Viruses – human immunodeficiency virus

What are the key principles of preventing viruses – human immunodeficiency virus?

“Universal precautions” were first recommended by the CDC in 1987 to be incorporated into health care settings in order to minimize health care workers’ exposure to blood and body fluids that may be infected with blood-borne viruses such as human immunodeficiency virus (HIV).

In the CDC guidelines for isolation precautions updated in 2007, universal precautions remain the principal mode of HIV prevention among health care workers.

Risk of human immunodeficiency virus transmission in health care settings

The overall risk of seroconversion after a percutaneous needlestick from a known HIV-positive source is 0.3% per exposure and 0.09% after mucous membrane exposure but the risk varies depending on the type and severity of exposure.

Post-exposure prophylaxis

After accidental mucous membrane or percutaneous exposure to blood from HIV-infected patients antiretroviral drugs should be prescribed to decrease the risk of infection. Each institution and health care facility should adopt procedures for managing such exposure based on the most recent guidelines published by the CDC in 2013.

The essential elements of management after needle stick or mucous membrane exposure include defining the type of exposure, appropriately evaluating the donor (patient) and recipient (health care worker) at the time of exposure, counseling of the health care worker and providing follow-up HIV testing. There is no longer the need to determine the severity of exposure to define the number of anretroviral drugs to be used and a regimen containing 3 (or more) drugs is now recommended for all occupational exposures to HIV. Expert counsultation should be sought in specific circumstances but initiation of PEP should not be delayed.

Health care workers with any kind of parenteral exposure should be counseled and evaluated for possible acquisition of HIV and should receive routine prophylaxis against hepatitis B virus (HBV). The source patient (donor) should be evaluated for HIV infection; if the donor’s HIV status is unknown, the donor should be informed about the incident and encouraged to allow voluntary, confidential screening of blood for HIV and hepatitis B antibody.

If a patient refuses or cannot give consent, that patient should be considered to be infected. In cases in which exposure to HIV is documented or presumed to have occurred, the health care worker should be evaluated serologically for the presence of HIV as soon as possible after the exposure (baseline) and again at 6 weeks, 12 weeks, and 6months after exposure if a fourth generation assay is used for HIV testing then follow up testing can be done at baseline 6 weeks and 4 months after exposure to determine whether HIV transmission has occurred.

The health care worker should report any acute illnesses that occur during the follow-up period, especially during the first 6 to 12 weeks after exposure. Exposed workers should follow the recommended guidelines for preventing HIV transmission, including using safe sexual practices; refraining from blood, semen, and organ donation; and avoiding breast-feeding especially during the first 6-12 weeks after exposure.

Antiretroviral drugs for PEP should be initiated within 72 hrs of exposure and continued for 4 weeks. The recommended regimen is tenofovir plus emtricitabine (available as a fixed dose combination pill) plus raltegavir.

If the source patient is seronegative for HIV and has no clinical manifestations of HIV disease, no further follow-up of the exposed health care workers is necessary, although some workers prefer follow-up for their own peace of mind. Serologic testing should be made available to all health care workers who are concerned about potential on-the-job exposure.

What are the key conclusions for available clinical trials and meta-analyses that inform control of viruses – human immunodeficiency virus?

A case-control study conducted by the CDC suggested that the risk of transmission of HIV to health care workers was increased when the device causing the injury was visibly contaminated with blood, when the device had been used for insertion into a vein or artery, when the device caused a deep injury, or when the source patient died within 2 months after the exposure.

That same study demonstrated that the risk of HIV seroconversion after occupational exposure was decreased by approximately 81% with the use of zidovudine (AZT).

This study supports the recommendation for the use of universal precautions and the use of antiretroviral post-exposure prophylaxis (PEP) for those cases in which exposure to HIV is likely to have occurred. Although that study only looked at zidovudine, there are no studies evaluating the use of two or three drug regimens for PEP as are now recommended in the most recent CDC guidelines.

Adherence and tolerability of post-exposure prophylaxis among health care workers

Reported rates of adherence to PEP are between 70-80% and a substantial number of health care workers are unable to complete a 4-week course of PEP due to tolerability issues.

In a French study the dropout rate due to adverse events appeared significantly lower in TDF/FTC+LPV/r tablet formulation however, an Italian study suggested that adding a third agent, in particular a protease inhibitor, was associated with poor tolerability and discontinuation of PEP.

What are the consequences of ignoring key concepts related to control of viruses – human immunodeficiency virus?

Ignoring universal precautions could lead to exposure not only to HIV but to other blood borne pathogens such as HBV and hepatitis C virus (HCV). After prescription of PEP to a health care worker the rates of non-completion due to poor adherence/intolerance are quite high. Cases have been reported of HIV transmission after PEP due to antiretroviral resistance in the source (patient).

What other information supports the key conclusions of studies of viruses – human immunodeficiency virus e.g., case-control studies and case series?

A Cochrane Review published in 2010, “Antiretroviral post-exposure prophylaxis (PEP) for occupational HIV exposure”, supports the use of occupational PEP.

Summary of current controversies.

The decision as to which antiretroviral regimen to use and how many to prescribe for PEP is mostly empiric.

What is the role of and impact of viruses – human immunodeficiency virus or infections and the need for control relative to infections at other sites or other specific pathogens?

Adherence to universal precautions is extremely important as any patient may be infected with a blood-borne infectious agent and it is difficult, if not impossible, to differentiate those with infection from their uninfected counterparts.

All specimens containing blood or blood-tinged bodily fluids obtained from any patient should be considered potentially infectious and handled as such. The use of universal precautions helps minimize the transmission of many transmissible diseases in addition to HIV.

Overview of important clinical trials, meta-analyses, case control studies, case series, and individual case reports related to infection control and viruses – human immunodeficiency virus.

See Table I.