Yolanda Foster has been very open about her battle with Lyme disease since she was diagnosed with the debilitating condition shortly after joining "The Real Housewives of Beverly Hills." In season 5 of the show, she was shown undergoing a treatment, and the star has been regularly posting updates on her Instagram account about her condition and treatments. 

Recently, Yolanda's husband, David Foster, has spoken out about his wife's condition, as he told the Daily Mail that the former model is "on a mission" to get well, not only for herself but also for others who are suffering from Lyme disease. 

"Yolanda feels that it's part of her job to get to the bottom of this. She believes that if she cracks the code, it will help a lot of other people with the disease," said the Grammy-winning composer. 

Lyme disease is caused by the bacteria Borrelia burgdorferi and people get it through the bite of an infected black-legged tick. The disease can cause fever, headache and fatigue, and despite treatment, people may have memory problems and feel very tired most of the time. In her Bravo blog post, Yolanda revealed that she was experiencing these symptoms, saying that she was "unable to read, write, or even watch TV" because of the effects of the disease. 

David said that he has asked his wife to focus on getting better first.

"I've said, 'You know honey, you should really try and get better yourself first,'" he narrated, adding that Yolanda said that if she "cracks the code," then a lot of people will get better, and that she is determined to help others. 

"That's just the way she rolls and that's just her," he said. 

Since being diagnosed with chronic Lyme disease, the reality TV star has been leaning on her husband and children Gigi, Bella, and Anwar for support. Earlier this year, Yolanda and David started a campaign called the Lyme Challenge in which they asked their celebrity friends to post pictures of them biting limes to help spread awareness about the disease. Yolanda's "RHOBH" co-stars have participated in the challenge, as well as other celebrities such as William Shatner, Erin Andrews, and Dr. Mehmet Oz.