Many celebrities have spoken out about their Lyme disease diagnoses over the years, and because the disease is easy to misdiagnose, many had to fight to be believed. According to the Mayo Clinic, Lyme disease is transmitted by ticks and caused by four species of bacteria in the United States, Europe and Asia. In fact, it's the most common tick-borne illness in those regions. Early symptoms include a rash in a bulls-eye pattern, fever, chills, fatigue, body aches, headache, neck stiffness and swollen lymph nodes. If the disease goes untreated, symptoms expand to severe joint pain and neurological problems such as meningitis and Bell's palsy. Justin Bieber confirmed his diagnosis in January 2020, and his wife, Hailey Bieber, rose to his defense on the same day. "For those who are trying to downplay the severity of Lyme disease, please do your research and listen to the stories of people who have suffered with it for years," she wrote. "Making fun of and belittling a disease you don't understand is never the way, all it takes is educating yourself." Scroll down to read more about other Hollywood stars who've battled the disease.