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Anonymous Survey for Simian Immunodeficiency Virus (SIV) Seropositivity in SIV-Laboratory Researchers -- United States, 1992

CDC recently reported on two laboratory workers who had seroconverted against simian immunodeficiency virus (SIV) following work-related exposure to the virus (1). In follow-up, the National Institutes of Health (NIH) and CDC have collaborated on an anonymous SIV seroprevalence study using stored serum samples from some laboratory workers and animal caretakers involved in SIV research at some of the NIH-sponsored facilities in the United States. This report summarizes the study.

A convenience sample of serum specimens previously collected from researchers and stored at -4 F (-20 C) were forwarded without any identification of the employee or research facility to CDC through a contract laboratory. Eleven serum specimens known to be seropositive for either human immunodeficiency virus type 1 (HIV-1) or human immunodeficiency virus type 2 (HIV-2) were included in the group of specimens as positive controls. A total of 483 serum samples (including the 11 controls) were screened blindly at CDC using a combination HIV-1/2 peptide-based enzyme-linked immunosorbent assay (ELISA) (Biochemical Immunogenetics, Montreal *). Repeatedly reactive samples were tested by HIV-1 and HIV-2 Western blot and by HIV-1 and HIV-2 peptide-based ELISA assays (Biochemical Immunogenetics; Genetic Systems, Seattle; and in-house). Because of the high degree of serologic cross-reactivity between HIV-2 and SIV, seropositivity to HIV-2 was considered to indicate the presence of antibody to either virus. All 11 control serum samples tested positive for either HIV-1 or HIV-2/SIV.

Three of the 472 samples tested were seropositive for HIV-2/SIV. An additional two samples had antibody to HIV-1. Reported by: National Institutes of Health. Retrovirus Diseases Br, Div of Viral and Rickettsial Diseases, and Laboratory Investigations Br, Div of HIV/AIDS, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: This blinded serosurvey was undertaken to rapidly estimate the prevalence of seroreactivity to SIV among laboratory workers and animal caretakers involved in SIV research. The findings indicated a low seroprevalence of HIV-2/SIV antibody (0.6%). However, the three SIV-seropositive persons in this blinded study may include one or both cases reported previously by CDC. Moreover, because of the high degree of cross-reactivity between HIV-2 and SIV, it is possible that these persons may be seropositive for HIV-2 rather than SIV.

Because HIV-1 shows some cross-reactivity with HIV-2, HIV-1 testing was conducted as a necessary part of this study. However, the two HIV-1-seropositive persons in this anonymous study cannot be identified or notified; these persons may be aware of their HIV-1 status.

To address concerns about the potential for transmission of SIV in research laboratories, NIH and CDC are planning to add voluntary testing for SIV to their existing medical surveillance programs. In addition, NIH and CDC are planning a collaborative prospective study to investigate SIV seropositivity among animal caretakers and laboratory workers in federally funded SIV-research laboratories to identify specific exposures associated with seropositivity. Based on CDC's investigation of the two previously reported cases (1) and the findings reported in this study, all laboratory and animal workers involved in SIV research should strictly adhere to recommended procedures for handling known and potentially SIV-infected clinical samples (2).


  1. CDC. Seroconversion to simian immunodeficiency virus in two laboratory workers. MMWR 1992;41:678-81.

  2. CDC. Guidelines to prevent simian immunodeficiency virus infection in laboratory workers and animal handlers. MMWR 1988;37:693-4,699-704.

    • Use of trade names and commercial sources is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services. The peptide-based assays used in this study are unlicensed by the Food and Drug Administration for diagnostic purposes; however, they were used here because they are highly sensitive for HIV-2/SIV.

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