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The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
HTLV-1 is also implicated as the causative agent in the neurological disorder HTLV-1-associated myelopathy (HAM) or tropical spastic paraparesis (TSP). HAM/TSP is a chronic demyelinating disease characterized by weakness and spasticity of the extremities, hyperreflexia, and mild peripheral sensory loss. The pathogenesis of HAM/TSP is not fully understood, but it appears to be distinct from ATL. Development of the myelopathy occurs within several years following infection, whereas development of the leukemia normally requires twenty to thirty years. HTLV-1 provirus is polyclonally integrated in the peripheral blood cells of HAM/TSP patients as opposed to mono or oligoclonally integrated with ATL. There are approximately three-times more infected cells in HAM/TSP patients than in asymptomatic carriers, and there are also higher titers of anti-HTLV-1 antibodies in the serum and CSF. It has been suggested that HAM/TSP is an autoimmune disease resulting from immune dysregulation. HTLV-1-infected patients exhibit an increased incidence of a variety of immune-mediated disorders. However, these disorders are less clearly associated with HTLV-1 than ATL and HAM/TSP.
Spinal Cord Disease
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
There are guidelines for the diagnosis of HTLV: MRI of the spinal cord may show edema in early disease with eventual thinning (atrophy).MRI of the brain may show white matter hyperintensities on T2 or FLAIR sequences in subcortical regions.CSF: pleocytosis (mild–moderate) and elevated protein: can regress later in the disease course.Testing specific to HTLV-1 virus in the combinations below can increase specificity and sensitivity of the diagnosis: Serum HTLV-1 antibodies.Oligoclonal IgG bands in the CSF.PCR for HTLV-1 DNA in the CSF.Evidence of intrathecal HTLV-1 antibody production.
Human T lymphotropic virus type 1 (HTLV-1)
Published in Avindra Nath, Joseph R. Berger, Clinical Neurovirology, 2020
Approximately 5–10 million people worldwide have HTLV-1 infection seen in endemic clusters in Japan, South America, the Caribbean and sub-Saharan Africa as well as foci in the Middle East and Austro-Melanesia, as shown in Figure 12.1 [6]. Importantly, approximately 90% of all individuals infected with HTLV-1 remain asymptomatic during their lifetime while no more than 10% develop HAM/TSP or adult T cell leukemia/lymphoma (ATL). Uveitis, arthritis, alveolitis, infective dermatitis and inflammatory myositis have also been linked to HTLV-1 infection [7]. As with other retroviruses, the three main modes of transmission include breast-feeding, sexual contact, and blood products. The distribution of infection is attributed to founder effect in combination with viral persistence due to high viral transmission rate. In non-endemic regions such as North America and Europe, HTLV-1 infection is mainly seen in immigrants from endemic regions [8]. Since a majority of infected immigrants will be asymptomatic carriers (AC), the virus can then spread in these communities.
Clinical features and human T-cell leukemia virus type-1 (HTLV-1) proviral load in HTLV-1-positive patients with rheumatoid arthritis: Baseline data in a single center cohort study
Published in Modern Rheumatology, 2020
Katsumi Eguchi, Masako Iwanaga, Kaoru Terada, Toshiyuki Aramaki, Yoshiko Tuji, Shouta Kurushima, Kanako Kojima, Kazuhiko Arima, Naoki Iwamoto, Kunihiko Ichinose, Atushi Kawakami, Naoyuki Hirakata, Yukitaka Ueki
HTLV-1 is the first discovered human retrovirus and is known to be etiologically associated with adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and HTLV-1 uveitis/HTLV-1-associated uveitis (HU/HAU) [2]. HTLV-1 mainly infects CD4-positive T-cells and the provirus is integrated into the host genome [2]. HTLV-1-infected people are present throughout the world; however, the highly endemic areas are limited to Japan, the Caribbean islands, South America, and a part of Central Africa [3]. In Japan, HTLV-1 carriers were estimated to be approximately 1.2 million people in the late 1980s [4] and 1.08 million in 2006 − 2007 [5], although most HTLV-1-infected individuals live in the southwestern area. The lifetime risk of developing ATL among HTLV-1 carriers is estimated to be 6 − 7% for male and 2 − 3% for female [6].
Biomedical and genetic characteristics of the Ryukyuans: demographic history, diseases and physical and physiological traits
Published in Annals of Human Biology, 2019
Kae Koganebuchi, Ryosuke Kimura
Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes a malignant tumour referred to as adult T-cell leukaemia (ATL) in some HTLV-1 carriers (Sonoda et al. 2011). HTLV-1 is known to be transmitted from mothers to their infants through milk, and is maintained within the infant’s family and regional population (Kinoshita et al. 1984; Hino et al. 1987). The worldwide distribution of HTLV-1 indicates that there are a large number of carriers in the Japanese, native South American, Caribbean and central African populations (Sonoda et al. 2011). In the Japanese Archipelago, the Ryukyuans (33.9%) and the Ainu (45.2%) show substantially higher frequencies of adults infected with HTLV-1 than the main islanders of Japan (0.5–7.8%) (Ishida et al. 1985). Since the Ryukyuans and the Ainu are thought to have more of a genetic influence from the indigenous Jomon people, this distribution suggests that the retrovirus had already been present in the Jomon population. In the Ryukyu Islands, the highest prevalence of HTLV-1 carriers was observed in Itoman city (35%) in Okinawa-jima (Kohakura et al. 1986). The frequency of carriers in Miyako-jima (1–6%) was much lower than in the other islands (14–31%) (Kohakura et al. 1986).
The time-sequential changes of risk factors for adult T-cell leukemia development in human T-cell leukemia virus-positive patients with rheumatoid arthritis: a retrospective cohort study
Published in Modern Rheumatology, 2019
Kunihiko Umekita, Yayoi Hashiba, Yumi Kariya, Kazuyoshi Kubo, Shunichi Miyauchi, Ayako Aizawa, Kazumi Umeki, Hajime Nomura, Takeshi Kawaguchi, Motohiro Matsuda, Ichiro Takajo, Toshihiko Hidaka, Akihiko Okayama
In conclusion, HTLV-1-positive patients with RA were found to be older than HTLV-1-negative patients with RA. Some HTLV-1-positive patients are considered to have a high risk for ATL development. No remarkable changes were observed in the viral biomarkers used for predicting ATL development. However, we observed ATL development in an HTLV-1-positive patient with RA who was at a high risk for ATL development. Therefore, the evaluation of the risk factors for ATL development may be important in daily clinical practice in HTLV-1-endemic areas in Japan. In the future, more long-term cohort studies with a larger number of participants must be conducted to validate the impact of anti-rheumatic therapies on ATL development in HTLV-1-positive patients with RA.