(CLAYTON, N.C.) -- Karli Bossman was a happy 5-year-old from Clayton, N.C., who loved going to kindergarten, until one day in 2008 when the easy-going child suddenly became obsessive and defiant.
She ripped off her socks and underwear because they "hurt" and insisted on wearing pajamas. And Karli refused to get in the car because she was afraid it would run out of gas.
At first, her parents thought the little girl was being bullied, but after checking with her teachers, that was not the case. What was so frightening was how quickly her behavior changed.
The little girl also had an irrational fear of elevators and was scared to go to bed at night for fear she would have a bad dream.
It took two years and 14 doctors to finally figure out what was wrong. Karli, who'd had at least 19 cases of strep throat in the last three years, had developed PANDAS -- pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection.
Symptoms include obsessive compulsive disorder (OCD) -- general anxiety, emotional mood swings, rages and oppositional defiance behavior. Some children have learning disabilities and lose fine motor skills movement.
"It's not a rare disorder, it's just rarely diagnosed," said Dr. Denis Bouboulis, an immunologist from Darien, Conn., and one of the top experts on PANDAS. "There are a lot of children actually misdiagnosed as having a primary psychiatric symptoms, when, in fact they are autoimmune and organic."
The disorder was first described in the mid-1990s, but has only recently been recognized by the National Institute of Mental Health (NIMH). For years, medical experts thought the link between a strep throat and OCD was only coincidental.
But in 2009, a Columbia University study confirmed that a strep infection could cause PANDA symptoms like OCD behavior and Tourette syndrome tics in mice. According to that research, those psychiatric disorders affect 25 percent of adults and more than 3 percent of all children.
Scientists think that PANDAS and its quick onset use the same pathways as rheumatic fever, affecting the part of the brain that controls movement and behavior in a phenomenon known as molecular mimicry.
Karli's journey, which continues today as her family strives to find an effective treatment, involved many misdiagnoses, including the use of antipsychotic drugs that have side effects like tremors and weight gain.
Now, the mother of four wants to try intravenous immune globulin (IV IG) treatment that was pioneered by Bouboulis. That helped Lauren Johnson, the Chesapeake, Va., girl who sneezed 12,000 times a day because of an OCD tic.
Copyright 2011 ABC News Radio