Rabies is an acute viral encephalomyelitis (inflammation of the brain and spinal cord) contracted as a result of an animal bite, usually from a rabid dog. The disease is transmitted in the saliva of infected animals, so mere licking can transfer the disease if there are also skin abrasions. Proper cleansing of the wound is of paramount importance. Untreated Rabies almost always ends in death. Wild animals, especially bats, skunks and raccoons, are the most common source of human Rabies in the USA.
After a bite the virus enters small nerve endings at the site and travels up the nerves to reach the central nervous system where it replicates and then travels to the salivary glands.
There may be no symptoms at first after a bite; but weeks or even years later Rabies - if untreated - can cause pain, fatigue, headache and fever followed by seizures, hallucinations and paralysis.
The symptoms of Rabies include hydrophobia (fear of water), convulsions and coma. The muscles associated with swallowing go into spasm, causing gagging, and are stimulated merely by the sight, sound or perception of water.
The disease is endemic in groups of wild animals all over the world, except the UK and Australia. Wild animals can bite and infect domestic animals. Human Rabies is rare in the USA, where there have been only 39 reported cases since 1990.
Most cases occur in India, where the WHO estimate that 30,000 cases are reported each year.
People most at risk of Rabies include veterinary surgeons and animal handlers.
The incubation period may last between 2 weeks to 6 months.