Human T-cell leukemia virus type 1 infection among Japanese immigrants and their descendants living in Southeast Brazil: a call for preventive and control responses

Abstract

Introduction: Human T-cell leukemia virus type 1 (HTLV-1) has worldwide distribution and is considered endemic in southwestern Japan. HTLV-1 infection has been associated with adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) besides other diseases. Objective: This cross-sectional study aimed to investigate the prevalence, risk factors, and molecular characterization of HTLV-1, among the world´s largest population of Japanese immigrants and their descendants outside Japan, in São Paulo, Southeast Brazil, as well as to analyze the phylogenetic relationship among isolates of HTLV-1. Methods: From July to December 2017, 2,139 individuals from five Japanese associations were interviewed and submitted to blood collection. All serum samples were first tested for the presence of anti-HTLV-1/2 antibodies by ELISA and then peripheral blood from individuals with positive serological results were analyzed for the presence of HTLV-1 5ʹLTR proviral DNA. Partial sequencing of the 5ʹLTR region of HTLV-1 proviral DNA was performed by Sanger. Results: The prevalence of HTLV-1 infection was 5.1% (95% CI 4.2-6.0). In the multiple logistic regression model, HTLV-1 infection was associated with age 45 years, female sex, first- and second-generation Japanese immigrants, and having sexual partners with a history of blood transfusion. The phylogenetic analysis revealed that all HTLV-1 were classified as Cosmopolitan (1a) subtype. Of them, 47.8% were classified as Transcontinental (A) subgroup and 52.2% as belonging to the Japanese (B) subgroup. Although most HTLV-1-infected patients were asymptomatic (97.3%), the blurred vision was associated with HTLV-1 infection. Conclusion: The high prevalence of HTLV-1 infection found in this study population and especially the intrafamily and interfamily HTLV-1 transmission presents an urgent need for preventive and control responses of this infection in Brazil.

Prevalence of infection by human T Cell lymphotropic viruses (HTLV-1/2) in adult population in Vitória-ES

“…HTLV-1 is endemic in South America, affecting 13 countries and prevailing in several ethnic groups. 19 , 20 , 21 In Brazil, HTLV-1 is found in immigrants from endemic areas such as Africa and Japan, 8 , 21 , 22 , 23 their descendants and in the descendants of Amerindians who have inhabited South America for thousands of years. 24 , 25 , 26 Several studies performed in Brazil on large populations of blood donors have found an heterogeneous HTLV-1 seroprevalence ranging from 0.04 to 1% depending on the geographical location.…”

Chitotriosidase 1 in the cerebrospinal fluid as a putative biomarker for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) progression

“…The human T-lymphotropic virus (HTLV) type 1 infection is associated with the development of two main diseases: a malignancy of CD4 + T-cells named adult T-cell leukemia/lymphoma (ATLL) and the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) ( 1 , 2 ), which is a chronic inflammatory neurodegenerative disease that affects mainly the upper motor neurons in the thoracic spinal cord ( 3 , 4 ). HTLV-1 infection is worldwide distributed but it shows hot spots of endemicity in several countries and regions, including Brazil, Japan, the Caribbean, Central and West Africa, the Middle Eastern, and Australia ( 5 – 9 ). In recent years, HTLV-1 infection has been also considered a matter of concern as it remains a threat to communities, particularly in low-income countries due to the lack of epidemiological surveillance and control measures but also in association with the rising levels of human migration ( 9 – 11 ).…”

“…HTLV-1 infection is worldwide distributed but it shows hot spots of endemicity in several countries and regions, including Brazil, Japan, the Caribbean, Central and West Africa, the Middle Eastern, and Australia ( 5 – 9 ). In recent years, HTLV-1 infection has been also considered a matter of concern as it remains a threat to communities, particularly in low-income countries due to the lack of epidemiological surveillance and control measures but also in association with the rising levels of human migration ( 9 – 11 ).…”