Rabies Challenge Fund Charitable Trust Begins Studies

Laurie S. Coger, DVM, CVCP   

In recent years many veterinarians have embraced progressive attitudes about vaccination and the dog owning public has become more aware of the dangers of over vaccinating their four footed companions. Many veterinary organizations and colleges, including the American Animal Hospital Association (AAHA), have supported extended vaccination intervals for common vaccines for several years. Vaccinating for certain diseases, such as coronavirus, has even been discouraged by the AAHA Canine Vaccine Task Force Guidelines.

Of all the vaccines veterinarians routinely administer, rabies is the most sacrosanct, largely because the disease is zoonotic, meaning transmissible to humans. Rabies is the only vaccine mandated by law for dogs and cats.  Currently available rabies vaccines are FDA approved for one or three year duration. The first vaccination of any animal using any vaccine is considered to provide one year of immunity. Subsequent vaccinations are considered to be good for three years, as long as a three-year vaccine is used. Yet any state may require vaccination annually or every second year, regardless of what product is used.

One of the most feared diseases of mammals, references to rabies go back thousands of years. Raccoons, skunks, foxes, and bats largely carry the virus, and are the most commonly diagnosed cases. Rabies is still a threat to a significant number of human and mammal lives every year. Vaccinations have helped to diminish the number of cases annually, but rabies still exists even in developed countries and runs rampant through some Third World countries. New York City had 44 animals test positive for rabies in 2006, including four cats. Over the upstate parts of New York, there were 612 animals confirmed to be rabid, including six cattle, two horses, and one dog. While these numbers may seem small, the potential exists for large numbers of people to be exposed. The public health concern is of course the driving force behind mandated vaccination. At this time, the only rabies-free countries and states currently are Australia, New Zealand, the British Isles, Hawaii, Scandinavia, Cyprus, and Japan.

One of the most challenging aspects of rabies is its variable incubation period. Signs of rabies may appear anywhere from a few weeks to many months after exposure. Once they have appeared there is no cure for the disease. The most common way in which an animal becomes infected with the rabies virus is by a bite from an infected animal. Transmission has also occurred by ingestion of infected tissue or by aerosol exposure. In humans, any contact with the saliva of a suspected rabid animal is considered exposure, as the virus could enter through lacerations or defects in the skin. In most cases in the US, the infected anima transmitting the disease is a fox, skunk, raccoon, or bat. Once in the body, the virus multiplies in muscle tissue at or near the point of entry. The virus remains in the muscle for a few days, then travels to local nerves and begins its journey to the brain. How long it takes to reach the central nervous system (CNS) and brain is somewhat dependent upon the site of infection; the closer it is to the brain, the shorter the incubation period will be. Even with this guideline however, incubation times are highly variable and impossible to predict.

Ultimately the virus arrives at the spinal cord and brain. About two days after this, viral particles are present in all body secretions and the victim is fully contagious. Clinical signs appear at or soon after this point. There is no typical rabies case or set of symptoms in any species of animal, though rabies generally takes one of two forms, either furious or dumb.  Animals with furious rabies usually have an increase in activity characterized by agitation. The animal is restless and soon becomes vicious, biting at anything and everything.  A lack of coordination and tremors are often apparent as well. Convulsions, paralysis, and mental and physical exhaustion occur just prior to death.  Those with dumb rabies simply become paralyzed and die shortly thereafter. Death usually occurs within ten days.

There is no treatment for rabies. However, there is prevention in the form of a number of very effective vaccines. Some veterinary immunologists believe the rabies vaccine confers a duration of immunity that exceeds three years - in fact, as much as five or seven years. However, there have been no clinical trials - in which dogs are vaccinated and then exposed to the disease - to prove that. And vaccine companies, which normally conduct the trials, have a strong economic incentive not to. After all, how much sense does it make to spend money to prove that consumers need less of your product?

Fortunately, two pioneers of veterinary vaccine science – Drs. Jean Dodds of Hemopet in Garden Grove, California, and Ronald Schultz at University of Wisconsin School of Veterinary Medicine in Madison, together with vaccine activist Kris Christine of Maine, have formed the Rabies Challenge Fund Charitable Trust to fund clinical trials conforming to FDA vaccine licensing guidelines that will determine the duration of immunity conveyed by rabies vaccine.

"This is one of the most important projects in veterinary medicine”, notes Dr. Dodds. “It will benefit all dogs by providing evidence that protection from rabies vaccination lasts at least 5 years, thereby avoiding unnecessary revaccination with its attendant risk of debilitating adverse reactions. "

Dr. Dodds has lectured endlessly on adverse reactions associated with vaccines. They include autoimmune diseases of the thyroid, joints, blood, eyes, skin, kidney, liver, bowel and central nervous system; anaphylactic shock; aggression; seizures; epilepsy; and fibrosarcomas at injection sites, especially in cats.

Killed vaccines like those for rabies virus can trigger immediate and delayed adverse reactions (termed "vaccinosis"). While there may be immediate hypersensitivity reactions such as hives or facial swelling, other acute events tend to occur 24-72 hours after vaccination. Delayed reactions can occur up to 45 post-vaccination. Reactions that have been documented include:

• Behavior changes such as aggression and separation anxiety
• Obsessive behavior, self-mutilation, tail chewing, shadow chasing       
• Pica - eating wood, stones, earth, stool
• Destructive behavior, shredding bedding
• Seizures, epilepsy
• Fibrosarcomas at injection site
• Autoimmune diseases such as those affecting bone marrow and blood cells, joints, eyes, skin, kidney, liver, bowel, and central nervous system.
• Muscular weakness and or atrophy

Obviously, many of these reactions affect not only the dog’s health, but also behavior.  Behavioral adverse effects can compromise not only a dog’s ability to train and compete but also to live a normal life. To further complicate matters, delayed adverse effects may not be associated with the vaccination until another vaccine is given and symptoms worsen.  And should a dog already have or be incubating an illness, a vaccination can trigger a worsening or relapse.

Thanks to the generosity of dog owners, clubs, and associations, funding for the first year’s work of the Rabies Challenge Fund Trust is assured.  The study trials will begin in summer 2007 under the supervision of Dr. Schultz, who is volunteering his time as principal investigator. The University of Wisconsin will donate all the overhead costs, and staff members of Hemopet are also donating their time. In five years, Dr. Schultz will likely have the proof of what he has known all along: That the rabies vaccine provides long-term immunity. In the face of that, governments can lengthen the mandated revaccination intervals.

Forty dogs will be involved in the study at the University of Wisconsin/Madison. Twenty will be used for a five-year study and the same number for a concurrently run seven-year study. Because Drs. Dodds and Schultz believe through monitoring of rabies serologic studies and other experiences that the two rabies vaccinations that a dog typically receives by one year of age are fully effective for life, they want to initially prove that effectiveness over a five-year as well as seven-year span. The successful completion of this research conducted according to federally mandated guidelines should allow USDA licensing and state legislative acceptance of the tested rabies vaccine for more than three years.

While the adverse effects of vaccination can be serious, properly vaccinating for rabies is vital. As Dr Ron Schultz notes, "Because it is almost always fatal, rabies is the most important zoonotic disease that can be transmitted from dogs and cats to human beings.  The most effective way to prevent this zoonotic disease is by vaccinating dogs and cats.  Showing that a vaccine for rabies can provide 5 or preferably 7 years of immunity would have great significance not only in controlling rabies but more importantly in reducing the adverse vaccine reactions that can occur in dogs and cats after vaccination." And fund founder Kris Christine adds, “The results [of the studies] will provide the scientific data base which state laws should reflect in order to avoid unnecessary over vaccination while maintaining immunity to rabies in the canine community."

Although the first year’s funding is in the bank, fundraising efforts and public education campaigns continue to expand. A total of $1.5 million is needed to complete the five and seven year challenge studies, and two companion projects: the adjuvant study, and the establishment of the vaccine adverse reaction reporting system. Dr. Dodds is very encouraged by the public response. "I've been an activist for a long time," she says, "and this is the first time I've seen the public mount a grass-roots effort…” Thanks to these dedicated people and those they have inspired, in five short years, we may be administering fewer vaccinations to our dogs, without compromising their protection or the public’s health.

To donate or to learn more, visit The Rabies Challenge Fund Charitable Trust on the web at  www.rabieschallengefund.org.