What is Rabies?
Rabies is a disease caused by a virus which belongs to a family of viruses called Rhabdoviruses. Rhabdoviruses are RNA (ribonucleic acid) viruses which are encapsulated within a rod-shaped envelope. Indeed, the name comes from the Greek (Rhabdos) meaning 'rod'. Rabies can infect mammals as well as birds. Most rabies infections in humans are caused by dog bites, though cats may be affected also by bats and other wild animals. If not treated soon after infection, rabies will result in death, as there is no treatment for the later (active) stages of the disease. There are only a handful of known cases when infected individuals survived. Following infection (dog bite) the virus is dormant at the site of the bite for a number of weeks or even months, incubating mostly within the muscles. After that time, the virus gains access to the peripheral neurons of the nervous system and spreads to the spinal cord. From there it moves rapidly into the brain. At this point, rabies changes into an active infection. Spread within the brain is rapid and victims will often fall into a coma which almost inevitably leads to death. In the active stage, the virus also spreads into the peripheral tissues (skin, saliva, eyes etc), and the risk of contagion increases.
The incubation time of rabies depends on a number of factors:
- The dose of the virus transmitted
- The site of the infection (ie the distance from the brain)
- The age of the victim
- The victim's overall health
One of the major problems with rabies infection is the lack of the immune response (That is, the body's defenses do not react to the invading virus). The virus is not cytolytic, that means it does not kill infected cells but rather hides within them. Therefore T cell responses, one of the body's main defenses against infection, are not effective. The body does start producing antibodies, but only in the late stages of the disease when the load of the virus is very large. Vaccination forces the immune system to produce antibodies early which can eliminate the virus during the very first stages of the disease.
The classical symptoms of rabies are: fever, headache, pain or itching at the bite site. Two to 10 days after this first manifestation of the disease, the neurological symptoms start. One of the most classic of these symptoms is fear of water, which is why the disease is sometimes known as hydrophobia. There follow generalized seizures, disorientation, hallucination and coma.
The UK is one of the very few countries which is free of rabies, which means that domestic animals are not routinely vaccinated in England. This is also the reason why quarantine was introduced. The UK is not only rabies-free, but desperately keen to remain so. This means that the authorities take a very dim view of attempts to bring in animals which are not certifiably clear of the disease. Because rabies can remain inactive for so long, and the early stages have so few symptoms, vaccination and quarantine are the ONLY ways to be certain. Just saying that there is 'no way' your Fluffy could have been infected will not save you from rightly receiving a severe punishment.
Pain, confusion and desperation will make any animal aggressive. This is particularly true for dogs and cats. Once they enter the active stage of the disease and the virus is established in the brain they will become progressively restless, irritable and hyperesponsive to light and noise. This stage of the disease normally lasts from 1 to 7 days. At this time they are particularly dangerous and difficult to control. Sometimes within that week they will collapse into a coma and die.
The information supplied here is intended as a guideline only. Make sure you discuss all these issues with your vet who will be able to give you the most up to date information and advise you on the vaccinations.