Stray dog rabies vaccination debate
In response to an ongoing rabies outbreak, Thailand has launched a program to vaccinate stray dogs. A posting to ProMed questioned this approach.
"The authorities plan to catch stray dogs, to vaccinate them, and to release them. This is inadvisable, since rabies incubation in dogs may extend to a year, although it is mostly between 2-3 months. Catching an animal which might already be incubating an infection and then vaccinating it will not only not protect the animal but put at risk the lives of people led to believe that the animal is safe", wrote Maya Kimchi.
True, you could not guarantee that a dog that was caught was not incubating rabies, and in that case, vaccination of the dog would not be effective. However, the odds of this are very low, and it doesn't make sense to not vaccinate. The worst case scenario is you have a dog that develops rabies, that would have developed rabies anyway, but it is less likely to spread it to the other dogs you've vaccinated. There would be no risk to people vaccinating the dog since it wouldn't be infectious at that point.
"In an endemic country where there are many stray dogs and many cases of rabies in animals and humans, as in Thailand, the solution of [the problem] of stray dogs is to reduce their number and carry out mass vaccination to all owned dogs, cats, and ferrets."
The problem is the stray animals. Vaccination of pets is very much an important component, but vaccinating pets and ignoring the reservoir (stray dogs) doesn't help in the long run.
"If a country decides to avoid the elimination of stray dogs, it will be necessary to catch them, to vaccinate them, and to [quarantine] them for 6 months at a minimum, and only subsequently, together with birth control measures (castration/sterilization), release them for adoption, after registration in a database for further control."
Here's what the World Health Organization's Expert Consultation on Rabies says:
"Mass canine vaccination campaigns have been the most effective measure for controlling canine rabies."
"There is no evidence that removal of dogs alone has ever had a significant impact on dog population densities or the spread of rabies. The population turnover of dogs may be so high that even the highest recorded removal rates are easily compensated for by increased survival rates."
and
"Attempts to control dog populations through culling, without alteration o f habitat and resource availability, have generally been unsuccessful."
Culling is rarely the answer. Vaccination of stray and pet dogs, education of the public to avoid contact with stray dogs, controlling roaming of pet dogs to decrease control with strays, educating the public about the need for post-exposure prophylaxis if they have been bitten by a stray dog and ensuring that the healthcare system has the appropriate resources (e.g. available rabies antibody and vacccine) and knowledge to handle exposed individuals is the best approach.
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On the whole I agree with your comments that mass vaccination is still the way to go, as opposed to mass culling of stray dogs. However, I take exception to the comment "There would be no risk to people vaccinating [stray dogs] since [the dogs] wouldn't be infectious at that point." The reason for the mass vaccination program is that the rabies risk in the stray population is too high and it's resulting in human cases/exposure. Dogs cannot transmit the virus until they develop clinical signs, but these signs do not necessarily come on suddenly and the signs can be highly variable. Particularly when dealing with trapped, unfamiliar feral dogs I think it is more than possible to miss early clinical signs of rabies, even though the dog is infectious.
As I said, I still think mass vaccination is the best route, but realistically the people doing the trapping and vaccinating are certainly at risk. In my opinion, an important part of this program would be ensuring that the people in these high-risk positions are properly vaccinated against rabies themselves, that at least enough post-exposure prophylaxis treatment is available for them if they are bitten by a stray dog, and that any dog that bites a worker during the course of the program IS quarantined for at least 10 days to ensure it was not infectious at the time of the bite.