Molecular surveillance of canine distemper virus in diarrhoetic puppies in northeast China from May 2014 to April 2015

LI, Chunqiu; GUO, Donghua; WU, Rui; KONG, Fanzhi; ZHAI, Junjun; YUAN, Dongwei; SUN, Dongbo

were positive for diarrheagenic E. coli (EIEC/EPEC/EHEC/typical EPEC), 32% were positive for V. cholerae, 18% were positive for Shigella spp., 12% were positive for Campylobacter spp., 2% were positive for S. enterica, 8% were positive for diarrheagenic E. coli and Shigella spp., 6% were positive for diarrheagenic E. coli and V. cholerae, 4% were positive for diarrheagenic E. coli, V. cholerae and Shigella spp., 4% were positive for diarrheagenic E. coli, V. cholerae and Campylobacter spp., 2% were positive for diarrheagenic E. coli, Shigella spp. and Campylobacter spp. (Table 1) . Mixed infections of canine enteric viruses and bacteria frequently occur in diarrheic dogs. Gizzi et al. (2014) reported that 68.3% were positive for at least one pathogen in 104 fecal samples of the diarrheic dogs; single infection and co-infection rates were 54.9 and 45.1%, respectively; 65.6% of the animals (21/32) had dual infections, 15.6% of the animals (5/32) had triple infections, and 18.8% of the animals (6/32) had quadruple infections [8] . In our study, the co-infection of CDV with least one other enteric pathogen was revealed to be 94%, of which 82% of co-infections had at least one enteric virus and 72% with at least one enteric bacteria. The most common single co-infection of CDV was with CPV-2 virus (30%), or with diarrheagenic Escherichia coli (38%). The co-infection of CDV with CPV-2, CaKV and CCoV reached 10%. The high co-infection rates of CDV positive samples with multiple pathogens are responsible for the high incidence of diarrhea in dogs. However, the effect of multiple pathogens on the disease outcomes remains unclear. Therefore, we suggest that further studies need to better explain the relationship between the high co-infection rates and the severity of clinical symptoms.