In the Canada, approximately 650,000 patients have developed
the acquired immunodeficiency syndrome (AIDS) from infection with
the human immunodeficiency virus (HIV). This figure reflects the cur-
rent definition of AIDS, which uses severe Immunodeficiency (a low
CD4 Iymphocyte count) and HIV positively as the criteria for diagnosis. One-quarter of the patients who have developed AIDS are dead.
The remainder are hospitalized for an average of one month per year. It
is estimated that 1,250,000 of the 253,000,000 people in the United
States are infected with HIV and will develop AIDS. In urban hospitals
with a substantial incidence of high risk patients, the proportion of
HIV-infected patients can approach one in ten or even one in five.
Potential sources of occupational HIV infection for hospital personnel
include the following: known AIDS patients; known HIV-positive
patients; HIV-positive patients unknown to be so; and HIV-infected
patients who have not yet seroconverted. Although the risk of acquiring HIV infection in an occupational setting is low, progression to
AIDS is considered inevitable. The interval from HIV infection to
clinical AIDS is probably shorter for occupationally acquired infection
than the present average of 10 years.
OCCUPATIONAL RISK
As of June 1990, 27 definite and 9 possible cases of occupational
acquisition of HIV infection have been reported by the Centers for
Disease Control, out of 5,425 cases of AIDS in healthcare workers.
An additional 36 cases have been investigated but lack confirmation.
Twenty-five of the 27 cases involved exposure to infected blood or
blood-contaminated fluids. The remaining two cases were laboratory
workers exposed to concentrated viral preparations. Twenty-two of the
27 occurred via puncture wounds with contaminated blood. The other
five were by exposure of open wounds or mucous membranes. The
additional nine cases of suspected occupational infection are
unconfirmed because of the absence of a baseline HIV to document
seroconversion.
The risk of infection from a single needle stick is estimated to be 0.3%
to 0.4%. Several factors predispose to a higher likelihood of infection;
namely, punctures with hollow needles, a large inoculum, and deep
penetration. The risk of acquiring HIV infection following a needle
stick, however, is considerably less than that for the hepatitis B virus,
which is 10% to 30%.
Most documented cases of occupationally acquired infection are from
patients known to have AIDS. The plasma concentration of HIV in
patients with AIDS is 100 to 1,000 times greater than that of asymptomatic HIV positive individuals, and the risk is probably greater. The healthcare workers most likely to be infected are nurses, phlebotomists, and laboratory workers. This is in sharp contrast to
occupational acquisition of hepatitis B infection, which occurs most
frequently among surgeons, dentists, and personnel working in emergency rooms, labor and delivery rooms, and dialysis centers. The
differences likely reflect the circumstances under which most AIDS
patients receive therapy and hospitalization.
CONCLUSIONS
Patient-to-healthcare worker transmission of disease was much more
prevalent in the era of widespread pulmonary tuberculosis than it is
today. With the exception of hepatitis B, occupational exposure to
infectious disease became uncommon after 1950, and this occurred
only in a defined pool of healthcare workers. The public's fear of
patients acquiring HIV infection from healthcare personnel has reached
alarming proportions, although it is an extremely unlikely possibility.
The negative impact on the healthcare industry could be substantial, if
the incidence of occupational HIV infection were to increase. A potential backlash in treating HIV infected patients could ensue.
For the safety of the profession and the continued mutually beneficial
relationship between healthcare workers and patients, every effort
should be made to educate both the public and healthcare workers and to
institute all available methods of decreasing potential HIV
transmission in the medical environment.
