It was the third week of an uprising in Syria that would eventually evolve into a brutal civil war and already the wounded were showing up at the hospital in the Damascus suburb where 29-year-old Ahmed was doing rotations during his medical residency. Ahmed, who asked that only one part of his name be published because he is afraid of repercussions from Syria’s security agencies, had only just started examining a young man with bruises and a deep puncture wound on his right side when two armed security officials burst into the examining room barking questions. Who was the patient, they wanted to know, and how did he get his injuries? When it emerged that the patient had been at a protest that afternoon against the government of Syrian President Bashar Assad the officials hauled the young man outside. Ahmed could do nothing. “I was so angry at myself,” he recalls, as he chain-smokes in a café in Lebanon nearly three years later. “Why didn’t I protect him? I was terrified. I was a coward.”

That scene in Ahmed’s examining room would play out hundreds of more times across Syria as regime thugs hunted hospitals for wounded protestors, and then later, for rebels fighting against Assad’s government. When the rebel forces in Douma, the suburb where Ahmed’s hospital is located, grew in number and strength they then took to roaming the hospital corridors, seeking to finish off any regime supporters who had been injured in the vicious street fighting. In July 2012, the Syrian government passed an anti-terrorism law that effectively made it a crime to provide medical care to anyone suspected of supporting the rebels. Ahmed was caught between the Hippocratic oath — a doctor’s promise to treat every patient — and the growing pressure to take sides. “The regime said ‘Why are you helping the Free Army?’ and the Free Army said ‘Why are you helping the regime?’” Once a supporter of the revolution, Ahmed has come to the conclusion that neither side will be able to save Syria. So he is giving up, abandoning his “patient”— Syria— once again, he says with a wry smile. Instead, he has opted for a life in the United States; relatives already there are helping him to emigrate. “Yes, maybe I feel guilty,” he admits. “Maybe I am a coward for leaving Syria. But as a doctor it is impossible to work there. I have to live, I have to eat.”

Ahmed is one of an estimated 15,000 doctors who have fled Syria over the past three years, according to a report released Feb. 2 by Physicians For Human Rights [PHR], representing half of the certified physicians in a country whose medical system was once the envy of the Arab world. The doctors who have fled have left behind a horrifying medical crisis. According to the World Health Organization, more than half of Syrian hospitals have been destroyed or severely damaged. Syria’s largest city, Aleppo, once boasted 6,000 doctors. According to the PHR report, only 250 remained as of July 2013, serving a population of 2,500,000. In the Damascus suburbs where Ahmed worked, a pre-war population of 1,000 doctors had been cut down to 30 by December, according to the PHR report. Nurses, technicians, ambulance drivers and medical support personnel have been forced to abandon their posts, the report says, unable to provide care in destroyed hospitals and clinics where supplies of life-giving medicine have run out. Even if the war were to end tomorrow, its medical legacy will last a generation. The U.N. estimates that more than half a million Syrians have suffered debilitating injuries that will require long-term care. Outbreaks of communicable disease are on the rise. Manageable chronic conditions, such as diabetes, kidney failure and heart disease, are escalating into life-threatening illnesses. When the war ends, Syria will need more physicians than ever before. Yet the likelihood of doctors returning from exile is slim. The longer the war lasts, the harder it will be for them to give up their new lives.

The medical staff who have fled Ahmed’s hospital have settled in France, Germany, Dubai and Saudi Arabia. Some have lucrative contracts with local hospitals; others have set up private clinics. Many are going through the arduous process of getting recertified so they can work in the United States and Europe. “Most doctors will not go back after the crisis,” says Dr. Zaher Sahloul, a Chicago-based pulmonologist and head of the Syrian American Medical Society, an organization that raises funds to provide salaries and supplies to doctors still working in Syria. “Once you set up a new practice in a safe country it is a difficult decision to go back, especially since the economic situation will be so bad.” He says that around 1,000 to 1,200 Syrian doctors are already in the process of resettling in the U.S since the conflict started. Though not all will continue in the medical field, it is a significant addition to the 7,000 Syrian doctors who were already in the U.S. prior to the war’s start. “It’s a huge brain drain,” Sahloul says. “I am not sure the Syrian medical system can recover from this.”

The shortage of doctors is taking an immense toll. Based on an assessment of mortality rates, hospital intake numbers, population and treatment rates for manageable diseases prior to the war, Sahloul estimates that some 200,000 people have died in Syria because they did not have access to routine medical care, what he calls a “secondary death toll” that is even higher than those killed by bombs and firearms. “These are the women who died in labor because there was no one to do a C-section, or the men who have a heart attack and can’t find a physician, or have complications from diabetes. People are dying of chronic diseases that three years ago would have been completely manageable.” The PHR report has found that 70,000 cancer patients and 5,000 dialysis patients have not been able to receive treatment.

Oncologist Michel Abdallah fled for Jordan last year, and is now treating refugees as an employee of an aid group. The situation in Syria, he says, “is really bad. There are situations where a dermatologist might play the role of a dentist or a surgeon. We are losing patients who could have easily survived in normal circumstances. That’s not easy to come to terms with.”

As Syria suffers, the American health system may benefit. Many Syrian doctors finished their advanced studies in the U.S. and are already licensed to work there. The U.S., with its high salaries and advanced medical care, has long been a magnet for doctors around the globe. Ahmed isn’t sure yet what he will do once he arrives in the U.S. After three years of war, he says he is tired of blood. “Real estate might be nice,” he muses. Still, he is hedging his bets. Unlike many doctors who fled, Ahmed is applying for official leave from his employer, the Syrian Ministry of Health. He hasn’t told them he is leaving the country, only that he is opening a private clinic. That way, if he does come back, he won’t be penalized.

Sahloul thinks it’s unlikely that someone like Ahmed will ever return. That’s why, he says, it is so important to persuade the doctors still in Syria to stay. But he admits it’s a losing battle. “Doctors there not only have to deal with patients and disease, but politics and fighting groups and security. I can see why they are fleeing, but for the sake of Syria’s future, I wish they would stay.”

—With reporting by Hania Mourtada / Beirut

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