Page 262 - AIDSBK23C

Page 262

UNIVERSAL PRECAUTIONS

The Centers for Disease Control (CDC) now recommends universal precautions for all
health care workers when dealing with all patients and specimens at all times. The rationale for
this is supported by a study which 24% of persons receiving care at an inner city hospital
emergency department had serologic evidence for infection with at least one of three viruses:
HBV (5%), HCV (18%), or HIV-1 (6%).[1068] In another study of patients seen in a large
metropolitan hospital emergency room, a 7.8% rate of HIV-1 seropositivity was found, but even
after initial HIV-1 testing by EIA and WB assays, 0.3% additional HIV infections were found by
HIV-1 p24 antigen and HIV-1 plasma RNA testing.[350,1069] Thus, potentially contaminated
specimens are received by a hospital's laboratories and, despite the very high sensitivity of
current testing methods for HIV, limitations of testing methods mean that it is not possible to
identify with certainty all infectious specimens.[342]
Despite increasing prevalence of HIV infection, the numbers of reported seroconversions
in health care workers have not risen significantly during the AIDS epidemic. Most of the
documented cases of occupational HIV transmission have occurred in nurses and laboratory
technicians performing many procedures with needles or other sharps that carry a risk for
accidental exposure. Percutaneous injury, usually inflicted by a hollow-bore needle, is the most
common mechanism of occupational HIV transmission. In a few instances, inapparent
inoculation through mucous membranes or inapparent breaks in the skin may occur. Contact
with saliva, urine, and feces carries little risk. Infection with HIV or hepatitis viruses from
aerosols has not been demonstrated.[1070,161]
The risk of HIV infection in hospitals, though very small, does exist, as with other
infectious agents, especially with failure to follow proper procedures or with accidents. The risk
for HIV seroconversion from inadvertent occupational exposures with blood borne transmission
is only about 0.3%. However, the risk for transmission for hepatitis B virus (HBV) ranges from
<6% to at least 30% based upon the absence or presence of hepatitis B e antigen. The risk for
hepatitis C seroconversion ranges up to 7%, with an average risk of 1.8%. Risk is primarily
based upon the number of virions present in blood, which is higher for hepatitis viruses than for
HIV, and body fluids other than blood contain far fewer HIV virions. The average volume of
blood inoculated during a needlestick injury with a 22-gauge needle is approximately 1 µL, a
quantity sufficient to contain up to 100 infectious doses of hepatitis B.[160,161,1070]
Every facility that handles the blood, body fluid, or tissue of AIDS patients must develop
safety procedures that are routinely employed on a daily basis. In-service or continuing
education programs should address the facts about AIDS and the proper approach of the
laboratory in dealing with it. Every laboratory worker has an important responsibility to promote
infection control. The real safety factor depends upon the least amount of precaution that will
routinely be taken, because any specimen could contain an infectious agent.
In hospital, HIV/AIDS patients should not require strict isolation when universal
precautions are employed, and legal actions have been taken against hospitals that did so.
Precautions used for patients with hepatitis are more than adequate. Segregation of HIV-infected
persons or specimens is impractical, leading to inefficient duplication of facilities or services and
undermining the philosophy and benefits of universal precautions. However, HIV-infected
patients should not be placed in close proximity to immunosuppressed patients, such as those