myxovirus /mik′sōvī″rəs/ [Gk, myxa + L, virus, poison] , any of a group of medium-size ribonucleic acid viruses that are further divided into orthomyxoviruses and paramyxoviruses. Infection with these viruses is usually caused by transmission of the respiratory secretions of an infected host. The viruses that cause influenza, mumps, and parainfluenza are myxoviruses.
