Ruth A. Thomson

Male-to-female transmission of human T-cell lymphotropic virus types I and II : Association with viral load

SUMMARY 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.

Retention of “safe” blood donors. The Retrovirus Epidemiology Donor Study

BACKGROUND: There are obvious advantages to increasing donor retention. However, for reasons of blood safety, certain donors may, in fact, be more desirable to retain than others. “Safe” donors are defined as those who provided a blood donation that was negative on all laboratory screening tests and who subsequently reported no behavioral risks in response to an anonymous survey. This study identifies the most important factors affecting the intention of “safe” donors to provide another donation.

The potential impact of incentives on future blood donation behavior

BACKGROUND: It is important to assess the potential efficacy and safety of offering donation incentives as part of recruitment and retention programs.

Absence of evidence of infection with divergent primate T‐lymphotropic viruses in United States blood donors who have seroindeterminate HTLV test results

BACKGROUND: Recent identification of divergent simian or primate T‐lymphotropic viruses (STLVs; PTLVs) in bonobos (formerly called pygmy chimpanzees; Pan paniscus; viruses: STLVpan‐p and STLVpp1664) and a baboon (Papio hamadryas; viruses: STLVph969 or PTLV‐L) have raised the possibility of human infection with these viruses. Divergent PTLV‐infected primate sera show p24 bands on HTLV‐I Western blots (WBs). It was investigated whether infection by divergent PTLV‐like viruses could explain a subset of United States blood donors who reacted on HTLV‐I EIAs and had indeterminate HTLV‐I WBs with p24 bands.

False-negative testing errors in routine viral marker screening of blood donors

BACKGROUND: The contribution of testing errors to the risk of virus transmission by transfusion depends on the rate of false‐negative testing errors and the prevalence of infected seropositive donations. Although the false‐negative testing error rate has been estimated at 0.1 to 1 percent on the basis of proficiency studies, it has not previously been measured in routine donor screening.

Delayed Hypersensitivity Skin Testing to Mumps and Candida albicans Antigens Is Normal in Middle-Aged HTLV-I- and-II-Infected U.S. Cohorts

It has been reported that human T cell lymphotropic virus (HTLV)-I-infected persons in Japan have decreased delayed hypersensitivity skin test reactivity to tuberculin purified protein derivative (PPD), but HTLV-I- or -II-infected persons do not generally develop opportunistic infections. We administered standardized intradermal testing with PPD, mumps, and Candida albicans antigens to 31 HTLV-I, 48 HTLV-II, and 143 seronegative subjects in the United States. Reactivity at 48 hr was compared among the three groups. Response rates to PPD were very low in all subjects. Fifty-five percent of seronegative subjects did not react to mumps antigen, compared with 55% of HTLV-I [adjusted odds ratio (OR) = 0.79, 95% confidence interval (CI) 0.27-2.33] and 38% of HTLV-II (OR = 0.73, 95% CI 0.33-1.64). Fifty-one percent of seronegatives did not react to Candida albicans antigen, compared with 34% of HTLV-I (OR = 0.37, 95% CI 0.15-0.93) and 46% of HTLV-II (OR = 0.71, 95% CI 0.34-1.52). Anergy was present in 33% of seronegatives, 28% of HTLV-I (OR = 0.60, 95% CI 0.20-1.78), and 19% of HTLV-II (OR = 0.56, 95% CI 0.22-1.44). HTLV-I- and -II-infected persons appear to have intact delayed hypersensitivity skin test responses to mumps and Candida albicans antigens.

False-Positive HIV-1 Test Results in a Low-Risk Screening Setting of Voluntary Blood Donation

Context.— Persons at risk of human immunodeficiency virus 1 (HIV-1) infection have been classified incorrectly as HIV infected because of Western blot results, but the frequency of false-positive Western blot results is unknown. Objectives.— To determine the frequency of false-positive HIV-1 Western blot results in US blood donors and to make projections to other screened populations. Secondarily, to validate an algorithm for evaluating possible false-positive cases. Design.— A retrospective cohort study of HIV-1 enzyme immunoassay (EIA) and Western blot results from large blood donor screening programs in which donors with suspected false-positive Western blot results underwent HIV-1 RNA polymerase chain reaction (PCR) testing and follow-up HIV-1 serology. Setting.— Five US blood centers participating in the Retrovirus Epidemiology Donor Study. Participants.— More than 5 million allogeneic and autologous blood donors who successfully donated blood at 1 of the 5 participating centers from 1991 through 1995. Main Outcome Measures.— Rate of false positivity by Western blot and true HIV-1 infection status as determined by HIV-1 RNA PCR and by serologic followup of blood donors more than 5 weeks after donation. Results.— Of 421 donors who were positive for HIV-1 by Western blot, 39 (9.3%) met the criteria of possible false positivity because they lacked reactivity to p31. Of these, 20 (51.3%) were proven by PCR not to be infected with HIV-1. The falsepositive prevalence was 4.8% of Western blot–positive donors and 0.0004% (1 in 251 000)ofall donors (95%confidence interval, 1 in173 000 to1 in379 000donors). Conclusions.— A false diagnosis of HIV-1 infection can result from the combination of EIA and Western blot testing in blood donor and other HIV-1 screening programs. Individuals with a positive Western blot result lacking the p31 band should be counseled that, although they may be HIV infected, there is uncertainty about this conclusion. These individuals should be further evaluated by RNA PCR testing (if feasible) and HIV serologic analysis on a follow-up sample. JAMA. 1998;280:1080-1085