Disinterested Affection: Dogs, Humans and Evolution: Dogs as vectors of rabies

Wednesday, July 23, 2014

Dogs as vectors of rabies

While rabies is considered a relatively rare disease in developed countries, in much of the developing world it remains a serious health issue for humans. Two recent papers deal with dogs as vectors of rabies to humans.

Electron micrograph of the Rabies Virus. This electron

micrograph shows the rabies virus - the small gray

bodies, as well as Negri bodies, or cellular inclusions.

CDC/Dr. Fred Murphy.

Aréchiga Ceballos et al. (2014) report that over 90% of human deaths from rabies worldwide are caused by dog bites. Mass vaccination, along with the effective control of dog populations, has been used successfully in industrialized countries to control this disease. However, a lower success rate in developing countries is due to a number of factors, including vaccination campaigns that do not cover a sufficient number of animals or reach all communities, and a wide biodiversity that increases the number of reservoirs of the rabies virus. Educational programs are needed, which focus on the commitment involved when acquiring a domestic animal, stating clearly what is required to provide it with a good quality of life. New technologies developed in the industrialized world will not always be successful in less developed countries. Approaches must be adapted to the particular conditions in each country, taking cultural and socio-economic issues into account. Authorities must promote research on dog population dynamics, the development of non-invasive methods to control dog populations and the most efficient, stable and low-cost options for vaccination. Under the One Health model, it is hoped that dog-transmitted human rabies will be accorded high priority as a zoonosis by human health authorities, international authorities and donor agencies to support ambitious eradication goals, particularly those being set in South-East Asia. Well-designed and adequately resourced vaccination programs, based on the World Organization for Animal Health (OIE) guidelines, will have significant animal welfare benefits, due to the availability of improved vaccines (in terms of efficacy, duration of immunity, ease of administration and lower cost), advances in dog population management and the more widespread implementation of the OIE Guidelines on stray Dog Control. Animal welfare benefits include not only the elimination of pain and suffering caused by the clinical disease itself, but also the avoidance of the indirect impact of inhumane culling when methods are used that have not been approved by the OIE.

In a second, recent paper on dogs and rabies Ajoke et al. (2014) review the risk factors associated with dog trading and slaughtering dogs for food in the transmission of rabies in Nigeria. Emphasis on the potential role that the butchers play in rabies transmission and their susceptibility to rabies through contact with infectious meat samples and materials is also discussed. Dog meat has become a delicacy in many parts of Nigeria. It is eaten for various reasons including medicinal values, source of protein, and in rituals. Dogs are transported to the slaughter-houses for processing and they may have multiple origins. The rabies virus has been confirmed in apparently healthy dogs to be slaughtered showing that butchers are at risk, especially in Nigeria, where the butchers neither wear protective gear nor have they been vaccinated against rabies. The authors recommend regular vaccination for butchers and dogs. They conclude that dog trading, slaughtering and consumption probably play a major role in the epidemiology of rabies from dogs to humans in Nigeria.

Citation
Ajoke E., Solomon A, and Ikhide E. 2014. The role of dog trading and slaughter for meat in rabies epidemiology with special reference to Nigeria - a review. Journal of Experimental Biology and Agricultural Sciences, 2:130-136.

Aréchiga Ceballos N, Karunaratna D, Aguilar Setién 2014. Control of canine rabies in developing countries: key features and animal welfare implications. A Revue Scientifique et Technique (International Office of Epizootics) 33:311-321

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Tens of thousands of dogs are bitten each year by snakes. The USA has about 25 species of venomous snakes; they occur in all states except Alaska, Hawaii, and Maine. Learn what simple steps you can take to protect your dog from snake envenomation. Learn what to do if you or, your dog, is bitten by a venomous snake. If you hunt, fish, camp or hike with your dog in areas where poisonous snakes occur you will want the information in this book. If you live in an area with rattlesnakes, you will want the information in Dogs & Snakes, Avoiding the bite.

This Blog

This blog is about dogs, dog-human relationships, and my thoughts on the origins and the domestication of dogs. When I say my thoughts, it needs qualification because much of the writing is not the result of my original thinking, but of reading research and anecdotes about dogs and humans, studies of fossils and archeological remains, anatomy, DNA, and behavior. The posts will be documented in standard fashion with author and date, and the literature cited and references are listed on a reference page or at the bottom of the post. The title comes from William Youatts’ 1846 [1857 edition] book, The Dog. On page 14 he wrote, "The dog is the only animal that is capable of disinterested affection. He is the only one that regards the human being as his companion, and follows him as his friend; the only one that seems to possess a natural desire to be useful to him, or from a spontaneous impulse attaches himself to man." Youatt’s book is remarkably insightful for the mid-19th century; he opens Chapter 1 with a comment about dogs being the most intelligent animal other than humans; notes the emotional attachments dogs and humans form, including the sense of loss when dogs loose the humans they have bonded with; and supports the idea that dogs were descended from wolves. This is an idea that was rejected and re-accepted numerous times in the 19th and 20th centuries, and one that will be discussed here.

John C. Murphy

John C. Murphy is a retired science teacher and science administrator. His most recent book Secrets of the Snake Charmer examines what we have learned about snakes in the first decade of the 21st century. Previous books include Tales of Giant Snakes, Amphibians and Reptiles of Trinidad and Tobago, and Homalopsid Snakes, Evolution in the Mud. Current interests and projects include, numerous squamate systematic projects that focus on the Neotropics and aquatic snakes. His interests also have expanded to dogs and their evolution. He is an avid photographer and a research associate in Science & Education at the Field Museum in Chicago.