Rabies is a viral disease of mammals that infects the central nervous system and causes disease in the brain and ultimately death. The disease is almost always fatal once clinical signs start. Rabies is present on all continents except Antarctica and occurs in more than 150 countries. Each year about 59,00 people die from rabies infection. Rabies is entirely preventable by appropriate vaccination.
In theory, any mammal can be infected with the Rabies virus. Rabies can infect domestic and wild animals and can be spread to people through bites or scratches, usually via saliva. In Canada, the animals that most often transmit rabies are bats, skunks and foxes. The majority of cases are found in Ontario, but the disease has also been seen in most of the provinces and territories.
Rabies can also infect humans. Rabies is a neglected disease of poor and vulnerable populations whose deaths are rarely reported and where human vaccines and immunoglobulin are not readily available or accessible. In 99% of human cases, the rabies virus is transmitted by domestic dogs, especially in Asia and Africa. In the Americas, bats are the source of most human rabies deaths. People are usually infected following a deep bite or scratch by an infected animal.
The incubation period for rabies is typically 1 – 3 months but can vary from less than 1 week to more than 1 year. The initial symptoms are fever and pain. There can be an unusual prickling or tingling sensation at the wound site. As the virus spreads through the central nervous system, progressive, fatal inflammation of the brain and spinal cord develops. There are 2 forms of the disease seen in people. In the “furious ” form, people exhibit signs of hyperactivity and excited behaviour. There can be confusion, partial paralysis , difficulty swallowing, hypersalivation and hallucination. After a few days, death occurs by cardiorespiratory arrest.
In “paralytic” rabies, the muscles gradually become paralyzed, starting at the site of the wound. A coma slowly develops and eventually death occurs.
There are no tests available to diagnose rabies infection in humans before the onset of clinical disease.
In animals, rabies is diagnosed by using a direct fluorescent antibody test which looks for the presence of rabies virus antigens in brain tissue. The test requires that the animal be euthanized.
Any animal bitten or scratched by either a wild carnivorous mammal or a bat that is not available for testing should be regarded as having been exposed to rabies. Dogs and cats that are currently vaccinated should be kept under observation for 45 days. Unvaccinated animals exposed to a rabid animal should be either euthanized or placed in strict isolation for 6 months and vaccinated one month before being released.
Rabies is a vaccine preventable disease. Vaccinating dogs is the most cost-effective strategy for preventing rabies in people. Preventive immunization in people is safe and effective. Vaccination for rabies is recommended for travelers spending a lot time outdoors, especially in rural areas or living in areas with a significant risk of exposure to dog bites. Pre-exposure immunization is also recommended for people in certain high risk occupations.
Post-exposure Prophylaxis (PEP)
PEP refers to the treatment of a bite victim that is started immediately after exposure to rabies in order to prevent the virus from entering the central nervous system. Effective treatment soon after exposure to rabies can prevent the onset of symptoms and death.
What can you do?
The first and most important thing you can do is to have your pets vaccinated against the rabies virus. The vaccine is safe and effective and helps to prevent the spread of rabies to other animals. Limiting your pets’ access to wild animals is also important to prevent the possibility of them being exposed to rabies. By spaying and neutering your pets, you help to decrease the number of stray animals. By reporting any stray or ill animals to animal control, you reduce the possibility of human exposure to rabies.
In 2006, a group of researchers and professionals formed a global Alliance for Rabies Control and started the World Rabies Day initiative. The goal of this outreach is to mobilize awareness and resources in support of human rabies prevention and animal rabies control. In many countries, the cost of a vaccine to prevent rabies disease in a dog is less than one US dollar. Combating rabies in dogs will go a long way in reducing the disease in people.