Challa Babu jolts ferociously from side to side, thrashing his head against a flimsy hospital bed as rabies consumes him. His eyes are wide, white spittle clings to the sides of his mouth and he bellows, pleadingly, between growls forced through clenched teeth. After an agonising three hours the 16-year-old is dead.

For 30 days his parents were repeatedly turned away from hospitals in Andhra Pradesh because they did not have 400 rupees (£5) for a vaccine. He was condemned to die of an antiquated disease, while modern technology meant the tragedy could be committed to film. Indian television crews immortalised his final moments for the internet.

The World Health Organisation (WHO) estimates there are 55,000 rabies deaths every year. According to the Global Alliance for Rabies Control, the total is 70,000, with 10 million treated for bites from potentially infected dogs. India has the highest annual rate of deaths in Asia: 20,000. The majority of victims are under 15. Around the world, rabies kills around 100 children every day. In Africa and Asia alone, the disease (the most potently lethal known on earth) threatens 3.3 billion people – just under half the world's population.

The risks lurking in these regions often elude visitors from countries with tighter rabies controls: Australian and European tourists in places such as India and Bali, and US servicemen and women in Afghanistan.

It was stray dogs that attacked specialist soldier Kevin Shumaker's remote Afghan base in the mountains of Chamanki in January. One plunged its fangs into the 24-year-old Californian's hand as he tried to break up a grisly fight. He needed six shots, but was only given three as the final half of the treatment had expired.

Months later his arm lurched into the grips of an intolerable tingling, his throat constricted and, finally, his brain haemorrhaged. He died in Fort Drum, New York on 31 August. "American soldiers don't realise the disease is much more common in Asian countries. So they sometimes take a chance and take care of a dog because they want companionship," says Major Loren Adams, veterinarian for soldiers serving in Afghanistan.

In south-east Asia, Bali is known to be an island of enchanting beaches, mesmerising temples, and now rabies. It had no history of the virus until 2008 but, within six months, no part of the island was left unaffected. The culprit was most likely a stray dog that had climbed aboard a trade ship from Indonesia. Hundreds of travellers from Australia and other countries have cut short their trips after attacks. Up to 300,000 dogs roam the island, lurking in back alleys, with potentially rabid drool bubbling in their mouths.

Bali has counted 132 deaths since the outbreak, but lacks proper records – so the number could be far higher. Demand for the vaccine far outstrips supply, meaning tourists need to make a frantic dash home for jabs. Rabies must be treated with a programme of injections very swiftly, preferably within 24 hours (they are given in the hips, not the stomach). Once symptoms show, death is inevitable.

The symptoms are like something from a horror film. Intense fear of air and water, throat surging into racking spasms at the sight of liquid and the gentlest of draughts feeling like a bomb blast, coupled with a frenzied energy and frothing at the mouth.

The post-bite jab was invented 126 years ago, but it has a huge price tag in the developing world: in Asia, it costs $49 (£32), and $40 in Africa, where the average daily income is between $1-$2. It is cheaper in India, which has developed its own vaccine.

Sarah Cleaveland, professor of comparative epidemiology at the University of Glasgow, found what she describes as a "classic rabies story" in northern Tanzania. A farmer had weeping bites and scratches carved into his back. He had been bitten by his rabid daughter. By the time his family scraped together money for treatment, it was too late – she was devoured by the disease, but he survived. Another family she met had enough money for one course of treatment after their five children were attacked by rabid dogs. They had just one day to choose which child to save.

Dr François-Xavier Meslin, head of neglected zoonotic diseases at the World Health Organisation, says patients are frequently condemned to a painful, brutal and often isolated death because they have no money.

Dogs are responsible for 97 per cent of human rabies cases. "They are the best conveyors of the virus," Dr Meslin says. While rabies might eventually be eliminated in dogs, it can never be stamped out in the wild, he says.

The US Centers for Disease Control spends $300m a year on rabies, yet people continue to die of the disease. America has virtually eradicated the virus in domestic animals, but wild creatures still pose a threat. Bats, raccoons and groundhogs are some of the worst culprits for transmitting the disease. Every year 40,000 Americans need a $1,000 series of shots. About 7,000 animals die of the disease in the US each year; Hawaii is the only state where there is no rabies. Around the world, Australia and Antarctica are also rabies-free.

Rabies is a virus that targets the brain and spinal cord. It is found in the saliva of infected animals and is most often transferred through a bite. Birds, fish, insects, reptiles and other non-mammals do not get rabies. It is rare in chipmunks, gerbils, guinea pigs, hamsters, mice, rabbits, rats and squirrels. In Cuba, the Dominican Republic, Haiti, Puerto Rico and Grenada, the main source is the mongoose. A bat was responsible for the only recent UK death: conservation worker David Macrae died in Angus in 2002 – the first case of indigenous rabies in Britain since 1902.

For Dr Meslin, attempting to draw attention to rabies is like wailing in a wind-tunnel. While any part of the world has the disease, vast swathes of the planet risk an outbreak, but other short-term epidemics get more attention. "Rabies is not as attractive to donors as other zoonotic diseases of recent years, such as Sars [a form of pneumonia]," he says.

The cost of eliminating rabies in Africa, says Peter Costa of the Global Alliance for Rabies Control, is around $1 per head – just over $1bn. To put that into context, malaria, which kills 881,000 each year, needs $60bn over the next 10 years, according to the Global Partnership for a Malaria-Free World. But even such funds would not guarantee ridding any region of the disease.

Specialists hope to mobilise efforts to combat the disease on World Rabies Day this Wednesday. The date commemorates the death of Louis Pasteur, the scientist who invented the first effective vaccine in 1885.

British victims: Broader travel triples caseload

The number of British holidaymakers having near misses with potentially rabid animals has tripled during the past decade, according to figures given to The Independent on Sunday by the Health Protection Agency. The disturbing new figures show how more than 1,000 Britons were treated last year after possibly being exposed to the deadly virus – usually after being bitten or scratched while overseas.

Overall,1,055 people were treated last year – up 18 per cent from 897 in 2008-09 and a record high. The figure has risen more than threefold since 2000, when 295 cases were recorded.

The rise reflects the increase in travel to countries where the virus is rife: up 67 per cent between 2000 and 2008, according to data from the International Passenger Survey. More than half of potential exposures in 2008-09 occurred in Asia, in countries such as India, Thailand and Turkey.

Dr Hilary Kirkbride, of the HPA, warned: "Travellers should be aware of the risk of rabies and avoid contact with animals in countries where rabies occurs."

But the threat of rabies is also present in Britain: 90 people were treated after coming into contact with bats, according to a study of 897 cases logged by the agency between July 2008 and 2009.