Molecular and Phylogenetic Evidence of Interfamilial Transmission of HTLV-1 in the Afro-Descendant Community of São José de Icatú in the Brazilian Amazon.

This study aimed to describe the prevalence of HTLV-1/2 in quilombola communities in the state of Pará and investigate the possible sociodemographic risk factors associated with the infection, as well as to trace the occurrence of the familial transmission of the virus. A total of 310 individuals living in eight quilombos located in the state of Pará (northern Brazil) were investigated for the presence of anti-HTLV-1/2 antibodies using an enzyme-linked immunosorbent assay (ELISA), and positive samples were confirmed using Western blot and/or real-time quantitative polymerase chain reaction (qPCR). Participants answered a questionnaire about sociodemographic aspects and risk factors for infection. Anti-HTLV-1/2 antibodies were detected in two individuals (one man and one woman), for an overall seroprevalence of 0.65%. Both individuals belonged to the community of São José de Icatú. The search for intrafamilial infection identified two other infected women, which increased the general prevalence of HTLV-1 among the Icatú to 6.25% (4/64). Western blot and qPCR confirmed their HTLV-1 infection, and phylogenetic analysis demonstrated that the isolates were of the cosmopolitan subtype and transcontinental subgroup. Epidemiological investigation of the cases revealed that the three women, at some point in their lives, had a relationship with the infected male individual. HTLV-1 is transmitted silently between individuals in the community of São José de Icatú with a present or past family relationship, stressing the need for screening and laboratory diagnosis to prevent further dissemination of the virus and surveillance of disease emergence.

Southern African Origin of HTLV-1 in Romania.

In Europe, most HTLV-1-infected individuals originate from highly endemic regions such as West Indies, sub-Saharan Africa, and South America. The only genuine endemic region for HTLV-1 in Europe is Romania where ATL series have been reported among Romanian patients. Our objective is to better understand the origin of this endemic focus based on a study of the genetic diversity of HTLV-1 in Romanians. DNA was obtained from PBMCs/buffy coats of 11 unrelated HTLV-1-infected individuals of Romanian origin. They include 9 ATL cases and 2 asymptomatic carriers. LTR sequences were obtained for all specimens. Complete genomic HTLV-1 sequences were obtained using four PCR series on 10 specimens. Phylogenetic trees were generated from multiple alignments using HTLV-1 prototypic sequences and the new generated sequences. Most of the complete LTR sequences (756-bp) showed low nucleotide diversity, ranging from 0% to 0.8% difference, and were closely related (less than 0.8% divergence) to the only previously characterized Romanian strain, RKI2. One strain, ROU7, diverged slightly (1.5% on average) from the others. Phylogenetic analyses both on partial LTR and the complete genome demonstrate that the 11 sequences belong to the HTLV-1a cosmopolitan genotype and 10 of them belong to the previously denominated a-TC Mozambique-Southern Africa A subgroup. In this study, we demonstrated that the HTLV-1 present in Romania most probably originated in Southern Africa. As most Romanian HTLV-1 strains are very closely related, we can assume that HTLV-1 has been introduced into the Romanian population recently. Further studies are ongoing to decipher the routes of arrival and dissemination of these HTLV-1 strains, and to date the emergence of this endemic focus in Central Europe.

Prevalence of HTLV-1 and Hepatitis B Surface Antigen (HBsAg) Positivity among MSM Attending a Large HIV Treatment Centre in Trinidad.

HIV-1, Hepatitis B and HTLV-1 have similar risk factors and shared routes of transmission and MSM are disproportionately affected by HIV. The aim of the study was to determine the prevalence of HTLV-1 and HBsAg positivity at initial enrolment among MSM attending a large HIV Clinic in Trinidad. Chart reviews were conducted between 2 and 15 January 2024, among self-identified MSM and a comparative group of randomly selected self-identified heterosexual males where sociodemographic, clinical and laboratory data were collected and analysed using SPSS Version 25. During the period April 2002-31 October 2023, in total there were 10,424 patients registered at the clinic, of whom 1255 (12.0%) were self-identified MSM, with an age range of 19-85 years and a median age of 40 years. There were 1822 randomly selected heterosexual males, with an age range of 18-94 years old and a median age of 52 years. Among the MSM, there were 21 (1.67%) patients who were HIV-1/HTLV-1-coinfected, 64 (5.10%) who were HIV-1/HBsAg-coinfected and two (0.16%) who were coinfected with all three viruses (HIV-1/HTLV-1/HBsAg) as compared to 47 ((2.58%) HIV-1/HTLV-1-coinfected (p = 0.12), 69 (3.79%) HIV-1/HBsAg-coinfected (p = 0.10) and three (0.16%) patients coinfected with all three viruses among the heterosexual males. There were no patients with HTLV-1-related diseases among the HIV-1/HTLV-1-coinfected patients and there were no deaths from chronic liver disease in patients coinfected with HIV-1/HBsAg. Despite the availability of an efficacious vaccine, there is a prevalence of hepatitis B of 5.1% among MSM attending the HIV Clinic in Trinidad; therefore, programmes to increase health literacy, screening and immunization are urgently needed.

Gene expression profiling of p53 and c-myc in HTLV-1 positive blood donors in Congo.

OBJECTIVES: The HTLV-1 infection persists for life, remaining as asymptomatic viral reservoirs in most patients, ensuring the chain of transmission, but around 4% develop adult T-cell leukemia/lymphoma (ATLL). HTLV-1 is an oncogenic retrovirus that transforms CD4+ T lymphocytes and deregulates the lymphoproliferative pathways that contribute to the development of ATLL. To achieve cell transformation, most oncogenic retroviruses use proto-oncogene capture transduction, with proviral integration disrupting the expression of tumor suppressors or proto-oncogenes. THE AIM: We conducted this study on the prevalence of HTLV-1 infection in blood donors to expand the HTLV-1 database, assess the risk of transmission via blood products, as well as evaluate the risk of persistent infection or development of neoplastic diseases in HTLV-1 carriers. MATERIALS AND METHODS: This is a cross-sectional study of blood donors of all categories. For this study, 265 blood donors were recruited at the Centre National de Transfusion Sanguine in Brazzaville. After testing for HTLV-1 antibodies by ELISA, proviral DNA was extracted from all ELISA-positive samples for detection by nested PCR, followed by RT qPCR using specific primers p53 and c-myc for gene expression. RESULTS: 20/265 were positive for anti-HTLV-1 antibody, 5 donors were positive for proviral DNA. The prevalence of HTLV-1 was 1.8%. All HTLV-1-positive donors were male (1.8%), with a positive correlation (p = 0.05); the 1.1% of positive donors were regular, with the majority aged between 31 and 45 years (1.5%), and concubine donors were the most frequent (1.1%). All samples showed normal expression of the p53 and c-myc genes. CONCLUSION: The prevalence, though low, remains a serious problem. No abnormal p53 or c-myc gene expression was detected in HTLV-1-positive donors, which could mean that none of the T lymphocytes in these donors had been transformed by HTLV-1.

HTLV-1/2 infection in Italy: a narrative review of epidemiological studies.

The human T-cell leukemia virus type 1 (HTLV-1) was first described in 1980. It is spread in highly endemic regions in the world, such as the Southwestern part of Japan, sub-Saharan Africa and South America, Caribbean, Middle East, and Australo-Melanesia regions. HTLV-1 causes adult T cell leukemia and is associated with many inflammatory conditions, most notably HTLV-1-associated myelopathy/tropic spastic paraparesis. HTLV-2, first isolated in 1982, was recognized as a common infection in intravenous drug users, but a clear association with disease remains elusive. The first estimate of HTLV-1-positive individuals worldwide, in 1993, was around 10-20 millions. Due to the lack of global population-based prevalence studies, this is considered an underestimate at the moment. Furthermore, HTLV-1 prevalence in Europe is impacted by changing migration flows. Particularly, no data on HTLV-1 prevalence in the general population in Italy are available. Here, we report a systematic literature review of studies conducted in Italy on HTLV-1/2 from 1980 to 2023. Based on the criteria we adopted a total of 426 publications were found (64 reviews, 99 epidemiological, and 263 translational studies). The contents of some representative publications are summarized and discussed. Moreover, an approximate estimation of about 26,000 HTLV-1 positive foreigners living in Italy was obtained from updated data of foreigners from each single country officially registered as resident in Italy and from data on HTLV-1 prevalence among the general population in the corresponding countries.

Human T-lymphotropic virus 1/2 infection among prisoners of a major penitentiary complex of Goiás State, Central-West Brazil.

Introduction: Studies on human T-lymphotropic virus 1/2 (HTLV-1/2) infection are scarce in incarcerated population. Therefore, this study estimated the prevalence of HTLV-1/2 infection among prisoners of the major penitentiary complex of Goiás State, Central-West Brazil, comparing it with available data from other Brazilian regions. Methods: A cross-sectional study was conducted with 910 prisoners of the major penitentiary complex in the State of Goiás, Central-West Brazil. All participants were interviewed, and their serum samples were tested for anti-HTLV-1/2 using an enzyme-linked immunosorbent assay (ELISA; Murex HTLV-I + II, DiaSorin, Dartford, UK). Seropositive samples were submitted for confirmation by a line immunoassay (INNO-LIA HTLV I/II, Fujirebio, Europe N.V., Belgium). Results: The majority of participants were males (83.1%), between 25 and 39 years old (56.1%; mean age: 31.98 years), self-reported brown ethnicity (56.2%) and reported 9 years or less of formal education (41.4%). Most reported using non-injectable illicit drugs and various sexual behaviors that present risk for sexually transmitted infections (STIs). The prevalence of anti-HTLV-1/2 was 0.33% (95% CI: 0.07-0.96), HTLV-1 (0.22%) and HTLV-2 (0.11%). The two HTLV-1 seropositive prisoners reported high-risk sexual behaviors, and the HTLV-2 seropositive individual was breastfed during childhood (> 6 months) by her mother and three other women. Conclusion: These data revealed a relatively low seroprevalence of HTLV-1/2 in prisoners in Central-West Brazil, and evidence of HTLV-1 and HTLV-2 circulation in the major penitentiary complex of Goiás State. Given the prevalence of high-risk sexual behaviors, there is a crucial need to intensify education and health programs in prisons to effectively control and prevent HTLV-1/2 and other STIs.

Impact and economic analysis of human T-cell lymphotropic virus type 1 (HTLV-1)-targeted antenatal screening, England and Wales, 2021.

BackgroundHuman T-cell lymphotropic virus type 1 (HTLV-1) is a neglected virus that can cause severe disease and be transmitted from mother to child through breastfeeding. Avoidance of breastfeeding prevents 80% of vertical transmission. The United Kingdom (UK) is currently assessing whether HTLV-1-targeted antenatal screening should be implemented.AimWe aimed to assess the impact and cost-effectiveness of a targeted programme to prevent HTLV-1 vertical transmission in England and Wales.MethodsWe estimated the number of pregnant women who have high risk of HTLV-1 infection based on their or their partner's country of birth. With data from 2021, we used a mathematical model to assess cost-effectiveness of HTLV-1 antenatal screening. We also estimated the annual number of infant infections and the number that could be prevented with screening and intervention.ResultsWe estimate that ca 99,000 pregnant women in England and Wales have high risk of HTLV-1 infection. In the absence of screening, 74 (range: 25-211) HTLV-1 infections in infants would be expected to occur every year in England and Wales. Implementation of targeted screening would prevent 58 (range: 19-164) infant infections annually. The intervention is effective (incremental 0.00333 quality-adjusted life years (QALY)) and cost-saving (GBP -57.56 (EUR -66.85)).ConclusionOur findings support implementation of HTLV-1 targeted antenatal screening to reduce vertical transmission from mothers to infants in the UK.

Infective dermatitis associated with human T-cell lymphotropic virus type-1, an underdiagnosed disease.

Infective dermatitis associated with human T-cell lymphotropic virus type-1 (HTLV-1) (IDH) is a severe form of chronically infected eczema occurring in early childhood, although very rarely cases have been reported in adults. Most of the cases are from Jamaica and Brazil and occur in individuals with low socioeconomic status. IDH is always associated with refractory Staphylococcus aureus or beta-hemolytic Streptococcus infection of the skin and nasal vestibules. Patients with IDH may develop other even more severe HTLV-1-associated diseases, such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) of early or late appearance and adult T-cell leukemia/lymphoma. In the context of the Brazilian experience, it has been observed that 54% of IDH patients exhibit the juvenile form of HAM/TSP while the estimated incidence of adult HAM/TSP is 3%. As there are no curative treatments for HTLV-1 infection (or vaccines) or most of its associated diseases, prevention of infection is fundamental, mainly by vertical transmission, as it is responsible for the development of IDH, infantojuvenile HAM/TSP, and ATL. Public measures to reduce this transmission must be implemented urgently. Furthermore, it is recommended, mainly in HTLV-1 endemic areas, to search for HTLV-1 infection in all patients with infected eczema, even in adults.

Prevalence of human T-cell lymphotropic virus-1/2 in Canada over 33 years: A unique contribution of blood donors to public health surveillance.

OBJECTIVES: Estimate HTLV-1/2 (human T-cell lymphotropic viruses) prevalence in Canadian blood donors and the association of demographic variables with infection and their corresponding risk factors. METHODS: First-time blood donors in all Canadian provinces (except Quebec) from 1990 to 2022 were included. Blood samples were tested for HTLV-1/2 by enzyme-linked immunoassay, confirmed by Western blot. Multivariable logistic regression with year, age group, sex, region, neighbourhood material deprivation, and ethnocultural composition indices predicted HTLV-1/2. Since 2005, all HTLV-1/2-positive donors (cases) were invited to participate in a risk factor interview, and 4 non-positive donors (controls per case) were matched for age, sex, and region. Case-control predictors of HTLV-1/2 were analyzed using logistic regression. RESULTS: There were 3,085,554 first-time donors from 1990 to 2022. HTLV-1/2 prevalence remained low (12 per 100,000 in 2022, 95% CI 6.4-23.5). The odds ratios predicting HTLV-1/2 were higher in females (2.0, 95% CI 1.5-2.6), older age groups (50 + ; 6.3, 95% CI 4.3-9.2), British Columbia and Ontario, those materially deprived (1.9, 95% CI 1.2-2.9), and those in ethnocultural neighbourhoods (7.5, 95% CI 3.2-17.3). Most HTLV-1/2 in Ontario was HTLV-1, whereas in British Columbia half were HTLV-2. Forty-three of 149 (28.8%) cases and 172 of 413 (41.6%) controls completed an interview. The strongest predictor of HTLV-1/2 in case-control analysis was birth in a high-prevalence country (OR 39.8, 95% CI 7.8-204.3) but about 50% of HTLV-1 and 90% of HTLV-2 were Canadian-born. CONCLUSION: HTLV-1/2 prevalence is low in blood donors. High-prevalence country of birth accounts for about half of HTLV-1; HTLV-2 positives are usually Canadian-born. HTLV-1/2 transmission likely occurs overseas and within Canada.

RéSUMé: OBJECTIFS: Estimer la prévalence des sous-types du virus T-lymphotrope humain (HTLV-1 et HTLV-2) dans le sang des donneurs de sang canadiens, et évaluer le lien avec des variables démographiques et des facteurs de risque donnés. MéTHODES: Cette étude a porté sur toutes les personnes ayant fait leur premier don entre 1990 et 2022 au Canada, sauf au Québec. Les échantillons de sang ont été soumis à un test immunoenzymatique, puis à un test Western Blot de confirmation. Les données ont été analysées au moyen de la régression logistique en utilisant comme indices l'année, la tranche d'âge, le sexe, la région, le quartier, la privation matérielle et la composition ethnoculturelle. Depuis 2005, tous les donneurs positifs au HTLV-1/2 (cas) ont été conviés à un entretien ayant pour but de déterminer leurs facteurs de risque, et quatre donneurs négatifs (cas-témoins) ont été appariés à chaque cas en fonction de l'âge, du sexe et de la région. Les facteurs de prédiction d'infection au HTLV-1/2 des cas-témoins ont été analysés au moyen de la régression logistique. RéSULTATS: Entre 1990 et 2022, le nombre de primodonneurs s'élevait à 3 085 554. La prévalence du HTLV-1/2 est demeurée faible (12,2 sur 100 000 en 2022, IC 95%: 6,4­23,5). Le rapport de cotes était plus élevé chez les femmes (2,0, IC 95% 1,5­2,6), chez les personnes de plus de 50 ans (6,3, IC 95% 4,3­9,2), en Colombie-Britannique et en Ontario, chez les personnes touchées par la privation matérielle (1,9, IC 95% 1,2­2,9) et chez les personnes vivant dans des quartiers ethnoculturels (7,5, IC 95% 3,2­17,3). La plupart des cas de HTLV-1/2 rencontrés en Ontario concernaient le HTLV-1, tandis qu'en Colombie-Britannique, la moitié des cas concernait le HTLV-2. Quarante-trois cas sur 149 (28,8 %) et 172 cas-témoins sur 413 (41,6 %) ont passé l'entretien. L'analyse des cas-témoins a révélé que le facteur de prédiction le plus important d'infection au HTLV-1/2 était le fait d'être né dans un pays à forte prévalence (RC 39,8, IC 95% 7,8­204,3); toutefois environ 50 % des cas-témoins de HTLV-1 et 90 % des cas témoins de HTLV-2 étaient nés au Canada. CONCLUSION: La prévalence du HTLV-1/2 est faible dans le sang des donneurs de sang. Pays de naissance à forte prévalence représente à peu près la moitié des cas de HTLV-1; les donneurs positifs au HTLV-2 la plupart du temps sont nés au Canada. La transmission du HTLV-1/2 survient probablement outre-mer et au Canada.

Period prevalence of uveitis in human T-lymphotropic virus 1 carriers versus noncarriers in a highly endemic area: The Nagasaki Islands Study.

The magnitude of the effect of human T-lymphotropic virus 1 (HTLV-1) infection on uveitis remains unclear. We conducted a cross-sectional study in a highly endemic area of HTLV-1 in Japan. The study included 4265 residents (men, 39.2%), mostly middle-aged and older individuals with a mean age of 69.9 years, who participated in our surveys between April 2016 and September 2022. We identified HTLV-1 carriers by screening using chemiluminescent enzyme immunoassays and confirmatory tests, and the proportion of carriers was 16.1%. Participants with uveitis were determined from the medical records of all hospitals and clinics where certified ophthalmologists practiced. We conducted logistic regression analyses in an age- and sex-adjusted model to compute the odds ratio (OR) and 95% confidence interval (CI) of uveitis according to HTLV-1 infection status. Thirty-two (0.8%) participants had uveitis. For HTLV-1 carriers, the age- and sex-adjusted OR (95% CI) of uveitis was 3.27 (1.57-6.72) compared with noncarriers. In conclusion, HTLV-1 infection was associated with a higher risk of uveitis among mostly middle-aged and older Japanese residents in a highly endemic HTLV-1 area. Our findings suggest that physicians who treat HTLV-1 carriers should assess ocular symptoms, and those who diagnose patients with uveitis should consider HTLV-1 infection.

A systematic review of immunosuppressive risk factors and comorbidities associated with the development of crusted scabies.

OBJECTIVES: Crusted scabies (CS, Norwegian scabies) is a severe form of scabies, characterized by hyper-infestation of Sarcoptes scabiei mites. CS is commonly associated with immunosuppression but is also reported in overtly immunocompetent individuals. We reviewed immunosuppressive risk factors and comorbidities associated with CS. METHODS: The National Library of Medicine (PubMed) database was reviewed for patient case reports of CS from January 1998 to July 2023. Two authors screened records for eligibility, extracted data, and one critically appraised the quality of the studies. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42023466126. RESULTS: A total of 436 records were identified, of which 204 were included for systematic review. From these, 683 CS patients were included. CS impacted both genders equally. Adults (21-59 years) were more commonly affected (45.5%) compared to children (0-20 years, 21%). Corticosteroid use was the most prevalent immunosuppressive risk factor identified (27.7% of all cases). About 10.2% of reports were associated with HIV/AIDS, and 8.5% with HTLV-1 infection. 10.5% of patients were overtly immunocompetent with no known risk factors. Overall, 41 (6.0%) died, many subsequent to secondary bacteremia. CONCLUSION: This study represents the first systematic review undertaken on immunosuppressive risk factors associated with CS. This provides insights into trends of immunosuppression and mechanisms of CS development.

Non-cancerous complications in HTLV-1 carriers.

INTRODUCTION: Human T-cell leukemia virus type 1 (HTLV-1) carriers may develop adult T-cell leukemia (ATL), or HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). The evidence is limited regarding other diseases potentially associated with HTLV-1, such as HTLV-1-associated autoimmune diseases. AREA COVERED: We summarized the available information on complications associated with HTLV-1 infection. EXPERT OPINION: Previous studies showed that HTLV-1 carriers have an increased incidence of collagen diseases including Sjögren's syndrome, as well as dysthyroidism, diabetes mellitus, and atherosclerosis. Furthermore, cognitive deficits are observed in asymptomatic carriers and in symptomatic carriers who develop HAM/TSP. It is hypothesized that altered immunoregulation occurs as a result of persistent HTLV-1 infection. A systematic review and meta-analysis demonstrated that HTLV-1 infection itself has an adverse impact on overall survival. ATL alone cannot entirely explain the adverse impact of HTLV-1 infection on overall mortality, because the incidence is low, and therefore HTLV-1-associated diseases as a whole may contribute to the inferior clinical outcome. However, there are insufficient data to determine the causal relationship between HTLV-1 infection and each complication. While non-cancerous events linked to HTLV-1 infection are not fatal, they are likely to reduce quality of life. Large prospective studies should be conducted by international collaborators.

Prevalence of HTLV-1/2 infection in pregnant women in Central and South America and the Caribbean: a systematic review and meta-analysis.

BACKGROUND: Human T-lymphotropic viruses (HTLV)-1 infection is endemic in many countries of Central and South America and Caribbean (CSA&C). Neither screening nor surveillance programs exist for HTLV-1/2 infection among pregnant women in this region. Neither in Western nations with large migrant flows from HTLV-1/2 endemic regions. METHODS: Systematic review and meta-analysis of the prevalence of HTLV-1/2 infection among CSA&C pregnant women. We included studies searching EMBASE, PubMed/MEDLINE, Scopus, and Web of Science from inception to February 15, 2023. This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. RESULTS: We identified a total of 620 studies. Only 41 were finally included in the meta-analysis. Most studies (61.0%) were from Brazil and Peru (14.6%). The total number of participants was 343,707. The pooled prevalence of HTLV-1/2 infection among CSA&C pregnant women was 1.30% (95% CI: 0.96-1.69) using anti-HTLV-1/2 antibody screening tests. There was a high heterogeneity (I2 = 98.6%). Confirmatory tests gave an HTLV-1 infection rate of 1.02% (95% CI: 0.75-1.33). CONCLUSIONS: The prevalence of HTLV-1/2 infection among CSA&C pregnant women is 1.3%, most cases being HTLV-1. This rate is greater than for other microbial agents regularly checked as part of antenatal screening (such as HIV, hepatitis B, or syphilis). Thus, HTLV-1/2 antenatal testing should be mandatory among CSA&C pregnant women everywhere.

HTLV in Sweden.

Sweden is a country with a low prevalence of human lymphotropic T-cell virus (HTLV) infection, estimated at < 0.005%, but the infection rate is notably higher in specific risk groups such as HTLV-2 among intravenous drug users (IVDU) and people originating from HTLV-1 highly endemic areas. Thus, in the most recent study from 2012, the prevalence of HTLV-2 among IVDU in Stockholm was 3.2%. However, much of the epidemiological data on HTLV in Sweden stems from studies conducted primarily between the 1990s and 2007, and the impact of migration to Sweden during the past 15 years has not been evaluated. Despite Sweden's status as a country with generally low prevalence of HTLV, it is prudent to anticipate and prepare for several potential challenges associated with HTLV infection in the future. Proactive measures to enhance awareness, alongside strategies to curtail transmission and mitigate complications, are crucial for addressing this relatively rare, but significant health issue. In this work, we review the current epidemiological knowledge about HTLV in Sweden and discuss future Swedish perspectives.

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).

High Ratio of Human T Cell Lymphotropic Virus Transmission and Prevalence of Human T Cell Lymphotropic Virus Type 1-Associated Diseases in Brazilian Family Groups Followed Up by the GIPH Cohort.

A silent spread of human T cell lymphotropic virus type 1 (HTLV-1) has been occurring for thousands of years, with a high prevalence in some regions due to the sexual and vertical transmission and formation of family clusters. The time from HTLV-1 infection until the onset of virus-associated diseases is extremely long, approximately one to three decades. In this study, we evaluated intrafamilial HTLV-1 transmission and associated diseases in 1,204 individuals enrolled and followed up by the GIPH cohort between 1997 and 2017. The family groups (n = 43) were composed of 279 individuals who were tested for HTLV-1/human T cell lymphotropic virus type 2 (HTLV-2) and were classified as two groups according to the index case: blood donor (blood donors referred to the GIPH cohort) and nondonor (individuals referred to the GIPH cohort by other health services). The observed rates of HTLV-1 transmission and associated diseases among the relatives were high. Of 236 family members and sexual partners tested for HTLV, 104 (44.1%) were confirmed as having HTLV infection, with 36.7% of relatives whose index case was blood donors and 56.9% of relatives with nondonor index cases. At least one case of HTLV-1-associated myelopathy was observed in 42.9% of the families with intrafamilial transmission of HTLV-1. Brazil is an endemic area for HTLV-1/2 and has implemented mandatory universal screening of blood donors for HTLV-1/2 since 1993. However, the lack of public health services offer diagnosis for HTLV to the general population and pregnant women in the country makes it difficult to identify infected people, and contributes to the silent spread of the virus.

Geographic characteristics of HTLV-1 molecular subgroups and genetic substitutions in East Asia: Insights from complete genome sequencing of HTLV-1 strains isolated in Taiwan and Japan.

BACKGROUND: Although Japan is a major endemic area for human T-lymphotropic virus type 1 (HTLV-1) and the virus has been well-studied in this region, there is limited research on HTLV-1 in surrounding regions. In this study, we determined the complete genome sequences of HTLV-1 strains isolated from Taiwan and Japan and investigated the geographic characteristics of molecular subgroups and substitution mutations to understand the spread of HTLV-1 and its correlation with human migration. METHODOLOGY/PRINCIPAL FINDINGS: The complete genome sequences of 26 HTLV-1 isolates from Taiwan were determined using next-generation sequencing and were compared with those of 211 isolates from Japan in terms of subgroup and genetic mutations. In total, 15/26 (58%) isolates from Taiwan belonged to the transcontinental subgroup and 11/26 (42%) isolates belonged to the Japanese subgroup. The transcontinental subgroup was significantly more prevalent among Taiwanese isolates than Japanese isolates (58% vs 18%, P < 0.0001). The mutation rate for the complete HTLV-1 sequence was as low as 0.2%. On examining individual base substitutions, the G-to-A mutation was predominant. Bayesian phylogenetic tree analysis estimated the time to the most recent common ancestor for the transcontinental and Japanese subgroups to be 28447 years. The transcontinental subgroups from Taiwan and Japan appeared to form clusters according to their respective regions. CONCLUSIONS/SIGNIFICANCE: The transcontinental subgroup of HTLV-1 is predominant in Taiwan, while the Japanese subgroup is common in Japan. The difference in subgroup distribution may be attributed to the initial spread of the transcontinental subgroup in East Asia, followed by the influx of the Japanese subgroup.