Objective To analyze the seasonal characteristics of hand foot and mouth disease (HFMD) in Ningbo, Zhejiang Province, as well as to clarify the high-incidence period, and provide a scientific basis for the early monitoring, prevention and control.

Methods Based on the Infectious Disease Reporting Information Management System of Chinese Disease Prevention and Control Information System, a total of 247 082 cases of HFMD in Ningbo from 2014 to 2023 were collected and sorted out. The incidence rate and trend of HFMD in this area were calculated by using Ningbo’s resident population data. On this basis, the seasonal characteristics of HFMD were systematically analyzed by using the seasonal index method, concentration method and circular distribution method.

Results The average annual incidence rate of HFMD in Ningbo was 292.70 per 100 000 population from 2014 to 2023, and the incidence rate exhibited a biennial surge pattern. The incidence of HFMD showed a distinct seasonal bimodal distribution during 2014-2017 and 2021-2022. The results of the seasonal index method showed that May to July and September to October were the high-incidence seasons. The total concentration M value was 0.34, indicating that the incidence of HFMD in Ningbo had a certain seasonality. The results of circular distribution analysis showed that r=0.34, \overline\alpha =166.75°, S=41.06° (Z=27 548.29>Z_0.05 (2.995 7), P<0.05), indicating that the peak day of HFMD in Ningbo was June 18th, and the peak period was from May 10th to July 27th.

Conclusions The incidence of HFMD in Ningbo, Zhejiang Province from 2014 to 2023 had certain seasonal characteristics, and the peak period of HFMD was from May to July. It is suggested that relevant epidemic prevention departments implement various HFMD prevention and control measures as early as possible before the high-incidence period to reduce the risk of epidemic outbreak.