{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T08:33:24Z","timestamp":1786523604165,"version":"build-2736575974"},"reference-count":31,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T00:00:00Z","timestamp":1786492800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Human T-cell lymphotropic virus type 1 (HTLV-1) is a neglected pathogen with a heterogeneous global distribution. In low-prevalence areas, diagnostic testing is challenged by limited clinical awareness and the low positive predictive value of screening tests. We retrospectively analyzed 10,891 HTLV-1\/2 test results from 7719 patient samples submitted to a specialized laboratory in Germany between 2004 and 2024. Antibody screening had a positive predictive value (PPV) of 31.7% for the Diasorin Murex HTLV I + II assay (39 of 123 reactive samples confirmed) and 34.5% for the Abbott Architect rHTLV-1\/2 assay (67 of 194 reactive samples confirmed). Raising the sample\/cutoff (s\/co) threshold to \u22655 would have increased the PPV to &gt;80%, with only two missed diagnoses per assay. HTLV-1 infection was confirmed in 124 carriers and HTLV-2 infection in three carriers. The vast majority of carriers originated from countries with higher endemicity. A delayed antibody response was observed in HTLV-1 infections via organ transplantation. In four patients with neurological disease, elevated HTLV-1\/2-specific antibody indices showed antibody production in cerebrospinal fluid (CSF). HTLV-1 proviral load was measured in 83 carriers, with a median of 20,000 HTLV-1 DNA copies per 106 cells (interquartile range, 4000\u2013119,600). Seventy-four percent (17\/23) of high-dose intravenous immunoglobulin (IVIg) preparations contained HTLV-1\/2 antibodies, which can lead to false-positive HTLV-1\/2 antibody screening results in recipients without underlying infection. Therefore, HTLV-1\/2 testing presents two major pitfalls: false-negative results in immunosuppressed patients and false-positive results following IVIg administration.<\/jats:p>","DOI":"10.3390\/v18080882","type":"journal-article","created":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T07:57:26Z","timestamp":1786521446000},"page":"882","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Experiences from Two Decades of HTLV-1\/2 Testing in a Low-Prevalence Area in Southern Germany, 2004 to 2024"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1891-2107","authenticated-orcid":false,"given":"Klaus","family":"Korn","sequence":"first","affiliation":[{"name":"Harald zur Hausen Institute of Virology, University Hospital Erlangen, Friedrich-Alexander-Universit\u00e4t, Erlangen-N\u00fcrnberg, Schlossgarten 4, 91054 Erlangen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4493-4556","authenticated-orcid":false,"given":"Philipp","family":"Steininger","sequence":"additional","affiliation":[{"name":"Harald zur Hausen Institute of Virology, University Hospital Erlangen, Friedrich-Alexander-Universit\u00e4t, Erlangen-N\u00fcrnberg, Schlossgarten 4, 91054 Erlangen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0059-0349","authenticated-orcid":false,"given":"Barbara","family":"Schmidt","sequence":"additional","affiliation":[{"name":"Institute of Medical Microbiology and Hygiene, Molecular Microbiology (Virology), University of Regensburg, Franz-Josef-Strau\u00df-Allee 11, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8568-9526","authenticated-orcid":false,"given":"Andrea K.","family":"Thoma-Kress","sequence":"additional","affiliation":[{"name":"Harald zur Hausen Institute of Virology, University Hospital Erlangen, Friedrich-Alexander-Universit\u00e4t, Erlangen-N\u00fcrnberg, Schlossgarten 4, 91054 Erlangen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lennart","family":"Forneck","sequence":"additional","affiliation":[{"name":"Harald zur Hausen Institute of Virology, University Hospital Erlangen, Friedrich-Alexander-Universit\u00e4t, Erlangen-N\u00fcrnberg, Schlossgarten 4, 91054 Erlangen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1294-6923","authenticated-orcid":false,"given":"Antje","family":"Kn\u00f6ll","sequence":"additional","affiliation":[{"name":"Harald zur Hausen Institute of Virology, University Hospital Erlangen, Friedrich-Alexander-Universit\u00e4t, Erlangen-N\u00fcrnberg, Schlossgarten 4, 91054 Erlangen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7415","DOI":"10.1073\/pnas.77.12.7415","article-title":"Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma","volume":"77","author":"Poiesz","year":"1980","journal-title":"Proc. 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