Desperate for results, Karen switched Bridget's therapist, bringing her to see Weg, who introduced Bridget to Exposure and Response Prevention Therapy, or ERPT, a type of therapy in which a patient is exposed to his or her fears in order to desensitize them until they are no longer all-consuming. ABC News was given rare access inside the treatment room.
In each session, Bridget struggled to get closer and closer to her mother -- as the two practiced the seemingly simple act of sitting on the same couch as one another at home. For Karen, that meant traveling more than 18,000 miles over the course of six months between her family's homes to get closer to Bridget.
"During ... her school day I would come home, do what I needed to do; go pick her up, bring her back to ... my mother's," Karen said. "Then we would get together. We would go to swim, or she would do her things.
"If she was at swim, I would drive her to swim, and then, again, come back home, try to see [my son] Mark and my husband for a little; go pick her up and ... bring her back," she added. "And that was kind of ... our cycle for many months."
Bridget's OCD fears began to attack her swim cap and then her swim bag. Her growing fears combined with the extensive cycle of transportation to treat her OCD caused Bridget to give up the sport she loved so much.
Karen had to divide her time among helping Bridget get well, caring for her sons and working, which she said was often excruciating.
Like Karen, many parents with children who battle OCD wonder: Was it something I did? Why my child?
"It's very difficult for parents to come in and not believe that they've done something wrong, that their kid has all these fears and these strange and bizarre fears," Weg said.
Diane LeClair asked herself the same questions when her 13-year-old daughter, Michelle, was diagnosed with OCD in September 2008. Michelle feared that other students were contaminated, keeping her from going to school or any public place where she has seen her classmates.
Michelle told ABC News how she wouldn't let her mother shop in stores nearby for basic household needs.
"We had to go like hours away just to go get like a pair of pants or get cleaning supplies ... to wash the washer, because everything around here was contaminated," Michelle said. "All the stores were [contaminated] because the kids from school had been there."
Her crippling fear kept her isolated at home. At her worst, during the fall and winter of 2008, Michelle's laundry had to be done separately from the rest of the family's. One laundry cycle often wasn't enough to convince Michelle her clothes were clean. Even the washer had to be washed.
Michelle's compulsion forced her to shower incessantly in blistering hot water. Even the allure of a brand new puppy couldn't get Michelle out of the shower.
"We were going to go get him puppy toys and take him to the store and she was so excited that whole day," Diane LeClair said. "And after an hour in the shower, I'm like, 'We need to leave if you want to go,' and she couldn't do it.
"I shut the water off, I pulled her out of the shower, and she [screamed], 'Don't touch me, don't touch me,' and ... just sat on the floor, rocked and cried," she added.
Diane LeClair quit her job as a teacher to work full time helping Michelle fight OCD. When school became too much to bear, Michelle took a leave of absence, turning to home-schooling.