Medicine: Sharper Tool

• Share

In the long war against the white plague, medicine's two most useful search tools have had a grave defect. Chest X rays and the tuberculin skin test both indicate whether the patient has ever had tuberculosis, but the skin test does not show—and X rays show only imperfectly —whether the disease is still active. Last week, doctors all over the U.S. were calling New York for details of a new, simple test which indicates how active the tubercle bacilli are in the patient's system at the time the test is made.

The basic technique was worked out at the Rockefeller Institute for Medical Research by a team including famed Microbiologist René J. Dubos and Dr. Gardner Middlebrook. Between 5 and 7 cc of blood (less than two teaspoons) are drawn from an arm vein. The serum (amber fluid) is separated from the cells and added to a specially treated preparation containing the red cells of sheep's blood. The mixture is kept at blood heat for two hours and then left at room temperature overnight.

If the contents of the test tube are unclotted in the morning, the patient has no active tuberculosis. But if the patient is tuberculous, his blood serum will contain antibodies manufactured in the body to combat the tubercle bacilli. These antibodies will cause the sheep's red blood cells to clot. The extent of the clotting gives a measure of the severity of the disease. Thus, repeated tests can show whether or not a course of treatment is working effectively.

Dr. Sidney Rothbard put the technique to wide practical use at Montefiore Hospital in The Bronx. Last week he reported at a meeting of the New York Tuberculosis and Health Association that on 1,200 serum samples from 950 patients the test was 92.3% accurate. "This test," said he, "gives the doctors a new tool. It should not be thought of as a test to displace the X ray or any other standard method."

But the advantages of the new and sharper tool were obvious. Unlike routine chest X rays, the serum test will disclose tuberculosis in other parts of the body besides the lungs. An X ray shows lung spots, but the serum test helps to determine whether the spots are healed tuberculosis scars or other lung diseases such as cancer, abscess, pneumonia or silicosis.

In its simplicity for patient and doctor, the serum test closely resembles the Wassermann test for syphilis. Its originators recommended that doctors use it the same way: take the blood sample and send it to a laboratory, instead of trying to complete the process themselves.