The man recovered of the bite,
The dog it was that died!
—Oliver Goldsmith

Unfortunately, this is untrue! An estimated 60,000 people die each year from rabies and most cases are due to dog bites. Rabies affects largely the poor rural populations of Africa and Asia, in India, Pakistan and Bangladesh, in Sri Lanka and Thailand, the Philippines, China, Iran, and also Colombia.¹ Children under the age of fifteen are the main victims. The incidence of disease may be underreported for political reasons or because it is not recognized as the cause of death. In the United States, more than 90% of cases are due to contact with infected bats. Racoons, skunks, and foxes can also spread the disease, as do cats, cattle, horses, donkeys, sheep, goats, ferrets, and llamas.

Rabies is caused by a lyssavirus, transmitted by the saliva of infected animals, usually through bites. There follows a variable incubation period during which the virus travels along peripheral nerves to the brain and that may last months or even years. Then the victims of rabies experience a flu-like prodromal incubation period followed by the onset of the devastating symptoms of an encephalitis with serious and generally fatal neurological manifestations, either as “furious” rabies or less commonly as a paralytic form with weakness and paralysis. Patients have been described as not being able to bear the touch of anything, not even the touch of the wind or hair on the face, and to have moments of screaming from horrible terror, unable to eat or drink, confused, hallucinating, incontinent of urine, and have a final cardiac arrest. Survival from symptomatic rabies is rare. The disease has been named hydrophobia, meaning fear of water, because of the characteristic symptoms of panic and dread brought on by the inability of thirsty people to swallow because of painful spasms of the muscles in the throat and larynx. These spasms may be so intense that they have been known to cause a rupture of the esophagus.

Rabies has been known for thousands of years. Its name “rabere” comes from the Latin and means “to rage.” The earliest description comes from ancient Mesopotamia, 1930 BC, where in an Assyrian manuscript it is stated, “If a dog is mad and the authorities have brought the fact to the attention of its owner; if he does not keep it in, and it bites a man and causes his death, then the owner shall pay two-thirds of a mina of silver.”

Aristotle in his Historia Animalium wrote about rabies, and so did Galen. In the Middle Ages, people believed the disease was caused by witchcraft or demons. In the sixteenth century the Italian physician Girolamo Fracastoro proposed that rabies was caused by a “virus,” a term he coined to describe the agent causing the disease. In many parts of Europe, the situation was so bad that a reward would be offered for the destruction of stray dogs that roamed in packs. In England, as late as the nineteenth century, there was a law enabling police to seize all vagrant dogs. In France, many people, also pigs and other domestic animals, would die from being bitten by rabid foxes, while cattle would be bitten by rabid wolves and had to be destroyed.¹

In late nineteenth century Louis Pasteur conducted research to seek “the causes of putrid and contagious diseases that affect man”, convinced that rabies did not occur spontaneously but that each case derived from another.¹ At considerable risk to himself, he collected saliva from rabid animals and reproduced the disease by injecting others. He then collected their brains and spinal cords and, by keeping them in the dark at a constant temperature, produced material that could no longer cause the disease but retained its immunological potency and could be used to make a vaccine. In 1885, Pasteur successfully used this vaccine to treat a nine-year-old boy bitten by a rabid dog.

Since Pasteur’s work and discovery, rabies vaccines have been developed and refined. They are now widely available for both humans and animals. In many countries, vaccination of domestic animals, especially dogs, is mandatory to prevent the spread of the disease. Vaccination of dogs is the key to primary prevention in humans² and is feasible even in the poorest parts of the world; vaccinating bats would also be effective but is not a realistic option. Post-exposure prophylaxis through vaccines and immunoglobulin given soon after exposure to rabies virus is highly effective in preventing the development of clinical rabies.

Further reading

1. Botting JH. Animals and Medicine. Open Book Publishers, 2015.
2. Crowcroft NS and Thampi N. The prevention and management of rabies. British Medical Journal Jan 12-18, 2015; 350.