In about one in four children who suddenly seem to have OCD when they were getting along just fine before, a strep throat earlier in the year may be behind it. You could also make the connection if you see low-level OCD children suddenly have a flare up after a strep throat infection. What happens is, when a child gets a strep throat, his body’s immune cells go and attack a certain part of the brain called the basal ganglia. Apparently to immune cells, it’s hard to tell any difference between the two. It’s a good thing though that it doesn’t happen in all children.

The reason it’s difficult to make the connection in most cases is that the OCD problem only occurs months after the strep throat; it’s very difficult to ever remember the minor infection all that time ago.