Rabies is a well known highly contagious disease which has fatal consequences and is caused by the rabies virus. The rabies virus infects most types of warm blooded animals such as foxes, cats, dogs, horses, some livestock and bats but also humans and so is known as a zoonotic disease. The level of resistance against it varies from species to species. Death is usually inevitable and there is no cure for the virus, thus allowing it to be known as a very dangerous disease. The virus is transmitted via the saliva of the infected organism, usually from a bite, and it makes its way towards the nervous system found in the spinal cord and then enters the brain. This is when the symptoms are eventually presented. It can take around two to eight weeks before any clinical signs are observed following infection. Animals most susceptible are those who often have contact with wildlife although it is relatively rare in the UK since travel control requires a rabies check and vaccination upon entering the country for most animals. People who are most at risk are veterinarians, zoologists and others who work closely with animals and so they are often vaccinated against the rabies virus. Vaccination is strongly recommended to animals and people in high risk areas.
If an infected animal bites another then it is very likely that the virus has been transmitted through the saliva. This is the most common method of transmittance. If an area is densely occupied by infected animals such as bats, without adequate ventilation, then it is possible for the virus to spread through aerosol droplets. Wild foxes, dogs, bats and raccoons are usually held responsible for the spread of the disease. If the dead tissue of an animal is eaten within the same day of its death then once again, it is possible to transmit the disease.
The rabies virus does not survive for long outside the host which is fortunate. Wounds suspected to be inflicted by an animal with rabies should be immediately washed with soap and water and medical assistance is most definitely required. Any animal which has the virus is often either euthanized or isolated for a period of six months or more depending on the regulations of that country or state.
Rabies has three main stages when referring to its symptoms. It is possible to go through all or just one of the stages. These are the prodromal phase, the furious phase and the paralytic phase.
This is the first wave of symptoms and, for dogs, lasts about two to three days. The animal may lick the wound, have slow eye reflexes and may have a high temperature. More commonly, the animal may be anxious, nervous and become shy or docile. This is usually more noticeable in animals which were previously more aggressive in nature prior to infection. The animal will also prefer solitude and shy away from humans.
The Furious Phase can last between two and four days and is the most dangerous when referring to other animals it can come into contact with. As inferred from the name, the animal becomes aggressive and chews or eats most things they can get a hold of. They will become restless, pacing back and forth and may lash out and bite people or other animals quite suddenly and without warning. The dog will be generally quite irritable and may bark a lot but it is cats which are more prone to getting this phase.
Lasting between two to four days it is also known as the “dumb phase”. The first sign is usually seen as drooling around the mouth and an inability to swallow. This is where the fear, in some humans of water, is presented due to a subconscious fear of choking. Choking sounds that do come from the animal lead owners into thinking that there is an object stuck in the animal’s throat. Foaming at the mouth is observed and one or both sides of the face become paralysed. There is also evidence of respiratory failure, coma and depression which then inevitably lead to death.
The incubation period of the virus depends on the species but usually results in death. Once the clinical signs are presented there is little any one can do for the survival of the animal.
Treatment and Prevention
There is no cure to treatment for rabies and death is almost always a certainty. Some humans and dogs have been known to survive though this is extremely rare. If an animal has been vaccinated and is bitten then it should be isolated and revaccinated. No matter how docile a pet prior to infection, care should be taken around the animal since it has been known for owners to catch the disease from their beloved pets. If not vaccinated euthanasia is recommended and then tested for rabies.
Vaccination is the best method for prevention. The saying “prevention is better than cure” does not relate here so instead we must say prevention is better than nothing at all. In some countries it is obligatory to vaccinate against rabies and unvaccinated dogs are not allowed to enter the UK. Humans thought to be at greater risk are advised to have the vaccination. Vaccination is extremely effective in terms of preventing the spread of the disease.
Diagnosis and Prognosis
Rabies is diagnosed by euthanizing the animal and then testing the brain under a microscope. Currently, blood tests cannot be used and so euthanasia remains the usual option. The prognosis of the rabies disease is very poor and death usually occurs within ten days time.