Prevalence and factors associated with depression and anxiety in people living with HTLV-1: A systematic review with meta-analysis and meta-regression

Human T-Lymphotropic Virus (HTLV): Epidemiology, Genetic, Pathogenesis, and Future Challenges

Human T-lymphotropic viruses (HTLVs) are deltaretroviruses infecting millions of individuals worldwide, with HTLV-1 and HTLV-2 being the most widespread and clinically relevant types. HTLV-1 is associated with severe diseases such as adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), while HTLV-2 shows a lower pathogenic potential, with occasional links to neurological disorders. HTLV-3 and HTLV-4, identified in Central Africa, remain poorly characterized but are genetically close to their simian counterparts, indicating recent zoonotic transmission events. HTLVs replicate through a complex cycle involving cell-to-cell transmission and clonal expansion of infected lymphocytes. Viral persistence is mediated by regulatory and accessory proteins, notably Tax and HBZ in HTLV-1, which alter host cell signaling, immune responses, and genomic stability. Integration of proviral DNA into transcriptionally active regions of the host genome may contribute to oncogenesis and long-term viral latency. Differences in viral protein function and intracellular localization contribute to the distinct pathogenesis observed between HTLV-1 and HTLV-2. Geographically, HTLV-1 shows endemic clusters in southwestern Japan, sub-Saharan Africa, the Caribbean, South America, and parts of the Middle East and Oceania. HTLV-2 is concentrated among Indigenous populations in the Americas and people who inject drugs in Europe and North America. Transmission occurs primarily via breastfeeding, sexual contact, contaminated blood products, and, in some regions, zoonotic spillover. Diagnostic approaches include serological screening (ELISA, Western blot, LIA) and molecular assays (PCR, qPCR), with novel biosensor and AI-based methods under development. Despite advances in understanding viral biology, therapeutic options remain limited, and preventive strategies focus on transmission control. The long latency period, lack of effective treatments, and global neglect complicate public health responses, underscoring the need for increased awareness, research investment, and targeted interventions.

Multi-cohort cross-omics analysis reveals disease mechanisms and therapeutic targets in HTLV-1-associated myelopathy, a neglected retroviral neuroinflammatory disorder

HTLV-1 is an enigmatic retrovirus triggering a debilitating neuroinflammatory disease, HTLV-1-associated myelopathy (HAM), with unknown pathogenesis. Both HTLV-1 infection and HAM predominantly affect women and non-white neglected populations. HAM is lacking disease-modifying treatment, as current treatment is mostly symptomatic and inspired by either HIV-1 or multiple sclerosis therapeutic strategies. We used systems biology analyses of novel and publicly available data comprising (epi)genomics, transcriptomics, metabolomics and proteomics of multi-ancestry cohorts from a total of > 2500 People Living with HTLV-1 from 5 countries (Brazil, Peru, Japan, UK, US). Leveraging an unique admixed Brazilian cohort, genome-wide association study (GWAS) revealed African-specific variants in inflammasome sensor AIM2 with genome-wide significance (p < 5x10-8). Suggestive loci (p > 5x10-8) corresponding to metabolic, immune and neuronal genes were validated using published Japanese GWAS. Polygenic risk score and proviral load were independent disease predictors across ancestries. Systems biology analysis revealed neuronal/synaptic signaling, monocyte count, glucose/lipid metabolism, and neurocognition/depression as genetically linked to HAM. In silico drug screening identified estrogen blocker Fulvestrant as the top hit, while also confirming existing (pre)clinical data for HDAC inhibitors and immunosuppressants. Validated GWAS genes were overexpressed in HAM patients' whole blood and CD4 T-cells, as well as in spinal cord astrocytes, oligodendrocytes, and microglia by single-cell RNAseq. We experimentally confirmed decreased ApoA1/lipid/cholesterol levels, higher monocyte levels and lower neurocognitive scores in multi-ancestry cohorts. We found striking biological similarities between retroviral Hbz/Tax overexpression, Hbz interactome and HAM multi-omics findings: enrichment for lipid/cholesterol metabolism, estrogen signaling, neurodegenerative diseases, and viral pathways including EBV, recently identified as the major driver of multiple sclerosis. In conclusion, our data-driven approach uncovers novel disease mechanisms and therapeutic targets, and a validated polygenic risk score allowing targeted surveillance for high-risk individuals. A strong molecular overlap to other neurodegenerative/neuroinflammatory diseases reveals shared neuropathogenic pathways between unrelated viruses.

Fibromyalgia in patients infected with HTLV-1 and HTLV-2

Background

Reports on the association between HTLV-2 infection and the development of diseases in the human host are rare, which has led the scientific community to believe that HTLV-2 is not an important etiological agent of lymphoproliferative or neurodegenerative disorders, which is the case for HTLV-1. In the present study, we demonstrated cases of fibromyalgia in HTLV-1 carriers and, in an unprecedented finding, in two patients with confirmed HTLV-2 infection.

Methods

A total of 957 individuals visited the Virology Laboratory at the Federal University of Pará for screening and confirmation tests for HTLV-1/2 infection. Individuals with confirmed HTLV-1 and HTLV-2 infection were clinically evaluated for signs and symptoms associated with infection.

Results

Sixty-nine individuals (7.2%) were identified as positive for HTLV infection, with 56 confirmed cases of HTLV-1 infection (5.9%), 12 cases of HTLV-2 infection (1.2%) and one case classified as undetermined (0.1%). Sixteen (23.2%) of these patients presented with rheumatological signs and complained of diffuse pain throughout the body; 12 of whom were infected by HTLV-1 (75%) and 4 were infected by HTLV-2 (25%). After anamnesis and careful evaluation, four patients were diagnosed with fibromyalgia, two of whom were infected by HTLV-1 (16.7%; 2/12) and two by HTLV-2 (50%; 2/4). The clinical follow-up and laboratory analysis results are reported in detail in this paper.

Conclusion

Considering the clinical cases presented herein as the first reports of patients with HTLV-2 infection with clinical symptoms of fibromyalgia, the importance of further studies on the pathogenicity of HTLV-2, similar to what have already been performed for HTLV-1, is highlighted. Our results also confirm previous evidence of an association between HTLV-1 infection and fibromyalgia.

Neurological aspects of HTLV-1 infection: symptoms in apparently asymptomatic carriers

Human T-lymphotropic virus type 1 (HTLV-1) is classically associated with the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), although the mechanisms of this neurological disorder remain unclear. In addition, some patients who develop "minor" neurological signs that do not meet diagnostic criteria for HAM/TSP are classified as asymptomatic carriers. This study aims to demonstrate the neurological symptoms of Brazilian patients living with HTLV-1 classified as not-HAM.TSP. This observational study evaluated patients treated in an HTLV reference center in Bahia, Brazil, between February 2022 and July 2023. The data were obtained through the analysis of medical records and neurological consultation. Those individuals classified as HAM/ TSP were excluded from this study. 74 patients were submitted to a careful neurological evaluation: 23 HAM/TSP, 22 were classified with intermediate syndrome (IS), and 29 were oligosymptomatic. Self-reported symptoms were significantly more common in the IS group, including urinary symptoms such as nocturia, urgency, incontinence, dysuria, weakness, paresthesia, lumbar pain, xerostomia, and xerophthalmia. Physical examination findings consistent with reduced vibratory and tactile sensitivity were more common in the IS group (p = 0.017 and p = 0.013). Alterations in the V and VIII cranial nerves were present in both groups. HTLV-1 can lead to the development of important neurological signs and symptoms in apparently asymptomatic individuals. This data highlights the need for more research into the neurological aspects of HTLV-1 infection and emphasizes the importance of early diagnosis, treatment, and support for individuals living with this virus.

How do socioeconomic determinants of health affect the likelihood of living with HTLV-1 globally? A systematic review with meta-analysis

Introduction

Human T Lymphotropic Virus type 1 (HTLV-1) is a neglected retrovirus associated with many clinical disorders, most notably Adult T-cell Leukemia/Lymphoma and HTLV-1-Associated Myelopathy (HAM). Found in endemic clusters across the world, high prevalence has been reported in minoritized groups who suffer from health inequities. This study investigates the association between HTLV-1 prevalence and the following socioeconomic determinants of health: education, income, and employment, which are markers of health inequity.

Methods

A systematic review was conducted by searching the following databases: Ovid/Medline, Embase, Global Health Database, Web of Science, LILACS and SciELO. Primary studies in English, Spanish and Portuguese mentioning HTLV-1 and one of education, income and/or employment were included. A random-effects meta-analysis was performed, and odds ratios (OR) were calculated to determine the association between these socioeconomic determinants of health and HTLV-1 prevalence.

Results

42 studies were included. The likelihood of having HTLV-1 was higher in individuals with less than completed primary education compared to those who completed primary education (OR 1.86 [95% CI 1.34-2.57]; p < 0.01). This may be because individuals with low education have reduced access to and understanding of health information, thus increasing the prevalence of risk factors associated with HTLV-1 infection. No other determinants were found to be statistically significant.

Conclusion

Fewer years of schooling are associated with increased likelihood of contracting HTLV-1. Therefore, health promotion materials and public health policies regarding HTLV-1 must consider those with lower educational levels to effectively reduce disease transmission.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=335004, identifier (CRD42022335004).

Prevalence of sexual dysfunction in HTLV-1 patients without spastic paraparesis and the association with psychiatric symptoms

Introduction

The findings of previous studies are inconclusive in terms of psychological abnormalities and sexual function in asymptomatic human lymphotropic virus type 1 (HTLV-1) carriers.

Aim

This study aimed to evaluate the prevalence of sexual dysfunction and its relationship with psychological abnormalities in asymptomatic HTLV-1 carriers.

Materials and Methods

This cross-sectional study was conducted on asymptomatic HTLV-1 patients who were referred to the Neurology Clinic of a tertiary hospital in Mashhad, Iran. Patients with spastic paraparesis, leukemia, and uveitis, and those with an expanded disability status scale (EDSS) score higher than 2 were excluded. Sexual function in male and female subjects was evaluated using the brief male sexual function inventory (BMSFI) and female sexual dysfunction index (FSFI) questionnaires, respectively. The severity of psychological symptoms was evaluated in all patients using the symptom checklist-90-revised (SCL-90-R) questionnaire.

Results

A total of 117 patients (61 males and 56 females) with a mean age of 35.3 ± 6.3 years were evaluated. Overall, 50.9% of males had a high and 39.3% of females had a good sexual function. Both male and female patients with poor sexual function were older and had more children compared to those with good sexual function (P < 0.05). There was no significant difference in the distribution pattern of SCL-90 domains between patients with high and low to moderate sexual function among male patients (P > 0.05). Depression, hostility, interpersonal sensitivity, paranoid ideation, and psychological abnormality were significantly more prevalent in female patients with poor sexual function compared to those with good sexual function (P < 0.05).

Conclusion

The prevalence of psychological abnormalities was high in female with sexual dysfunction and these disorders might have a negative effect on various dimensions of sexual function.