Early warning of hand, foot, and mouth disease transmission: A modeling study in mainland, China

Author summary Hand, foot, and mouth disease (HFMD), a global infectious disease, has a high disease burden in China. This study aimed to explore the temporal and spatial distribution of the disease by analyzing its epidemiological characteristics and to calculate the early warning signals of HFMD by using a logistic differential equation (LDE) model. Our findings showed that 1) the HFMD disease burden in China remained high and HFMD incidence in the southern region was higher than that in the northern region; and 2) the HFMD early warnings times across China were heterogeneous. One high incidence period occurred in the northern regions during summer, peaking in June every year, while in the southern regions two waves emerged every year. Over the southern regions, the disease appeared to spread faster in the spring wave than in the autumn wave. These results provide important information for public health authorities such as the Centers for Disease Control and Prevention staff to predict and prepare for the onset of the high active periods of HFMD, especially by indicating the heterogeneous warning times of HFMD outbreak across different geographical regions in Mainland China. Background Hand, foot, and mouth disease (HFMD) is a global infectious disease; particularly, it has a high disease burden in China. This study was aimed to explore the temporal and spatial distribution of the disease by analyzing its epidemiological characteristics, and to calculate the early warning signals of HFMD by using a logistic differential equation (LDE) model. Methods This study included datasets of HFMD cases reported in seven regions in Mainland China. The early warning time (week) was calculated using the LDE model with the key parameters estimated by fitting with the data. Two key time points, "epidemic acceleration week (EAW)" and "recommended warning week (RWW)", were calculated to show the early warning time. Results The mean annual incidence of HFMD cases per 100,000 per year was 218, 360, 223, 124, and 359 in Hunan Province, Shenzhen City, Xiamen City, Chuxiong Prefecture, Yunxiao County across the southern regions, respectively and 60 and 34 in Jilin Province and Longde County across the northern regions, respectively. The LDE model fitted well with the reported data (R-2 > 0.65, P < 0.001). Distinct temporal patterns were found across geographical regions: two early warning signals emerged in spring and autumn every year across southern regions while one early warning signals in summer every year across northern regions. Conclusions The disease burden of HFMD in China is still high, with more cases occurring in the southern regions. The early warning of HFMD across the seven regions is heterogeneous. In the northern regions, it has a high incidence during summer and peaks in June every year; in the southern regions, it has two waves every year with the first wave during spring spreading faster than the second wave during autumn. Our findings can help predict and prepare for active periods of HFMD.