Have you ever heard of neuromyelitis optica spectrum disorder, or NMOSD? NMOSD is considered a rare disease because just 15,000 people in the United States are diagnosed. Historically, NMOSD was thought to affect between one and four in every 100,000 people. Today, it is estimated to affect up to 10 in every 100,000. Innovative research, new diagnostic tests and increased awareness have all contributed to a growing number of diagnoses - but the condition continues to be overlooked and misunderstood.