It was not an unusual death. Kunj Desai, a young doctor in training at University Teaching Hospital in Lusaka, Zambia, had seen many that were not so different and were equally needless. Still, this was the one that altered all his plans. “A guy came in, and he had a stab wound,” Desai recalled, “and his intestines got injured.” The operation was delayed, and the wound became infected. “Whatever he was eating would come out of his belly,” Desai said. A carefully managed diet would have helped the man heal, but there were no dietitians at the hospital nor any IV drips of liquid nutrients with which to feed him. “He withered away to probably about 100 pounds when he died.”

The man was in his 30s, and his wife and children would have to fend for themselves. It was 2004, and Desai had worked at the chronically understaffed and underfinanced hospital for a year and a half. The hospital blood bank was often out of blood, and the lab was unreliable. The patients were often so poor that Desai would pay for private lab tests out of his own pocket. Desai came home in tears one day after being unable to save a premature baby boy. When the man with the stab wound died, the accumulation of preventable deaths — at what was, he kept reminding himself, the best public hospital in the country — finally became too heavy to bear.

“We were pretending to be doctors,” Desai, who is 35, told me when we first met. This was in the cafeteria of University Hospital in Newark, and Desai was still in his surgical scrubs after a 30-hour shift. He talked about what he saw in Lusaka in the somewhat stream-of-consciousness way that war veterans sometimes speak about the battlefield. “What was I really doing?” he said. “Making myself feel happy? No.”

As an idealistic, energetic young doctor, Desai imagined he would spend his career in Zambia, serving those in desperate need. But over the months at the hospital, he found himself fantasizing about another life — as a doctor in America. And in 2004, after he finished his internship, Desai quit his job at the hospital and began studying for the exams for a training position at an American hospital. Even while he did so, he told himself that after his stint in America, he would return to Zambia. His fellow Zambians, he knew, suffer from some of the gravest health crises in the world, not least of which is that Zambia’s doctors tend to leave the country and never come back. “After completing residency training in the United States, I hope to return to Zambia and work where the need is the greatest, the rural areas,” he wrote in a personal statement when applying for jobs in the United States in 2005. “I am Zambian, and I am committed to improving the quality of care that fellow Zambians receive.”

Two years from now, Desai will be a fully qualified surgeon in America. He has a wife and a young daughter (he had neither when he moved to the United States), and once he’s qualified, he can expect to make a very good living — the median salary of a surgeon in New Jersey is $216,000. In the main hospital in Lusaka, where Desai worked, a surgeon makes about $24,000 a year. The uncomfortable question that Desai put to the back of his mind when he arrived in the United States has begun to resurface and trouble him: Will he really fulfill his promise to himself and his country?

As we sat in the cafeteria, I suggested that if he did return to Zambia, he might be seen as something of a returning hero. Desai is a naturally polite and courteous man, but he is also disinclined to hold back from criticizing when he finds fault. In this case, his target was himself. He looked at the table and said: “The heroes are the guys that stayed. They didn’t quit, and they didn’t run away.”

In a globalized economy, the countries that pay the most and offer the greatest chance for advancement tend to get the top talent. South America’s best soccer players generally migrate to Europe, where the salaries are high and the tournaments are glitzier than those in Brazil or Argentina. Many top high-tech workers from India and China move to the United States to work for American companies. And the United States, with its high salaries and technological innovation, is also the world’s most powerful magnet for doctors, attracting more every year than Britain, Canada and Australia — the next most popular destinations for migrating doctors — combined.

The Council on Physician and Nurse Supply estimates that in 10 years, the United States could have a shortage of 200,000 doctors. Already, one in four doctors working in this country is trained in a medical school overseas (though this includes some American doctors who attended medical school outside the United States). American medical schools are producing more graduates, but many of them will become specialists who can command better pay. The demand for primary-care doctors is expected to stay high, perpetuating the demand for foreign medical graduates.

Even in the unlikely event that American medical schools produce more general practitioners, nothing but legislation would prevent American hospitals from cherry-picking the most promising young doctors the world has to offer, according to Laurie Garrett, a senior fellow at the Council on Foreign Relations. “If you can take from an applicant pool from the whole planet, why would you only take from Americans?” Garrett said. “For the foreseeable future, every health provider, from Harvard University’s facilities all the way down to a rural clinic in the Ethiopian desert, is competing for medical talent, and the winners are those with money.”

Some of the responsibility for the migration of health care workers lies with the immigration laws in the host countries. In 1994, Senator Kent Conrad, a Democrat from North Dakota, introduced legislation that empowered states to grant waivers to foreign doctors on J-1 student visas. They could stay in the United States after finishing residencies in American hospitals if they agreed to practice in communities where doctors were in short supply. The law, which has been continually renewed by Congress, has allowed more than 8,500 foreign doctors to gain jobs in rural communities, where patients often have to drive great distances to get medical care, and in underserved cities.

For a diabetic or someone with heart disease in rural Nebraska, this is unquestionably a good thing. They may be unaware, however, that their gain is a poor country’s loss. The migration of doctors and nurses from poor countries to rich ones elicits some highly emotional responses, not to mention a great deal of ethical debate. Writing in the British medical journal The Lancet in 2008, a group of doctors, several of them from Africa, titled their paper “Should Active Recruitment of Health Workers From Sub-Saharan Africa Be Viewed as a Crime?” (PDF) They concluded that it should. Other critics have used terms like “looting” and “theft.”

Some of the anger is directed toward the doctors who leave. The managing director of University Teaching Hospital in Lusaka, Lackson Kasonka, suggested to me that doctors who received government financing for their educations and then left exhibited “a show of dishonesty and betrayal.” (Desai is not in this group; his parents, who immigrated to Zambia, paid for his medical education in India, where they were born.) Peter Mwaba, the most senior civil servant in Zambia’s ministry of health, said that doctors overseas should not “hold their country to ransom” by staying away until things, in their minds, sufficiently improve.

The public health challenges in Zambia are intimidating: life expectancy is 46, more than one million of Zambia’s 14 million people are living with H.I.V. or AIDS and more than 1 in 10 children will die before they reach 5. To cope with this, there are slightly more than 600 doctors working in the public sector, which is where most Zambians get their health care. That is 1 doctor for every 23,000 people, compared with about 1 for every 416 in the United States. If Desai decides to stay here, the world’s richest country will have gained a bright young doctor. The loss to Zambia will be much greater.

Salaries and working conditions in a country like Zambia are never going to match those in the United States, but there are other factors that influence a person’s decision to emigrate: family ties, the cost of living, language and the comforting sense of living in a familiar culture. Doctors from Ghana once fled to the United States almost as a matter of course. But its retention rates of doctors and nurses in recent years have greatly improved as salaries rose enough to weigh the scales in favor of staying.

The medical brain drain from poor countries gets a fair amount of attention in international health circles, and initiatives both private and public are trying to resolve the shortage of doctors. The teaching hospital in Lusaka where Desai trained, for example, is one of 13 sub-Saharan medical schools receiving support from a United States-financed $130 million program to generate more and better graduates. The Global Fund to Fight AIDS, Tuberculosis and Malaria provided money to Zambia’s ministry of health to recruit and retain doctors. Western aid agencies, many financed by donors like Bill and Melinda Gates, have also hired local doctors at higher salaries. But apparent solutions can create further problems; many of the doctors hired by aid agencies are doing research. They don’t see patients. Frustrated public health officials in Zambia and other developing countries call this the “internal brain drain.”

George Ofori-Amanfo, a Ghanaian associate professor of pediatric cardiology at Duke Children’s Hospital in Durham, N.C., is involved with the Ghana Physicians and Surgeons Foundation, whose members, based in the United States, work to improve graduate education in Ghana’s four medical schools. He makes three trips a year to Ghana to teach young doctors. “I do feel guilty sometimes,” said Ofori-Amanfo, who came to the United States in 1995, when he was 30. About 530 Ghanaian doctors practiced in the United States in 2006, which amounted to about 20 percent of the doctors left in Ghana, according to an article in The New England Journal of Medicine. Ofori-Amanfo, for one, doesn’t think he’ll ever return for good.

“Particularly when I look at the investment that the nation had put in me to give me my basic training and what the nation would have expected me to contribute,” Ofori-Amanfo said. “There’s a lot of guilt in that. Some cocoa farmer worked very hard to pay his taxes so I can go to school.”

Had Kunj Desai stayed in Zambia, his experience might have looked like that of his old friend Emmanuel Makasa. An orthopedic surgeon, Makasa is 38 and earns about $24,000 a year. He does some work in private clinics for extra money. Makasa is something of an authority on the emigration of doctors. “The human-resource crisis in Zambia has reached a disastrous stage with the health system at breaking point,” Makasa wrote in a 2008 paper in The Medical Journal of Zambia (PDF), though he has no harsh words for his colleagues who left. He studied at the University of Alabama, Birmingham, on a Fulbright scholarship and also took and passed the first of two exams the British require of international medical graduates seeking jobs there. He told me that he had been tempted to emigrate permanently.

But during his time living in the United States and visiting Britain, he felt subtle racism. He hated the weather in Britain and found Zambian doctor friends living stressful lives in undesirable parts of the country. And he knew the difference a single surgeon in Zambia could make. So his American wife and their two daughters moved to Zambia at the end of 2010.

“There are very few doctors in this part of the world,” Makasa told me, “and if you left, yeah, it means you have a better life. Yes, you get more money. Yes, but you can’t enjoy a meal when you know your mother is hungry.”

In 2005, Makasa and his colleagues set up Doctors Outreach Care International, which provides medical care to underprivileged communities and is financed by corporate sponsors. “I don’t stay in Zambia because of lack of opportunities to go,” Makasa said. “I stay in Zambia because of what I think I can do in Zambia.”

I wanted to tell Desai what it would be like to practice in his old hospital, so I observed Makasa and a colleague fix a man’s broken leg. In the operating theater, there was a dirty-looking scalpel blade on the floor. The assisting staff ambled in late, causing the operation to start 30 minutes behind schedule. The air-conditioner was broken. A nurse took two personal cellphone calls in the operating room. When it came time for the surgeon to drill holes in the patient’s bones, a nurse produced a case containing a Bosch power drill. By way of sterilization, she wrapped it in a green cloth, binding it tight with a strip of muslin.

Doctors at University Teaching Hospital do their best to improvise, as Desai once did, to make sick people well again, even if it is with an off-the-shelf power tool. And there have been some significant material improvements at the hospital since Desai left. Makasa took me to the intensive-care unit, where a doctor from Uzbekistan was supervising the installation of monitors, ventilators and electrically operated beds that any modern hospital would be happy to own, all donated by the Japanese government. Much of the equipment in the operating theaters was new, and the theaters themselves were being renovated. The hospital had a new M.R.I. machine, a new CT scanner and new dialysis machines. What it does not have — what can’t be donated — is enough doctors.

I stopped by the neonatal-intensive-care unit, which many years earlier drove Kunj Desai to tears. Desai stayed up all night manually pumping air into a baby’s lungs, because there was no available ventilator. The next night, he returned to find that the baby had disappeared from the ward. He did not ask about the boy’s fate, but surmised that the doctor who followed him on duty had not been able to continue ventilating the boy by hand. I looked around at the dozens of babies in the unit. There were three new ventilators, also donated by the Japanese, but none were plugged in; the staff had not yet been trained to use them. I asked Jackie Banda, the doctor in charge of the unit that day, how long the unit had been without ventilators. “We’ve had none for the last two to three years,” she said.

Kasonka, the managing director of the hospital, said that he didn’t blame Desai for leaving to pursue his surgical education. As we spoke in his office, I told him that Desai wanted to become a laparoscopic surgeon. At that, Kasonka sat forward in his chair with interest. Zambia, he said, had no surgeons performing this less-invasive surgery, though the Netherlands had recently donated a laparoscope.

“If I have to say something to Dr. Desai, it is: ‘Hey, Dr. Desai, I know you have now acquired extra skills in surgery including laparoscopy,’ ” Kasonka said. “I have got a state-of-the-art laparoscope — please come back and practice.’ You see, he will pack up his bags and come back.”

When I returned from Lusaka last May, I went to visit Desai at his home in Jersey City. Desai’s wife, Bhavana, a pharmacist who also is Zambian of Indian descent, and their 17-month-old daughter, Kaiya, greeted me at the door of the town house they rent in a gated community that sits on Newark Bay, across from the airport. Some relatives were visiting from England, and we discussed the trying times of Liverpool, the soccer team Desai supports. Desai turned up a few minutes later, in scrubs, after a 14-hour shift.

Like Ofori-Amanfo, Desai feels a strong need to help his country. “It is still my homeland,” he told me when we first met. “It is still where I plan to die. I have spots picked out where I plan to retire.” In the course of our conversations, I noticed an unmistakable look of anger pass over Desai’s face sometimes, and I suspected his anger was directed in several directions at once: at the failings of his own country, at the inequities of the globalized economy, at himself. We in the West create the demand for his talents and are the beneficiaries. The first doctor to look after my son was a Nigerian pediatrician, whose country suffers from a chronic shortage of doctors and who could, presumably, help many more children in more dire need there.

In our conversations and e-mail, Desai seemed to be exploring a way to go home. He’s an only child who worries about abandoning his parents in their last years, and he wants Kaiya to grow up as a Zambian, not as an American. But he despairs of the public health system in Zambia and can’t stomach the idea of catering to the wealthy in the private sector. He talked of returning to open up his own private clinic, which would serve everyone, not just the wealthy. Or perhaps he could work for a foreign aid agency there, he said.

Desai’s enthusiasm for each alternative, however, seemed limited and fleeting — as if he recognized that his contradictory desires were never going to be fully resolved. “I’m so caught up in my day-to-day stuff,” he said. “It’ll be 30 years from now, and I’ll wake up, and I’ll be like, ‘Whatever happened to my idea of going back?’ ”

I wondered if he would be at all encouraged to change his plans based on what I found at the teaching hospital. We sat in front of my computer at his dining table. He drank a beer while I showed him photographs of the hospital and told him what I found there. He was pleasantly surprised by the images of the newly equipped I.C.U., the renovated operating theaters and dialysis machines, and he was disheartened by my photographs of packed wards and accounts of broken elevators and the unplugged ventilators at the neonatal unit.

I showed him photographs of the Bosch power drill in action.

“Oh, it’s fantastic,” he said, laughing, appreciative of his former colleagues’ resourcefulness. “That’s fantastic.” He noted that the power drill was in fact a big step forward from the manual drills he used when he worked at the hospital.

When I told him about Kasonka’s new laparoscope and the managing director’s offer to give Desai full access to it if he chose to return, he was surprised.

“Interesting, interesting,” he said. “Wow. That’s crazy.”

But his surprise almost instantly gave away to skepticism. “Sounds great, but, yeah, we’ll go back, and how long will that work?” Desai found it hard to believe that the laparoscope and other equipment required for keyhole surgery would be properly looked after. He took a gulp from his bottle of beer. “The fundamental flaws and root causes are there.”