Estimating the transmissibility of hand, foot, and mouth disease by a dynamic model.

ABSTRACT

OBJECTIVE: Hand, foot, and mouth disease (HFMD) is a serious public health issue in many countries; however, its transmissibility in county-level outbreaks remains unclear. The aim of this study is to estimate the transmissibility of HFMD epidemics on both city level and county level, for a better understanding of the transmission dynamics of HFMD epidemics. STUDY DESIGN: Simulation based on data obtained from the China Information System for Disease Control and Prevention. METHODS: The weekly number of reported HFMD cases from April 2009 to December 2017 in nine regions of Changsha City was collected. A susceptible-infectious-recovered model was used to estimate the transmissibility of HFMD. The reproduction number of reported cases during the ascending (denoted as Rasc) and descending (denoted as Rdes) period was used to describe the transmissibility of HFMD. RESULTS: The Rasc and Rdes for HFMD in Changsha was 1.44 (95% confidence interval [CI] 1.41-1.48) and 0.71 (95% CI 0.69-0.73), respectively. There was no statistical significance of Rasc values among nine regions (F = 1.056, P = 0.396), nor of Rdes values among nine regions (F = 1.676, P = 0.106). The average Rasc (1.53, 95% CI 1.46-1.61) from 2009 to 2012 was higher than the one (1.37, 95% CI 1.34-1.40) from 2013 to 2017 (t = 3.974, P < 0.001), but the average Rdes (0.67, 95% CI 0.63-0.70) from 2009 to 2012 was lower than the one (0.74, 95% CI 0.73-0.76) from 2013 to 2017 (t = -3.751, P < 0.001). CONCLUSIONS: The epidemic of HFMD in Changsha City is still grim, and integrated strategies should be taken for controlling and preventing HFMD.