Genetic characterization of canine distemper virus from infected dogs in Can Tho City, Mekong Delta, Vietnam

The study aimed to evaluate the endemicity and determine the genetic characteristics of canine distemper virus (CDV) in Can Tho City. A study was carried out on 1,120 dogs raised in Can Tho City, and there were 150 dogs showed clinical signs of canine distemper. The result showed 68/150 (45.33%) dogs were positive for CDV, which was determined based on the test kit of Rapid Test Immumo provided by Asan company (Korea). Dogs under 6 months-age had the highest infection rate (68.00%), significantly higher than other age groups (P<0.05). Male dogs (50%) were more affected than females (41.86%). Exotic dogs showed a higher CDV infection rate compared to domestic dogs, with statistical significance (P<0.05). All dogs displayed clinical signs such as anorectic, moodiness, fever, sneezing, and eye conjunctivitis. Vaccinated dogs had a lower infection rate (6.25%) compared to unvaccinated or under-vaccinated dogs (80% and 69.57% respectively). The study on genetic characteristics of 7 representative Distemper virus strains isolated from the infected dogs was conducted via sequencing the H gene. Genetic analysis of seven representative CDV strains revealed a high similarity (99.82-99.96%) among isolated strains, indicating a common origin and frequent circulation in the study area. Nucleotide similarity with strains in the GenBank ranged from 93.26% to 99.56%, and with vaccine strains from 96.72% to 97.08%. The isolated CDV strains belonged to the Asia 1 lineage, commonly found in Vietnam and other Asian countries.