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Controlling rabies outbreaks in developing countries

Dr. Darryn Knobel was troubled by the high incidence of canine rabies in certain impoverished areas in his country. The disease posed a significant risk to both humans and dogs, and the potential spread to other communities and wildlife was a concern. As a veterinarian at the University of Pretoria in South Africa, Dr. Knobel knew a rabies protection program was desperately needed, but it had to be easy to implement, inexpensive, and acceptable to diverse communities across South Africa.

While rabies is a vaccine-preventable disease, and outbreaks are rare in the United States, this is not the case in many parts of the world. According to the World Health Organization, an average of 60,000 people worldwide die every year from rabies, most of these in Africa and Asia. In addition, 15 million people receive post-exposure, life-saving treatment every year. Dogs are the primary source of transmission.

For his protection program, Dr. Knobel decided a rabies vaccination strategy based on the concept of “herd immunity” might be the best way of protecting impoverished communities from outbreaks. Herd immunity focuses on vaccinating a critical mass of the population which, in turn, provides protection to unvaccinated individuals (people and animals) in the same group or community.

He first developed a method to understand the dynamics (how many are coming and going) of the canine population in a defined region. This information is critical to determine the target number of dogs that need to be vaccinated to give overall protection to both people and their animals.

Dr. Knobel chose a region with a high incidence of rabies for his study. He and two local veterinary technicians monitored dog migrations in and out of the community, as well as recorded births and deaths. In addition, the team vaccinated and implanted microchips in the dogs to improve tracking. After analyzing the data, Dr. Knobel found his “magic” number; vaccinating 70 percent of the dogs in this population each year would provide adequate protection to the community and significantly reduce rabies outbreaks.

In poorer countries, large-scale dog vaccination campaigns against rabies often coincide with outbreaks. With resources scarce, knowing this key number allows appropriate amounts of rabies vaccine to be allocated to a community in a targeted, cost-effective effort.

“People in this community truly care about their pets, and are grateful for the work we do in protecting them and their dogs from rabies,” said Dr. Knobel. “We aim to apply the lessons we learn here to other dog populations in developing countries, so that the benefits from this study will extend beyond this single community.”

Dr. Knobel presented his findings at the 2014 World Small Animal Veterinary Association congress in Cape Town, South Africa. His hope is to study another community to see if his methodology is robust. “If so, this paves the way for a regional approach to rabies elimination from dogs in Africa.”

Dr. Knobel’s research is supported by a grant from Morris Animal Foundation.


Categories: Animal health
September 22, 2015