Recently a specific subgroup of patients with a childhood onset of obsessive-compulsive disorder (or tic disorders) have been described. Clinical observation showed a marked association between a streptococcal bacterial infection and the occurence and severity of clinical symptoms of obsessive-compulsive disorder. This subgroup has been called PANDAS = pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (beta-haemolytic streptococci GABHS):

• Presentation of obsessive-compulsive disorder (OCD) or tic/tourette syndrome.
• Early onset (prepubertal, in early childhood)
• Sudden beginning or worsening (exacerbations) of symptoms
• Additional neurological problems (motoric dysfunction) associated with this worsening of OCD symptoms
• Clinical evidence in blood tests (GABHS) associated with severity of symptoms

The proposed poststreptococcal inflammatory explanations provides a unique opportunity for treatment and prevention, including therapies on the immune system such as blood plasma exchange and intravenous immunoglobulin. A placebo-controlled trial revealed that both intravenous immunoglobulin and plasma exchange were effective in reducing the OCD symptoms (40 and 55% reductions, respectively) for a group of severely ill children in the PANDAS subgroup. Further research is required to determine why the treatments are helpful and to ascertain whether or not antibiotic prevention can help prevent this disorder.

The PANDAS symptoms can come and go, get worse during an infection, get better when the infection is cured.