Mumps is a viral infection that primarily affects saliva-producing (salivary) glands that are located near your ears. Mumps can cause swelling in one or both of these glands. Mumps was common in the United States until mumps vaccination became routine. Since then, the number of cases has dropped dramatically. However, mumps outbreaks still occur in the United States, and the number of cases has crept up in recent years. These outbreaks generally affect people who aren't vaccinated, and occur in close-contact settings such as schools or college campuses. Complications of mumps, such as hearing loss, are potentially serious but rare. There's no specific treatment for mumps.