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 R_asc) and descending (denoted as R_des) period was used to describe the transmissibility of HFMD.

Results: The R_asc and R_des 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 R_asc values among nine regions (F = 1.056, P = 0.396), nor of R_des values among nine regions (F = 1.676, P = 0.106). The average R_asc (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 R_des (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.

Keywords: Hand, foot, and mouth disease; Mathematical model; Reproduction number; Transmissibility.