RESUMEN
BACKGROUND: Syphilis testing conventionally relies on a combination of non-treponemal and treponemal tests. The primary objective of this study was to describe the positive predictive value (PPV) of a screening algorithm in a combination of a treponemal rapid diagnostic test (RDT) and rapid plasma reagin (RPR) test at Komfo Anokye Teaching Hospital (KATH), Ghana. MATERIALS AND METHODS: From February 2014 to January 2015, 5 mL of venous blood samples were taken from 16 016 blood donors and tested with a treponemal RDT; 5 mL of venous blood was taken from 526 consenting initial syphilis sero-reactive blood donors. These RDT reactive samples were confirmed with an algorithm, applying the Vitros® /Abbott-Architect® algorithm as gold standard. RESULTS: A total of 478 of 526 RDT reactive donors were confirmed positive for syphilis, making a PPV of 90·9%. Of the 172 (32·7%) donors who were also RPR positive, 167 were confirmed, resulting in a PPV of 97·1%. The PPV of the combined RDT and RPR (suspected active syphilis) testing algorithm was highest among donors at an enhanced risk of syphilis, family/replacement donors (99·9%), and among voluntary donors above 25 years (98·6%). DISCUSSION: Screening of blood donors by combining syphilis RDT and RPR with relatively good PPV may provide a reasonable technology for LMIC that has a limited capacity for testing and can contribute to the improvement of blood safety with a minimal loss of donors.
Asunto(s)
Algoritmos , Anticuerpos Antibacterianos/sangre , Donantes de Sangre , Selección de Donante/métodos , Serodiagnóstico de la Sífilis/métodos , Sífilis/sangre , Adulto , Estudios Transversales , Países en Desarrollo , Selección de Donante/organización & administración , Selección de Donante/normas , Femenino , Ghana , Humanos , Masculino , Persona de Mediana Edad , Serodiagnóstico de la Sífilis/normasRESUMEN
The incidence of reported infections of non-typhoid Salmonella is affected by biases inherent to passive laboratory surveillance, whereas analysis of blood sera may provide a less biased alternative to estimate the force of Salmonella transmission in humans. We developed a mathematical model that enabled a back-calculation of the annual seroincidence of Salmonella based on measurements of specific antibodies. The aim of the present study was to determine the seroincidence in two convenience samples from 2012 (Danish blood donors, n = 500, and pregnant women, n = 637) and a community-based sample of healthy individuals from 2006 to 2007 (n = 1780). The lowest antibody levels were measured in the samples from the community cohort and the highest in pregnant women. The annual Salmonella seroincidences were 319 infections/1000 pregnant women [90% credibility interval (CrI) 210-441], 182/1000 in blood donors (90% CrI 85-298) and 77/1000 in the community cohort (90% CrI 45-114). Although the differences between study populations decreased when accounting for different age distributions the estimates depend on the study population. It is important to be aware of this issue and define a certain population under surveillance in order to obtain consistent results in an application of serological measures for public health purposes.