Excluding blood donors at high risk of HIV infection in a west African city.

OBJECTIVE: To examine the potential impact of deferral of blood donors at high risk of HIV infection in a west African city where blood is screened for HIV antibodies but no other special measures are taken to protect the blood supply. DESIGN: Cross sectional study. SETTING: National Blood Transfusion Centre and Project RETRO-CI, an international collaborative AIDS research project, Abidjan, Côte d'Ivoire. SUBJECTS: 1257 male first time blood donors. INTERVENTIONS: Blood donors were interviewed about demographic and behavioural characteristics and tested for HIV antibodies by enzyme immunoassay and, if positive, synthetic peptide based tests. MAIN OUTCOME MEASURES: HIV antibody status in relation to presence of behavioural risk factors; calculation of sensitivity, specificity, and predictive values of specific criteria for excluding HIV infected donors. RESULTS: The overall prevalence of HIV infection was 11.4%. The most important risk factors for HIV positivity were prostitute contact and being aged 30-39 years. For identifying seropositive donors individual criteria had sensitivity, specificity, and positive predictive values ranging from 15% to 98%, 38% to 91%, and 17% to 30% respectively. Prostitute contact in the past five years would have excluded 31% of all donors and 73% of HIV infected donors. 27% of those excluded would have been HIV positive. CONCLUSIONS: The widespread assumption that donor deferral is not feasible in sub-Saharan Africa needs reassessment. In Abidjan this approach was well accepted and potentially effective. Donor deferral requires evaluation as a strategy for improving blood safety in resource poor areas with high rates of HIV infection.

PIP: During February-November 1991 in Abidjan, the Ivory Coast, interviews with 1257 male first-time blood donors and screening of their blood for antibodies to HIV-1 and HIV-2 were conducted at the National Blood Transfusion Center to determine whether it is feasible to exclude or defer donors at high risk of HIV infection. 143 (11.4%) men had antibodies to HIV. The multivariate analysis showed that the strongest risk factor for HIV infection was sex with prostitutes in the last 5 years without regular condom use (odds ratio [OR] = 10, confidence interval [CI] = 6.6-15) followed by prostitute contact in the last 5 years regardless of condom use (OR = 8.4, CI = 5.6-12.6), and an age of 30-39 years (OR = 6.9, CI = 18). 27% of all donors with prostitute contact in the last 5 years were infected (positive predictive value). If the center had used prostitute contact in the last 5 years as a criterion, it would have discarded 31% of all units of blood. Thus, more than 75% of all potentially excluded units would have been from donors infected with HIV. The sensitivity, specificity, and positive predictive values ranged from 15% to 98%, 38% to 91%, and 17% to 30%, respectively. These findings suggest that it is feasible in Abidjan to exclude donors based on behavioral characteristics of those most at risk of HIV infection. Donor deferral should be evaluated as a strategy to improve blood safety in resource-poor areas with high rates of HIV infection.

Risk of HIV infection from transfusion with blood negative for HIV antibody in a west African city.

OBJECTIVE: To estimate the risk of infection with HIV (HIV 1 or HIV 2, or both) from transfusion of a screened unit of blood in a high prevalence area in west Africa. DESIGN: Retrospective cohort study for January-July 1991. SETTING: National Blood Transfusion Centre, Abidjan, Côte d'Ivoire. SUBJECTS: Repeat donors (5831 units of blood) and first time donors (5076 units) in the first five months of 1991. MAIN OUTCOME MEASURES: Prevalence and estimated incidence of HIV infection in repeat and first time donors; estimated rate of potentially infected, HIV antibody negative units; and rate of (false negative) potentially infected units assuming a laboratory test sensitivity of 99%. RESULTS: Overall HIV prevalence was 11.0% in first time donors and 2.1% in repeat donors. In the first seven months of 1991, 29 HIV antibody positive (27 HIV 1, 1 HIV 2, 1 dually reactive) donors with a seronegative unit of blood earlier in the year were identified; 26 had donated blood eight weeks or less before their estimated dates of seroconversion and may have been infectious (minimum rate 26/5831 (4.5/1000 potentially infected units)). Estimated incidence of infection in repeat donors was 1.2-2.5%. Laboratory test insensitivity would result in an estimated 1.1/1000 false negative units from first time donors and 0.2/1000 units from regular donors. The overall rate of potentially infected units (all donors, seroconversions, and errors) was estimated at 5.4-10.6/1000. CONCLUSIONS: The risk of HIV infection from a single unit of blood remains substantial (5.4-10.6/1000 units). To prevent infection from blood transfusion in areas of high incidence and prevalence of HIV all but absolutely essential transfusions should be avoided, and donors with low incidence of HIV infection should be selected.