THE DISEASE DETECTIVES

The Center for Disease Control, a complex of red brick buildings sprawling on the outskirts of Atlanta, represents for the health of the U.S. what the grim, gray Pentagon does for national defense. The CDC's purpose is to identify, seek out and destroy both present and potential enemies of U.S. public health. Its activities take varied forms, some statistical and educational, but the most celebrated group on its roster is the disease detectives like those who have been struggling with the mystery of the American Legionnaires'Philadelphia fever.

Of course the medical sleuths are not officially called disease detectives: they are commissioned officers in the Epidemic Intelligence Service, part of Dr. Philip Brachman's Bureau of Epidemiology. They use their most sophisticated laboratory devices to discover a virus or other killer, but their sleuthing also extends far outside the lab. In an outbreak of fever among Camp Fire Girls in California, for instance, the disease was easy to identify: malaria. The question was, who introduced it to the camp area? The disease detectives had to find not a microbe but a man. In an epidemic of food poisoning by salmonella in Sioux City, Iowa, it was not the microbe but its means for spreading infection that had to be tracked down. The culprit was a machine--a meat slicer.

Dr. David Eraser, 32, chief of CDC'S special bacterial pathogens branch, flew to Philadelphia as soon as the CDC received Pennsylvania's call for help. He supervised the collection, by a staff of 18 investigators, of the materials that his laboratory colleagues at headquarters would need: throat swabbings, garglings, blood samples, urine and fecal specimens and--from victims already dead --snippets of lung and other tissue. Batch after batch of these were collected and flown to Atlanta, where they were hand-carried to the CDC.

There, each batch was subdivided into minute quantities needed by the many specialists--bacteriologists, virologists, parasitologists, rickettsiologists (for microbes that cause typhus and Rocky Mountain spotted fever), hematologists, lexicologists, and veterinarians. All the lab scientists and technicians wore protective masks, gowns and gloves and worked under exhaust hoods. But it was not felt necessary to invoke use of the sanctum sanctorum, the "hot lab," where only the deadliest organisms known to cause fast, fulminating and fatal diseases are handled.

One of the most sophisticated techniques is the fluorescent antibody test, which can be used for many types of infectious disease. A specimen (it may be liquid, a thin slice of tissue or a fecal smear) is put on a slide. Then the technicians add a mixture of antibodies (from the blood serums of animals or of patients who have recovered from known diseases), tagged with a fluorescent substance. If any of the antibodies have had a "charge effect," the equivalent of a magnetic attraction, joining a virus or one of the bacteria, some of the antibody mixture will glow under ultraviolet light. If there has been no take, all the antibody will have been washed off. Hence, no glow.

One of the quickest and most dramatic tests of all is for certain classes of virus that can be identified by their size and shape. It may take no more than three hours to prepare a specimen for Electron Microscopist Frederick Murphy to magnify up to 200,000 times. If he has caught his prey, its picture can be thrown onto a screen for a roomful of epidemiologists to see. Last week Dr. Murphy prepared such a specimen, and CDC Director David Sencer asked him: "Where is your picture?" A frustrated Murphy replied, "The picture is blank." Dr. Sencer then admitted: "We do not know what the disease is."

With failure following failure the doctors have now turned to toxicological testing. For that they use a gas chromatograph, which heats a specimen until it vaporizes. When a bright light is shone through the vapor and passed through a prism, it yields a distinctive spectrum. Yet further tests will be run with an atomic spectrometer, which searches for deadly heavy metals like mercury and lead. A shotgun approach like this, says Sencer, should disclose whether "there are chemicals you would not expect to find in human tissue." If such chemicals can be found, the detectives may have their solution.

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