Saliva of vaccinated dogs and apparently healthy may still be an avenue to contract rabies, a disease responsible for 55,000 annual human deaths globally, a study has said.
Experts said they have characterised rabies virus from the saliva of apparently healthy domestic dogs in the country, and as such the need for a widespread surveillance to identify prospective candidates for the development of rabies vaccines for effective control of the disease in Nigeria.
Professor David Olaleye, a virologist, reacting to a study that found 22.2 per cent of vaccinated and apparently healthy dogs having rabies, said the situation is worrisome given the fatality of rabies in humans.
The study had tested the saliva of 54 dogs and found 33.3 per cent of the presumed vaccinated dogs (25) had classical rabies virus in their saliva, thus underscoring the reservoir status of domestic dogs in the incidence, distribution, and possible control of rabies in Nigeria.
The study presented at the sixth Uniibadan Conference of Biomedical Research indicated that the classical rabies virus was similar to those circulating in China, Korea and France, suggesting that they may have probably been imported into Nigeria from these countries.
It was entitled “Detection of Rabies Lyssavirus in the Saliva of Vaccinated Dogs in Ibadan, Nigeria and its Potential Public Health Risks”. It involved Dr Ishaya Tekkil in collaboration with Professors Georgina Odaibo and David Olaleye.
Professor Olaleye, a co-author of the study, declared that the presence of rabies in the saliva of vaccinated dogs could be due to a failure of vaccines used to control the disease in Nigeria, saying the major risk lies in people assuming that “one’s a dog is vaccinated, it is safe from rabies.”
Rabies transmission occurs when saliva containing the rabies virus is introduced into an opening in the skin, usually through the bite of a rabid animal. Though rare, transmission could occur through infected saliva contacting a scratch or other break in the skin.
The don said that a dog is vaccinated does not mean the dog is immunised against rabies, adding: “There is a whole lot of difference between vaccination and immunisation. Like in humans, you can find cases of vaccinated individuals that are not immunised.”
According to him: “A lot of things, including the vaccine ineffectiveness and even the dog being immune-suppressed may be the reason. Also, the rabies vaccine administered may not be protective against all the circulating strains of rabies virus.
“If in doubt, the dog can be taken to the veterinary clinic to ascertain its rabies status. After the second week of receiving the three doses of rabies vaccine, the level of the antibody can be checked in the dog’s blood sample to be sure that such a dog is protected and they will not transmit the virus.”
The virologist, however, called for mass vaccination of all domestic dogs in Nigeria and a widespread surveillance to identify prospective candidates for the development of effective rabies vaccines in Nigeria.