Yoshimi Kawabe's daughter was 2 years old in 2008 when an unusual rash broke out on her hands and feet. Her family doctor at first thought the rash was caused by hand, foot and mouth disease — a contagious viral infection common in young children — but decided to investigate further after her condition took a turn for the worse.

The doctor ordered a blood test, then informed Kawabe that her daughter had been infected with hepatitis B. As if that wasn't shocking enough, a subsequent examination of her entire family revealed that her two other children and Kawabe herself also carried the virus.

To this day, the 37-year-old nurse does not know how they became infected, but their doctor suspects one of her children picked it up at a day care center.