The rabies vaccine is extremely effective at preventing this fatal disease in dogs, but new research, funded by Morris Animal Foundation, shows that the vaccine may have a positive effect on overall canine health as well and is associated with a decrease in rates of death from all causes.
The unexpected finding could have implications for the future design of rabies control programs as well as provide a model to study this same effect in people. Dr. Darryn Knobel, associate professor of epidemiology and population health at the Ross University School of Veterinary Medicine, recently published his research results in the journal Vaccine.
The study showed that rabies vaccination reduced the risk of death from any cause by 56% in dogs up to three months of age. While all dogs had decreased mortality, the percentage decrease was highest in young dogs, with the effect diminishing over time.
Knobel's study area incorporated an impoverished region of South Africa, where infectious diseases, including rabies, are an ever-present threat to both people and dogs. The research team concluded that the decrease in mortality couldn't be explained by a reduction in deaths due to rabies alone.
"This led us to propose that rabies vaccine may have a non-specific protective effect in dogs, perhaps through boosting the immune system to provide enhanced defense against other unrelated diseases," Knobel said. "A similar phenomenon has been observed in children, although it remains to be substantiated through more definitive trials."
Rabies remains a global health threat with tens of thousands of human deaths every year, mostly in Asia and Africa. Dogs are the main source of human rabies deaths, so rabies control programs are essential to both canine and human health.
Understanding the mechanisms responsible for the enhanced immunity could have broad implications not only for veterinary medicine but also for human medicine. Knobel said he hopes to continue his research in collaboration with veterinary immunologists and infectious disease specialists to further study this effect in dogs.
"This is a fatal disease shared by dogs and people, and the work we and Dr. Knobel have undertaken has the potential to save both human and canine lives by further exploring the findings of this study," said Dr. John Reddington, president and chief executive officer of Morris Animal Foundation.
While great strides have been made in rabies prevention and treatment since 1983, the World Health Organization continues to include rabies on its neglected tropical disease road map. As a zoonotic disease, rabies requires close cross-sectional coordination at the national, regional and global levels.
Established in 1948, Morris Animal Foundation is dedicated to improving and protecting the health of animals through scientific innovation, education and inspiration. Its investment in research has yielded life-saving vaccines, new treatments for critical diseases, superior screening tests and advanced diagnostic tools.