Following needlestick injury involving a known HIV-positive source, the one-year risk of seroconversion has been estimated to be 0.3%.5,6 In 1997, Cardo and colleagues identified four factors associated with increased risk for seroconversion after a needlestick/sharps injury from a known positive-HIV source:
- Deep injury;
- Injury with a device visibly contaminated with the source patient’s blood;
- A procedure involving a needle placed in the source patient’s artery or vein; and
- Exposure to a source patient who died of AIDS in the two months following the occupational exposure.5
Hepatitis B virus. Widespread immunization of healthcare workers has led to a dramatic decline in occupationally acquired HBV. The CDC estimated that in 1985, approximately 12,500 new HBV infections occurred in healthcare workers.3 This estimate plummeted to approximately 500 new occupationally acquired HBV infections in 1997.3
Despite this improvement, hospital-based healthcare personnel remain at risk for HBV transmission after a needlestick injury from a known positive patient source. Few studies have evaluated the occupational risk of HBV transmission after a needlestick injury. Buergler and colleagues reported that, following a needlestick injury involving a known HBV-positive source, the one-year risk of seroconversion was 0.76% to 7.35% for nonimmunized surgeons and 0.23% to 2.28% for nonimmunized anesthesiologists.7
In the absence of post-exposure prophylaxis (PEP), an exposed healthcare worker has a 6% to 30% risk of becoming infected with HBV.3,8 The risk is greatest if the patient source is known to be hepatitis B e antigen-positive, a marker for greater disease infectivity. When given within one week of injury, PEP with multiple doses of hepatitis B immune globulin (HBIG) provides an estimated 75% protection from transmission.
(Click for larger image) Table 3. Know your risks
Healthcare workers who have received the hepatitis B vaccine and developed immunity have virtually no risk for infection.6,7
Hepatitis C virus. Prospective evaluation has demonstrated that the average risk of HCV transmission after percutaneous exposure to a known HCV-positive source ranges from 0% to 7%.3 The Italian Study Group on Occupational Risk of HIV and Other Bloodborne Infections evaluated HCV seroconversion within six months of a reported exposure with enzyme immunoassay and immunoblot assay. In this study, the authors found a seroconversion rate of 1.2%.9
Further, they suggested that HCV seroconversion only occurred from hollow-bore needles, because no seroconversions were noted in healthcare workers who sustained injuries with solid sharp objects.
Post-Exposure Management
The CDC does not recommend prophylaxis when source fluids make contact with intact skin; however, if a percutaneous occupational exposure has occurred, PEPs exist for HIV and HBV but not for HCV.3,6 If a source patient’s HIV, HBV, and HCV statuses are unknown, occupational health personnel can interview the patient to evaluate his or her risks and initiate testing. Specific information about the time and nature of exposure should be documented.
(Click for larger image) Table 4. Risk of infection and required post-exposure prophylaxis for the three most commonly transmitted pathogens*After needlestick injury from a known positive patient source HBIG-Hepatitis B immune globulin Source: Adapted from Exposure to blood: What healthcare personnel need to know. Centers for Disease Control and Prevention website.
When testing is indicated, it should be done following institutional and state-specific exposure control policies and informed consent guidelines. In all situations, the decision to begin antiviral PEP should be carefully considered, weighing the benefits of PEP versus the risks and toxicity of treatment.
Human immunodeficiency virus. If a source patient is known to be HIV-positive, has a positive rapid HIV test, or if HIV status cannot be quickly determined, PEP is indicated and should be started as quickly as possible.3,8,10