There are two main types of flu viruses that are known to circulate among dogs: the H3N8 virus, which was discovered in 2004 after it jumped from horses to dogs in the United States, and the H3N2 virus, which was discovered in 2007 after it jumped from birds to dogs in Asia. Five years ago, scientists uncovered viruses jumping between birds and dogs.
And so it was in 2009 - avian flu jumped to pigs, mixed with existing strains of the virus to create something different, then made the jump into unsuspecting humans.
According to a new study released this week by mBio, a journal published by the American Society for Microbiology, there could be a new pandemic of the deadly influenza virus, particularly Influenza A, transmitted by dogs and transferred to humans. "In this study, we identified influenza viruses jumping from pigs into dogs", study author Adolfo Garcia-Sastre said.
Influenza can jump among animal reservoirs where many different strains are located and these reservoirs serve as mixing bowls for the genetic diversity of strains, according to the researchers.
"The majority of pandemics have been associated with pigs as an intermediate host between avian viruses and human hosts", says one of the researchers, Adolfo García-Sastre, from the Icahn School of Medicine at Mt Sinai in NY. Scientists believe that the new family of pathogens belonging to the group of H1N1, is spread by airborne droplets and can infect dogs and pigs. They are starting to interact with each other. "This is very reminiscent of what happened in swine 10 years before the H1N1 pandemic", Garcia-Sastre said.
The dogs involved in the study were all from a single region in China, which is one reason not to panic yet - the picture may not be the same worldwide.
With flu vaccines on the rise every season, and with proper steps to lower the risk of the avian and swine flu from spreading in the past, there are still concerns with how to contain the furry pooches from becoming the source of the next pandemic. The researchers called these viruses "CIV-H1N1r", "CIV-H3N2r" and "CIV-H1N2r", (with "r" standing for "reassortant").
The team of researchers examined dogs that were experiencing respiratory problems and confirmed that around 15 percent of the dogs had the flu virus.
In China, dogs are often raised to be eaten but are also kept as pets, while free-roaming street dogs are also a factor in the spread of various canine diseases. As the report shows, these viruses can intermix and create new forms of the flu in the animal population that are unknown to human immune systems.
"The continued expansion of IAV (influenza A viruses) diversity in canines with high human contact rates requires enhanced surveillance and ongoing evaluation of emerging pandemic threats", the study read.
"The diversity in dogs has increased so much now that the type of combinations of viruses that can be created in dogs represent potential risk for a virus to jump to a dog into a human". They, in turn, can infect humans.
"The spread of influenza viruses among dogs is unsafe in that their level of genetic diversity is nearly as high as among men".