Faecal shedding of parvovirus deoxyribonucleic acid following modified live feline panleucopenia virus vaccination in healthy cats

Positive canine parvovirus (CPV) faecal test results have been reported in dogs after modified live virus (MLV) vaccination. Thus, the aim was to investigate feline panleucopenia virus (FPV) shedding in recently vaccinated, adult, clinically healthy cats and to assess related factors. Forty cats were vaccinated with an FPV MLV vaccine. Faeces of cats were tested for presence of parvovirus DNA on days 7, 14, 21 and 28 by quantitative real-time PCR; DNA-positive samples were subjected to partial VP2 gene sequencing. Virus isolation was performed whenever sufficient amounts of faeces were available. Serum antibody titres were measured by haemagglutination inhibition on days 0, 7 and 28. Overall, 30.0 per cent (12/40; 95% CI 18.0 to 45.6) of cats shed parvovirus DNA. Sequencing revealed FPV vaccine virus DNA in three cats, FPV field virus DNA in four cats and CPV field virus DNA in one cat. Shedding was significantly associated with lack of prevaccination antibody titres (40) (P=0.016; OR: 6.44; 95% CI 1.44 to 28.89) and with postvaccination titre increases (fourfold) (P=0.029; OR: 5.00; 95% CI 1.17 to 21.39). Shedding of field or vaccine virus DNA seems to be common in healthy cats which can be a concern in shelters and catteries. Diagnostic tools should be developed to facilitate differentiation of vaccine and field virus shedding.