ATLANTA -- Kristy Murray's mind raced as the plane arched across the Atlantic Ocean. She was exhausted, but there was no time for sleep. People were dying.
Puzzled, she leafed through medical textbooks. What Murray knew was that drug users were turning up dead in Ireland. There was little warning -- delirium, then death, all in minutes.
On the ground, the Irish press was in a frenzy. "U.S. Expert Here to Fight Killer Bug," the headlines said.
In the air, Murray felt the pressure. She was a 27-year-old aspiring veterinarian. What did she know about heroin addicts?
"At first I thought my supervisor was kidding," she said.
She wasn't. Murray is one of 130 officers with the Epidemic Intelligence Service. They are the nation's disease detectives, sent on a moment's notice to solve outbreaks that baffle health officials -- and to stop them fast.
The program, an arm of the Centers for Disease Control and Prevention, celebrates its 50th anniversary this week. Its history includes some of the world's best-known health crises: Legionnaires' disease, HIV, Ebola, E. coli.
They were all mysteries once, handed to the young, often idealistic EIS officers.
"You walk in the door, you show up, and within the first couple of weeks you're handed a situation, and you're just asked to run with it," said Peter McElroy, who completes his two years in the program this summer.
There's more than microscopes and white lab coats. For EIS officers, it's gumshoe work -- scouring an inner city or a remote corner of Africa, mapping connections among people who may have passed disease to each other.
McElroy has followed strippers in Kansas, homeless people in North Carolina and a network of East Coast transsexuals who passed tuberculosis at dancing and fashion competitions.
"That's one of the best things -- you have to deal with the entire spectrum," he said.
EIS has expanded its scope in the past 10 years, tackling less traditional public health problems -- from school violence to accidental fire deaths to widespread obesity.
The CDC's top epidemiologist, Stephen Thacker, is training this year's crop of about 65 new EIS officers. He wants to give the program a more global reach.
"What are people dying from? What's costing society the most? If the CDC's going to make a difference, this is what it has to deal with," he said.
In Ireland, Murray methodically interviewed and made records on addicts -- tracing their steps, their purchases, the people they knew.
Their scarred veins were so weak that they were injecting heroin directly into muscles. Autopsies showed lungs full of fluid and extremely high white blood cell counts -- both signs of several possible bacteria.
Murray's interviews showed infected users had all complained of having to use high amounts of citric acid to dissolve heroin before injecting it into their thighs and abdomens.
That was it: All that citric acid was giving the fatal bacteria an ideal breeding ground.
"It's fascinating to come in the next day and say, `I think there's something here,"' she said. "You get home at the end of the day and you stay up all night long, and you start to see the pieces come together."
In the end, 22 cases of the bacteria had been reported, and eight people had died. No more had to.
Murray was on the front lines of the 1999 U.S. West Nile virus outbreak and helped Seattle plan for bioterrorism during its tumultuous World Trade Organization meeting the same year.
It's been enough to convince her to set aside her earlier medical plans to join the CDC to study new infectious diseases.
"Everything I worked for, I wanted to change," she said. "There's a lot of questions out there."
On the Net:
Epidemic Intelligence Service: http://www.cdc.gov/eis