Emergence of Canine Parvovirus - 2 Variants and its Impact on Vaccination

Canine parvovirus-2 (CPV-2) has been considered to be an important pathogen of domestic and wild canids and has spread worldwide since its emergence in 1977. It has been reported from Asia, Australia, New Zealand, the Americas and Europe. There are two distinct parvoviruses known to infect dogs the pathogenic CPV-2 and CPV-1 or the canine minute virus (CnMV). The disease caused by CPV-2 is characterized by two prominent clinical forms, enteritis with vomition and diarrhea in dogs of all ages and myocarditis and subsequent heart failure in pups of less than 3 months of age with high morbidity (100%) and frequent mortality up to 10% in adult dogs and 91% in pups. The disease condition has been complicated further due to emergence of a number of variants namely CPV-2a, CPV-2b, CPV-2c, New CPV2a, New CPV2b and Asp 300 (2a/2b) over the years and involvement of domestic and wild canines. Vaccination is the most cost effective and ideal method to control the canine parvovirus infections in canines. Both live attenuated and inactivated vaccines are available to control the disease in animals. Vaccines used during the late 1970s and early 1980s were of feline panleukopenia virus (FPV) origin which was followed by the use of inactivated and live attenuated vaccines of CPV-2 and CPV-2b of canine origin. High-titer, low-passage CPV vaccines containing a canine origin attenuated virus are currently the vaccines of choice for use in pups of any breed. In spite of large scale vaccination to control the disease in dogs, the disease has been reported both in vaccinated and the unvaccinated dogs. Considering the enormous importance of the disease, the article is aimed to discuss the emergence of canine parvovirus -2 variants and its impact on vaccination for the benefit of the scientific fraternity, dog owners, veterinary practitioners, students, researchers and diagnosticians which in turn help in the better and effective management and ultimately control of the disease.