The risk of AIDS infection from casual job contact.
Among those whose life-styles do not place them at high risk for contracting AIDS, the most anxiety-provoking aspect of the current epidemic relates to the possibility of infection through casual contact with infected individuals or their blood specimens or secretions.
When they first became aware of the risk of contagion and the likelihood of death should they contract AIDS, health care workers dressed up like astronauts to examine or treat infected patients. Their duties completed, they disposed of protective garments in sealed plastic bags to be autoclaved or burned.
After it became clear that the causative agent of AIDS is difficult to transmit except through sexual contact, intravenous drug use, or transfusion, health care workers shed their goggles, booties, masks, and gowns. They continued, however, to adhere to basic safety precautions spawned by the reality of the epidemic-- such precautions as not recapping hypodermic needles after use and wearing gloves to protect cuts or abrasions on hands.
At the same time, accumulated knowledge about the epidemiology of human immunodeficiency virus (HIV) infection suggested that the risk of casual contagion was minimal or nil. Let's summarize some key scientific reports supporting the conclusion that casual contagion need not be a serious concern of individuals with low-risk life-styles, including health care professionals:
1. A boarding school in western France housed 60 sick and handicapped children, about half of them hemophiliacs. Half of the hemophiliacs had been infected with HIV from transfusions of contaminated blood products. Not one of these infected children-- who ate, played, and shared living quarters and classrooms with uninfected children over a three-year period--transmitted HIV to a classmate.1
2. Two nurses gave mouth-to-mouth resuscitation to a 28-year-old hemophiliac with AIDS-related complex who had a cardiopulmonary arrest while hospitalized for hemophilic arthropathy. Both sustained mucous membrane exposure to potentially infectious saliva. Followed with HIV antibody tests and helper/suppressor ratios for nine months (at the time of the report), neither showed evidence of seroconversion.2
3. San Francisco General Hospital has large numbers of AIDS patients as well as infected individuals who do not exhibit AIDS or ARC. Dr. Julie L. Gerberding has followed 500 employees who have had intense, sustained exposure to these patients. Wall Street Journal and New England Journal of Medicine articles reported Dr. Gerberding's findings: Except for homosexual employees whose life-styles accounted for their infections, not one of the employees studied has seroconverted.3, 4
4. A Florida surgeon contracted AIDS as a result of his at-risk life-style and died from the disease. An epidemiologic survey of 400 patients whom he had operated on between 1978 and 1983 (80 per cent had endoscopic procedures; 20 per cent, through-the-skin procedures) revealed none had contracted AIDS.
Note that this was an epidemiologic, not a serologic study, and that some of the patients were lost to follow-up. When the report was published, more than three years had elapsed since treatment for 347 patients, more than 25 months for the remainder.5
5. A study covered 101 nonsexual household contacts of 39 AIDS/ARC patients with oral yeast infections ("thrush'). All contacts had lived in the same household as the index patient, sharing household items and facilities for a median of 22 months (the range was 3 to 48 months).
Only one contact, a five-year-old boy, showed evidence of infection, and it is probable that he acquired it perinatally (vertically) rather than through household contact (horizontally). The authors conclude that except for sexual partners of, or children born to, infected individuals, household contacts are at minimal risk of infection.6
6. The Centers for Disease Control has studied more than 1,750 health care workers with intense exposure to AIDS patients. Less than 0.1 per cent of those who were not members of high-risk groups (homosexual men or intravenous durg users) were antibody-positive.7
7. Morbidity and Mortality Weekly Report recently reviewed three ongoing prospective studies dealing with the risk of HIV infection among health care workers. The groups consisted of 1,097 workers with parenteral or mucous membrane exposure, studied by the CDC; 103 workers with percutaneous exposure and 229 with mucous membrane exposure, studied by the National Institutes of Health; and 63 workers with open wounds exposed to blood or body fluids of AIDS patients at the University of California-San Francisco.8 The San Francisco study represents an update of Dr. Gerberding's data.
Of all these health care workers studied, only one became infected with HIV. That individual is one of 10 worldwide who seroconverted as a result or probable result of their health care activities.
The majority of the public was either unaware--or only peripherally aware--of the above studies and in any event lacked the training to evaluate their significance. Many anxious, poorly informed, but articulate citizens lobbied to keep infected children out of school, infected GIs out of tanks, infected food servers out of restaurants, and infected office employees out of their workplaces.
Front-line physicians in cities with large populations of AIDS patients dismissed these unfounded concerns, often ridiculing those who espoused them. The controversy between doctors and laymen over casual contagion and its prevention provided good foot-age for the evening TV news.
What about the 10 known cases worldwide where health care workers have become infected on the job? On May 22, 1987, the CDC reported that three female hospital workers from different areas of the U.S.--including a medical technologist and a phlebotomist--became infected with HIV after their skin came in contact with infected blood of AIDS patients. Two of the workers were apparently not in high-risk categories, but some question existed about the third. Although the CDC did not formally release this information, there are rumors that she is married to a bisexual man.9 The CDC did report that the patient's husband of more than eight years tested negative for HIV antibodies.
All three had skin conditions: chapped hands, dermatitis, or abrasions that could have permitted the virus to traverse the skin, which is normally an impenetrable barrier. Blood also splattered into the mouth of one of the workers as she was drawing a specimen from an AIDS patient.3, 8
Of the six previously reported cases of health care workers who were infected by AIDS patients, two were in the United States, four abroad.9 Four of the six became infected following needle-sticks after drawing blood from AIDS patients. Epidemiologic investigations revealed no other risk factors for HIV infection.
The two other cases involved women constantly exposed to the infected secretions and excretions of AIDS patients under their care. In one of these, the patient was an infant with transfusion-associated AIDS. It was concluded that diaper changing--the infant had continuous bloody diarrhea--was most likely the mechanism whereby the worker (actually the child's mother providing health care) became infected.10
A recent survey of 1,231 dentists and hygienists revealed that one dentist apparently contracted AIDS through contact with infected patients.11 There has also been one well-publicized case of a surgically impotent man who apparently infected his wife through forceful kissing.
The CDC went to some lengths to emphasize that these cases appear to be "outliers,' and that the risk of casual contagion--though apparently real--is quite small. Still, the announcement predictably panicked many already concerned about catching AIDS without "doing anything wrong.'
This AIDS panic brings to mind an occurrence best known in the aviation industry: the near miss. Imagine for a moment you are on a Boeing 727 about to land at Burbank Airport, and the pilot must abort his landing and circle the field because a private plane gets in his way on the final approach.
Although the plane lands safely and you are not aware of what has happened until then, you are still shaken up when you hear about the incident. The intuitive implication of the near miss is that if a midair collision is even remotely possible, sooner or later it is going to happen.
Of course, the more planes you have in the air, the more near misses you will encounter per unit of time. And the more near misses, the greater the probability that a midair collision will occur.
The analogy to contraction of HIV by casual contact is immediately apparent. The number of cases in which infection was transmitted by casual contact is indeed small, yet the occurrence of even a single case reminds us that there already may have been many close calls. Perhaps we were involved in one or more of them. At the end of this line of reasoning, we become anxious-- or worse--and obliged to develop a strategy to avoid such near misses in the future.
This raises an obvious question: What reasonable precautions should health care personnel take in view of the possibility of casual contagion? Much has already been written on this subject, and almost all hospitals have developed protocols to address the problem. While it is not the purpose of this article to discuss recommended precautions, I encourage the interested reader to read the articles listed below as general references.
1. Associated Press. AIDS didn't spread in study, expert says. New York Times, Oct. 23, 1985.
2. Saviteer, A.M.; White, G.C.; Cohen, M.S.; et al. Letters to the editor. N. Engl. J. Med. 313: 1606-1607, 1985.
3. Chase, M. Medical personnel scramble to reassess safety stance following AIDS infection. Wall Street Journal, May 21, 1987.
4. Sande, M.A. Transmission of AIDS--The case against casual contagion. N. Engl. J. Med. 314: 380-381, 1986.
5. Sacks, J.J. Letter to the editor. N. Engl. J. Med. 313: 1017-1018, 1985.
6. Friedland, G.H., et al. Lack of transmission of HTLV-III/LAV infection to household contacts of patients with AIDS or AIDS-related complex with oral candidiasis. N. Engl. J. Med. 314: 344-349, 1986.
7. Centers for Disease Control. Update: Evaluation of human T-lymphotropic virus type III/ lymphadenopathy-associated virus infection in health care personnel--United States. Morbidity and Mortality Weekly Report 34: 575-578, 1985.
8. CDC. Update: Human immunodeficiency virus infections in health care workers exposed to blood of infected patients. MMWR 36: 285-289, May 22, 1987.
9. AIDS Alert 2(6): 1, 1987.
10. CDC. Apparent transmission of human T-lymphotropic virus type III/ lymphadenopathy-associated virus from a child to a mother providing health care. MMWR 35: 76-79, 1986.
11. Majority of hospital doctors worried about getting AIDS. Las Vegas Review-Journal, June 5, 1987.
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|Author:||Soloway, Henry B.|
|Publication:||Medical Laboratory Observer|
|Date:||Sep 1, 1987|
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