Parvoviruses

What are parvoviruses?

Parvoviruses are small viruses with a DNA genome. They require actively dividing cells to replicate, so the age of the host influences what type of tissue is infected.

In older animals, parvoviruses replicate in tissues like the gastrointestinal tract lining where there’s a rapid turnover of cells, while in neonates and fetuses they replicate in a range of additional tissues such as the developing heart (dogs), and brain (cats).  

Although they cause disease in a wide range of species, parvoviruses aren’t associated with host species jump events to the same extent as more adaptable RNA viruses like influenza. 

Canine parvovirus

Canine parvovirus type 2 (CPV-2) is a contagious virus mainly affecting dogs. It’s spread from dog to dog by direct or indirect contact with faeces.

Although live-attenuated vaccines have been available since the virus first emerged in the 1970s, there’s a window of vulnerability for puppies. The virus replicates in the intestinal epithelium, causing vomiting and haemorrhagic diarrhoea, which can be fatal.

Since its discovery CPV-2 has undergone genetic evolution, with CPV-2a, -2b and -2c arising consecutively. The original CPV-2 strain no longer circulates, but -2a, -2b and -2c co-circulate worldwide, leading to concerns that vaccines containing older strains may no longer protect against the most recent variant.