During a large epidemic of DENV-4 infection in Brazil, >0.5% of donations were RNA positive, and approximately one third of components resulted in TT. However, no significant clinical differences were evident between RNA-positive and RNA-negative recipients.

T-cell malignancies in Brazil have a high seroprevalence rate of HTLV-I antibodies. We have analyzed the disease features in 188 Brazilian patients with a T-cell disorder. These included 40 with T-lymphoblastic leukaemia or lymphoma (T-ALL/T-LbLy) and 148 with mature T-cell diseases: 5 T-prolymphocytic leukaemia, 53 adult T-cell leukaemia/lymphoma (ATLL), 54 cutaneous T-cell lymphomas, 29 pleomorphic T-cell lymphomas and 7 large granular lymphocyte leukaemia. The diagnosis was based on clinical, morphological and immunological features and HTLV-I serology. ATLL in Brazil has the same diseases features as in other endemic regions, the only apparent differences being: age, Brazilian patients being younger than Japanese, and ethnic grouping, one third of Brazilians being white Caucasians of European descent. We applied a scoring system based on the presence or absence of typical features associated with ATLL; hypercalcaemia, cell morphology, immunophenotype, histopathology and HTLV-I status, to see whether it may help in diagnosing cases of ATLL. All had high scores, whereas all other T-cell diseases scored low. Only 5 ATLL cases were HTLV-I-negative by serology, but they had otherwise typical features of ATLL, and their cells did not have HTLV-I proviral sequences by DNA analysis. Such cases suggest that ATLL may develop in a minority of individuals living in regions where it is endemic, without evidence of HTLV-I infection, and that other factors may contribute to the pathogenesis of the disease.

Molecular studies have demonstrated the existence of at least two major subtypes of human T-cell lymphotropic virus type 2 (HTLV-2), designated HTLV-2a and HTLV-2b. To further investigate the heterogeneity of this family of viruses, we have characterized the HTLV-2 subtypes present in several urban areas in Brazil. DNAs from peripheral blood mononuclear cells of a large number of infected individuals, the majority of whom were intravenous drug abusers, were analyzed by using PCR with restriction fragment length polymorphism and nucleotide sequencing analysis. Restriction fragment length polymorphism analysis of the env region suggested that all individuals were infected with the HTLV-2a subtype, and this was confirmed by nucleotide sequence analysis. In contrast, nucleotide sequence analysis of the long terminal repeat demonstrated that although the viruses were more related to the HTLV-2a than to the HTLV-2b subtype, they clustered in a distinct phylogenetic group, suggesting that they may represent a new and distinct molecular subtype of HTLV-2. This conclusion was supported by nucleotide sequence analysis of the pX region, which demonstrated that the Tax proteins of the Brazilian viruses differed from that of prototype HTLV-2a isolates but were more similar to that of HTLV-2b in that they would be expected to have an additional 25 amino acids at the carboxy terminus. In transient expression assays, the extended Tax proteins were found to be much more potent transactivators of the virus long terminal repeat than the Tax protein of the prototype HTLV-2a subtype. The studies suggest that the Brazilian viruses analyzed in this study, while being phylogenetically related to the prototypic HTLV-2a seen in North America, are phenotypically more related to HTLV-2b and can be justifiably classified as a new molecular subtype, which has been tentatively designated HTLV-2c.

Human T-lymphotropic virus type 1/2 (HTLV-1/2) infection is endemic in Brazil but representative donor prevalence and incidence data are lacking. All blood donations (2007)(2008)(2009)) from three blood centers in Brazil were studied. Samples reactive on one HTLV screening test (EIA) were retested with a different EIA; dual EIA reactivity correlated strongly with a confirmatory Western blot. Prevalence, incidence, and residual transfusion risk were calculated. Among 281,760 first-time donors, 363 were positive for HTLV on both EIAs (135 per 10 5 , 95% CI 122-150). Prevalence differed considerably by region, from 83 to 222 per 10 5 . Overall incidence rate was 3.6/10 5 person-years and residual transfusion risk was 5.0/10 6 per blood unit transfused. The logistic regression model showed significant associations with: age [adjusted odds ratio (aOR) = 5.23 for age 50 + vs. < 20], female sex (aOR = 1.97), black (aOR = 2.70 vs. white), and mixed skin colors (aOR = 1.78 vs. white), and inversely with education (aOR = 0.49, college vs. less than high school). HTLV testing with a dual-EIA strategy is feasible and can be useful in areas with low resources. Incidence and residual risk of HTLV-1 transmission by transfusion were relatively high and could be reduced by improving donor recruitment and selection in high prevalence areas. Blood center data may contribute to surveillance for HTLV infection.

Approximately 3500 children with sickle cell disease (SCD) are born in Brazil each year, but the burden of SCD morbidity is not fully characterised. A large, multi-centre cohort was established to characterise clinical outcomes in the Brazilian SCD population and create the infrastructure to perform genotype-phenotype association studies. Eligible patients were randomly selected from participating sites and recruited at routine visits. A biorepository of blood samples was created and comprehensive demographic and clinical outcome data were entered in a centralized electronic database. Peripheral blood genome-wide single nucleotide polymorphism (SNP) genotyping was performed using a customized Transfusion Medicine (TM) Array. A total of 2795 participants at six Brazilian sites were enrolled between 2013 and 2015. The cohort included slight predominance of children <18 years (55·9%) and females (53·0%). Haemoglobin (Hb) SS was the most common SCD genotype (70·7%), followed by HbSC (23%), Sβ0 (3·0%) and Sβ+ (2·9%). SNP data from the TM Array were analysed to evaluate the genetic ancestry of the cohort and revealed significant admixture among the population. Demographics and clinical complications, stratified by age and SCD genotype, are summarized and future studies in this cohort are discussed.