Epidemiological Survey of Severe Hand, Foot, and Mouth Disease in Guangxi, China

A hospital-based epidemiological survey was conducted in Guangxi, a province in southern China where HFMD is prevalent. Cases of severe HFMD from 2014 to 2018 were collected from Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control (CDC) system. The definition of severe HFMD was referred to the “diagnosis and treatment guidelines for HFMD” (2010)” [11 ], and the diagnosis criteria are as follow: (1) frequent convulsions, coma and cerebral hernia; (2) breathing difficulties, cyanosis, bloody frothy sputum and pulmonary rales; and (3) shock and circulatory insufficiency. In our study, subjects were included if: (1) Severe HFMD cases: clinical severity was defined as the patient experienced any neurological complications (aseptic meningitis, encephalitis, encephalomyelitis, acute flaccid paralysis, or autonomic nervous system dysregulation) and/or cardiopulmonary complications (pulmonary edema, pulmonary hemorrhage, or cardiorespiratory failure) and/or circulatory system symptoms (pale face, cold limbs, fingers (toes) cyanosis, cold sweat, et al.), Severe HFMD cases were classified if the patients experienced any symptoms belonging to the clinical severity, others were categorized as mild cases [11 , 12 (link)]. (2) Patient’s parents approved of participation; (3) Individuals with completed investigation data. Subjects were excluded if: (1) The neurological dysfunction was caused by non-HFMD; (2) Patients with incomplete investigation data. All participants understood the purpose of the study and signed the informed consent forms. An investigation was performed following the relevant guidelines and regulations; cases of severe HFMD from 2014 to 2018 were collected from Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control (CDC) system, the investigation was done by the staff of the CDC.
The sample size can be calculated by the following formula: $\mathrm{n}=\frac{Z_{1-\alpha /2}^2\ast \pi (1-\pi )}{{\delta }^2}$ . The annual proportion of severe HFMD diseases was set at about 20% [3 (link), 10 (link)], then we calculated the sample size using the PASS software.