Risk factors for HFMD and herpangina included playing with
neighborhood children (odds ratio [OR]: 11 [95% confidence interval (CI):
6.2–17]), visiting an outpatient clinic for another reason 1 week before
onset (OR: 20 [95% CI: 5.0 –88]), and community exposures to crowded
places (OR: 7.3 [95% CI: 4.1–13]). By using a score summarizing responses
to 4 hand-washing questions, we found that 50% of the case-children and
2.5% of control-children had a poor score of 1 to 3, whereas 12% of the
case-children and 78% of control-children had a good score of 7 (OR:
0.00069 [95% CI: 0.0022–0.022]) after we adjusted for residency, age, and
community exposures by using logistic regression.