Evaluation of positive and false-positive results in syphilis screening of blood donors in Rio de Janeiro, Brazil.

OBJECTIVES: We propose to analyse the positive and false-positive results of treponemal and nontreponemal tests in blood donors from Brazil and to evaluate possible factors associated with the results of treponemal tests. BACKGROUND: Treponemal tests have been used widely for syphilis screening in blood banks. The introduction of these tests in donor screening has caused an impact and a loss of donors who need to be assessed. METHODS: This was a retrospective cross-sectional study of syphilis screening and confirmatory test results of blood donors that were obtained before and after adopting a chemiluminescent immunoassay (CLIA). A comparative analysis was performed using a second sample drawn from positive donors. The possible factors associated with CLIA-positive or CLIA-false-positive results were investigated in a subgroup. Statistical tests were used to compare the proportions and adjusted estimates of association. RESULTS: The reactivity rate increased from 1·01% (N = 28 158) to 2·66% (N = 25 577) after introducing the new test. Among Venereal Disease Research Laboratory (VDRL)- and CLIA-confirmed results, the false-positive rates were 40·5% (N = 180) and 37·4% (N = 359), respectively (P = 0·5266). Older donors (OR = 1·04; P = 0·0010) and donors with lower education levels (OR = 6·59; P = 0·0029) were associated with a higher risk of positivity for syphilis. CONCLUSIONS: CLIA represents an improvement in blood bank serological screening. However, its use in a healthy population appears to result in high rates of false positives. Identifying which characteristics can predict false positives, however, remains a challenge.

[Prevalence of rheumatic fever in children from a public high school in Belo Horizonte]. / Prevalência da febre reumática em crianças de uma escola da rede pública de Belo Horizonte.

PURPOSE: To determine the prevalence of rheumatic fever (RF) among children of a public high school in Belo Horizonte, Brazil. METHODS: The study was performed from March to December/92, and involved high school students coming from families of the medium and low-medium social classes. Considering the total of 1,400 students registered in a public school and the estimated RF prevalence in the developing country, 729 students were randomly chosen to be interviewed and examined by a researcher. The children suspected of being affect by RF were submitted to echocardiography in order to find any cardiac lesions. RESULTS: Due to several different factors, only 550 students aging from 10 to 20 years were admitted in this study. Four children, previously under secondary prophylactics, had already had the diagnosis of RF. Among these children, only one had heart disease (combined mitral incompetence and stenosis, and aortic incompetence). From the other three children, only one had the diagnosis of RF confirmed according to the Jones criteria. CONCLUSION: From the ata obtained, the prevalence of RF was calculated in 3.6/1000.