Mumps is caused by a virus that is passed from one person to another through saliva, nasal secretions, and close personal contact. The condition primarily affects the parotid glands.Parotid glands –also called salivary glands–are the organs responsible for producing saliva.umps is caused by a virus that is passed from one person to another through saliva, nasal secretions, and close personal contact. The condition primarily affects the parotid glands.