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Title: Investigations of syphilis testing and of test cross-reactions in Ghanaian blood donors
Author: Sarkodie, Francis
ISNI:       0000 0004 7428 507X
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2017
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Blood transfusion is an important element of health care which saves millions of lives each year but has life-threatening risks. In low-resource countries in Africa, a significant proportion of donated blood remains unsafe if blood units are not screened appropriately for all major transfusion-transmitted infections (TTIs). Syphilis, one of the TTIs, remains a public health problem in developing countries including Ghana if testing is not performed in a well-controlled manner. Thus, there is the possibility of infecting recipients with syphilis which may have long-term sequelae. The study investigated syphilis testing practices in transfusion facilities in Ghana, test cross-reactions between various techniques, and the potential infectivity of 'true' positive blood samples, in the Ghanaian blood donor population. The goal of the research was to guide transfusion policies and practices, and advance transfusion medicine research in Ghana by improving syphilis testing. Data collection was in three parts based on five specific objectives. The first part was a survey, carried out in 149 transfusion facilities in Ghana and found a syphilis seroprevalence of 3.7% for blood donors. The laboratories used predominantly non-approved test kits at variable costs. In the second part, using rapid diagnostic test, Fortress RDT, and rapid plasma reagin (RPR), syphilis testing was performed on 16,016 prospective blood donors who came to donate blood for the Komfo Anokye Teaching Hospital (KATH) blood bank. Positive predictive values of the RDT and RPR were found to be 90.9% and 97.1% respectively. The third part was a quality assessment to determine the performance of the frequently used syphilis test in Ghana, the ABON RDT, in four selected facilities. Sensitivity and specificity were found to be 99.2% and 82.5% respectively. Finally, we determined the relative proportions of confirmed syphilis antibody positive donors with clinical histories attributable to yaws rather than syphilis. Our data from the surveys showed a considerable mismatch between recommendations and practice of syphilis testing in Ghana, with potential serious consequences for blood safety and public health. This study found that the combination of syphilis RDT and RPR which have a relatively good PPV, as a novel strategy, could contribute to improving blood safety when screening blood donors for syphilis. It was confirmed that quality systems for syphilis testing are generally weak in Ghana, but are important for any laboratory or testing site to ensure accuracy, consistency, and reliability of test results which directly contributes to the safety of blood supply. Finally, the question, whether some of the syphilis positivity in blood donors could be attributable to yaws rather than syphilis remained speculative.
Supervisor: Hassall, Oliver ; Bates, Imelda ; Ullum, Henrik Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral