan Province should continue to increase the investment in monitoring public health emergencies, improve the information system of public disease prevention and control, and carry out real-time monitoring of public health emergencies of infectious diseases.

Spotted fever caused by spotted fever group rickettsiae (SFGR) is found throughout China. During 2007–2008, 28 human SFGR isolates and 34 rat SFGR isolates including 15 isolates from Rattus fulvescens, 5 isolates from R. edwardsi, 7 isolates from Callosciurus erythraeus roberti and 7 isolates from Dremomys rufigenis) were obtained from L929 cell culture. Previous research indicated that the 62 strains of SFGR mentioned above shared not only the same serophenotype but also 100% of identity sequences of 16S rRNA, gltA, ompA, groEL and 17KD, which enabled us to apply multispacer typing (MST) to the 62 SFGR isolates in the study. Six primer pairs, which were used for typing of Rickettsia rickettsii and Rickettsia conorii, were chosen, and the results exhibited greater nucleotide polymorphisms among the 62 isolates tested. A total of 48 distinct genotypes were identified. The dominant genotype, represented by h3 isolates, accounted for 21.7% (13/60) of the isolates tested, and the remaining 47 genotypes were all unique. Phylogenetic analysis showed that all the 48 genotypes could be classified in the same clade, while the genetically related strain, R. heilongjiangensis, was close but not the same as the cluster. We concluded that the genetically diverse of spotted fever group rickettsiae strains are endemic in Chengmai County, Hainan Province, China.

Spotted fever caused by spotted fever group rickettsiae (SFGR) is found throughout China. During 2007—2008, 28 human SFGR isolates and 34 rat SFGR isolates including 15 isolates from Rattus fulvescens, 5 isolates from R.edwardsi, 7 isolates from Callosciurus erythraeus roberti and 7 isolates from Dremomys rufigenis) were obtained from L929 cell culture. Previous research indicated that the 62 strains of SFGR mentioned above shared not only the same serophenotype but also 100% of identity sequences of 16S rRNA, gltA, ompA, groEL and 17KD, which enabled us to apply multispacer typing (MST) to the 62 SFGR isolates in the study. Six primer pairs, which were used for typing of Rickettsia rickettsii and Rickettsia conorii, were chosen, and the results exhibited greater nucleotide polymorphisms among the 62 isolates tested. A total of 48 distinct genotypes were identified. The dominant genotype, represented by h3 isolates, accounted for 21.7% (13/60) of the isolates tested, and the remaining 47 genotypes were all unique. Phylogenetic analysis showed that all the 48 genotypes could be classified in the same clade, while the genetically related strain, R.heilongjiangensis, was close but not the same as the cluster. We concluded that the genetically diverse of spotted fever group rickettsiae strains are endemic in Chengmai County, Hainan Province, China.