||Contents: (Full text available in print edition.)
|Although according to the Centre for
Disease Control statistics, the risk of contracting HIV following occupational exposure is
less than one half of one per cent, the fear associated with accidental exposure to HIV is
something we can all appreciate! The common sense approach to treatment outlined below
provides a plan of therapeutic action based on current therapeutic experience and should
go a long way towards allaying such fears.
|Stuart Maddin, Editor
What Constitutes Occupational
Exposure to known or suspected HIV positive blood or infectious body fluid by means of
a needlestick or a cut with a sharp object such as a scalpel or other surgical instrument.
Risk of Transmission
The risk of seroconversion after a documented percutaneous exposure has been estimated
to be 0.32% per needlestick injury.1-4 In the USA, between 1978
and June 1996, there were 51 cases of occupational HIV transmission documented: 44 had
percutaneous exposure, five had mucocutaneous exposure, one had both percutaneous and
mucocutaneous exposures, and one had an unknown route of exposure. Forty-six exposures
were to blood from an HIV-infected person, one to visibly bloody fluid, one to an
unspecified fluid, and three to concentrated virus in a laboratory. Twenty-four of these
health care workers developed AIDS. A further 108 cases of occupational exposure have been
classified as possible transmission of HIV; percutaneous or mucocutaneous exposure to HIV
was reported, but HIV seroconversion specifically resulting from the occupational exposure
was not documented.4 The risk of occupational
infection resulting from mucous membrane exposure is still too low to accurately measure,
although one study has calculated it to be 0.09%.2,5
During a specific exposure, the risk of occupational HIV infection is affected by the
relative immunity of the health care worker, the volume of inoculum, the quantity of
virus, depth of penetration, type and size of needle (the risk is considerably greater
with hollow-bore needles), and the actual injection of blood.5,6 For mucocutaneous exposures, large volumes of
blood, prolonged duration of contact, and a portal of entry appear to be common factors in
the few individuals who have become infected.5 During surgical procedures,
factors associated with increased risk include the type of procedure, a longer duration of
procedure, and the use of hands rather than instruments to hold material for suturing.
Recapping needles is the single most common (and potentially avoidable) hazard.5
|All persons working in dermatologic surgery units should have
Hepatitis B immunization and puncture-proof sharp containers should be available (a lot of
people use old milk containers, which are not puncture proof).
|Prof. Alastair McLeod,
St. Pauls Hospital, Vancouver, Canada
Chair, Committee on Accidental Exposures to HIV7
Management of Occupational Exposure
The source patient should be tested for HIV after appropriate counselling and obtaining
informed consent. Health care workers who sustain massive, definite, or possible
parenteral exposures should undergo baseline serum testing for HIV, hepatitis B and
hepatitis C, or have their serum frozen and stored.5 When the source
patient is potentially infected with HIV, follow-up HIV testing of the worker is generally
performed at six weeks, three months, and six months. The exposed worker should be
informed about the symptoms of an acute retroviral infection and should observe
precautions to prevent possible secondary transmission. Seroconversion should occur within
six months of exposure.5
Because most occupational exposures to HIV do not result in infection transmission,
potential toxicity must be carefully considered when prescribing post exposure
- The Centre for Disease Control recommends postexposure prophylaxis (PEP) for workers
after high-risk occupational exposure. For exposures with a lower, but non-negligible
risk, PEP should be offered, balancing the lower risk against the use of drugs having
uncertain efficacy and toxicity. For exposures of negligible risk, PEP is not justified.4
- Zidovudine, (ZDV, Retrovir®, Glaxo Wellcome and generics) 600
mg per day should be considered for all PEP regimens, because it is the only
agent for which data support the efficacy of PEP in the clinical setting. In a case
control study among health care workers, zidovudine PEP was associated with a decrease of
approximately 79% in the risk for HIV seroconversion after percutaneous exposure to
HIV-infected blood.8,9 In a prospective trial, the direct effect of
ZDV prophylaxis may have contributed to an observed 67% reduction in perinatal HIV
failures of zidovudine PEP have occurred.3
- Lamivudine (3TC, Epivir®, Glaxo Wellcome) 150 mg
twice daily should usually be added to ZDV for increased antiretroviral activity
and activity against many ZDV-resistant strains.4
|However, it is impossible to identify resistant strains of HIV and
therefore unrealistic to base post-exposure prophylaxis on resistance. If the source has
been on long-term antiretroviral therapy with AZT, they can be assumed to be resistant to
the drug; the same goes with 3TC. While waiting for expert advice, the exposed
person should start standard prophylaxis.7
these drugs are not very available in pharmacies. If the accident victim walks out of the
office with a prescription, it might take him or her a couple of days to find a
satisfactory source. Therefore it might be appropriate for dermatologic surgery units to
keep a five-day supply of AZT, 3TC, and indinavir with their emergency supplies.
|Prof. Alastair McLeod, Vancouver, Canada7
- A protease inhibitor (preferably indinavir4, Crixivan®, Merck) should be added after
high-risk exposures and might be considered for lower-risk exposures if ZDV-resistant
strains are likely.4 To avoid a potentially
life-threatening drug interaction (e.g. cardiac arrhythmias, prolonged sedation),
indinavir must not be administered concurrently with terfenadine, astemizole, cisapride,
triazolam, or midazolam.11
For HIV strains resistant to both ZDV and indinavir or resistant to a protease inhibitor,
or if these drugs are contraindicated or poorly tolerated, the optimal PEP regime is
uncertain and expert consultation is advised.4
- PEP should be initiated promptly, preferably within 1-2 hours post-exposure. Even though
animal studies suggest that PEP is ineffective when delayed more than 24-36 hours
following exposure, in humans the interval after which there is no benefit from PEP is
undefined. In patients who have experienced a high risk exposure, PEP might be initiated
after a longer interval (e.g. 1-2 weeks), as even if the infection is not prevented, early
treatment of acute HIV infection may be beneficial.9,12
- The optimal duration of PEP is unknown, but because ZDV treatment for four weeks appears
protective; if tolerated, PEP should probably be continued for four weeks.4
- Drug-toxicity monitoring should include a complete blood count and renal and hepatic
chemical function tests at baseline and two weeks after starting PEP. If toxicity is
noted, experts should be consulted and dose reduction or drug substitution considered.
Further diagnostic studies may be indicated.4
- Finally, universal precautions including the routine use of appropriate barrier
precautions and techniques to reduce the likelihood of exposure to bloodborne pathogens
are even more important for hepatitis B and C and nosocomial infections than they are for
- Henderson DK, Fahey B, Willy M, et al. Risk for
occupational transmission of human immunodeficiency virus type 1 (HIV-1) associated with
clinical exposures: a prospective evaluation. Ann Intern Med 1990;113:740-746.
- Ippoloito G, Puro V, De Carli G. The risk of occupational
human immunodeficiency virus infection in health care workers: Italian multicenter study. Arch
Intern Med 1993;153:1451-1458.
- Tokars JI, Marcus R, Culver DH, et al. Surveillance of HIV
infection and zidovudine use among health care workers after occupational exposure to
HIV-infected blood. The CDC Cooperative Needlestick Surveillance Group. Ann Intern Med
- Provisional public health recommendations for
chemoprophylaxis after occupational exposure to HIV. MMWR 1996;45:No. 22.
- Fraser VJ, Powderly WG, Risks of HIV infection in the
health care setting. Annu Rev Med 1995;46:203-211.
- Gerberding JL, Lewis FR, Schecter WP. Are universal
precautions realistic? Surg Clin North Am 1995;75:1091-1104.
- McLeod WA. Personal communication. February 1997.
- CDC. Case-control study of HIV seroconversion in health
care workers after percutaneous exposure to HIV-infected blood France, United
Kingdom, and United States, January 1988- August 1994. MMWR 1995;44:929-933.
- Gerberding JL. Prophylaxis for occupational exposure to
HIV. Ann Intern Med 1996; 125:497-501.
- Connor EM, Sperling RS, Gelber R, et al. Reduction of
maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine
treatment. N Engl J Med 1994;331:1173-1180.
- Drug Facts & Comparisons. St. Louis,
Missouri: Facts and Comparisons, 1996.
- Kinloch De Loes S, Hirschel BJ, Hoen B, et al. A
controlled trial of zidovudine in primary human immunodeficiency virus infection. N
Engl J Med 1995;333:408-413.
We are indebted to Dr. Alastair McLeod (Chair, Committee on
Accidental Exposures to HIV, St. Pauls Hospital, Vancouver, Canada) for his helpful
suggestions, and to Rita Fahrner (San Francisco General Hospital) for information
||Approval Dates and Comments
Ortho Tri-cyclen® tablet
|This OC containing norgestimate, a progestin with reduced
androgenic effect, was approved by the FDA December 1996 for the treatment of moderate
acne vulgaris in females who have no known contraindications to oral contraceptive therapy
and are unresponsive to topical anti-acne medications. See article page one.
|This allylamine antifungal was approved by the FDA December
1996 for the topical treatment of tinea corporis and tinea cruris. Previously approved by
the FDA in 1996 for the treatment of tinea pedis.