Phylogenetic tree for partial P gene sequences of representative CDVs plus those detected in cases 18133, 21261, 19876, and 25259 (shown in boxes). The unrooted tree was generated using the distance matrix program NEIGHBOR with the jumble option invoked. Distance values were calculated by the DNADIST program within the PHYLIP software package using the Kimura two parameter. Only bootstrap values greater than 70 are shown, and the branch lengths are proportionate to genetic distances. The country of origin of each CDV is indicated by a two- or three-letter abbreviation following the isolate designation: Bul, Bulgaria; Jpn, Japan; Ger, Germany; SA, South Africa; USA, United States of America; Sib, Siberia; Swd, Sweden. Canine distemper viruses used for comparison with the country of origin and year of isolation (if known), plus the accession numbers, are as follows: A75/17 (USA, 1975), AF164967; dog Alaska (USA, 2003) (25); dog Hamamatsu (Japan, 1992 to 1994), AB028915; dog Jujo (Japan), AB028916; dog Yanaka (Japan, 1992 to 1994), AB028914; dog (Germany, 1993), AF259549; dog 5804 (Germany, 1990), AY386315; ferret (Germany, 1989), AF259550; PDV-2 (Siberia, 1988), AF259551; raccoon 98-2645 (USA, 1998), AY445077; raccoon 98-2646 (USA, 1998), AY542312; raccoon 98-2654 (USA, 1998), AY466011; raccoon 00-2601 (USA, 2000), AY443350; Rockborn (Sweden), AF181446.