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AIDS risks and precautions for laboratory personnel.

AIDS risks and precautions for laboratory personnel

Over the last several years, laboratorians have seen enough reports in newspapers, magazines, and professional journals to be well aware of the risk of transmission of acquired immunodeficiency syndrome in various settings. Whatever concern they felt intensified last spring when they read that three health care workers tested positive for the AIDS antibody following mucous membrane and skin exposures to blood from patients who also had positive AIDS antibody results.1

Then, as the year progressed, came reports about a young doctor from Johns Hopkins who claimed he was exposed in 1983,2 and about two National Institutes of Health AIDS researchers whose seroconversion appeared to be work-related.3, 4

Such developments force laboratory personnel and other health care workers to deal with important questions every day. How should they protect themselves when working with patients and their specimens? Should certain patients be put on precautions and their specimens labeled accordingly?

This article will review protective guidelines established by the Centers for Disease Control, discuss the measures our laboratory has implemented, explore the world literature concerning exposure of health care workers to the AIDS virus, and outline how a health care worker should be managed after an accidental exposure.

Published precautions. Articles in the scientific literature have documented that the human immunodeficiency virus, found in patients with AIDS and AIDS-related complex, can be isolated from blood, semen, tears, saliva, breast milk, vaginal secretions, organs, and cerebrospinal fluid.5-12 Only blood, semen, vaginal secretions, transplanted organs, and possibly breast milk, have been implicated in HIV transmission, however.13

Since 1982, the CDC has published precautions for health care workers, including doctors, nurses, dentists, phlebotomists, laboratory workers, dialysis personnel, emergency medical technicians, and morticians.14-18 The overall aim is to avoid direct contact between their skin or mucous membranes and blood or body fluids from any patient.

Figure I lists the CDC's most recent precautions for laboratorians,19 which will now be enforced by the Occupational Safety and Health Administration. Institutions failing to follow these Federal guidelines may face fines of up to $10,000. If workers file a complaint, OSHA will conduct an on-site inspection.20 The agency is also considering its own regulations to protect workers (not only those in the health care field) from bloodborne diseases.21 (Also see the Washington Report in this issue of MLO.)

All of the precautions are based on a "worst case' scenario, involving hepatitis B virus transmission from an infected patient to a health care worker. We now have more than 15 years of experience with HBV transmission in the health care setting. Both HBV and HIV can be transmitted through sexual contact, through exposure to blood or body fluids by means of transfusion or accidental percutaneous exposure, or from an infected mother to her fetus in utero.

The viruses cannot be transmitted in the home or workplace by casual, nonsexual contact.22 Neither the ingestion of food or water nor inhalation has been documented as a mode of transmission for HIV.23

The risk of HBV transmission far exceeds that of HIV. The likelihood of acquiring HBV infection after an accidental needlestick is an estimated 6 to 30 per cent, compared with less than 1 per cent for HIV.24 The much higher number of HBV particles in a given volume of accidentally inoculated blood--10(13) versus 10(4) for HIV--is believed to account for the marked difference in transmissibility.25

Inoculum size is a very important factor in determining the relative risk.26 Also, since health care workers are usually immunologically competent, their risk is much less than that of a person who has been immunocompromised in some way. For example, male homosexuals who have other forms of veneral disease are thought to be at greater risk of contracting AIDS.

Many health care workers would probably favor having all patients tested for HIV antibody upon admission. Then workers would know when to be more careful and when to wear protective attire. The Task Force on AIDS at the University of California at San Francisco recently concluded that standard procedures used for any patient with a transmissible disease provide adequate protection when one is dealing with HIV-infected patients or their specimens. The task force held that screening all patients for anti-HIV to determine which should be placed on precautions was not indicated, except in certain high-risk situations.

Pregnant women with known risk factors for AIDS were one of the two cited exceptions. The purpose of screening these patients is to insure appropriate medical care for the newborn and to determine whether breast feeding should be allowed. The other exception was in a long-term-care psychiatric facility, where screening for all sexually transmitted diseases might take place.

In all other situations, the assumption should be that every patient is potentially infectious. Attempting to identify some as "high risk' could prove unreliable and give a false sense of security.27 In the most recent report of health care workers exposed to HIV, all three incidents occurred in an emergency room or outpatient setting.1 Such patients would not have been tested under a hospital screening policy.

Our implementation of precautions. In our 379-bed teaching hospital, laboratory physicians in the blood bank worked closely with nurse epidemiologists and clinicians to establish infection control policies. We always believed that all specimens should be considered potentially hazardous, but this was a difficult concept for some laboratory staff members and nurses to accept. They felt safer when certain patients were placed on precautions, so at first we identified those patients who might have been infected with either hepatitis or HIV.28

A generic precautions sign posted outside patient rooms maintained confidentiality concerning the specific reason for the action. A "blood precautions' label was used on all specimens obtained from the identified patients.

Among these patients were individuals known or suspected to be at higher risk of infection with HIV, such as known intravenous drug abusers, persons who had had multiple sexual partners, and persons transfused with potentially infectious blood products prior to routine donor testing in 1985. Others included patients who had signs and symptoms of immuno-deficiency without a known underlying cause, those for whom an HIV test had been ordered previously, and those with known positive test results for hepatitis or HIV antibody.

In this broad grouping, some patients placed on precautions were not actually infected. Conversely, others not placed on precautions may have harbored the HIV virus, even if they tested negative for anti-HIV29 or were unaware that they fell into a high-risk group. In fact, a recent study at Walter Reed Army Medical Center found that when both inpatients and outpatients were tested anonymously, one or two a week were anti-HIV positive despite a negative clinical history.30

For these reasons, and because employees had grown more aware of their risk, our laboratory and hospital adopted a policy of "universal precautions.' We no longer distinguish between high-risk and other patients. We do not use any warning signs or labels unless the patient has a condition requiring nursing personnel to take more than the standard precautions --for example, tuberculosis or infection with oxacillin-resistant Staphylococcus.

Establishing an adequate level of protection at bedside or for laboratory workstations depends on the relative risk of splashes, spills, or aerosolization for a given test or procedure. The type of patient is not a criterion. We feel the procedure should be evaluated, and the same level of precautions should be taken for every patient or specimen processed by that procedure. Our personnel just have to become familiar with the requirements for a specific procedure or lab test. They don't have to worry about assessing the infectivity status of a patient or specimen.

Laboratory supervisors and directors decided that, at the very least, all lab employees would wear gloves when working with blood and body fluids. This policy also covered the drawing of blood donors since we cannot be sure of their HIV status.

More extensive protection is required for procedures that carry a greater risk of instrument malfunction or spilling or splashing. Anyone performing apheresis procedures, using one instrument with an external centrifuge, must wear a gown, mask, and eye protection, in addition to gloves. To protect against aerosolization and splashes, masks and eyewear are also the rule in laboratory areas where extensive specimen manipulation is performed, such as in ELISA testing. Ideally, all of these lab areas would have a protective benchtop hood or safety cabinet.

In the blood donor room, a piece of gauze keeps blood from spraying when the phlebotomist cuts the plastic tubing that joins the blood collection bag to the needle. This safety technique is also employed at the blood bank's crossmatch bench.

Besides protective clothing, frequent handwashing is recommended. Hands should be washed immediately if a glove breaks, when gloves are removed, and when regloving between patients.

Our employees take precautions to prevent needlesticks and open wound contamination. A 1985 CDC study of 938 health care workers exposed to HIV found that 40 per cent of these accidents could have been prevented. Sixteen per cent resulted from recapping a used needle, 13 per cent from improper disposal of a needle or sharp, 10 per cent from contamination of an open wound when no gloves were worn, and 1 per cent from use of a needle-cutting device.24

In each patient room, there is a box of gloves and a red plastic biohazard box for needle disposal. The latter, attached to the wall, has a device that allows phlebotomists to safely remove the needle from the sleeve holding the evacuated tube. Gloves and needle-disposal boxes are also available in the laboratory.

As a final precaution, we decontaminate the work area immediately after accidental spills and at the end of each work period. A 10 per cent solution of household bleach, or a commercial mycobactericidal cleaning solution, is preferred.

Reports of health care workers exposed to HIV. The first reported case of on-the-job HIV transmission to a health care worker--she accidentally injected herself with blood from an AIDS patient--was published in England in 1984.(31) Since then, numerous studies have followed health care workers after parenteral or mucous membrane exposure to blood or body fluids from patients positive for anti-HIV.

Those deemed infected at work must be shown to be seronegative for anti-HIV by both the ELISA and Western blot tests, or by other confirmatory methods, at or shortly after the time of the accidental exposure; then they must seroconvert to become anti-HIV positive on one of the subsequent tests.32

The criteria are essential since some health care workers belong to high-risk groups or have sexual relations with members of high-risk groups. A work-related infection can be ruled out if such individuals test positive for anti-HIV at the time of their accidental exposure.

Applying the criteria, most authors accept nine cases in the literature, reported through May 1987, as true work-related exposures.1, 24, 31, 33-38 At that time, more than 2,400 health care workers had been exposed to HIV, including more than 800 with parenteral or mucous membrane exposure.39

All of the nine health care workers were known to be seronegative either before or within one month of the accidental exposure. All tested positive between 49 days and nine months afterward. Here is a summary of their exposures:

Case 1 (England): A nurse had an accidental needlestick from a syringe containing blood of a patient with AIDS who had lived in Africa for six years.31 The nurse had no other known risk factors.

Case 2 (France): A nurse injured herself while recapping a needle that contained bloody pleural fluid from a patient who was HIV- and HBV-positive.33

Case 3 (U.S.): In this incident, a nurse experienced a deep needlestick injury. The needle and syringe were visibly contaminated with blood from a patient with AIDS.24, 34, 35

Case 4 (Martinique): A 24-year-old student nurse pricked her finger with a needle used to draw blood from an AIDS patient.36

Case 5 (U.S.): A 32-year-old mother providing extensive nursing care to her HIV-positive infant often had blood and secretions on her ungloved hands.37

Case 6 (England): Skin lesions on the hands of a 44-year-old home nursing attendant became contaminated by a patient's body secretions.38

Case 7 (U.S.): A health care worker with chapped hands held a piece of gauze over an arterial puncture site with her bare finger for 20 minutes.1

Case 8 (U.S.): A phlebotomist splashed blood on her facial acne and into her mouth when the top of an evacuated tube popped off.1

Case 9 (U.S.): A medical technologist was using an apheresis instrument that malfunctioned, causing an extensive blood spill. She wore no gloves and may have touched a skin lesion on her ear.1

Four additional cases have been reported since last summer. Although none is officially part of the CDC data, we will include them in our compilation.

Case 10 (U.S.): A researcher at the National Institutes of Health reported that equipment had leaked while he or she was working with HIV. Although gloves were worn, the researcher said it was possible that he or she had abrasions of the hands and the gloves had leaked. The virus recovered from this worker was the same as the virus under research.3

Case 11 (U.S.): Another NIH researcher was routinely tested for HIV exposure as part of his job. In 1985, he reported cutting his finger. He first tested positive for anti-HIV in May 1986.(4)

Case 12 (U.S.): A physician is suing Johns Hopkins for breach of confidentiality about his HIV antibody status. He alleges that he was exposed in 1983 and that subsequent testing of stored frozen specimens showed the patient had been infected with AIDS.2

Case 13 (U.S.): Last July, a medical worker accidentally stuck herself with a needle infected with the AIDS virus.40

Seven other health care workers may also have had occupational exposure. This cannot be proved conclusively, however, because of inadequate histories, a lack of testing at the time of exposure, the possibility that the workers belonged to high-risk groups, or the fact that there was no record of exposure to a patient who was known to be HIV-positive.41-44

In a study of 1,231 dentists, one was reported to have seroconverted, but he had no identifiable HIV-infected patients.45 There were no seroconversions reported in other studies of health care workers.46, 47

Interestingly, two reports describe accidental inoculation of health care workers with blood from patients positive for human immunodeficiency virus as well as HBV48 or Cryptococcus.49 The health care workers became positive for the other diseases but not for HIV. In follow-up testing, they remained seronegative for the virus at 15 and 26 months, respectively.

In another report, two nurses remained seronegative nine months after performing mouth-to-mouth resuscitation on a patient with AIDS-related complex50 (the usual length of time from exposure to seroconversion is six to 12 weeks18). This demonstrates how difficult it is to transmit HIV in a small inoculum to a healthy person.

Management of health care workers after exposure. When a laboratorian or other health care worker is accidentally exposed to blood or body fluids, the source patient or specimen should be identified. This may not be possible when sharps or grossly contaminated materials are disposed of improperly. In that event, how to proceed depends on the likelihood of exposure to HIV.

If the patient can be identified, he or she should be evaluated for possible HIV infection. The appropriate physicians at the institution --the employee health, infectious disease, laboratory medicine, and admitting physicians, perhaps--should review the patient's physical examination, clinical history, and pertinent laboratory test results. If HIV infection is a possibility, the patient should be told of the accident and encouraged to undergo anti-HIV testing. Many states require a patient's consent for such testing.51

The health care worker should be tested immediately for anti-HIV if the patient tests positive for anti-HIV or refuses to be tested, or if there is a possibility the patient has an HIV infection. When a health care worker's initial test is negative, subsequent testing is usually done at six weeks, three months, six months, and one year following exposure.

Since most infected individuals seroconvert within the first three months of exposure, health care workers should be counseled about the risk of HIV infection and how to prevent transmission to sexual partners. They should also be advised not to share personal belongings, such as razors or toothbrushes, which can become contaminated with blood.

These individuals should refrain from donating blood, semen, or organs, and postpone any attempt to conceive. They should also inform their dentists and doctors to protect themselves.

In short, potentially exposed health care workers should act cautiously--as if they were infected --until their ultimate HIV status is known.1, 18, 52

1. Centers for Disease Control. Update: Human immunodeficiency virus infection in health care workers exposed to blood of infected patients. MMWR 36:285-289, 1987.

2. Barker, T. Physician sues Johns Hopkins after contracting AIDS. Am. Med. News: 30, June 19, 1987.

3. Gianelli, D.M. Indirect transmission cited in AIDS worker's infection. Am. Med. News: 12, Oct. 2, 1987.

4. Second NIH AIDS researcher becomes infected with HIV. Am. Med. News: 9, Oct. 23/30, 1987.

5. Gallo, R.C.; Salahuddin, S.Z.; Popovic, M.; et al. Frequent detection and isolation of cytopathic retroviruses (HTLV-III) from patients with AIDS and at risk for AIDS. Science 224: 500-503, 1984.

6. Zagury, D.; Bernard, J.; Leibowitch, J.; et al. HTLV-III in cells cultured from semen of two patients with AIDS. Science 226:449-451, 1984.

7. CDC. Recommendations for preventing possible transmission of human T-lymphotropic virus type III/lymphadenopathy-associated virus from tears. MMWR 34:533-534, 1985.

8. Ho, D.D.; Byington, R.E.; Schooley, R.T.; et al. Infrequency of isolation of HTLV-III virus from saliva in AIDS. N. Engl. J. Med. 313:1606, 1985.

9. Thiry, L.; Sprecher-Goldberger, S.; Jonckheer, T.; et al. Isolation of AIDS virus from cell-free breast milk of three healthy virus carriers. Lancet 2:891-892, 1985.

10. Vogt, M.W.; Witt, D.J.; Craven, D.E.; et al. Isolation of HTLV-III/LAV from cervical secretions of women at risk for AIDS. Lancet 1:525-527, 1986.

11. Leads from the MMWR. HIV human immunodeficiency virus infection transmitted from an organ donor screened for HIV antibody--North Carolina. JAMA 258:308-309, 1987.

12. Ho, D.D.; Rota, T.R.; Schooley, R.T.; et al. Isolation of HTLV-III from cerebrospinal fluid and neural tissues of patients with neurologic syndromes related to the acquired immunodeficiency syndrome. N. Engl. J. Med. 313:1493-1497, 1985.

13. Ziegler, J.B.; Cooper, D.A.; Johnson, R.O.; and Gold, J. Postnatal transmissions of AIDS-associated retrovirus from mother to infant. Lancet 1:896-897, 1985.

14. CDC. Recommendations for preventing transmission of infection with human T-lymphotropic virus type III/lymphadenopathy-associated virus during invasive procedures. MMWR 35:221-223, 1986.

15. CDC. Recommended infection-control practices for dentistry. MMWR 35:237-242, 1986.

16. CDC. Acquired immune deficiency syndrome (AIDS): Precautions for clinical and laboratory staffs. MMWR 31:577-580, 1982.

17. CDC. Acquired immunodeficiency syndrome (AIDS): Precautions for health care workers and allied health professionals. MMWR 32:450-451, 1983.

18. CDC. Recommendations for preventing transmission of infection with human T-lymphotropic virus type III/lymphadenopathy-associated virus in the workplace. MMWR 34:681-686, 691-695, 1985.

19. CDC. Recommendations for prevention of HIV transmission in health care settings. MMWR 36(2S):1S-18S, 1987.

20. Washington report: OSHA puts teeth into AIDS prevention guidelines. MLO 19(11):21-22, November 1987.

21. OSHA is weighing disease measures. New York Times, p. B19, Nov. 27, 1987.

22. Friedland, G.H.; Saltzman, B.R.; Rogers, M.F.; 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.

23. CDC. Human T-lymphotropic virus type III/ lymphadenopathy-associated virus: Agent summary statement. MMWR 35:540-542, 547-549, 1986.

24. McCray, E., and the Cooperative Needlestick Surveillance Group. Occupational risk of the acquired immunodeficiency syndrome among health care workers. N. Engl. J. Med. 314:1127-1132, 1986.

25. Sande, M.A. Transmission of AIDS. The case against contagion. N. Engl. J. Med. 314:380-382, 1986.

26. Friedland, G.H., and Klein, R.S. Transmission of the human immunodeficiency virus. N. Engl. J. Med. 317:1125-1135, 1987.

27. Gerberding, J.L., and the University of California, San Francisco, Task Force on AIDS. Recommended infection control policies for patients with human immunodeficiency virus infection. An update. N. Engl. J. Med. 315:1562-1564, 1986.

28. CDC. Prevention of acquired immune deficiency syndrome (AIDS): Report of interagency recommendations. MMWR 32:101-103, 1983.

29. Groopman, J.E.; Hartzband, P.I.; Shulman, L.; et al. Antibody seronegative human T-lymphotropic virus type III (HTLV-III) infected patients with acquired immunodeficiency syndrome or related disorders. Blood 66:742-744, 1985.

30. Lenox, J.L.; Redfield, R.R.; and Burke, D.S. HIV antibody screening in a general hospital population. JAMA 257:2914, 1987.

31. Needlestick transmission of HTLV-III from a patient infected in Africa. Lancet 2:1376-1377, 1984.

32. Vlahov, D., and Polk, B.F. Transmission of human immunodeficiency virus within the health care setting, pp. 429-450 in "Occupational Medicine. Health Problems of Health Care Workers,' vol. 2(3), E.A. Emmett, ed. Philadelphia, Hanley and Belfus, 1987.

33. Oksenhendler, E.; Harzic, M.; LeRoux, J-M.; et al. HIV infection with seroconversion after a superficial needlestick injury to the finger. N. Engl. J. Med. 315:582, 1986.

34. Stricof, R.L., and Morse, D.L. HTLV-III/LAV seroconversion following a deep intramuscular needlestick injury. N. Engl. J. Med. 314:1115, 1986.

35. Marcus, R., and the Cooperative Needlestick Surveillance Group. Update: Prospective evaluation of health care workers parenterally exposed to blood of patients infected with human immunodeficiency virus. Abstract, International Conference on AIDS, p. 200, Washington, D.C., June 1-5, 1987.

36. Neisson-Vernant, C.; Arfi, S.; Mathey, D.; et al. Needlestick HIV seroconversion in a nurse. Lancet 2:814, 1986.

37. 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.

38. Grint, P., and McEvoy, M. Two associated cases of the acquired immune deficiency syndrome (AIDS). Communicable Disease Report 42:4, 1985.

39. Gerberding, J.L.; Bryant-LeBlanc, C.E.; Nelson, K.; et al. Risk of transmitting the human immunodeficiency virus, hepatitis B virus, and cytomegalovirus to health care workers exposed to patients with AIDS and AIDS-related conditions. J. Infect. Dis. 156:1-8, 1987.

40. Medical worker gets AIDS from needle. Boston Globe, Oct. 29, 1987.

41. Belani, A.; Dutta, D.; Rosen, S.; et al. AIDS in a hospital worker. Lancet 1:676, 1984.

42. CDC. An evaluation of the acquired immunodeficiency syndrome (AIDS) reported in health care personnel--United States. MMWR 32:358-360, 1983.

43. CDC. Update: Evaluation of human T-lymphotropic virus type III/lymphadenopathy-associated virus infection in health care personnel-- United States. MMWR 34:575-578, 1985.

44. Weiss, S.H.; Saxinger, C.; Rechtman, D.; et al. HTLV-III infection among health care workers. Association with needlestick injuries. JAMA 254:2089-2093, 1985.

45. Kline, R.S.; Phelan, J.; Friedland, G.H.; et al. Low occupational risk for HIV infection for dental professionals. Abstract, International Conference on AIDS, p. 155, Washington, D.C., June 1-5, 1987.

46. Hirsch, M.S.; Wormer, G.P.; Schooley, T.R.; et al. Risk of nosocomial infection with human T-cell lymphotropic virus III (HTLV-III). N. Engl. J. Med. 312:1-4, 1985.

47. Henderson, D.K.; Saah, A.J.; Zak, B.J.; et al. Risk of nosocomial infection with human T-cell lymphotropic virus type III/lymphadenopathy-associated virus in a large cohortof extensively exposed health care workers. Ann. Intern. Med. 104:644-647, 1986.

48. Gerberding, J.L.; Hopewill, P.C.; Kaminsky, L.S.; and Sande, M.A. Transmission of hepatitis B without transmission of AIDS by accidental needlestick. N. Engl. J. Med. 312:56-57, 1985.

49. Glaser, J.B., and Garden, A. Inoculation of cryptococcosis without transmission of the acquired immunodeficiency syndrome. N. Engl. J. Med. 313:266, 1985.

50. Saviter, S.M.; White, G.C.; Cohen, M.C.; and Jason, J. HTLV-III exposure during cardiopulmonary resuscitation. N. Engl. J. Med. 313:1606-1607, 1985.

51. Lewis, H.E. Acquired immunodeficiency syndrome. State legislative activity. JAMA 258:2410-2414, 1987.

52. Conte, J.E. Infection with human immunodeficiency virus in the hospital. Epidemiology, infection control, and biosafety considerations. Ann. Intern. Med. 105:730-736, 1986.

Photo: Figure I The CDC's recommended precautions for laboratory workers
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Author:Carlson, Desiree A.
Publication:Medical Laboratory Observer
Date:Jan 1, 1988
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