Occupational transmission of HIV is extremely rare, with just 58 documented transmissions and 143 possible transmissions in the United States reported as of 2010. Only one case has been documented since 2008. Overall, the Centers for Disease Control and Prevention (CDC) estimates that even those workers exposed to HIV-infected blood or bodily fluids at work have just a 0.3% risk of infection.
The low rate of occupational transmission is likely due to the widespread acceptance and use of post-exposure prophylaxis (PEP), said David T. Kuhar MD of the CDC. He is the lead author of updated guidelines recently from the U.S. Public Health Service on preventing occupational-related HIV infection in exposed individuals. The update is the first since 2005 and the fourth since the guidelines were issued in 1996.
The changes were prompted by several issues:
• Difficulties determining levels of risk of HIV transmission for individual exposure incidents;
• Problems determining the appropriate use of two versus three or more drugs in PEP regimens;
• The high frequency of side effects and toxicities associated with the recommended PEP; and
• Initial management of healthcare workers immediately following potential exposure.
There are two major changes to the guidelines, said Dr. Kuhar. The first is that those exposed immediately begin a PEP regimen of three or more drugs for four weeks, regardless of the level of risk associated with the exposure. The previous recommendation was for two or more drugs.
“The reason for this change is really multifactorial,” said Dr. Kuhar, particularly the fact that today’s less toxic, better-tolerated medications make completion of PEP regimens more likely. “Before, we always had to weigh the risk of side effect toxicities that might lead to non-completion of a full PEP regimen against the risk of the exposure itself. With better-tolerated drugs, the risk of non-completion with a triple-drug regimen is less than with previous regimens.”
The second change is that exposed individuals may conclude followup testing at four months rather than six if they are tested with the fourth-generation HIV antigen-antibody combination test, which can detect the virus earlier.
|What About PrEP?|
|The approval of Truvada (tenofovir disoproxil fumarate plus emtricitabine, also known as TDF/FTC) to prevent HIV infection in high-risk individuals raises the question of whether pre-exposure prophylaxis (PrEP) should be used for healthcare professionals.
Not likely, said Dr. Kuhar. “We don’t have a perfect surveillance system to detect occupational transmission of HIV, but in light of infrequent exposures and very, very few transmissions that occur, I don’t know that we could make a strong argument for pre-exposure prophylaxis.”
While occupational transmission of HIV is rare, the incidence of exposure to blood and body fluids is much higher. What percentage of those exposures are to HIV-infected fluids is unknown, said Dr. Kuhar.
The most recent National Surveillance System for Healthcare Workers (NaSH) report found that percutaneous injuries are the most common route of exposure to blood or other body fluids. The majority of these exposures (36%) occur in the inpatient setting, usually on medical/surgical wards or in intensive care units. It estimates the rate of sharps injuries in the United States at 350,000 a year.
Of course, a small proportion of those are related to HIV-infected individuals,” Dr. Kuhar said. “But with no mandated reporting of exposure at a national level, it’s difficult to know. To a great extent, it depends on the job of the provider and the prevalence of blood-borne pathogens in the population seen at the facility.”
Sharps injuries have declined over time, Dr. Kuhar noted, as safer devices entered the market. For instance, surgeons can now use blunt-tip fascia suturing needles that reduce the risk of injury.
The Public Health Service guidelines also recommend:
• Beginning PEP immediately, even before testing the source for infection. (“Thinking promptly is the most important step in preventing infection,” said Dr. Kuhar. “Don’t wait.”) For instance, a surgeon who is exposed during a procedure should complete a surgical scrub and seek medical evaluation, if possible. Delaying PEP means that the risks of the treatment may not outweigh the benefits. If the source of the exposure tests negative, stop the treatment.
• Prescribing emtricitabine plus tenofovir plus raltegravir for PEP after occupational exposure. This recommendation is based on the efficacy and minimal side-effect and drug-interaction profile of the regimen. Several drugs are contraindicated unless an HIV expert recommends them.
• Consulting an HIV expert or the National Clinicians’ Post-Exposure Prophylaxis Hotline at 888-448-4911 in the following cases (but do not delay starting PEP while waiting for the consult):
1. Women who are breastfeeding, pregnant or have a suspected pregnancy;
2. Unknown source of exposure (e.g., needle in sharps disposal container);
3. Delayed reporting of the exposure (more than 72 hours);
4. Known or suspected resistance of the source virus to antiretroviral agents;
5. Toxicity of the initial PEP regimen; or
6. Serious medical illness in the exposed person.
Prevent the Exposure
The best way to prevent occupationally related HIV exposure and transmission is, of course, with prevention.
The CDC recommends that providers assume that blood and other body fluids from all patients are potentially infectious and follow all infection control precautions, including:
• Routine use of barriers such as gloves and/or goggles if there is the possibility of contact with blood and/or body fluids;
• Immediately washing hands and other skin surfaces after contact with blood or body fluids; and
• Careful handling and disposal of sharp instruments during and after use.