A second scientific worker has become infected with the AIDS virus as the result of an accident in a local research laboratory associated with the National Institutes of Health, officials reported yesterday.
The worker's first positive blood test, containing antibodies indicating infection with the virus, showed up in a blood-sampling study of AIDS researchers in May 1986, but the worker and NIH safety officials were informed of the test result only last week, according to Dr. Robert McKinney, director of NIH's division of safety.
McKinney said the worker, a technician at a laboratory performing AIDS research under a contract with NIH, cut his finger in 1985 while cleaning the rotor of a special type of centrifuge, a piece of equipment that was being used to produce a highly concentrated solution of the AIDS virus. The NIH report said the accident involved equipment and procedures not used in most AIDS research laboratories or in hospital settings.
McKinney said the technician did not report the accident. A "weak positive" antibody test, called an ELISA test, turned up in the research study about seven months later, but the worker was not contacted at that time.
"This is an unfortunate situation where this particular case, somehow or other, was missed," McKinney said.
McKinney would not say who was in charge of the blood-sampling study, citing the need to protect the worker's identity. He said NIH is investigating why the worker and others at the agency were not told of the test result. A number of studies of laboratory workers handling the AIDS virus are being made at NIH and elsewhere.
The first case of a laboratory worker becoming infected with the AIDS virus was reported a month ago and also involved a laboratory performing research under contract to NIH. McKinney said the new case occurred at a different laboratory.
McKinney said the worker was wearing rubber gloves and protective clothing and, according to safety officers, was following recommended safety precautions. He said that in the centrifuge involved in the accident, fluid flows continuously through a rotor that spins to separate cells from fluid containing free AIDS virus particles. He said investigators are interviewing the technician to determine whether he has any other risk factors for infection with the virus. Researchers will also try to isolate the AIDS virus from his cells and compare it with the strains being used at the laboratory.
"At this point we are working on the assumption that this is a laboratory-acquired infection," McKinney said.
He said that when NIH officials learned of the positive test result last week, they tested two additional blood specimens from the worker. A second ELISA test and a more accurate blood test called a Western blot were both positive, he said.
McKinney said the technician has shown no symptoms of illness related to the infection. AIDS often does not develop for years after initial infection with the virus. And researchers do not know what proportion of those infected will ultimately develop the disease.