Over the years, there have been several serotypes of Parvovirus but the one thought causing the majority of canine disease is CPV-2b. Regardless of the serotype, it is a debilitating virus that affects all unvaccinated dogs. Dogs under the age of 6 months are the most commonly infected. Doberman Pinscher and Rottweiler dogs, or their crosses, get this disease more than any other breed of dog. A lot of this is based upon the immune status of the animal. This is under genetic control.
Parvovirus is spread from one animal to another via the oral-fecal route. Feces contaminated with the virus are ingested by the unvaccinated dog. What makes Parvo extremely dangerous is that the virus can be carried on the soles of shoes and other inanimate objects such as food and water bowls. This can transfer the virus readily from an infected household to another. Making matters worse, is that Parvovirus does not act like most viruses. The majority of viruses can not survive if there isn’t a new host for it to replicate in. They die off in a few days. Not Parvo. It can sit in a snow drift for months. When the snow melts, the virus is still active!! That is why I treated a bunch of cases in late winter in my OH practice.
The Parvo problem really started in full force in 1979. I started practice in 1981 and half of a days case load was treating Parvo dogs. Every dog was coming down with it. It still exists today, particularly in shelters, but nothing like it was 30 years ago. You can give thanks to vaccines that were introduced around 1983. What we did figure out, before Parvovirus vaccine was available, that dogs could be immunized against Parvovirus by injecting them with the Cat Distemper vaccine!! It worked and prevented the disease in many a dog as a result of that heads up thinking!