Sometimes the interests of humans and animals are the same, but humans have to save the animals first.

Seven young men sprinted down paths, darting behind houses and vaulting low walls. Each one carried a long-handled net.

From yards, alleys and streets the din of canine outrage filled the air, announcing the invasion of the neighborhood. Some dogs hid, others retreated a bit before resuming their chorus of barking. The most wary fled long before the catchers got near.

Too bad. Getting caught could be the best thing that ever happened to them. T-shirts emblazoned with a paw print logo are the uniform worn by the dogcatchers who work for Mission Rabies, and the team carries the canine rabies vaccine. Once given a shot, a dog should be safe for at least a year.

Goa, India’s smallest state that was originally colonized by the Portuguese, is a popular tourist destination set between the Arabian Sea and the mountain range of the Western Ghats. Although its churches and the importance of Roman Catholicism set it apart from the rest of India, Goa shares with other states the same abundance of street dogs. In town centers, in middle-class neighborhoods with fenced yards, and around palm-thatched huts where women cook over open fires, dogs — black and white, dusty brown, friendly and furtive — are everywhere.

As is rabies. Worldwide, about 59,000 people a year die from rabies, most in Africa and Asia, 99 percent of them because they were bitten by a rabid dog. About 40 percent of the victims are children, according to the World Health Organization, which has announced a campaign to reduce human deaths from dog-transmitted rabies across the globe to zero by 2030. The W.H.O. estimates the death toll in India at about 20,000 a year.

Mission Rabies, which is part of Worldwide Veterinary Service and supported partly by Dogs Trust Worldwide, both nonprofits, has targeted Goa as a place to demonstrate the viability of its program to stop the spread of canine rabies. It spends about $300,000 a year and has vaccinated 100,000 dogs a year since 2017, about 50,000 a year before that. Deaths of people from rabies in Goa fell to zero last year from 15 in 2014, when the campaign started. There are none so far in 2019.

The program has gained the full support of the state government, which now contributes about $70,000 per year. And its work is widely recognized as effective. Ryan M. Wallace, a veterinarian who heads the rabies epidemiology unit at the Centers for Disease Control and Prevention in Atlanta and who has collaborated with Mission Rabies in Haiti, said its effort in Goa is “one of the most successful programs in lower/middle income countries that I have seen in a decade.”

Part of that effectiveness depends on men in yellow shirts whom I’ve been trailing as they sprint after dogs, between houses, in 90-degree weather.

“They’re so fit,” says Julie Corfmat, who manages the Goa project. “They do this every single day all year round, during the monsoon, in the heavy rains.” Actually, she said the downpours help. “The dogs are taking shelter, they hesitate before they run out, because of the heavy rain, that makes it easier to catch them.”

I missed several captures, as the teams split up and I followed the wrong group. The next time there was a shout I followed two catchers down a dirt path on the right side of a house. One catcher, net high, was positioned perfectly when a medium-size dog sprinted off the top of a thigh-high wall. As its forefeet touched ground, the catcher slapped down the net, trapping the dog, then lifted and twisted the net so the dog was quickly immobilized and stopped trying to escape.

Within moments a team member arrived with a small cooler containing syringes and doses of the vaccine. He pinched some skin below the nape of the dog’s neck and gave it a shot. Another team member marked the dog’s forehead with paint so follow-up crews would know it had been vaccinated. Freed, the dog raced away.

Attaining global eradication is the goal of anti-rabies organizations, but most see it as an aspiration, not a likely achievement. Not because the science is difficult, or the practical methods are unproven. Medically, rabies is easy to prevent, in dogs and people. Organizationally, the path to stopping rabies is well understood.

But, like all public health problems, rabies control depends on large and continuing government action. Eradication of canine rabies in a dog population, which is how human deaths drop to zero, requires a long-term commitment. To reach zero human deaths the 120 countries in which the disease is endemic would need to find the money and act efficiently, now.

Even in India, with a powerful central government, Maneka Gandhi, a member of parliament and widow of Indira Gandhi’s son Sanjay, as well as a former government minister and animal welfare activist, said rabies “is not really a priority issue with the government, unfortunately.”

Goa is an exception that Mission Rabies hopes can lead the way, if not for the globe, then for India, and if not for India, then for other countries. The state government is fully behind the program of Mission Rabies, which has published data that not only shows it is remarkably effective, at reasonable cost, but also offers lessons on what needs to be done to stage effective anti-rabies campaigns — vaccinating dogs.

Most Lethal Disease

Case by case, rabies is the most lethal disease known. The virus enters the body at the time of a bite. It then begins to travel up nerves toward the brain. In humans, once it reaches the brain stem, usually after about two weeks, but perhaps months later, it starts to cause excessive salivation, convulsions, impaired movement, sensitivity to light and noise, and sometimes avoidance of water.

Once symptoms appear, it is nearly 100 percent fatal. But it can be prevented even if a person is infected with the virus. A series of shots, given before symptoms appear, can stop the virus in its tracks.

About 15 patients are known to have survived the disease once symptoms have appeared, according to the W.H.O., but all of them except one had at least one dose of vaccine before symptoms appeared. And many of them had permanent neurological damage.

In most cases, and in most parts of the world, rabies is a death sentence. The patient is kept isolated and tied to a bed in a dark room. Death is often preceded by seizures, pain, and hallucinations.

As if the deadliness of the virus weren’t terrifying enough, rabies is spread by humanity’s oldest animal friend. For 15,000 years or more we have lived with dogs, loved them, buried them alongside us, written poetry and songs to them. And for 4,000 years at least, and probably much longer, some of them have wagged their tails and licked our faces one day only to infect us the next.

The disease is described in texts from Greek and Roman antiquity, and in an ancient Ayurvedic text, the Sushruta Samhita. Some of the old records suggest an understanding that it was the saliva that transmitted the disease. But it wasn’t until Pasteur developed his vaccine more than a century ago that anything could be done. Since then, the rabies virus, which looks like a bullet in images made with an electron microscope, has been exhaustively studied.

Neuroscientists have even adapted a disabled version of the virus to study how the brain works, because the virus predictably travels through nerve and brain cells, synapse by synapse.

Control and Eradication

Rabies perfectly illustrates the concept of “one health,” the idea that the health of human and animal populations are inextricably tied together. If cattle have tuberculosis, it can spread to people. An ebola reservoir in apes or bats can spread to humans.

For rabies, the link is direct. Wherever there are people, there are dogs. If dogs are suffering and dying from rabies, humans will also suffer and die. In essence, if you save dogs, you save humans.

The consensus among rabies experts is that if the level of vaccination in the dog population can be kept at 70 percent over a period of seven years, the variant of the rabies virus that thrives in dog populations will disappear.

Effective vaccination depends not only on technical tools but also on an understanding of dog-human relations. Who owns or cares for dogs in any given community? And how much control do the humans have over the dog population?

In countries where dogs have become leash-bound pets, like the United States and Western Europe, canine rabies has been eliminated. The result is that there are one to three deaths a year caused by rare contact with bats, dog bites outside the country or bites from other animals, like raccoons. In most of the Americas, North and South, national governments have devoted the money and political will to vaccinate the vast majority of dogs every year, so even in countries where the disease is not eliminated, deaths are rare.

In Africa, where tens of thousands of people die from rabies each year, most dogs, even if they run free, are owned by families, as in the Americas, and vaccination drives can concentrate on the owners, who will bring them to vaccination locations.

India is different. Street dogs and people in India often have a kind of understanding. The dogs aren’t wild, but they aren’t owned either. Free-roaming dogs are often supported by the community, but nobody decides when and where they live, eat or mate.

Some, like village dogs around the world, are a pale, dusty brown, but there are black and white dogs, and brown and white dogs that have a look of spaniel or hound, most likely because owned dogs, some of them purebred, also run free and breed as they choose if they haven’t been sterilized. Almost all street dogs are short-haired and medium size, weighing 25 to 30 pounds.

Rahul Sehgal, the India-Asia director for the Humane Society International, who is based in Ahmedabad, said, “In other places people don’t feed dogs.” But, he said, “I haven’t seen a single place in India where dogs are not fed by individuals or community.”

For example, a family living by the side of the road in Vadodara, where the Humane Society was conducting a sterilization campaign, shared their life and what food they could earn, or were given, with a few dogs. They said quite definitely that they did not own the dogs, but they did want to know when the black dog taken away to be neutered would be returned.

Not everyone in India loves dogs, of course. Packs of dogs have attacked people. And occasionally communities erupt with violence against dogs. In Kerala in 2016 when several people died from being mauled by dogs vigilantes engaged in widely publicized killing of street dogs.

There are about 35 million dogs in India, Dr. Sehgal estimated, compared with 90 million dogs in the United States. India is only a third the size of the United States, geographically, and three times the size in population, so the number of dogs per suburban acre, or city block, is about the same, and the number of dogs per person far less. But any visitor walking through a neighborhood in India could be forgiven for thinking that India has a much denser dog population. The difference is that in India, the dogs are mostly outside; in the United States, they’re mostly indoors.

Rabies campaigns in other countries often involve getting owners to bring dogs to central vaccination points, but that poses problems in India, because of the lack of individual ownership. The answer, according to Mission Rabies, is to send out teams to find and vaccinate street dogs, using a variety of techniques with about 40 percent requiring capture by nets.

The vaccination workers in Goa first cover neighborhoods in pairs, traveling by foot or on a scooter, calling to friendly dogs who will approach and allow themselves to be held and vaccinated and talking to people who own or feed dogs. All vaccinated dogs get a paint marking that will last for a week or so. When I went along during this phase, we picked up puppies to vaccinate, were invited in for tea by one devoted dog lover and encountered none of the frantic barking that accompanies the net catchers.

The parkour-like athleticism of the net catchers comes with the second pass through a neighborhood. And finally another team makes a third pass, looking for any dog that hasn’t been marked.

On one of those cleanup passes, an adult dog wouldn’t move from her spot by a low stone wall until the team got really close. She was hiding puppies, five fur bundles about a week old.

As a veterinarian handled the pups and the mother watched from a distance, a neighbor politely asked if we could take the puppies away.

Beyond Goa

Andy Gibson, a veterinarian from Sussex, based in England, oversees the Goa project for Mission Rabies and frequently visits India. He joined Mission Rabies not long after he found himself doing an M.R.I. on a cat, and wondering whether a life spent caring for the pets of the rich was what he wanted.

Gowri Yale, a veterinarian from Bangalore, who works in Panjiim for Mission Rabies, took a similar turn. She was working with livestock but felt the industry was cruel.

“I’m a vegan now,” she said. “And when I thought about becoming a small animal vet — cats and dogs — I felt I was helping rich people keep fancy pets, so I thought I want to do something with more impact.”

In a small Mission Rabies office in Panjim, the two vets discussed the central importance of data gathering to the project in Goa. “If you don’t measure it, you can’t prove it,” Dr. Gibson said. And if you can’t prove it, you can’t get political support.

The Mission Rabies program has three aspects: vaccination, education and data gathering.

At the heart of the plan is a smartphone app that allows the vaccination teams to track their GPS-monitored progress through a neighborhood on a map as they move from street to street. Team leaders can easily see each day’s progress. And the accumulated data helps set the next day’s plan and provide information for analysis. The C.D.C., which advises the Haitian government, used the app there and achieved an increase in dogs vaccinated to 76 percent from 40 percent.

Mission Rabies estimates the vaccination cost per dog, including salaries and other costs, at $2.50, far lower than the cost of treating humans, which involves not only a more expensive vaccine, but also potential hospital stays. By that accounting, every dog in India could theoretically be vaccinated for under $90 million. India now spends $490 million a year on post-bite treatment, Dr. Gibson estimated.

Dr. Gibson has heard criticism that Goa’s project is too small a model to be replicated at a large scale.

Applying the Goa project’s methods on a larger scale would require at least one technical piece that is missing — an oral vaccine. Western Europe eradicated rabies in foxes by dropping baits with oral vaccines, beginning in 1990 when rabies was widespread and lasting more than 20 years.

The oral vaccine has also been tested in dogs in Haiti and other countries with success. And Dr. Gibson has run tests to show how the oral vaccine can reduce the number of people needed to reach hard-to-vaccinate dogs. Many dogs now caught in nets might approach hand-tossed bait.

The End of Street Dogs?

While international experts, like Dr. Wallace, are insistent that mass vaccination is the way to stop rabies and that Mission Rabies’ work in Goa has been successful, the response to such efforts in India is mixed.

“In India it will never be possible to do it in a disciplined and effective manner because that costs too much and it needs an army with cameras, data gathering, computer recording etc.,” Maneka Gandhi said in an email.

In addition, she said, dogs that are vaccinated but not sterilized “will have 12 puppies in the coming year and then the process starts again.”

Instead she supports population control. “The sterilization of dogs is a must,” she wrote. “There is no other way.”

The parent organization of Mission Rabies does include programs that train vets and sterilize dogs. And population control of dogs, through sterilization (with vaccination), is the approach preferred by Humane Society International.

But that approach poses its own challenges for the future. In North America and Western Europe, increasing wealth has led to a change in the status of dogs, which has certainly made rabies control by vaccination much easier. As Dr. Wallace put it, they move off the streets, “into our yards, then our houses, then our beds.”

In India, a big reduction in street dog populations would mark a significant cultural change, which, Mr. Sehgal said, is already beginning. As India becomes more urban and standards of living increase, he said, “Suddenly people are intolerant of dogs.” People travel to other countries, he said, and “they don’t see dogs in the street.” Over time, street dogs may disappear in the cities. “There will be apartments, there will be malls, there will be gated communities that will not tolerate the survival of these dogs.”

If so, that would be a very different India. Despite noise, feces, bites and the always present chance of rabies, the attitude of many Indians toward free-roaming dogs is still extraordinary tolerance.

At a community meeting in Vadodara, run by the Humane Society, people complained about dogs stealing shoes. But when I asked if they wanted fewer than the 20 or so dogs that lived in their neighborhood, there was not the outcry I expected.

No, several people said. They didn’t want the dogs taken away. And they didn’t want fewer dogs. But if the dogs could bark less, that would be much appreciated.