The risk for HIV-1 infection after percutaneous exposure to HIV-infected body fluids was 0.56% per exposure
ACP J Club. 1991 Mar-Apr;114:57. doi:10.7326/ACPJC-1991-114-2-057
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Henderson DK, Fahey BJ, 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;113:740-6. [PubMed ID: 2240876]
To estimate the risk for HIV-1 infection among health workers that is associated with different types of exposures to blood or blood-containing body fluids from patients infected with HIV-1.
Prospective inception cohort study spanning 6 years; the median follow-up for employees sustaining parenteral exposures was 30.2 months (range 6 to 69 mo).
Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
1344 health care workers who responded to a questionnaire about occupational percutaneous and mucous membrane exposures to HIV-1. (The number of potential respondents was not stated.) 1286 (96%) were followed ≥ 1 year.
Assessment of prognostic factors
Questionnaires were sent at 6- to 12-month intervals. Workers were asked to estimate the frequency of cutaneous, percutaneous, and mucous-membrane exposures to blood or other blood-containing body fluids from patients with HIV-1 infection.
Main outcome measures
Seroconversion to HIV-1 was assessed by ELISA at 6-month intervals between 1983 and 1986 and then yearly until 1989. Serum samples that tested as repeatedly reactive or borderline with ELISA were evaluated by Western blot. A sample was considered to be positive if antibodies were present against both core (gag) and envelope (env) gene products.
During 6 years, 159 of 1344 respondents reported 179 percutaneous exposures, and 243 reported 346 mucous-membrane exposures to fluids from patients known to have HIV-1 infection. Of 661 workers responding to a supplementary questionnaire on cutaneous exposures (which was sent to 983 workers), 136 reported 2712 cutaneous exposures to blood from HIV-1-infected patients during a 12-month period. Occupational transmission of HIV-1 occurred in a single worker after a parenteral exposure (a deep cut with a sharp, blood-contaminated object), giving a risk after a percutaneous injury of 0.56% per exposure (95% CI 0.01% to 3.06%). No infections occurred after either mucous membrane or cutaneous exposures (upper bounds of the CI 0.86% and 0.11% per exposure, respectively).
The risk for HIV-1 infection after percutaneous exposure to HIV- infected body fluids appeared to be 0.56%. Mucous-membrane and cutaneous exposures were more common than parenteral exposure but no case of HIV infection was documented.
Sources of funding: National Institutes of Health and Dupont Laboratories.
Address for article reprint: Dr. D.K. Henderson, Building 10, Room 2C146, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
This study by Henderson and colleagues confirms the results of other published reports on the risk for occupational transmission of HIV after percutaneous exposure to blood or body fluids from patients infected with HIV. These prospective studies of health care workers have estimated that the average risk for HIV transmission after a percutaneous exposure to HIV-infected blood is approximately 0.3% (95% Cl 0.2% to 0.5%). After a mucous membrane exposure, the risk is lower at 0.09% (CI 0.006% to 0.5%) and even lower again after skin exposure (1). This information is useful when counselling health care workers who are exposed to HIV. Data from a case-control study of HIV seroconversion in health care workers after percutaneous exposure have identified those risk factors that are associated with seroconversion and provide the basis for current recommendations for post-exposure prophylaxis.
Barrier precautions to prevent HIV transmission are widely accepted, but the low risk for infection means the effectiveness of these actions cannot be easily assessed. Percutaneous exposures are associated with the greatest risk for transmission, and, as described in this study, occur frequently. Measures to decrease these injuries as a potential source of infection are important.
The results of this study by Henderson and colleagues support the use of routine diagnostic tests (ELISA and Western blot) after health care workers are exposed to HIV. Additional investigations (e.g., gene amplification, antigen capture assays, and viral culture) done on some workers did not reveal additional cases of occupational transmission and the routine use of these tests is not recommended (1).
Fiona Smaill, MB, ChB
McMaster University Health Sciences CentreHamilton, Ontario, Canada
2. Cardo DM, Culver DH, Ciesielski CA, et al., for the Centers for Disease Control and Prevention Needlestick Surveillance Group. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. N Engl J Med. 1997;337:1485-90.