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“A CHILD dying of rabies is a particularly dreadful thing,” says Neil Kennedy, a paediatrician from Belfast, UK. Kennedy last treated a person with rabies in Malawi in East Africa. The patient was a 10-year-old boy he calls David, who had been brought to the hospital after several bouts of delirium. Soon David began to show the telltale sign of the disease: being unable to swallow water and even his own saliva, leaving him foaming at the mouth. All that could be done was to keep him hydrated with a drip and sedated for the few days it took him to die.

The manner of death was horrible, but even worse was the knowledge that it was completely needless, says Kennedy. Rabies is one of the most lethal infectious diseases known to humankind. Once symptoms appear, it is almost always fatal. It kills 60,000 people a year, and disproportionately affects children. Almost all the deaths are in Africa and Asia, where people lack access to the vaccine and treatment.

Yet it may be possible to nearly eliminate human deaths from rabies – not by treating people, or tackling the many wild species that carry the disease, but by targeting dogs. Several small-scale trials suggest that this should make elimination possible in just a few years. If such an approach works, rabies would become only the third infectious disease to be eliminated, after smallpox and cattle disease rinderpest. “It’s going to take a sustained effort for several years, but this is definitely achievable,” says Kennedy.

Rabies is an age-old foe. While many animals from bats and skunks to monkeys and raccoons can carry the disease, in most of these species, the virus is specially adapted to the host. It is only rabies from dogs that poses a significant threat to people, causing over 95 per cent of human deaths, mainly through bites from dogs whose saliva is infected. In ancient Mesopotamia, failing to stop your rabid dog biting someone could land you with a fine of up to 40 shekels of silver: enough to buy . There was good reason for this law. At the time, the only remedy for someone who was bitten was holy water and prayer.

“In ancient Mesopotamia, the only remedy for someone who was bitten by a rabid dog was holy water and prayer”

A combined vaccine and treatment has been available since 1885, when Louis Pasteur treated a French boy of about David’s age who had been bitten by a rabid dog. Pasteur’s vaccine was made from the dried spinal cord of an infected rabbit, and, after several applications, . Like that vaccine, the modern equivalent can be used as both prevention and treatment because of an unusual feature of the disease: the virus doesn’t immediately take hold after entering the body. It can take weeks to travel up the nerves from the bite wound into the spinal cord or brain.

This slow process means that if someone bitten by a rabid animal gets treatment – up to five shots over a month – fast enough, they won’t get sick. Thanks to this remedy, in the US, for instance, there are only , usually because someone was bitten by a wild animal that wasn’t obviously rabid.

The vast majority of human deaths from rabies today are in Africa and Asia, where most dogs are allowed to wander the streets. The concept of dog ownership is often looser than in the West. People might feed their favourite mutt with scraps and perhaps give it a bed for the night so it acts as a guard dog, but there’s not nearly as much mollycoddling – or money for rabies vaccines. Similarly, if someone gets bitten, treatment with the rabies shots may be out of reach. In countries like Malawi, one of the poorest in the world, treatment costs more than a month’s wages. Even if a family can afford it, local hospitals may not have it in stock.

That’s why rabies control in developing countries often focuses on reducing the dog population. A common community response to a rabies outbreak is a cull, which can be as brutal as people seeking out dogs and clubbing them over the head.

But culling isn’t a long-term solution, says , UK, who has studied rabies transmission in Tanzania. It does lead to a temporary drop in numbers, but other dogs soon move in to fill the gap. Street dogs breed so quickly that by the time half have been killed, the rest have had enough puppies to replace them.

“I saw children playing and I thought, ‘This is worse than a tiger loose in the village’”

What works better is leaving the dogs alive and vaccinating them. The vaccine for dogs is relatively cheap: around 25 cents a dose, compared with over $100 for a course of human treatment. If enough dogs in an area can be vaccinated every year for several years, there is a good chance of ridding the population of the virus for good.

A factor that works in the favour of such programmes is that, unlike a highly contagious disease such as measles, where each infected person passes it on to about 15 others, a rabid dog only infects an average of 1.2 others before it dies. This means that if 70 per cent of dogs in an area can be vaccinated, the disease will peter out – it’s likely that the one or two dogs bitten by each infected animal will have immunity. And without the gap in the population left by a cull, there is no space for dogs from outside to move in, bringing the virus with them.

Reservoir dogs

This approach hasn’t always been taken seriously in the past because of the worry that so many other animals carry the virus. It has been argued that even if the disease were eradicated from one species, there will always be a reservoir in nature to replenish it. But that’s misguided, says , a veterinary epidemiologist at the University of Glasgow. While a dog can be infected by a bite from a bat and might then bite a human, the bat variant won’t go on being passed from dog to dog because the bat rabies virus isn’t adapted to dogs, so is transmitted from one to another even less efficiently than the dog variant. she says.

Proof comes from the great success that many South American and Caribbean countries have had using this approach. Typically, they have set up free vaccination clinics in the community for people to bring in their dogs, who are then given a distinctive red collar. This has worked so well in Uruguay, Chile and southern Brazil that they have been able to stop mass dog vaccination campaigns. Several other countries are still vaccinating, but have seen no or very few human deaths from dog rabies for many years. The list includes Argentina, Colombia, Costa Rica, Ecuador, Mexico, Nicaragua, Panama and Paraguay.

Other places, by contrast, have made little progress despite a great deal of effort. For instance, the Indonesian island of Bali has been struggling to rid itself of rabies for nearly a decade using a mix of vaccination and culls. Hampson, who has advised Bali on rabies control, argues that the two-pronged approach is part of the problem. Indiscriminate culling hinders vaccination campaigns, she says, because when vaccinated dogs are killed, it lowers herd immunity below the target 70 per cent level. It can also antagonise the public, who may be wary of bringing their dogs in for vaccination if they have seen other dogs being killed. At times, dogs were being shot with strychnine-loaded blow darts. “It’s a horrific way to die,” says Hampson. “People were upset.”

On Bali, eradication should be easier since it’s an island. By comparison, it seems India has a huge task on its hands. This country has a disproportionate share of global rabies deaths – 35 per cent of the total – mainly because of its high numbers of street dogs. Inadequate rubbish collection in towns and cities means they often feed off food waste. Some rubbish dumps are no-go areas after dark because of ferocious packs of dogs, says , a vet based in Fordingbridge in the UK, who also works in India.

Not only does India have the highest number of street dogs, but the animals are also wilder. Those that are semi-owned tend to have a looser bond with the person who feeds them. This means that person may well be incapable of catching their dog to bring it to a clinic for vaccination.

Gamble became passionate about eradicating rabies when doing charity work in India in 2012. A rabid dog was brought to him to be killed and he was told that it had bitten three other dogs that couldn’t be caught. “I saw children playing in the dirt nearby, and thought these dogs are worse than having a tiger loose in the village,” he says.

So Gamble hatched a plan to vaccinate India’s street dogs by catching them in nets, jabbing them through the mesh and marking them with spray paint. Back in the UK, he set up a charity called Mission Rabies, aiming to provide proof of principle that could work even in India.

The approach has so far been used successfully in Goa, India’s smallest state. It is a good target as it is bounded by the ocean on one side and mountains on the other. There, human rabies deaths have been reduced from 14 in 2014 to four in 2015 and one in 2016. Two years ago, the Goan government began funding half the costs. “They never would have done that if we hadn’t shown it was possible,” says , a UK vet who works for Mission Rabies.

The charity has now expanded operations into Blantyre in Malawi, motivated by . That city, too, has since seen a dramatic fall in rabies cases. David was the last person at Kennedy’s hospital to be treated for rabies, and he was bitten when staying with relatives in the countryside.

While these successes are encouraging, they are still relatively small-scale projects. Real progress in eliminating dog rabies will only happen with buy-in from national governments and international bodies. Rabies isn’t as tempting a target as smallpox, for instance, which had no animal hosts to keep the disease going (see “Goodbye diseases“). That’s partly because even when a country has got rid of dog rabies, doctors still need to watch out for any cases in people, because of the handful of infections that come from wildlife. Yet wiping out rabies would still save by avoiding the need to give the human vaccine as treatment for dog bites. It would also avoid the unnecessary deaths of 60,000 people a year who are too poor to get that treatment.

Still, there are many other neglected tropical diseases crying out for more funding, so those campaigning for rabies elimination have to fight its corner. A shift came at the end of 2015 when the World Health Organization and several other international bodies set the goal of ending all human .

The WHO can’t dole out funds, but Cleaveland says the edict is galvanising people into action – helping to get governments on board and non-governmental organisations to open their purses. “This is a no-brainer,” she says. “Rabies has the highest fatality rate of any disease and it’s totally preventable. All it takes is the will.”

This article appeared in print under the headline “Beware of the dog”