New canine rabies research: One vaccine to save them all?

Rabies prevention affects both canine kind and humankind. (Shutterstock.com)Canine rabies is common in many parts of the world. In Asia and Africa, rabies from dog bites kills more than 50,000 people each year. Large international efforts are dedicated to this public health crisis, including mass rabies vaccination of dogs. A recent publication suggests the canine rabies vaccine may have additional benefits to dog health beyond protection from rabies.1 That's right-vaccinate for rabies, get rabies protection PLUS additional dog health benefits. Sound odd, too good to be true or just plain hocus pocus? I was skeptical too … at first.

The study followed 2,500 households in South Africa over four years and found that dogs vaccinated for rabies had a reduced risk of canine death from any cause as compared to dogs not vaccinated for rabies. The greatest reduction was noted in very young dogs with a 56% reduced risk of death. This decrease in canine mortality was not explained by a reduction in deaths due to rabies alone. The researchers proposed that rabies vaccination boosted the immune system and may have provided enhanced defense against other diseases unrelated to rabies. Previous studies have similarly identified this nonspecific protective effect by rabies vaccination in children and animals, providing further support for the research team's current findings.

The research team's discovery is very exciting. If rabies vaccination extends the life of immunized dogs, this benefits both the dogs and people in the area. In order for a canine rabies vaccination program to be effective in reducing human rabies in areas such as Africa, a minimum percentage (threshold) of dogs in the region must be vaccinated. Public health groups often dedicate enormous time and financial resources to reach this vaccination threshold. If vaccinated dogs have additional health advantages over nonvaccinated dogs, this may ease the ability to reach and sustain this rabies vaccination threshold-having large human health benefits. And of course, more healthy dogs that live longer (in any area of the globe) is something all of us can get behind.

Before you start touting the additional benefits of rabies vaccination to your dog-owning clients, it's important to recognize this study was performed in a low-income area of South Africa. Most dogs in the study were owned, free-roaming, with an average of two to six dogs per residence, and overall canine mortality was very high. Does that sound like your usual clientele? For this reason, the team's findings may not be applicable to dogs in North America. The research team acknowledged a variety of study limitations (e.g. manner in which data were collected, nonrandomized nature of the study).

The study did not specifically adjust for dog husbandry and preventive healthcare practices, so it's possible the observed health benefits may have been due to owner behavior (e.g. people who vaccinated their dogs for rabies also provided additional preventive veterinary care measures). However, as canine rabies vaccination in this low-income area was provided through free mass public (door-to-door) vaccination efforts, while other canine healthcare was not, the research team argues owner behavior may not have played an important role in their findings but do encourage additional work in this area to provide support for their conclusions. Nonetheless, this is an exciting finding for international rabies prevention efforts and veterinary medicine and may illuminate prevention of a disease that has challenged human health for centuries.

Reference

1. Knobel DL, Arega S, Reininghaus B, et al. Rabies vaccine is associated with decreased all-cause mortality in dogs. Vaccine 2017;35:3844-3849.

Dr. Jason Stull is an assistant professor at The Ohio State University, Department of Veterinary Preventive Medicine, and owner of Island Dog Consulting. He enjoys teaching and conducting research in the areas of companion animal epidemiology and infectious disease prevention and control. Jason currently lives with his wife, two daughters and two (very spoiled) dogs in Prince Edward Island, Canada.