The window period of serological tests allow blood contaminated with transfusion- transmitted pathogens to present a negative test. This requires questionnaires on sexual behaviour and investigation of other possible exposures to pathogens in the population of candidates for blood donation, which may characterize the potential donor as deferred. Candidates deferred for donation are dismissed without performing serological tests, so the frequency of infection by blood-borne pathogens in this population is unknown. Knowing the seropositivity rates for transfusion-transmitted pathogens among deferred donors could improve donor selection strategies. NATs are also capable of detecting infections by these agents before seroconversion, reducing the window period and increasing the safety of transfusions.

To determine and compare the prevalence of transfusion-transmitted infections in unfit and fit blood donors.

A cross-sectional survey was conducted at the Roraima Blood Bank (Hemoraima) to obtain sociodemographic data and blood samples for serological testing for HIV, syphilis, hepatitis B and C, HTLV, and Chagas disease from unfit and fit blood donors. In the period from 06/2024 to 10/2024, 8159 donors were screened at Hemoraima, of which 1719 (21.1%) were rejected for various reasons and 6440 (78.9%) were approved. A random sample of 212 rejected donors was established.

The main reasons for unsuitability for blood donation were low hemoglobin concentration (27,83%, n = 59), potential exposure to malaria (19,34%, n = 41), and risky sexual behaviour (17,92%, n = 38). Among the 212 rejected donors, the seropositivity rates and the number of seropositive individuals were 0.94% (n = 2) for anti-HIV, 1.4% (n = 3) for syphilis, 2.8% (n = 6) for anti- HBC, 0% (n = 0) for HBsAg, 0.94% (n = 2) for anti-HCV, 0% (n = 0) for HTLV I/II and 0.94% (n = 2) for Chagas disease. Among the 6440 eligible donors, the seropositivity rates and the number of seropositive individuals were 0.14% (n = 9) for anti-HIV, 0.96% (n = 62) for syphilis, 0.99% (n = 64) for anti-HBC, 0.09% (n = 6) for HBsAg, 0.2% (n = 13) for anti-HCV, 0.03% (n = 2) for HTLV I/II, and 0.02% (n = 1) for Chagas disease. The comparison of seropositivity rates in unfit and fit blood donors generated the following prevalence ratios (PR) and respective 95% confidence intervals (CI): HIV, PR = 6.75 (1.46 – 31.05), p = 0.046, syphilis, PR = 10.12 (2.76 – 37.2), p = 0.006, anti-HBC, PR = 2.84 (1.24 – 6.50), p = 0.023, anti-HCV PR = 4.67 (1.06 - 20.58), p=0,080, Chagas disease, PR = 60.75 (5.53 – 667.43), p = 0.003. For HBsAg and HTLV I/II the PRs were undefined.

The greatest causes of clinical inaptitude were factors associated with hemoglobin, malaria and sexual behaviour. The positive serological prevalence of anti-HIV, syphilis, anti-HBC and Chagas markers was significantly higher in unfit blood donors suggesting that the current screening strategy is efficient on contributing to transfusion safety and avoid financial waste by purging of hemocomponents with positive serologies.