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Epidemiologic Notes and Reports
April 22, 1988 / 37(15);229-234
AIDS and HIV Update: Acquired Immunodeficiency Syndrome and Human
Immunodeficiency Virus Infection Among Health-Care Workers
Acquired immunodeficiency syndrome (AIDS) among health-care workers in
the United States results primarily from human immunodeficiency virus
(HIV) infections that occur outside of the health-care setting. However,
a small number of health-care workers have been infected with HIV
through occupational exposures, and one such worker has developed AIDS
after documented seroconversion. This report summarizes and updates both
national surveillance data for AIDS among health-care workers and data
from prospective studies on the risk of HIV transmission in the
Health-Care Workers with AIDS
The AIDS case report form used by CDC requests that state and local
health departments collect information on employment since 1978 in a
health-care or clinical laboratory setting. For surveillance purposes,
any person who indicates such employment is classified as a health-care
As of March 14, 1988, a total of 55,315 adults with AIDS had been
reported to CDC. Occupational information was available for 47,532 of
these persons, 2,586 (5.4%) of whom were classified as health-care
workers. A similar proportion (5.7%) of the U.S. labor force was
employed in health services (1).
Forty-six states, the District of Columbia, and Puerto Rico have
reported health- care workers with AIDS. Like other AIDS patients,
health-care workers with AIDS had a median age of 35 years. Males
accounted for 91.6% of health-care workers with AIDS and 92.4% of other
patients with AIDS. The majority of health-care workers with AIDS
(62.8%) and of other AIDS patients (60.5%) were white.
Ninety-five percent of the health-care workers with AIDS were classified
into known transmission categories (Table 1). Health-care workers with
AIDS were significantly less likely than others with AIDS to be
intravenous drug abusers and more likely to be homosexual or bisexual
men. They were also less likely to have a known risk factor reported (p
less than 0.001).
To determine the possible cause of HIV infection, state and local health
departments investigate those AIDS patients reported as having no
identified risk. As of March 14, 1988, investigations had been completed
for 121 of the 215 health-care workers initially reported with
undetermined risk. Risk factors were identified for 80 (66.1%) of these.
Of the 135 health-care workers who remain in the undetermined-risk
category, 41 (30.4%) could not be reclassified after follow-up; 20
(14.8%) had either died or refused to be interviewed; and 74 (54.8%) are
still under investigation.
Overall, 5.3% of health-care workers with AIDS had an undetermined risk.
When examined by year of report to CDC, the proportion of such
health-care workers appears to have increased from 1.5% in 1982 to 6.2%
in 1987. However, 71 of the 135 health-care workers for whom risk is
still undetermined have been reported since March 1987, and 80.0% of
these 71 cases are still under investigation. The proportion of other
AIDS patients with an undetermined risk has also increased over time.
However, previous experience suggests that other risk factors for HIV
infection will be identified for many of these persons when
investigations have been completed (2). Ten percent of all reported AIDS
patients with undetermined risk are health-care workers; this proportion
has not changed over time.
A health-care worker reported to have developed AIDS after a
well-documented occupational exposure to blood and HIV seroconversion is
included among the 80 health-care workers who were reclassified after
follow-up. The worker was accidentally self-injected with several
milliliters of blood from a hospitalized patient with AIDS while filling
a vacuum collection tube. Investigation revealed no other risk factors
for this health-care worker.
Forty-one health-care workers could not be reclassified after
investigation; 68.3% were men. In contrast, 23.0% of individuals
employed in hospitals and health services in the United States are men
(1). These 41 health-care workers comprised eight physicians, four of
whom were surgeons; one dentist; five nurses; eleven nursing assistants
or orderlies; seven housekeeping or maintenance workers; four clinical
laboratory technicians; one respiratory therapist; one paramedic; one
mortician; and two others who had no contact with patients or clinical
specimens. A comparison of the occupations of these 41 health-care
workers with those of health-care workers for whom risk factors and job
information were available showed that maintenance workers were the only
occupational group significantly more likely to have an undetermined
risk (7 (17.1%) of 41 health-care workers with undetermined risk,
compared with 160 (7.1%) of 2,263 health-care workers with identified
risk, p = 0.02).
Seventeen of the 41 investigated health-care workers with undetermined
risk (including two of the seven maintenance workers) reported
needlestick and/or mucous-membrane exposures to the blood or body fluids
of patients during the 10 years preceding their diagnosis of AIDS.
However, none of the patients was known to be infected with HIV at the
time of exposure, and none of the health-care workers was evaluated at
the time of exposure to document seroconversion to HIV antibody. None of
the remaining 24 health-care workers reported needlestick or other
nonparenteral exposures to blood or body fluids.
Other Health-Care and Laboratory Workers with HIV Infection
As of December 31, 1987, 1,176 health-care workers had been enrolled and
tested for HIV antibody in ongoing CDC surveillance of health-care
workers exposed to blood or other body fluids from HIV-infected
patients. Of the 1,070 workers tested greater than or equal to90 days
after exposure, 870 (81.3%) had parenteral exposures to blood; 104
(9.7%) had exposures of mucous membrane or nonintact skin to blood; and
96 (9.0%) had exposures to other body fluids (Table 2).
Four (0.5%) of the 870 workers with parenteral exposures to blood were
seropositive for HIV antibody (upper bound of the 95% confidence
interval (CI) = 1.1%). However, one of these four was not tested until
10 months after exposure (3,4). In addition, this worker had an HIV-seropositive
sexual partner, and heterosexual acquisition of infection could not be
excluded. Of the 489 health-care workers who sustained parenteral
exposures to blood and for whom both acute- and convalescent- phase
serum samples had been obtained, three, or 0.6%, seroconverted to HIV
within 6 months of exposure (upper bound of the 95% CI = 1.6%) (4-6).
Investigation revealed no nonoccupational risk factors for these three
Two other ongoing prospective studies assess the risk of nosocomial
acquisition of HIV infection among health-care workers in the United
States (7,8). As of April 30, 1987, the National Institutes of Health
had tested 103 health-care workers with documented needlestick injuries
and 691 health-care workers with more than 2,000 cutaneous or
mucous-membrane exposures to blood or other body fluids of HIV-infected
patients; none had seroconverted (7). As of March 15, 1988, a similar
study at the University of California of 235 health-care workers with
644 documented needlestick injuries or mucous-membrane exposures had
identified one seroconversion following a needlestick (9; University of
California, San Francisco, unpublished data). Prospective studies in the
United Kingdom and Canada show no evidence of HIV transmission among 220
health-care workers with parenteral, mucous- membrane, or cutaneous
In addition to the health-care workers enrolled in these longitudinal
surveillance studies and the case reported here, six persons from the
United States and four persons from other countries who denied other
risk factors for HIV infection have reportedly seroconverted to HIV
after parenteral, nonintact skin, or mucous- membrane exposures to
HIV-infected blood or concentrated virus in a health-care or laboratory
setting (Table 3) (12-20). Six additional health-care workers with no
other identified risk factors reportedly acquired HIV infection, but the
date of seroconversion is unknown (3,15,21-23). Reported by: AIDS
Program, Hospital Infections Program, Center for Infectious Diseases,
CDC. Editorial Note: These data are consistent with previous
observations that the occupational risk of acquiring HIV in health-care
settings is low and is most often associated with percutaneous
inoculation of blood from a patient with HIV infection. Prospective
surveillance studies, which provide data on the magnitude of the risk of
HIV infection, indicate that the risk of seroconversion following
needlestick exposures to blood from HIV-infected patients is less than
1.0%. The level of risk associated with the exposure of nonintact skin
or mucous membranes is likely far less than that associated with
needlestick exposures. Individual published case reports must be
interpreted with caution because they provide no data on the frequency
of occupational exposures to HIV or the proportion of exposures
resulting in seroconversion.
The reasons that a higher proportion of health-care workers with AIDS
have no identified risk than do other persons with AIDS are unknown.
They could include a tendency of health-care workers not to report
behavioral risk factors for HIV infection, the occupational risk of HIV
infection as a result of blood exposure, or both. The first hypothesis
is suggested by the overrepresentation of men among these health-care
workers, a finding that is similar to the overrepresentation of men
among AIDS patients infected with HIV through sexual activity or
intravenous drug abuse. The second hypothesis is suggested by the
documentation of HIV
transmission in the health-care setting. Similar
hypotheses may be raised for the apparent excess of maintenance
personnel among health-care workers with no identified risk for AIDS.
Occupationally acquired HIV infection in such workers would be difficult
to determine unless the source patient or clinical specimen was known to
be HIV-positive, the occupational exposure had been well documented, and
the HIV seroconversion of the health-care worker had been detected.
The increasing number of persons being treated for HIV-associated
illnesses makes it likely that more health-care workers will encounter
patients infected with HIV. The risk of transmission of HIV can be
minimized if health-care workers use care while performing all invasive
procedures, adhere rigorously to previously published recommendations,
and use universal precautions when caring for all patients (5). In
addition, employers should instruct health-care workers on the need for
routine use of universal precautions, provide equipment and clothing
necessary to minimize the risk of infection, and monitor workers'
adherence to these precautions (5,24). References
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DC: US Department of Labor, Bureau of Labor Statistics,
Castro KG, Lifson AR, White CR, et al. Investigations of AIDS
patients with no previously identified risk factors. JAMA
Weiss SH, Saxinger WC, Rechtman D, et al. HTLV-III infection
among health care workers: association with needle-stick injuries. JAMA
McCray E, The Cooperative Needlestick Surveillance Group.
Occupational risk of the acquired immunodeficiency syndrome among health
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Centers for Disease Control. Recommendations for prevention of
HIV transmission in health-care settings. MMWR 1987;36(suppl 2S).
Stricof RL, Morse DL. HTLV-III/LAV seroconversion following a
deep intramuscular needle- stick injury (Letter). N Engl J Med
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health care workers exposed to human immunodeficiency virus-1, with one
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