Abstract:

Objective To analyze the epidemiological characteristics and changing trends of typhoid and paratyphoid fever incidence in provinces and cities at prefecture level in China from 2005 to 2024 for evidences to formulate region-specific prevention and control strategies and measures for typhoid and paratyphoid fever. Methods Case data of typhoid and paratyphoid fever from 2005 to 2024 were retrieved from the Chinese Information System for Disease Control and Prevention. Descriptive epidemiology was used to analyze the epidemiological characteristics, and the Joinpoint regression model was applied to observe the trends in incidence rates. Results A total of 263 767 cases of typhoid and paratyphoid fever were reported nationwide in China from 2005 to 2024, with an average annual incidence rate of 0.97 per 100 000 population. The annual reported incidence rate showed a declining trend over the years, decreasing from 2.69 per 100 000 to 0.33 per 100 000. The seasonal indices were all greater than 1 from May to October, during which the reported cases accounted for 63.87% of the total cases (168 474/263 767). The number of reported cases was 141 813 in males and 121 954 in females, with average annual incidence rates of 1.02 per 100 000 and 0.92 per 100 000, respectively. The proportion of reported cases was the highest in the age group of 35-59 years (29.26%, 77 191/263 767), and maximal incidence rate was seen in the age group under 3 years (2.57 per 100 000). By occupational distribution, farmers were the dominant group (36.09%, 95 206/263 767). By regional distribution, Yunnan Province reported the largest number of cases (n= 72 679). The top three prefecture-level cities in terms of reported case number were Honghe Hani and Yi Autonomous Prefecture (n=11 896) and Kunming City (n= 11 863) in Yunnan Province, and Guilin City (n=11 133) in Guangxi Zhuang Autonomous Region. In terms of incidence trends, the national reported incidence rate showed an overall downward trend (AMPC=-0.67%, 95%CI: -1.03% to -0.31%, t=-3.64, P<0.05). Analysis based on provincial data revealed that the reported incidence rate tended to be a downward trend in 10 provinces, with AMPC values ranging from -1.77% to -0.29% (all P<0.05), whereas the overall trend in the rest of the provinces showed no statistical significance. Observation at the prefecture-level cities indicated that the reported incidence rate decreased in 140 cities, with the AAPC ranging from -2.15% to -50.68% (all P<0.05), and another 15 cities showed an upward trend (AAPC: 4.41% to 16.90%, all P<0.05). Among provinces with a declining incidence trend, 54.47% (67/123) of their prefectural-level cities showed a downward trend and 1.63% (2/123) presented an upward trend. In provinces with no significant temporal trend, 34.93% (73/209) of their subordinate cities exhibited a declining trend and 6.22% (13/209) showed an increasing trend. Conclusion The national overall incidence rate of typhoid and paratyphoid fever declined from 2005 to 2024. However, the incidence trends varied distinctly with changing magnitudes across provinces and prefecture-level cities. Within some provinces, the trends in certain prefectural-level cities were inconsistent with the provincial trend. These findings suggest that differentiated prevention and control strategies should be formulated according to local conditions, and precise interventions should be implemented in key areas and during critical time periods to achieve more efficient control of typhoid and paratyphoid fever.

Key words: Typhoid, Paratyphoid fever, Incidence, Epidemiological characteristics, Temporal trend