Risk assessment of HTLV-I/II transmission by tissue/cell transplantation

Risk assessment

ECDC was asked to assess the epidemiological history of Human T-lymphotropic Virus (HTLV), possible risks ofHTLV transmission through transplantation of human tissues and cells, and possible measures to prevent suchtransmission, in particular with regard to tissues and cells imported from the United States. Testing for HTLV-I/IIinfection among most tissue and cell donors was recently discontinued in the US.
This report is the first of two separate technical reports in which ECDC presents the results of itsassessment. This part of the assessment addresses theepidemiological history of HTLV.

Executive summary

Following a request from the European Commission in August 2010, ECDC assessed the epidemiological history of Human T-lymphotropic Virus (HTLV) across the world, possible risks of HTLV transmission through transplantation of human tissues and cells, and possible measures to prevent such transmission.

HTLV infects a type of white blood cell called a T-cell or T-lymphocyte and HTLV types I and II can be transmitted through blood contact, breast feeding, sexual contact (less common for HTLV-II) and injecting drug use. 

Testing for HTLV-I/II infection among most tissue and cell donors was discontinued in the United States while testing for HTLV type I is required for certain donors in the European Union (EU). The change of testing requirements thus raised the question on safety of tissues and cells imported from the United States.A literature review of the epidemiology of HTLV-I/II revealed that the general frequency and incidence of these viral infections in the population is unknown in most parts of the world. However, the review indicated that epidemiology for both HTLV types in the United States do not substantially differ from that of the EU region.

The primary aim of the risk assessment is to present the results of the literature review and the conclusions of an ad hoc panel of national experts on tissues and cells from the Competent Authorities, as recommended to the Commission by ECDC.A second part of this report, entitled Risk assessment of HTLV-I/II transmission by tissue/cell transplantation Part 2: Risks by tissue type, processing impact and effectiveness of prevention measures, is due for publication later in 2012.