Commandos of Viral Combat

They call it EPI-AID, short for "epidemic aid," and it's the medical equivalent of parachuting into a war zone. Once the virus jocks get the call-usually from the America ambassador in a foreign country or from an international agency like the World Health Organization (WHO) -- they grab their bags and hop the first commercial flight that will drop them within striking distance of the outbreak. Staring down customs officers suspicious of the high-tech medical equipment and test tubes filled with mysterious liquids, brow-beating terrified pilots to fly into the infected area, the doctors and scientists from the U.S. Centers for Disease Control, Paris's Pasteur Institute and WHO's own staff cut through daunting medical and logistical barriers. Their goal: identify the cause of the epidemic, pinpoint its source and trait its spread. In her gripping 1994 book "The Coming Plague," Laurie Garrett aptly calls them "disease cowboys." When local does hit the roads in a panic, as they did during the plague outbreak in India last year and the Ebola epidemic in Zaire last week, the virus hunters itch to go in.

CDC fields about 1,000 S.O.S. calls a year. Most require just over-the-phone advice, about how to contain, say, an outbreak of Lyme disease. But a CDC team heads into the field about 100 times a year, sometimes with the U.S. Amy Medical Research Institute of Infectious Diseases in Fort Detrick, Md. (USAMRIID battled the Ebola outbreak described in Richard Preston's best-seller "The Hot Zone.") Typically they take examination gloves, disposable boots, plasma, gowns with impermeable linings, syringes, needles, generators and refrigerators to store samples of blood, kidney and liver. And body bags. Once in-country, each member of a team may be ordered to take his or her temperature twice a day to catch an incipient fever that is often the first sign era deadly infection. And they work in groups, so partners can monitor each other for fatigue that could lead to such fatal mishaps as pricking oneself with a contaminated needle. Especially with an unknown virus, "you hold your breath for a couple of weeks," says former CDC virologist Karl Johnson, who led the investigation of the 1976 Ebola outbreak in Zaire. "You never know where an epidemic will go."

Specialists divvy up the sleuth work. An entomologist or ecologist searches for insects or other animals that harbor the disease. In Zaire in 1979, a CDC/WHO team captured and tested several hundred animals, from mosquitoes to cows, for signs of current or past infection to discover where Ebola hides between human out-breaks (to this day, no one knows). Epidemiologists search for the "index" case, the first person to contract the disease. Then they trace the contagion to determine how it spreads (through sex? through the air?) and how long after infection symptoms appear. They seek out people who have fought off infection; their blood will contain antibodies that can identify virus in others' blood, and possibly provide serum that might save the lives of infected people. Often this requires jettisoning the impermeable suits and headgear that scare off the very people the scientists need to study. "One look at the doctors and the people would be gone, into the woods," says Johnson, now a consultant to CDC.

Primitive conditions push the epi-aid team to the breaking point. In Zaire in 1976, "we always had radios that didn't work," recalls Johnson. "Any time it mined - and that was every afternoon -- the phones [in Kinshasa, their base of operations] shorted out." The sheer terror that mysterious new viruses inspire also hampers the epi-aid team. Johnson was forever persuading pilots to ferry his team into or out of the epidemic region. And when virologist Don Francis, investigating the Sudan strain of Ebola in 1976, chartered a plane in Nairobi, "the people there said they'd burn it if it came back," he recalls.

Once they find pilots to fly them to the outbreak, the doctors take blood and tissue samples from disease victims. USAMRIID's Aeromedical Isolation Teams whisk infected Americans -- usually soldiers -- back to the "Slammer," a two-bed maximum-isolation ward at Fort Detrick, where doctors take Lysol showers after checking to see if their medevaced patients are still alive. The blood and tissue samples get pigeoned out to any of the world's six biosafety level 4 (BL-4) labs, facilities that can handle the deadliest viruses. With electron microscopy, a sample of blood is examined for the presence of a new or known virus. The viruses are so deadly that scientists have to work in the equivalent of spacesuits. "I'm the thickness of a glove away from certain disease and possible death at any point," says USAMRIID's Peter Jahrling. "From time to time, I get a reality check and ask myself, 'What the hell am I doing this for?'"

Just when environmental destruction and human mobility threaten to unleash ever more new viruses, the ranks of the disease cowboys are dwindling, says Jim Meegan, a virologist at the National Institutes of Health. With budget cuts, there are now only four epidemiologists in CDC's pathogen group, the core of the epi-raiders. A shrinking defense budget has cost USAMRIID a third of its staff since the 1980s. WHO has few resources of its own--it has to tap outside virologists--and can be slow to recognize an emerging virus. (As one scientist says in "The Coming Plague," "By the time WHO realized there was an AIDS epidemic it already existed on four continents.") "It's a very lean front line separating mankind from the emerging viruses," says Francis, now at the biotech firm Genentech. "Almost everyone has run away. Except for the viruses."

The "Black Death" killed a full quarter of Europe's population during the 18th and 14th centuries.

Millions died in Asia during the Dark and Middle Ages, Still resistant to all antibiotics.

In 1764, nearly one 10th of the Swedish population succumbed.

More than 3 million Russians were killed during World War I.

During the winter of 191819, an estimated 20 million people worldwide died.

A virus consists of a shell of proteins surrounding genetic material. Viruses make their hosts sick by redirecting cellular machinery to produce more viruses.

1. The virus attaches to the host cell. The entire virus may enter the cell or it may simply inject its genetic material, or genome.

2. The viral genome uses teh host cell's machinery to replicate again and again.

3. Each new copy of the genome directs the cell to make it a protein shell.

4. The new viruses emergency from the host cell capable of infecting other cells. In the process, the first cell is often destroyed.