Paramyxoviridae are a group of enveloped viruses with a single-stranded, linear RNA with negative polarity as genome. Paramyxoviridae include virus species that affect the respiratory system itself (e.g. the respiratory syncytial virus of the subfamily Pneumoviridae) or originate from it (species of the subfamily Paramyxoviridae).
Paramyxoviridae are not transmitted by vectors but almost exclusively by droplet infection. This virus group is widespread in mammals and birds. Diseases as important as distemper and Newcastle disease are transmitted in animals. In humans, paramyxoviridae are responsible for infections such as measles, mumps, parainfluenza and RSV infection.