Most people, at some point in their lives, have seen or heard rumors of the mad neighborhood cat or skunk that had to be destroyed because of suspected rabies. We warily watch the bats, raccoons and skunks in our backyards, suspicious of their ability to carry deadly disease. We worry that our cats will catch a rabies-infected bat or our dogs will get in a scrap with an infected raccoon.
We also worry about the safety of the rabies vaccine and rightly so: it is perhaps the most lethal of them all and threatens our dogs with loss of health and even loss of life. Some of us take great care to avoid any wildlife at all while others have a more cavalier attitude and find comfort in the fact that there really aren’t that many cases of rabies in dogs each year.
The dog would have to find an infected animal in the first place and then the virus would have to be spread via a bite: those can be pretty long odds for most dogs. In fact, in the five years between 1997 and 2001, most states reported about one case of a rabid dog each year (JAVMA, Vol 235, No. 6, September 15, 2009). Regardless, rabies continues to be one of the most feared zoonotic diseases.
In an effort to control the spread of rabies in wildlife, the US and Canada regularly dump rabies-laced baits into rural areas. You may see the planes fly by, dropping their little fish-meal covered bait bombs in the forests and fields surrounding your home. You may even feel a little safer, knowing that the foxes, skunks and raccoons in your neighborhood might now be a little less likely to pass rabies on to your dog. You may be wrong and both you and your dog may now be in even more danger than before. Those little baits may pack a lot more punch than anyone ever suspected.
These baits are recombinant vaccinia/rabies glycoprotein, which is an oral vaccine intended to control rabies in wildlife. Recombinant means they have spliced two viruses together. In addition to the rabies virus, these baits also carry vaccinia which is the immunizing agent used in smallpox vaccines. This combination of two viruses is an example of a genetically modified vaccine. Genetically modified vaccines have some pretty nasty and unpredictable habits. The first problem is the viruses in rabies baits are live and that can cause some problems.
Dangers of the Live Virus
The live virus vaccines found in the oral rabies baits are supposedly comprised of a weakened strain of rabies. This is theoretically done by recombining it with the pox virus. If that is true and if all goes well, the body will form an immune response to the vaccine, and the animal that eats the bait will be successfully vaccinated against rabies. That’s what happens when things go right.
When things go wrong, the animal is in a weakened state when he consumes the bait. When modified live vaccines are given to animals that are ill or stressed at the time of vaccination, there is a very real risk of vaccine failure or the vaccine actually producing the disease it is supposed to protect against. Alternately, any latent disease the animal may be harboring will become a full blown disease once he consumes the bait because of the resulting stress on his immune system. With humans encroaching on their territory at an alarming rate, it is likely safe to say that many members of the wildlife population are stressed and malnourished, making them susceptible to vaccine-induced illness.
Dr. Michael Fox wrote an outstanding account of the dangers of vaccines (Genetically Modified and Engineered Live Virus Vaccines: Public Health and Animal Welfare Concerns) where he notes:
Lions in Serengeti National Park, followed by those in the Masai Mara of Kenya, died like flies in 1994 from a new strain of canine distemper (CD). This followed a period between 1992-94 when domestic dogs of agropastoralists and farmers to the west, and Maasai pastoralists’ dogs to the east of the SNP boundaries, were being with experimentally vaccinated against rabies during a vaccination trial. The same new strain of CD in the rabies vaccinated domestic dogs was subsequently found in the lions and was then found to have caused the death from CD of most of a captive colony of wild dogs in Mkomzai Game Reserve in Tanzania in 2000-2001: these wild dogs had been vaccinated against CD.
Following this, in 2007 the same new CD strain was for the first time identified in free living African wild dogs in Maasai areas to the east of SNP where mass vaccinations of local domestic dogs were being carried out against CD, CPV and rabies. The outbreak confirmed in one large wild dog pack was associated with high mortality of this highly endangered canid species.
That’s not the only danger. Add to that the danger of pairing two viruses together to make one vaccine. The World Health Organization states that the widespread use of vaccinia against smallpox protection is not recommended due to potentially serious complications, yet we are bringing it back into the environment with these vaccines. In 2000, a pregnant woman found her dog eating one of these wildlife baits. When she tried to take it off the dog, she received a small puncture wound to her finger and a minor abrasion to her forearm. Eight days later, she was hospitalized with growing blisters, lesions and necrosis. Thankfully after five days of hospitalization, she recovered and her baby showed no obvious signs of trauma.