OBJECTIVETo explore the recurrent epidemiological characteristics of hand, foot and mouth disease (HFMD) among children aged <4 years to provide evidence for HFMD prevention and control.

METHODSPrinciples on historical cohort study were followed when analyzing data related to HFMD surveillance in Fujian province. All the research objects were restricted to patients aged <4, with HFMD and who were permanent residents in Fujian province. Characteristics of the study objects were extracted as potential factors when the patients first showed symptoms of HFMD. These factors might cause the recurrence of HFMD and were filtered by the logistic stepwise regression with SAS 9.0.

RESULTSA total of 82 949 children were included. Among them, 2 612 had repetitiously suffered from HFMD(occupied 3.15%), including 2 510 who had the histories of suffering twice, 98 suffering three times, 3 suffering four times, and 1 even suffering five times. Comparing with the objects who had the first onset at the age of 3, also with the risk increased to 4.39 (95%CI:3.80-5.07) times, when compared to those who had the first onset at the age below 2. Again, the risk among children whose first onset was at the age of 2 had increased to 2.73 (95% CI: 2.35-3.18) times. According to the current residents areas, the morbidities of patients under 6 years old were below 2% when the symptoms first started, but the risk of the objects whose morbidities were higher than 4% , had increased 2.15(95% CI:1.88-2.45)times. Again, risk of the objects whose morbidities were between 3% and 4% had increased to 2.10 (95%CI:1.85-2.38) times. Among those whose specific morbidities were between 2% and 3% , the risk had increased to 1.65 (95% CI: 1.44-1.89) times. Comparing with the objects who never visited any maternal/child care settings when started the first onset, the risk among the ones who had been to the maternal/child care settings, had increased to 1.64 (95% CI:1.51-1.78) times. Boys had the risk 1.34 (95% CI:1.23-1.46)times increase than girls. The preponderant pathogen causing HFMD recurrence was EV71 (33/60). Recurrence might cause more severe symptoms or signs (8/2 612). Pathogens causing the initial infection and recurrence might both belonged to the same-EV71 (3/6).

CONCLUSIONRecurrence of the disease were closely related to the opportunities of contacting the pathogens. Interventions should be imposed on patients in time as soon as the disease initiated, especially at the younger age.