Health care workers (HCWs) and other employees in medical, public safety, sanitation, and laboratory settings are at risk of occupational exposure to HIV. Although avoiding exposure to HIV is the only reliable way of preventing HIV infection, postexposure prophylaxis (PEP), can reduce the risk of HIV infection in exposed HCWs. PEP is defined as antiretroviral (ARV) therapy that is initiated soon after exposure to HIV with the intention of preventing HIV infection.
This chapter examines the general issues involved with PEP in occupational settings. The information is based on the U.S. Public Health Service (USPHS) guidelines for PEP (see "References," below). For information on PEP for nonoccupational HIV exposures (such as sexual exposure), see chapter Nonoccupational Postexposure Prophylaxis. Note that other bloodborne pathogens, particularly hepatitis B virus (HBV) and hepatitis C virus (HCV), also may be transmitted through occupational exposure; it is important to consider these potential infections when assessing occupational exposures. For information on the management of occupational exposures to HBV and HCV, refer to the 2001 USPHS PEP guidelines (see "References," below). In addition, the National Clinicians' Post-Exposure Prophylaxis Hotline (PEPline) is available for telephone consultation at 888-HIV-4911 (888-448-4911).
The risk of HIV infection after exposure depends on several factors that are related to the exposure itself and to the source patient (see below). To make sound PEP recommendations, the clinician must assess the risk of HIV infection from the particular exposure. After this assessment, the clinician and the exposed worker must discuss the possible benefit of PEP (given the risk of HIV transmission from the injury) in relation to the willingness of the exposed worker to adhere to a 28-day course of ARV medicines, the potential toxicity of the regimen, and drug interactions. HCWs who are pregnant at the time of their exposure must weigh the risk of fetal exposure to HIV against the potential teratogenic and other risks of the ARV drugs (it should be noted that pregnancy is not a contraindication to PEP, and that a number of ARVs are recommended for use during pregnancy, based on safety and efficacy data (see chapter Reducing Maternal-Infant HIV Transmission). The efficacy of PEP is related to the specific PEP regimen, the timing of PEP, and the exposed worker's level of adherence to the PEP regimen. PEP is most likely to be effective if it is started within hours of an exposure, and outcomes may be compromised as the time from exposure increases. Nevertheless, it may be reasonable to offer PEP up to 72 hours after exposure. Although the optimal duration of PEP is not known; studies support ARV treatment for 28 days.
In the work setting, HIV infection may occur through percutaneous injuries (e.g., needlesticks) or mucocutaneous exposures (e.g., mucous membrane or nonintact skin exposure to blood or other potentially infectious body fluids). The risk of HIV seroconversion after occupational exposure with an HIV-contaminated hollow-bore needle is best described as 0.3%, on average. Another way of describing this to an exposed HCW is that, without PEP, HIV transmission occurs about once in 300 instances of needlestick from a known HIV-infected source patient. In a retrospective case-control study of HCWs with percutaneous exposure to HIV, the following exposure and source patient factors were associated with an increased risk of HIV transmission:
The factor described as "terminal AIDS in the source patient" is considered a surrogate for a source patient with a high HIV viral load (this study was done prior to the routine use of HIV viral load assays); high HIV viral load is known to be a substantial risk factor for HIV transmission.
Compared with percutaneous injury, exposure of infectious body fluids to mucous membranes (e.g., eye or mouth) or to skin with an obvious impairment of integrity (e.g., abrasion or wound) typically involves a lower risk of HIV transmission (the transmission risk for mucous membrane exposure to HIV is approximately 1 in 1,000, and less than 1 in 1,000 for cutaneous exposure). However, mucocutaneous exposures that involve large volumes of blood or other infectious fluid from an HIV-infected patient with a high HIV RNA level or prolonged duration of contact are considered increased-risk exposures.
An HCW reports possible exposure to HIV through a needlestick injury or mucocutaneous exposure.
Ideally, the HCW immediately decontaminated the injured or exposed skin with soap and water, or flushed the exposed mucous membranes with copious amounts of water or saline. The HCW should report the exposure immediately to appropriate authorities in the health care institution (e.g., the institution's needlestick hotline).
Take a thorough history of the specific exposure, including the type of exposure, the type and amount of body fluid involved, the point of entry or exposure, the time it occurred, the HIV status of the source patient (if known), and HIV risk factors of the source patient (if HIV status is not known).
Assess potential exposure to HIV (and to HBV and HCV). Consider the HIV status of the source and the characteristics of the exposure to estimate the risk of HIV infection. The decision about whether to offer PEP should be based on the estimated risk of HIV exposure. See Table 1 (percutaneous exposures) and Table 2 (mucocutaneous exposures) for recommendations about PEP.
|Infection Status of Source*|
|Exposure Type||HIV Negative||HIV Positive (Class 1)||HIV Positive (Class 2)||Unknown HIV Status||Unknown Source|
|Less Severe (e.g., solid needle, superficial injury)||No PEP warranted||Recommend basic 2-drug PEP||Recommend expanded ≥3-drug PEP||Generally, no PEP warranted; however, consider basic 2-drug PEP for source with HIV risk factors# §||Generally, no PEP warranted; however, consider basic 2-drug PEP if exposure to HIV-infected persons is likely#|
|More Severe (e.g., large-bore hollow needle, deep puncture, visible blood on device, needle used in patient's artery or vein)||No PEP warranted||Recommend expanded ≥3-drug PEP||Recommend expanded ≥3-drug PEP||Generally, no PEP warranted; however, consider basic 2-drug PEP for source with HIV risk factors# §||Generally, no PEP warranted; however, consider basic 2-drug PEP if exposure to HIV-infected persons is likely# §|
|Infection Status of Source#|
|Exposure Type||HIV Negative||HIV Positive (Class 1)||HIV Positive (Class 2)||Unknown HIV Status||Unknown Source|
|Small Volume (e.g., a few drops)||No PEP warranted||Consider basic 2-drug PEP§||Recommend basic 2-drug PEP||Generally, no PEP warranted**||Generally, no PEP warranted|
|Large Volume (e.g., a major blood splash)||No PEP warranted||Recommend basic 2-drug PEP||Recommend expanded ≥3-drug PEP||Generally, no PEP warranted; however, consider basic 2-drug PEP for source with HIV risk factors**§||Generally, no PEP warranted; however, consider basic 2-drug PEP if exposure to HIV-infected persons is likely§|
(The institution should perform appropriate testing of the source patient testing for bloodborne pathogens [e.g., HIV, HBV, and HCV] if the patient's status is unknown.)
Consult Table 1 or Table 2 to determine whether the HCW should be offered PEP medications. For occupational exposures to infectious body fluids from an HIV-infected source patient, the USPHS guidelines state that PEP should be either recommended (in most cases) or considered (in the small-volume mucocutaneous exposures), depending on the assessed risk. The assessed risk also helps to determine whether a "basic" two-drug regimen or an "expanded" regimen consisting of three or more drugs should be selected. Other considerations in choosing the medications for a PEP regimen include:
If the HCW is a candidate for PEP, provide counseling about the potential risks and benefits of PEP. If the HCW elects to start therapy, consider potential regimens (Table 3). Note that these recommendations are drawn from the 2005 guidelines for occupational PEP but have been adapted to reflect more recent PEP strategies, the availability of newer ARVs, and current DHHS adult treatment guidelines.
Select a regimen that is likely to be effective but tolerable; consider the potential adverse effects of ARVs. Certain ARVs are not recommended for PEP, including abacavir, delavirdine, nevirapine, and the combination of didanosine + stavudine. The 2005 guidelines list lopinavir/ritonavir as the preferred third agent for the expanded PEP regimen, and it continues to be a commonly used agent. Newer protease inhibitors (i.e., atazanavir, darunavir) or the integrase inhibitor raltegravir may be appropriate for individual HCWs, and should be considered particularly if HCW factors (e.g., comorbidities or interacting drugs) or source patient factors (e.g., concern for resistance) make therapy with lopinavir/ritonavir problematic. Although the 2005 guidelines list it as an alternative agent, efavirenz may have a higher rate of significant adverse effects than other listed agents. Additionally, efavirenz should not be used with pregnant women, because of possible teratogenicity. Refer to the appendix in the updated USPHS guidelines and to the DHHS adult ARV treatment guidelines for more complete information on the dosing, advantages, and disadvantages of the various ARV agents available for PEP. Consider consultation with experts (see "Expert Consultation," below).
|Basic Regimens with Two Nonnucleoside Reverse Transcriptase Inhibitors|
|Expanded Regimens (one of the following may be added to a basic regimen)|
If the HIV status of the source patient is unknown, a rapid HIV test may help in determining the need for PEP (see chapter Rapid HIV Testing). Although a positive rapid test result requires confirmation before the individual is diagnosed as HIV infected, for the purposes of PEP, it should be considered a true positive until proven otherwise, and the exposed worker should be counseled accordingly. If, upon further testing, the source patient is determined to be HIV uninfected, PEP can be discontinued. A negative rapid test result is considered reliable unless the source reports recent high-risk HIV exposure or symptoms of primary HIV (see chapters Rapid HIV Testing and Primary HIV Infection). If a rapid test is not available, PEP is considered "generally not warranted" for exposures involving source patients whose HIV status is unknown. However, PEP can be considered if the source patient has risk factors for HIV infection. PEP should not be delayed (beyond 1-2 hours) while awaiting information about the source patient. PEP is not recommended for exposures to HIV-seronegative source patients.
If the source patient is known or suspected to have infection with HIV that is resistant to ARV medications, seek expert consultation in selecting an appropriate PEP regimen. However, PEP should not be delayed while consultation is being solicited, and it is possible to adjust regimens based on expert advice. Begin ARV prophylaxis as soon as possible after the exposure occurs, preferably within a few hours and no later than 72 hours postexposure. Treatment should be continued for 28 days unless the source person is determined to be HIV uninfected.
Provide counseling about the efficacy of PEP, including the importance of protection against future HIV exposures, timely initiation of PEP medications, adherence to these medications for 28 days, and management of common adverse effects. Counsel exposed workers to use latex barriers with their sex partners until transmission of HIV infection has been ruled out.
Exposed workers should be evaluated at 1 week for review of all test results. For patients taking PEP, adherence assessment and evaluation of any side effects should be included. At 2 weeks, blood testing (e.g., CBC, creatinine, liver function tests) should be done for patients on a 28-day PEP regimen to monitor for PEP toxicity, as indicated by the particular ARV regimen. PEP is discontinued at 4 weeks, and laboratory studies generally should not be repeated unless there is a need to recheck an abnormal result. Follow-up HIV antibody testing should be done at 6 weeks, 3 months, and 6 months after the exposure. In addition to health education counseling, many exposed workers need emotional support during their follow-up visits.
Symptoms of primary HIV infection such as fever, rash, and lymphadenopathy (see chapter Primary HIV Infection) may occur in HCWs who have been infected with HIV through occupational exposure. Exposed HCWs should be counseled about the symptoms of primary HIV infection and instructed to return for reevaluation as soon as possible if symptoms develop. If symptoms consistent with primary HIV appear within 4-6 weeks after an occupational exposure, the HCW should be evaluated immediately (and an HIV RNA test should be obtained if acute HIV infection is suspected). If an HCW is found to be infected with HIV, that individual should be referred immediately to an HIV specialist for further evaluation and care.
For consultation on the treatment of occupational exposures to HIV and other bloodborne pathogens, the clinician managing the exposed person can call the National Clinicians' Post-Exposure Prophylaxis Hotline (PEPline) at 888-HIV-4911 (888-448-4911). This service is available 7 days a week, at no charge (additional information is available at the PEPline website). PEPline support may be especially useful in challenging situations, such as when drug-resistant HIV strains are suspected to be involved in the exposure or when the HCW is pregnant.
Prophylaxis against HBV is recommended for patients with potential exposure to HBV who do not have immunity against HBV. Give hepatitis B immune globulin (HBIG) as a 0.06 mL/kg intramuscular injection and initiate the vaccination series. For patients who received the vaccination series but did not develop protective antibodies (HBV sAb+), give HBIG at the time of the postexposure workup and initiate revaccination; consider repeat of HBIG in 1 month. For patients with immunity to HBV, no treatment is indicated.
For HCV, no prophylactic treatments are recommended. After potential exposure, conduct a baseline HCV antibody test. If the source is known to have HCV infection, consider alanine aminotransferase (ALT) and HCV viral load testing at 4-6 weeks. HCV antibody testing should be repeated at 4-6 months. If HCV seroconversion occurs (indicated by ALT elevation, detectable HCV viral load, or confirmed positive HCV antibody test result), refer the patient to a hepatologist because early treatment of HCV may be indicated.
* Legal issues vary from state to state. In many states, institutions and clinics have no obligation toward nonemployees or students who are exposed to HIV in their settings. In such situations, clinical supervisors or school or university officials often are the first contact for notification. However, everyone working in a health care setting should be familiar with the procedures and financial responsibility for HIV exposure management to avoid delays in HIV PEP treatment.