Paramyxoviridae (from Greek para-, beyond, -myxo-, mucus or slime, plus virus, from Latin poison, slime, thus meaning "slime beyond slime") is a family of viruses in the order Mononegavirales. Humans, vertebrates, and birds serve as natural hosts. There are currently 36 species in this family, divided among 18 genera. Diseases associated with this negative-sense single-stranded RNA virus family include: measles, mumps, respiratory tract infections.