Injection drug use (IDU) is a known risk factor for hepatitis C virus (HCV) infection, but the strength of other parenteral and sexual risk factors is unclear. In 1997, we performed a case-control study of 2,316 HCV-seropositive blood donors and 2,316 seronegative donors matched on age, sex, race/ethnicity, blood center, and first-time versus repeat-donor status. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. Questionnaires were returned by 758 (33%) HCV ؉ and 1,039 (45%) control subjects (P ‫؍‬ .001). The final multivariate model included only the following independent HCV risk factors: IDU (OR ‫؍‬ 49.6; 95% CI: 20.3-121.1), blood transfusion in non-IDU (OR ‫؍‬ 10.9; 95% CI: 6.5-18.2), sex with an IDU (OR ‫؍‬ 6.3; 95% CI: 3.3-12.0), having been in jail more than 3 days (OR ‫؍‬ 2.9; 95% CI: 1.3-6.6), religious scarification (OR ‫؍‬ 2.8; 95% CI: 1.2-7.0), having been stuck or cut with a bloody object (OR ‫؍‬ 2.1; 95% CI: 1.1-4.1), pierced ears or body parts (OR ‫؍‬ 2.0; 95% CI: 1.1-3.7), and immunoglobulin injection (OR ‫؍‬ 1.6; 95% CI: 1.0-2.6). Although drug inhalation and a high number of lifetime sex partners were significantly more common among HCV seropositives, they were not associated with HCV after controlling for IDU and other risk factors. IDU, blood transfusion among non-IDU, and sex with an IDU are strong risk factors for HCV among United States blood donors. Weaker associations with incarceration, religious scarification, being stuck or cut with a bloody object, pierced ears or body parts, and immunoglobulin injection must be interpreted with caution. (HEPATOLOGY 2000;31:756-762.)Since the discovery of hepatitis C virus (HCV) was reported in 1989, much has been learned about its epidemiology and pathogenesis. HCV seroprevalence in the general population ranges from 1% to 2% in a number of countries including the United States 1-3 to 12.6% in parts of Italy, 4 and 14.1% in areas of Japan. 5 As a result of selection for those at low risk of infectious disease, HCV prevalence is lower among blood donors, ranging from 0.06% to 1.3% in several countries, and 0.4% in the United States. [6][7][8][9][10] It is hyperendemic among injection drug users (IDUs) in industrialized countries, with infection rates of up to 90%, 11,12 consistent with the high frequency of parenteral blood exposures in this subgroup. Most HCV seropositives have persistent viremia, more than half have chronic hepatitis, and cirrhosis may occur in up to 20%. 13 Other investigators have implied that up to 40% of HCV seropositives do not have recognized parenteral risk factors, 14 leading to speculation that other as-yet-undiscovered modes of transmission may exist. Whether heterosexual transmission occurs at more than a negligible rate is also controversial. [15][16][17][18] Furthermore, a recent study reported that intranasal inhalation of cocaine appeared to be a risk factor for HCV infection in United States blood donors. 19 Clarification of the risk factors for and transmiss...

Risk factors for male-to-female sexual transmission of human T-lymphotropic virus types I and II (HTLV-I/II) were investigated among HTLV-seropositive volunteer blood donors and their long-term (> or = 6 month) sex partners. Direction of transmission in concordantly seropositive pairs was assessed by analyzing risk factors for HTLV infection. Donors and their partners were also questioned regarding sexual behaviors during their relationships; HTLV antibody titers and viral load were determined for specimens from male partners. Among 31 couples in whom HTLV-infected men likely transmitted infection to their partners (11 HTLV-I and 20 HTLV-II) and 25 male-positive, female-negative couples (8 HTLV-I and 17 HTLV-II), HTLV transmitter men had been in their relationships longer (mean 225 months vs. 122 months) and had higher viral loads (geometric mean 257,549 vs. 2,945 copies/300,000 cells for HTLV-I; 5,541 vs. 118 copies/300,000 cells for HTLV-II) than non-transmitters (P = 0.018 and P = 0.001 for duration of relationship and viral load, respectively, logistic regression analysis). Transmitter men also tended to have higher antibody titers against various env and whole virus proteins than non-transmitters. The identification of high viral load and duration of relationship as risk factors provides a biologically plausible framework in which to assess risk of sexual transmission of the HTLVs.

These findings suggest that offering blood credits and (though to a lesser extent) items of limited value could be safe and effective strategies for retaining donors. Although medical tests were found to have broad appeal, studies are needed to identify tests in which donors would be most interested.

These data suggest that efforts to improve donors' perceptions of their donation experience, as well as attention to the physical effects of blood donation, may aid in the retention of both repeat and first-time donors.

Our data also suggest that HAM occurs more frequently among HTLV-I-infected subjects than reported by previous studies. The HTLV-II infected myelopathy patient identified in this cohort, together with three other case reports in the literature, implies a pathogenic role for this human retrovirus. The diagnosis of HTLV-associated myelopathy should be considered in cases of spastic paraparesis or neurogenic bladder when risk factors for HTLV-I or HTLV-II infection are present.