Rabies is a viral disease that is transmitted between animals, most commonly through aggressive behavior such as biting. The virus affects the central nervous system (CNS) and causes hyperactivity and possible paralysis of the limbs due to motor neuron damage.
The rabies virus replicates and becomes concentrated in the saliva of infected animals, which is the reason why the infection is usually transmitted via a bite. In most cases, rabies causes death to infected animals by respiratory arrest.
Signs of rabies
The first signs of rabies in infected animals may also be indicative of other health conditions and are not specific to the often fatal condition. These initial symptoms may include lethargy, fever, vomiting, and signs of anorexia.
As the infection progresses, the symptoms become more specific to rabies virus and animals may include:
- Cerebral dysfunction
- Cranial nerve dysfunction
- Breathing and swallowing difficulty
- Excessing salivation
- Aggressive and abnormal behavior
From the emergence of these symptoms, there is no known cure for the rabies virus and the disease is almost always fatal for the affected animals. Care should be taken that infected animals are not presented with the opportunity to transmit the infection to other animals or humans.
Rabies has been associated with dogs throughout history and accounts for the majority of humans affected by the disease today due to stray dog bites. Even early in history, it was understood that dogs could pass on the infection; therefore, dog owners were often required to take precautions to prevent a dog in their possession from biting people, often with the use of a muzzle.
Since the introduction of rabies vaccinations for domestic pets in the 20th century, the prevalence of rabies amongst dogs has greatly reduced in many countries throughout the world. In some regions, such as India and other areas of Asia, dogs remain a large threat to humans for rabies, as particular cultural beliefs have prevented control of the disease.
Rabies virus is also very common among bats and currently accounts for the only animal able to transmit the infection to humans in some regions like Australia. The Australian Bat Lyssavirus (ABLV) was discovered in 1996, prior to which there had been no reported cases of rabies in Australia. Like most animals, bats transmit the rabies virus by biting other animals or humans.
Rabies can affect many warm-blooded mammals including:
Any bite from a wild animal that may be infected with the rabies virus should be treated with care. To this end, individuals should be subjected to post-exposure prophylaxis to prevent the growth of the virus in the new host.
Animal to human infection
As rabies is a zoonotic disease, all human infections of this virus occur as a result of contact with infected animals. From a theoretical perspective, it is possible for an infected human to pass the virus on to another human; however, there have been no cases reported of this occurring.
As a result, reducing the prevalence of rabies among animals will help to minimize the impact of the disease on the human population. This has begun in some areas of the world, particularly in Europe, where rabies in animals was once prevalent but has lowered significantly since the introduction of vaccines.