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.

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. 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 of Japan, in São Paulo, Southeast Brazil, as well as to analyze the phylogenetic relationship among isolates of HTLV-1. 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 5'LTR proviral DNA. Partial sequencing of the 5'LTR region of HTLV-1 proviral DNA was performed by Sanger. The prevalence of HTLV-1 infection was 5.1% (CI 95%: 4.2-6.0). In the multiple logistic regression model, HTLV-1 infection was associated with age ≥ 45 years, female sex, being first and second-generation Japanese immigrants, and having sexual partners with 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%), blurred vision was associated with HTLV-1 infection. The high prevalence of HTLV-1 infection found in this studied population and especially the intra- and interfamily HTLV-1 transmission presents an urgent call for preventive and control responses of this infection in Brazil

High Prevalence of HTLV-1 Infection among Japanese Immigrants in Non-endemic Area of Brazil

<div><p>Background</p><p>Human T-lymphotropic virus type 1 (HTLV-1) has worldwide distribution and is considered endemic in many world regions, including southwestern Japan and Brazil. Japanese immigrants and their descendants have a high risk of acquiring this infection due to intense population exchange between Brazil and Japan.</p><p>Objective</p><p>This cross-sectional study aimed to estimate the prevalence of HTLV, analyze the main risk factors associated with this infection, identify the main circulating types and subtypes of HTLV in Japanese immigrants and descendants living in Campo Grande-MS (Middle-West Brazil), as well as analyze the phylogenetic relationship among isolates of HTLV.</p><p>Study Design</p><p>A total of 219 individuals were interviewed and submitted to blood collection. All collected blood samples were submitted for detection of anti-HTLV-1/2 using the immunoassay ELISA and confirmed by immunoblot method. The proviral DNA of the 14 samples HTLV- 1 positive were genotyped by nucleotide sequencing.</p><p>Results</p><p>The overall prevalence of HTLV-1 was 6.8% (IC 95%: 3,5-10,2). Descriptive analysis of behavioral risk factors showed statistical association between HTLV-1 and age greater than or equal to 45 years. The proviral DNA of HTLV-1 was detected in all HTLV-1 positive samples. Of these, 14 were sequenced and classified as Cosmopolitan subtype, and 50% (7/14) belonged to subgroup A (transcontinental) and 50% (7/14) to the subgroup B (Japanese).</p><p>Conclusion</p><p>The high prevalence of HTLV-1 found evidence of the importance of early diagnosis and counseling of individuals infected with HTLV-1 for the control and prevention of the spread of this infection among Japanese immigrants and their descendants in Central Brazil.</p></div

Box plot (interquartile intervals and ranges) for the age distribution (years) of anti-HTLV-1 seropositive and anti-HTLV-1 seronegative individuals from the Japanese community of Campo Grande-MS (n = 219).

<p>Whiskers represent maximum 1.5 IQR.</p

Phylogenetic tree constructed by neighbor-joining (NJ) method using the Kimura-2-parameters distance model for the partial LTR region of 635bp of HTLV-1 showing the phylogenetic relationships among 14 isolates of proviral DNA of HTLV-1 studied (OKW) with 15 isolates available in GenBank.

<p>Phylogenetic tree constructed by neighbor-joining (NJ) method using the Kimura-2-parameters distance model for the partial LTR region of 635bp of HTLV-1 showing the phylogenetic relationships among 14 isolates of proviral DNA of HTLV-1 studied (OKW) with 15 isolates available in GenBank.</p

Descriptive analysis of risk behaviors among Japanese immigrants and Japanese descendants living in Campo Grande, MS, Brazil, 2012–2013 (n = 219).

<p>Descriptive analysis of risk behaviors among Japanese immigrants and Japanese descendants living in Campo Grande, MS, Brazil, 2012–2013 (n = 219).</p