There is some research suggesting that strep throat infections may result in the development of antibodies that, in some children, actually attack the basal ganglia in the brain (an area associated with the development of OCD).
When this occurs, OCD symptoms may develop. This is referred to as PANDAS, or pediatric autoimmune neuropsychiatric disorders associated with strep. This is most common in prepubescent children.
Differentiating between the development of OCD from PANDAS and how it usually develops is not difficult if you know what to look for. Although OCD typically develops over the course of months or years, PANDAS is rapid in onset, with some parents saying that one day their children were fine, and the next day they had OCD. This is the main indicator of PANDAS. Other indicators in children may be the rapid development of tics, acting infantile or much younger than they actually are, or separation anxiety.
In order to conclusively diagnose PANDAS, it is important to get a strep throat culture to assess the presence of group A betahemolytic streptococcal infection, or to get blood work done to check for the level of strep-related titers in the blood.
In relation to PANDAS, titers are a measure of the level of certain antibodies in the blood. Normal levels of these titers are 200–300, whereas many individuals with PANDAS OCD will have blood titer levels 500-700 and above.
Successful treatment of PANDAS is dual, you need to eliminate both the underlying strep infection and the OCD symptoms.