A two-and-a-half-year-old girl, Duoduo, was hospitalized for stomach bleeding due to Helicobacter pylori (HP) infection. The doctor said that it is very rare for Duoduo to suffer from gastric bleeding at his age. The hospital receives about 20 children with gastric bleeding every year, but they are usually 5 to 14 years old. Small ones like Duoduo are relatively rare. How could such a young child be infected with Helicobacter pylori…