Human T-Lymphotropic Virus-1/2 Infection in Central Brazil Prisons: A Multicenter Study

Multicenter cross-sectional study of HTLV-1 prevalence and associated risk factors in epidemiologically relevant groups across Brazil

Background

Human T cell lymphotropic virus type 1 (HTLV-1) is highly endemic in Brazil, necessitating surveillance studies to understand its epidemiology. While previous research has focused on either specific cities or populations, there is a need for multicenter studies encompassing epidemiologically relevant populations to ascertain more accurate prevalence rates and predictors of HTLV-1 infection in the country.

Methods

We conducted a multicenter, cross-sectional study involving 3,184 participants across seven cities and five study populations in Brazil. Blood samples were collected, and the prevalence of HTLV-1 infection was determined by enzyme-linked immunosorbent assay (ELISA) and Western blot. Binary logistic regression analysis was used to determine risk factors of HTLV-1 infection.

Results

Among the total study population, 1,135 (35.7%) were aged >40 years and 1,704 (53.5%) were female. The overall prevalence of HTLV-1 infection was 0.5% (95% CI: 0.3-0.8), with variation observed among the cities or study populations. Factors associated with HTLV-1 infection included age > 40 years (OR, 8.867; 95% CI: 1.824-43.099), female gender (OR, 4.604; 95% CI: 1.184-17.903), and Hepatitis C virus (HCV) infection (OR, 13.995; 95% CI: 2.374-82.506). The identification of older age and female gender, coupled with the high prevalence of HTLV-1 in HIV-positive patients, suggests sexual transmission as the primary route of HTLV-1 infection.

Conclusion

Our study reveals varied prevalence rates of HTLV-1 infection across diverse populations and cities in Brazil. The association of older age, female gender, and HCV, emphasizes the need for tailored interventions to prevent HTLV-1 transmission.

HTLV infection in urban population from Mato Grosso do Sul, Central Brazil

BACKGROUND

Brazil has the highest number of HTLV-1 infection in Latin America, with around one million cases spread unevenly across regions. However, there is a limited number of studies on this infection in the general population. This cross-sectional study aimed to estimate the prevalence of HTLV as well as identify types, and subtypes of HTLV among the urban population of Campo Grande, capital of Mato Grosso do Sul state (MS).

RESULTS

Between July 2023 and March 2024, all information was obtained from self-reported interviews, and blood samples were collected and screened for anti-HTLV-1/2 by immunoassay and confirmed using the immunoblot method. The proviral DNA of HTLV-1/2 in positive samples was quantified by real-time PCR (qPCR) and genotyped by nucleotide sequencing (Sanger's method). The study enrolled 611 participants, with the majority being women (90.54%), mixed race (46.32%), heterosexual (87.64%), and with a median age of 39 years. The prevalence rate of anti-HTLV-1 infection was 0.82% (CI 95% 0.34-1.96). All positive samples (n = 5) were identified as belonging to the Cosmopolitan subtype, one belonging to Japanese and four to Transcontinental subgroups. Among the five positive individuals, two presented symptoms associated with HTLV-1 infection.

CONCLUSION

This study highlights an intermediate prevalence of HTLV-1 in the urban population of Campo Grande, Mato Grosso do Sul, and provides epidemiological information that could help bridge the gaps in the distribution of HTLV in the general population. Also, medical care was provided for individuals presenting clinical manifestations who were previously unaware of their serological status.

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.

HTLV infection in blood donors from Mato Grosso do Sul state: a closer look at HTLV screening in Brazilian blood banks

Human T-lymphotropic virus (HTLV) infection has a worldwide distribution and currently, more than 2.5 million individuals have been infected in Brazil. The study aimed to investigate HTLV infection prevalence among blood donors in Mato Grosso do Sul, characterizing seroepidemiological profiles of HTLV-1/2 positive individuals and evaluating the blood bank's HTLV screening system. A cross-sectional survey was conducted among blood donors from Mato Grosso do Sul state (MS)-Central Brazil, between January to December 2021. The information was obtained from databases, samples from the collection of HEMOSUL, and active searching, with the completion of laboratory analyses. 35,278 blood donors were screened for anti-HTLV-1/2 by chemiluminescence immunoassay (CMIA). Among them, 78 were initially reactive for anti-HTLV-1/2 (2.21/1000). Out of 78, 67 returned to the blood center to collect a second sample for retesting with a second screening with CMIA. After confirmation, 8 samples were indeterminate, and 8 were confirmed as positive for HTLV antibodies. New tests were performed for the 8 positive samples, and 6 were confirmed as HTLV-1 infection (0.17/1,000), one as negative, and one as indeterminate. The present study describes the low prevalence of HTLV infection in blood donors from MS and contributes to the definition of the regional infection profile. The prevalence found in this study (0.017%-0.17/1000) shows to be a much lower value than the rates reported in other states in Brazil. We highlight the need for confirmatory testing for those seropositive donors in screening assays and the need for adequate counseling and patient management for those confirmed HTLV individuals.

Human T Cell Lymphotropic Virus Type 1 Global Prevalence Associated with the Human Development Index: Systematic Review with Meta-Analysis

In 2012, the number of people infected with human T cell lymphotropic virus type 1 (HTLV-1) was estimated to be 10 million worldwide. Prevalence varies according to geographic location, ethnic factors, sex, age, populations exposed to risk factors, income, and education, reaching countries with the worst socioeconomic scenarios. There is a need to determine the current global prevalence of HTLV-1 and examine its association with countries' human development index (HDI) to provide data for global health policy. Systematic review with meta-analysis is according to PRISMA 2020 recommendations. It was registered at PROSPERO, CRD42021223146. Prevalence or cross-sectional studies of HTLV-1 infection with at least 100 participants, screening, and confirmatory serologic testing were included. Studies with incomplete or unavailable results or with duplicate information were excluded. Data were selected by two independent investigators and analyzed using R software, a metapackage that generated the forest plots [95% confidence interval (CI)]. Heterogeneity was assessed using the I² statistic, and funnel plot asymmetry was assessed using Egger's test. Countries were compared using an HDI cutoff ≥0.8. Methodological quality was assessed using Joanna Briggs Institute (JBI) criteria. The overall prevalence of HTLV-1 infection was 0.91% (95% CI: 0.80-1.02, p < .0001) and was higher in low HDI countries [1.18% (95% CI: 1.03-1.34)] than in high HDI countries [0.41% (95% CI: 0.27-0.57)]. Prevalence varied according to the populations studied: it was higher in the general population [1.65% (95% CI: 1.08-2.34)] compared to pregnant women [0.34% (95% CI: 0.17-0.57)] and blood donors [0.04% (95% CI: 0.01-0.08)]. Consistently, prevalence for each population group was higher in low HDI countries than in high HDI countries. The worldwide prevalence of HTLV-1 infection is highly heterogeneous, with a global prevalence of 0.91%. In high HDI countries, the observed prevalence is approximately three times lower than in low HDI countries. In the general population, the observed prevalence is about 5 times higher than in pregnant women and 41 times higher than in blood donors.

Spread of Human T-Lymphotropic Virus 1 and 2 Among Relatives of People Who Use Illicit Drugs in Northern Brazil

The human T-lymphotropic virus 1 (HTLV-1) and 2 (HTLV-2) can be transmitted between humans by mechanisms associated with horizontal and vertical routes. Recently, high prevalence rates and levels of genetic diversity for HTLV-1 and HTLV-2 were detected among people who use illicit drugs (PWUDs) in the Brazilian state of Pará. None of the PWUDs with HTLV-1 or HTLV-2 were aware of their carrier condition of the retrovirus, and they ability to spread it to their family group, sexual partners, and other contacts. Thus, this study evaluated the presence of HTLV-1 and HTLV-2 in families of PWUDs in the state of Pará, in Northern Brazil. This descriptive study used convenience sampling and accessed 37 PWUDs and their respective families (n = 97) in 18 municipalities in the state of Pará, northern Brazil. All participants provided personal data and were tested for the presence of HTLV-1 and HTLV-2 using enzyme-linked immunosorbent assay and western blotting. HTLV positive samples were selected for Nested-PCR, and viral genotyping by nucleotide sequencing and phylogenetic analysis. HTLV-1 or HTLV-2 infections were detected in 15 families of PWUDs: 27 family members of PWUDs were infected with HTLV-1 (27.8%) and another 20 of them with HTLV-2 (20.6%). Subtypes 1a [subgroup A (54.5%)], 2b (20.5%), and 2c (25.0%) were detected. High horizontal (76.9%) and vertical (61.4%) transmission rates of HTLV were ascertained. Factors that facilitate the acquisition and transmission of HTLV-1 and HTLV-2 were reported by the participants, such as long-term relationships, unprotected sex, breastfeeding, and lack of knowledge about the condition of being a carrier of the retrovirus. Evidence indicates intrafamilial transmission of HTLV from PWUDs to members of their respective families. Key interventions should urgently be employed for the control and prevention of HTLV-1 and HTLV-2 to reduce the spread of this retrovirus in PWUDs and the general population in Northern Brazil and elsewhere.