Updated USPHS Guidelines for Managing Occupational Exposures to HBV, HCV, and HIV and Considerations for Dentistry*
Postexposure management is an integral component of a complete program to prevent infection after an occupational exposure to blood.1 An exposure that might place health care personnel, or HCP, at risk of experiencing infection with a bloodborne pathogen is defined as a percutaneous injury (e.g., needle stick or a cut with a sharp object) or contact of mucous membrane or nonintact skin (e.g., exposed skin that is chapped, abraded, or afflicted with dermatitis) with blood, tissue or other body fluids that are potentially infectious (such as blood, body fluids containing visible blood, semen and vaginal secretions).
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RISK OF HIV INFECTION AFTER OCCUPATIONAL EXPOSURE AMONG HEALTH CARE PERSONNEL
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In prospective studies of HCP, the average risk of HIV transmission after a percutaneous exposure to HIV-infected blood has been estimated to be 0.3 percent (range: 0.2 percent-0.5 percent)2 and after a mucous membrane exposure, approximately 0.1 percent.3 The precise risk of transmission after skin exposures is unknown, but it is estimated to be less than the risk for mucous membrane exposures.
Several factors affect the risk of HIV transmission after an occupational exposure. Laboratory studies have found that during an exposure, needles that pass through latex gloves, are solid rather than hollow-bore, or are of small gauge, such as those commonly used in dentistry, transfer less blood.4 In a retrospective case-control study of HCP, an increased risk for HIV infection was associated with exposures to a relatively large volume of blood as indicated by a deep injury, injury with a device that was visibly contaminated with the patient’s blood, or a procedure that involved a needle placed in the patient’s vein or artery.5 The risk was also increased if the exposure was to blood from patients with terminal illness, possibly reflecting the higher titer of HIV in late-stage AIDS.
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RATIONALE FOR PEP AFTER AN OCCUPATIONAL EXPOSURE TO HIV
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The ideal study to evaluate the efficacy of PEP after occupational exposure—prospective, randomized, placebo-controlled—is impractical because of the large sample of HCP needed to detect a significant benefit from PEP. Thus, the rationale and recommendations to establish HIV PEP as a standard of care following an exposure to HIV-infected blood are based on indirect evidence of PEP efficacy, including data on HIV pathogenesis and human and animal studies on PEP.
Current information suggests that systemic infection does not occur immediately after an exposure. Thus, PEP can be considered biologically plausible, as there is a short window of opportunity in which it may limit or prevent viral replication. Data from animal studies have found that PEP prevented retroviral infection altogether or decreased its rate in some cases; delaying time to treatment, shortening its duration, or decreasing the dose of treatment all decreased efficacy. The extent to which data from animal studies can be extrapolated to humans is largely unknown, however.
In the retrospective case-control study among HCP, PEP was associated with an 81 percent decrease in the risk of HIV seroconversion after percutaneous exposure to HIV-infected blood.5 Although the results of this study suggest PEP efficacy, it was limited by relatively few cases and by the use of cases and controls from different sources. Trials of zidovudine (ZDV) and other antiretroviral drugs to prevent perinatal HIV transmission have shown a significant decrease in transmission.6 Only part of the protective effect of ZDV was explained by reduction of the HIV viral load in the maternal blood, however, suggesting that other mechanisms were involved. Recent studies have also shown a reduction, although small, in transmission when the antiretroviral drug was given only to the newborn within 48–72 hours after birth, highlighting the role of PEP.7–10
Although these studies tend to support the use of PEP for occupational exposures, this protection is not absolute. Failure of PEP to prevent HIV infection in HCP has been reported in at least 21 instances.1,11 Possible contributing factors have included exposure to a resistant strain, high titer or large inoculum, delayed initiation or short duration of the regimen, and possible host factors such as diminished cellular immune response.
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PEP FOR OCCUPATIONAL HIV EXPOSURES
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Because most occupational HIV exposures do not result in the transmission of HIV, the decision to recommend PEP must carefully balance the risk of HIV infection (represented by the exposure and information about the exposure source) and the efficacy and adverse side effects of PEP. First, the exposure should be evaluated for potential to transmit HIV based on the type of body substance involved and the route and severity of the exposure (Table 2). For example, exposure to a blood-filled, large-bore hollow needle or visibly bloody device suggests a higher risk for transmission than exposure to a needle used for an injection.1 A basic regimen using two nucleoside analogs (e.g., ZDV and 3TC, or 3TC and d4T) is recommended if the source is Class 1 (asymptomatic or has a known low viral load [
1,500 RNA copies/mL]) and the exposure was "less severe" (e.g., solid needle and superficial injury). An expanded PEP regimen, which adds a protease inhibitor, is recommended for "more severe" injuries (large-bore hollow needle, deep puncture, visible blood on the device, or needle used in a patient’s artery or vein) or if the source is Class 2 (symptomatic, has AIDS, or has a known high viral load [
1,500 RNA copies/mL]), regardless of the severity of the exposure. In most cases, if the HIV status is unknown, no PEP is warranted. PEP may be considered, however, for source patients with HIV risk factors or in settings where patients are likely to be HIV-positive. Because drug regimens for PEP are subject to change (based on the availability of new drugs and the development of resistant strains), a previously identified physician or occupational health specialist with expertise in antiretroviral therapy should be consulted when the decision is being made whether to begin PEP and should decide which drugs to prescribe. If PEP is indicated, it should be started as soon as possible (within hours rather than days). The exposed person should be reevaluated within 72 hours so that regimens can be altered as additional information becomes available. If a source patient is determined to be HIV-negative, PEP should be discontinued.
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TREATMENT OF EXPOSURE SITE, EXPOSURE REPORT AND EVALUATION OF THE EXPOSURE
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After an occupational blood exposure, first aid should be administered as necessary. Puncture wounds and other injuries to the skin should be washed with soap and water; mucous membranes should be flushed with water.1 Exposed personnel should immediately report the exposure to the infection control coordinator, who should initiate referral to the qualified health care professional and complete necessary reports. Because many factors contribute to the risk of infection after an occupational exposure to blood, the following information should be included in the exposure report, provided to the evaluating health care professional and recorded in the exposed person’s confidential medical record:
- – date and time of exposure;
- – details of the procedure being performed, including where and how the exposure occurred and whether the exposure involved a sharp device, the type and brand of device and how and when during its handling the exposure occurred;
- – details of the exposure, including the type and amount of fluid or material and the severity of the exposure. For a percutaneous injury, this would include the depth of the wound, gauge of the needle, and whether fluid was injected; for a skin or mucous membrane exposure, the estimated volume of material, duration of contact, and the condition of the skin (e.g., chapped, abraded, or intact);
- – details about the exposure source—whether the source material contained HIV or other bloodborne pathogens and, if the source was infected with HIV, the stage of disease, history of antiretroviral therapy, and viral load, if known;
- – details about the exposed person (e.g., hepatitis B vaccination and immune status at follow-up, and
- – details about counseling, postexposure management, and follow-up.
Each occupational exposure should be evaluated individually for the potential to transmit a bloodborne pathogen. This evaluation is based on the following: 1) the type and amount of body substance involved, 2) the type of exposure (e.g., percutaneous injury, mucous membrane or non-intact skin exposure, bites resulting in blood exposure to either person involved), 3) the infectious status of the source, and 4) the susceptibility of the exposed person.1 All of these factors should be considered in assessing the risk of infection and the need for further follow-up (e.g., PEP).
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CONSIDERATIONS FOR DENTISTRY
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During dental procedures, saliva will predictably be contaminated with blood.12,13 If blood is not visible, however, it is likely that only very small quantities of blood are present, and the risk for transmission of hepatitis B virus, or HBV; hepatitis C virus, or HCV; and HIV is extremely small.4 Despite this small risk of transmission, a qualified health care professional should evaluate any occupational exposure to saliva, regardless of the presence of visible blood.
Dental practices should make available to their personnel a written, comprehensive program that includes HBV immunization and post-exposure management protocols that: 1) describe the types of blood contact that may place DHCP at risk for infection; 2) describe procedures for promptly reporting and evaluating such exposures; and of particular importance to outpatient dental settings 3) identify a health care professional who is qualified to provide counseling and perform all medical evaluations and procedures in accordance with the most current recommendations of the USPHS, including PEP when indicated. As part of their job orientation and ongoing job training, DHCP and students who might reasonably be considered at risk of occupational exposure to blood or other potentially infectious fluids should learn strategies to prevent blood contacts and the principles of postexposure management, including options for PEP. Educational programs for dental staff and students should emphasize reporting all exposures as soon as possible, because certain interventions that may be indicated must be initiated promptly to be effective. Policies must be consistent with the practices and procedures for worker protection required by OSHA and current USPHS recommendations for managing occupational exposures to blood.1,14
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FOOTNOTES
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* Adapted from U.S. Public Health Service, Centers for Disease Control and Prevention,4 with the exception of the section on considerations for dentistry. 
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REFERENCES
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- U.S. Public Health Service, Centers for Disease Control and Prevention. Updated U.S. Public Health Service guidelines for the management of occupational exposures to HBV, HCV, and HIV and recommendations for postexposure prophylaxis. MMWR Recomm Rep 2001;50(RR-11):1–52.[Medline]
- Bell DM. Occupational risk of human immunodeficiency virus infection in health care workers: an overview. Am J Med 1997;102(5B):9–15.[Medline]
- Ippolito G, Puro V, De Carli G. The risk of occupational human immunodeficiency virus infection in health care workers: Italian multicenter study—the Italian Study Group on Occupational Risk of HIV Infection. Arch Intern Med 1993;153:1451–8.[Abstract]
- Mast ST, Woolwine JD, Gerberding JL. Efficacy of gloves in reducing blood volumes transferred during simulated needlestick injury. J Infect Dis 1993;168:1589–92.[Medline]
- Cardo DM, Culver DH, Ciesielski CA, et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group. N Engl J Med 1997;337:1485–90.[Abstract/Free Full Text]
- Connor EM, Sperling RS, Gelber R, et al. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. N Engl J Med 1994;331:1173–80.[Abstract/Free Full Text]
- Saba J, PETRA Trial Study Team. Interim analysis of early efficacy of three short ZDV/3TC combination regimens to prevent mother-to-child transmission of HIV-1: the PETRA trial (abstract S-7). Paper presented at: Sixth Conference on Retroviruses and Opportunistic Infections, Foundation for Retrovirology and Human Health in scientific collaboration with the National Institute of Allergy and Infectious Diseases and the Centers for Disease Control and Prevention; Jan. 31–Feb. 4, 1999; Chicago.
- Musoke P, Guay LA, Bagenda D, et al. A phase I/II study of the safety and pharmacokinetics of nevirapine in HIV-1-infected pregnant Ugandan women and their neonates (HIVNET 006). AIDS 1999;13:479–86.[Medline]
- Guay LA, Musoke P, Fleming T, et al. Intrapartum and neonatal single-dose nevirapine compared with zidovudine for prevention of mother-to-child transmission of HIV-1 in Kampala, Uganda: HIVNET 012 randomised trial. Lancet 1999;354:795–802.[Medline]
- Wade NA, Birkhead GS, Warren BL, et al. Abbreviated regimens of zidovudine prophylaxis and perinatal transmission of the human immunodeficiency virus. N Engl J Med 1998;339:1409–14.[Abstract/Free Full Text]
- Jochimsen EM. Failures of zidovudine postexposure prophylaxis. Am J Med 1997;102(5B):52–5.[Medline]
- U.S. Public Health Service, Centers for Disease Control and Prevention. Update: universal precautions for prevention of transmission of human immunodeficiency virus, hepatitis B virus, and other bloodborne pathogens in health-care settings. MMWR Morb Mortal Wkly Rep 1988;37:377–82, 387–8.[Medline]
- U.S. Public Health Service, Centers for Disease Control and Prevention. Guidelines for prevention of transmission of human immunodeficiency virus and hepatitis B virus to health-care and public-safety workers. MMWR Morb Mortal Wkly Rep 1989;38(supplement 6):1–37.[Medline]
- U.S. Department of Labor, Occupational Health and Safety Administration. Occupational exposure to bloodborne pathogens: final rule. CFR Part 1910.1030. Fed Reg 1991;56:64004–182.
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