HTLV Screening of Blood Donations in England Between 2002 and 2021-Comparison of Screening Strategies

Abstract

<p><b>Background. </b>Human T-lymphotropic virus (HTLV) is associated with adult T-cell leukemia/lymphoma and myelopathy. Here we present virological and epidemiological data on HTLV screening of blood donations in England between 2002 and 2021, implemented to prevent its transmission via blood transfusion. <br></p><p><b>Methods. </b>Data on HTLV testing of blood donations was reviewed; it was initially conducted in pools (2002-2012) and subsequently using individual samples (all donors, 2013-2016; first-time donors and non-leucodepleted component donors, 2017-2021). Data included annual number of donations screened, initial and repeat reactives as well as confirmed positives. Further information, such as likely source of infection, was obtained for HTLV-positives. <br></p><p><b>Results. </b>Over the 20-year study period, a total of 30 679 741 blood donations were screened for HTLV in England. Under pooled screening strategy, the annual rate of repeat reactive donations remained <5:100 000. However, this rate increased to 51:100 000 with individual screening and further to 123:100 000 with selective screening. A total of 5032 samples were repeat reactive, of which 278 were confirmed HTLV-positives. Although the specificity under each scenario exceeded 99.9%, the rate of repeat reactives was around 50-fold higher in individual compared to pooled screening. Most HTLV infected were UK-born, most likely acquired their infection unknowingly through breast feeding or heterosexual intercourse with an individual associated with an HTLV-endemic country. <br></p><p><b>Conclusions. </b>These data highlight that pooled testing can be advantageous in low-prevalence settings due to its high specificity and reduced non-specific reactivity. Whether pooling is an applicable strategy to tackle the burden of HTLV infection in resource-poor, HTLV-endemic countries requires further investigations.<br></p>