Rapid tests for diagnosing syphilis: validation in an STD clinic in the Amazon Region, Brazil.

Correct, early diagnosis and treatment of syphilis are essential for its control. Traditional diagnostic tests depend on specialized equipment, installations, and human resources. In the search for quick, simple tests, a project was conducted on the validation and reproducibility of four different tests, previously assessed by WHO reference laboratories. The study also verified the operational characteristics and acceptance by patients and health professionals. Samples obtained at an STD clinic were from 541 and 248 patients with 51 and 52 positive results according to FTA-Abs (gold standard) in studies 1 and 2, respectively. The sensitivity varied from 84 to 96%, specificity was greater than 98%, and PPV was >90%. Reproducibility was >97% and kappa index 0.94, comparing the results obtained by different health workers. The tests took less than 20 minutes to perform, and more than 90% of patients agreed to wait up to two hours for the results. The tests presented the necessary requirements for use in diagnosis of syphilis, thus providing an additional option for controlling this disease.

Rapid tests for diagnosing syphilis: validation in an STD clinic in the Amazon Region, Brazil

Correct, early diagnosis and treatment of syphilis are essential for its control. Traditional diagnostic tests depend on specialized equipment, installations, and human resources. In the search for quick, simple tests, a project was conducted on the validation and reproducibility of four different tests, previously assessed by WHO reference laboratories. The study also verified the operational characteristics and acceptance by patients and health professionals. Samples obtained at an STD clinic were from 541 and 248 patients with 51 and 52 positive results according to FTA-Abs (gold standard) in studies 1 and 2, respectively. The sensitivity varied from 84 to 96 percent, specificity was greater than 98 percent, and PPV was > 90 percent. Reproducibility was > 97 percent and kappa index 0.94, comparing the results obtained by different health workers. The tests took less than 20 minutes to perform, and more than 90 percent of patients agreed to wait up to two hours for the results. The tests presented the necessary requirements for use in diagnosis of syphilis, thus providing an additional option for controlling this disease.

O diagnóstico e o tratamento corretos e precoces da sífilis são essenciais para o seu controle. Os testes diagnósticos tradicionais dependem de equipamentos, instalações e recursos humanos especializados. Na busca de testes de execução simplificada e rápida, realizou-se projeto de validação e da reprodutibilidade de quatro diferentes testes anteriormente avaliados pelos laboratórios de referência da Organização Mundial da Saúde. Verificaram-se também as características operacionais e aceitabilidade dos pacientes e dos profissionais de saúde. As amostras obtidas numa clínica de DST constaram de 541 e 248 pacientes com 51 e 52 positivos no FTA-Abs (padrão ouro) nos estudos 1 e 2, respectivamente. A sensibilidade variou entre 84 e 96 por cento, especificidade superior a 98 por cento e valor preditivo positivo > 90 por cento. A reprodutibilidade foi superior a 97 por cento e 0,94 no índice de kappa, comparando-se os resultados obtidos pelos diferentes profissionais. A execução dos testes foi de menos de vinte minutos, e mais de 90 por cento dos pacientes concordaram em esperar o seu resultado até duas horas. Os testes apresentaram requisitos necessários para serem empregados no diagnóstico da sífilis, dando assim mais uma opção para o controle desta infecção.

Congenital syphilis and fluorescent treponemal antibody test reactivity after the age of 1 year.

BACKGROUND: Many believe that a persistently reactive fluorescent treponemal antibody absorption (FTA-ABS) is manifested with congenital syphilis after the age of 1 year, that it is useful in the retrospective diagnosis of children with congenital syphilis, and that it can be used to confirm other treponemal tests. GOAL: To determine whether a reactive FTA-ABS after the age of 12 months is indicative of congenital syphilis. STUDY DESIGN: Prospective outpatient follow-up evaluation until at least the age of 12 months was conducted for 194 babies born to mothers with reactive syphilis serology at delivery, and for two additional children with congenital syphilis diagnosed when they were younger than 1 year (total, 196 children). RESULTS: In the study group, 54 children had reactive FTA-ABS (reactors) until the age of at least 12 months or more, and 142 children had nonreactive FTA-ABS (nonreactors) at the age of 12 months or more. Of the 54 reactors, 17 (31%) had evidence of congenital syphilis at birth, whereas evidence of congenital syphilis was seen in 14 of the 142 (10%) nonreactors (P = 0.0002). At 15 months, nonreactive FTA-ABS developed in six reactors, and eventually in 15 of 44 reactors (34%) tested. CONCLUSIONS: A reactive FTA-ABS may be seen at 12 months in children with and without evidence of congenital syphilis at birth. Not all children with congenital syphilis will manifest reactive FTA-ABS at 12 months, and FTA-ABS reactivity wanes with time.

Finding neurosyphilis without the Venereal Disease Research Laboratory test.

BACKGROUND: The cerebrospinal fluid (CSF)-Venereal Disease Research Laboratory (VDRL) test is only 27% sensitive for diagnosing neurosyphilis. Discriminant analysis, used on 124 patients, shows that other commonly used laboratory tests can, in combination, identify 87% of patients with neurosyphilis with 94% specificity. STUDY DESIGN: The insensitivity of the CSF-VDRL (27% in persons with neurosyphilis) and the foreseen greater need to identify and treat neurosyphilis in the era of human immunodeficiency virus caused us to analyze the serum and cerebrospinal fluid results of 73 patients with syphilis and of 51 patients with clinically diagnosed neurosyphilis. Discriminant analysis was applied to different sets of laboratory tests to find the combination of test results best able to predict retrospectively the clinical diagnosis of syphilis or neurosyphilis, without reference to the CSF-VDRL. RESULTS: The predicting function averages 94% specificity and 87% sensitivity. Test result variables considered together are: CSF-FTA-ABS, serum FTA-ABS, CSF-TPHA, serum TPHA, and CSF cells. CONCLUSIONS: The authors conclude that clinicians or laboratories can, independently of the CSF-VDRL, compute a score showing whether the results of a set of commonly used tests suggest neurosyphilis in a patient.

Comparison of maternal sera, cord blood, and neonatal sera for detecting presumptive congenital syphilis: relationship with maternal treatment.

The incidence of congenital syphilis has increased rapidly over the past few years. Most infected mothers and their newborns are asymptomatic at birth and diagnosis depends on serologic testing during pregnancy and at delivery. This study was initiated to compare maternal sera, cord blood, and neonatal sera for detecting presumptive congenital syphilis and to assess the role of maternal treatment (administration of penicillin to the mother at least 1 month before delivery) on the serologic results at the time of delivery. The serologic results from all live deliveries complicated by a positive maternal and/or neonatal test for syphilis during a 12-month period were compared using chi 2 analysis and multiple comparisons for proportions. Of 3306 livebirths, 73 (2.2%) were complicated by a positive maternal or neonatal serology. At delivery, the serologic test was positive in 68 (94%) of 72 maternal sera, 30 (50%) of 60 cord sera, and 43 (63%) of 68 neonatal sera. In the absence of maternal treatment, 95% of the maternal sera, 66% of the cord blood samples, and 86% of the neonatal sera were positive. If the mother had been treated, 94% of maternal sera, 36% of cord sera, and 39% of neonatal sera were positive. Cord blood and neonatal sera appear to be inferior to maternal sera for detecting prenatal exposure to syphilis. Cord serology is also inferior to neonatal serology at 2 to 3 days of age. The most effective way to identify newborns at risk for congenital syphilis is to obtain a maternal serologic diagnosis during pregnancy and to test maternal and neonatal sera at delivery.

Evaluation of the fluorescent treponemal antibody-absorption (FTA-Abs) test specificity.

Serum samples from 43 patients with positive test for syphilis only in the FTA-Abs test, were evaluated. Three had primary or treated syphilis. Twenty-one (49%) had clinical and/or serological signs of Lyme borreliosis as assessed by whole-cell sonicate Borrelia burgdorferi ELISA and Western blot techniques. Seven (16%) had genital Herpes simplex infection and the remaining 12 patients, miscellaneous disorders. In control sera from 30 patients with Lyme borreliosis an isolated positive FTA-Abs reaction was found in 13 patients (43%). Elevated Borrelia ELISA titres were found in nine of 30 (30%) syphilitic patient serum samples, whereas Western blots for Borrelia were negative. Six per cent of healthy blood donors were seropositive for Borrelia. Lyme borreliosis is an important cause of cross-reactions in the FTA-Abs test. Other serological tests for syphilis and Western blot for Borrelia are useful for discrimination.