Some kids do get recurrent strep infections, thanks to a combination of bad luck and anatomy.
Here's what happens: Having an infection often creates some immunity against the bacteria that caused the illness. But the tonsils of a child who has had strep sometimes seem to attract the bacteria instead.
When your child has a strep infection, his tonsils and adenoids enlarge. Instead of getting smaller after the infection has been cleared up, the swelling sometimes remains, leaving the tonsils vulnerable. If your child is then exposed to the strep bacteria again — by a sibling or a playmate at school, for example — he may well become infected.
Having two strep infections in a month isn't too unusual or a cause for concern. If your child has had three or more infections over the course of a few months, his doctor may want to try a different antibiotic. She'll also take a look at whether your child's tonsils are remaining inflamed and enlarged.
If this is the case — or if your child has seven episodes in one year, five episodes over two years, or three episodes a year for three years — the doctor may refer your child to an ear, nose, and throat specialist for evaluation and a possible tonsillectomy.
Keep in mind that many people, including children, normally carry the strep bacteria in their nose, so they'll test positive for strep even if they show no symptoms of the illness. You don't need to worry about recurrent strep unless your child tests positive for strep and has the classic strep throat symptoms (sudden onset of fever, fatigue, sore throat, headache, abdominal pain). Talk with the doctor if you have any questions or concerns about your child's health.