Abstract
Introduction
The present study had the objective to describe the molecular prevalence and epidemiological aspects of the human T-lymphotropic virus 2 (HTLV-2) infection in the blood donor population of the Pará state.
Methods
The present study is a descriptive, retrospective, and cross-sectional review of epidemiological, serological, and molecular data on inapt blood donors in the State Center for Hematology and Hemotherapy from January 2015 to December 2021. The data were digitalized to create a database using the Statistical Package for Social Sciences program. The prevalence of HTLV-2 was calculated based on the total number of donations during the study period. Descriptive frequency was used to analyze the qualitative data.
Results
A total of 665,568 blood donations were made. Out of these, 1884 (0.2%) samples presented serological detection to HTLV and further were evaluated using molecular confirmatory tests. Out of these, 36 samples were positive for HTLV-2 using qPCR Taqman assay based on pol gene region (0.005%). The HTLV-2 was found to be more prevalent in women (63.9%); aged between 39 and 59 years (55.6%); residents of the metropolitan region of Belém (80.6%); with self-declared race as brown (80.6%); individuals who had completed high school (58.6%); and first-time donors (58.3%)
Conclusion
The present study identified the presence of HTLV-2 (1 HTLV-2 case/20,000 donations; 0.005%) in the specific population of blood donors in Pará state. These findings can contribute to the existing literature on the subject both for specific population groups under study and for understanding the prevalence of HTLV-2 in the general population.
Keywords: HTLV-2, Prevalence, Blood bank, Blood donors, Molecular epidemiology
Introduction
The human T-lymphotropic virus 2 (HTLV-2) was discovered in 1982 and is a retrovirus belonging to the Retroviridae family and the Deltaretrovirus genus. Currently, 4 viral types have been described (HTLV-1, HTLV-2, HTLV-3, and HTLV-4), among which the most prevalent are HTLV-1 and HTLV-2. HTLV-1 has a tropism for TCD4+ cells and is associated with tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM) and adult T cell lymphoma/leukemia. On the other hand, HTLV-2 has a tropism for TCD8+ cells. And, it has been linked to paraparesis, demyelination neuropathies, and bladder disorders as well as co-morbidities with HTLV-1. The nucleic acid sequences of both have approximately 60% similarity, while their amino acid sequences have around 70% similarity [1–4].
Among the transmission routes, direct transmission can occur through two routes: vertical and sexual. Vertical is the most frequent transmission route of infection and typically occurs through prolonged breastfeeding. The sexual route is through unprotected sexual contact. The indirect transmission occurs through the parenteral route, which is the most efficient transmission method, and occurs through contaminated blood transfusions or the shared use or reuse of needles among injecting drug users [5–8].
The HTLV-2 is considered an ancient infection and can serve as a marker of human migration over time. It originated in Asia, and spread to the native populations of America through the Bering Strait, which explains its presence in several native populations of America and Asia. The virus has also been identified in Europe, and in populations of pygmies in Africa [9–12].
It is estimated that 15 to 20 million people worldwide are infected with HTLV, and approximately 670,000 to 890,000 are HTLV-2 infected globally [13]. The exact number of HTLV-2-infected people in Brazil is still unknown but is estimated that around 2.5 million people have HTLV-1/HTLV-2 antibodies by serological testing, depending on the sociodemographic area studied [14, 15].
Pará is a region where HTLV-2 infection is prevalent [16, 17]. This is due to the presence of populations of indigenous ancestry in both the urban and rural areas of Pará, as well as the high molecular prevalence of the virus among these populations [11, 12]. The study aimed to describe the molecular prevalence and the epidemiological aspects of HTLV-2 infection in a blood donor population in the state of Pará. The goal is to increase knowledge of HTLV-2 epidemiology.
Methods
The present study was conducted at the Pará State Center for Hematology and Hemotherapy (HEMOPA), composed of 9 donation units, including the main office in Belém city; the regional blood centers located in Castanhal, Santarém, and Marabá; and the blood therapy centers in Redenção, Tucuruí, Abaetetuba, Capanema, and Altamira. The study was approved by the Research Ethics Committee of Centro Universitario Metropolitano da Amazônia–UNIFAMAZ, with CAAE number 55535222.4.0000.5701.
The study is based on a descriptive, retrospective, and cross-sectional review of the serological (chemiluminescence and electrochemiluminescence), molecular data (HTLV qPCR and nucleic acid test to HIV/HCV/HBV), and epidemiological data (gender, age, geographical origin, education level, marital state, race, type of donor, type of donation, and quantitative of donations) from samples of inapt blood donors due to a reagent result on the screening serological test. These samples were sent for confirmation by HTLV qPCR between January 2015 and December 2021.
The inclusion criteria for this study included data from donors who had reactive results in the serological screening, were referred to confirmatory tests, and were registered in the Cellular and Molecular Biology Management (GEBIM). As exclusion criteria, donors who did not have registered results for either the serology or molecular tests were excluded, as well as data with duplicate records and data from donors outside of Pará.
During the period under study, the HEMOPA foundation utilized two serological screening tests. From 2015 until December 2019, the ARCHITECT rHTLV-I/II screening test was utilized using the chemiluminescence method. From January 2020 to December 2021, the screening test utilized was the Elecsys HTLV-I/II which used the electrochemiluminescence method. The ARCHITECT rHTLV-I/II immunoassay boasts a manufacturer-reported sensitivity of 100% and specificity of 99.95%. Similarly, the Elecsys HTLV-I/II test has a manufacturer-reported sensitivity of 100% and specificity of 99.94%. The molecular screening test utilized was the Bio-Manguinhos® nucleic acid test (NAT) for HIV/HCV/HBV.
The confirmatory test utilized during the study period was the real-time polymerase chain reaction (qPCR) method which employed the TaqMan® system (AppliedBiosystems). The test involved three targets, namely the albumin gene and the non-homologous regions of the HTLV-1 and HTLV-2 pol gene. Primers and probes were designed and synthesized by the Assay-by-Design SM service using sequences of interest sent to Applied Biosystems with the primer sequence CAACCCCACCAGCTCAGG and GGGAAGGTTAGGACAGTCTAGTAGATA. The detection limit is 215 copies/mL and with the reaction conditions already described [18].
The data was analyzed using statistical methods. Descriptive statistics were used to determine the absolute and relative frequencies of qualitative variables. For quantitative variables, measures of central tendency such as mean and median were calculated, along with standard deviation, minimum, and maximum values. The characteristics of each variable were analyzed using the Statistical Package for Social Sciences (SPSS) version 20.
Results
A total of 665,568 blood donations were serologically screened in the state of Pará between January 2015 and December 2021. Out of these, 1884 (0.28%) were considered inapt due to the serological detection of anti-HTLV antibodies through chemiluminescence or electrochemiluminescence. The donors were then called for a second collection to carry out the confirmatory test, obtaining a total of 1043 submitted to the confirmatory test by real-time PCR for the detection of HTLV-1 and HTLV-2 proviral DNA. A total of 176 samples were excluded from the data analysis due to having duplicate entries in the system, incomplete donor information, and residency outside of Pará. Finally, data from 867 samples were analyzed, of which 705/867 (81.3%) did not have detectable proviral DNA, while 162/867 (18.7%) showed detection of HTLV. HTLV-2 was detected in 36/162 (22.2%) of these samples, while HTLV-1 was detected in 126/162 (77.8%). Thus, the prevalence of HTLV-2 among candidates for blood donation was 0.005%, which means that there was 1 case of every 20,000 donations.
The epidemiological profile of samples confirmed by qPCR as detectable for HTLV-2 proviral DNA indicates a higher frequency among older age groups. The age range of 39 to 59 years had the highest number of samples included, as shown in Table 1, which accounts for more than half (20/36; 55.6%) of the samples. The mean age was 42 ±13 years, with a minimum of 19 years and a maximum of 64 years.
Table 1.
The age gap of the blood donors diagnosed with detectable proviral DNA of HTLV-2
| Age | N | % |
|---|---|---|
| 18–38 | 12 | 33.3 |
| 39–59 | 20 | 55.6 |
| >60 | 4 | 11.1 |
| Total | 36 | 100 |
Among the samples presented in Table 2, there was a predominance of females (23/36; 63.9%) and individuals who were single, widowed, or divorced (22/36; 61.1%). In terms of geographic region, the vast majority of samples (29/36; 80.6%) originated from the Metropolitan Region of Belém, which included Ananindeua, Belém, Benevides, Castanhal, Marituba, Santa Barbara do Pará, and Santa Izabel do Pará. Only 7/36 (19.4%) samples were collected from the interior of the state, with 2 from Marabá, 1 from Capanema, 1 from Tracuteua, 1 from Altamira, 1 from Santarém, and 1 from Bujaru. In relation to the racial group (Table 2), the majority of samples are from brown (self-declared) individuals (29/36; 80.6%). Regarding the candidates’ education level, a higher percentage of those who reported completing high school are more present as detectable for HTLV-2 (21/36; 58.6%).
Table 2.
Epidemiological profile of detectable donor data for HTLV-2
| Variable | N = 36 | % |
|---|---|---|
| Sex | ||
| Female | 23 | 63.9 |
| Male | 13 | 36.1 |
| Marital status | ||
| Married | 14 | 38.9 |
| Single/divorced/widow | 22 | 61.1 |
| Geographic region | ||
| Metropolitan Region of Belém | 29 | 80.6 |
| Interior of the state | 7 | 19.4 |
| Race (self-declared) | ||
| White | 5 | 13.9 |
| Black | 2 | 5.5 |
| Brown | 29 | 80.6 |
| Education level | ||
| Elementary school graduate | 4 | 11.1 |
| Elementary school (unfinished) | 3 | 8.3 |
| High school graduate | 21 | 58.6 |
| High school (unfinished) | 4 | 11.1 |
| College student | 2 | 5.5 |
| College student | 2 | 5.5 |
| Type of donor | ||
| First-time donor | 21 | 58.3 |
| Sporadic donor | 10 | 27.8 |
| Repeat donor | 5 | 13.9 |
| Type of donation | ||
| Spontaneous | 26 | 72.2 |
| Linked | 10 | 27.8 |
More than half of the detectable samples (21/36; 58.3%) are from first-time donors while 10/36 (27.8%) are sporadic donors, who are donors that have had their last two donations within a period longer than 1 year. The remaining (5/36; 13.9) belong to repeat donors (Table 2), who have had their last two donations within the period of 1 year. The mean number of donations among sporadic donors throughout their entire donation history was 3.7 ± 2.4 donations, whereas, for repeat donors, the mean was 9.6 ± 7.09. The vast majority of detected donations (26/36; 72.2%) are from spontaneous donors; these are donors who do not have a defined receiver for the blood bag, while the smallest part (10/36; 27.8%) are linked donors, who have a receiver for the blood bag.
Of the samples detectable in qPCR for the presence of HTLV-2, none (0/36; 0%) had detectable molecular screening (NAT) data for HIV, HCV, and HBV as reported in the HEMOPA Foundation system database.
Discussion
Research on the actual prevalence of HTLV-2 in both the Brazilian population and the population of Pará has yet to be carried out. So far, the only prevalence of specific groups has been reported, such as indigenous peoples [11, 16, 17, 19, 20], blood donors [6, 9, 10, 21–24], pregnant women [14, 25], and intravenous drug users [26, 27]. This leaves the estimation of the presence of HTLV in the general population, as the population studied in the present paper is just a cluster of the population in the state of Pará, and should not be generalized.
The molecular prevalence results of HTLV-2 found in this study were compared with studies that conducted genotyping for HTLV-2 [6, 9, 21–24] in the blood donor population across Brazil. There were some discrepancies concerning the prevalence of the present study, which can be attributed to differences in sample size and the population studied.
The studies conducted by Colin and Ribeiro [23, 24], carried out in the north and northeast regions of the country in 2003 and 2018, respectively, reported a higher prevalence rate than that found in the current study. Both studies found a prevalence rate of 0.02% among total donors. The sample size may have directly affected the calculation of HTLV-2 prevalence. Both studies utilized PCR as the confirmatory test for the samples analyzed during the period. Although both are molecular methodologies, they differ in specifications regarding manufacturers and techniques for DNA extraction and gene amplification. These differences can lead to variations in results.
The studies conducted by Segurado, Gomes, Morais, and Maneschy [6, 9, 21, 22] have shown similar prevalences to those presented in this study. Additionally, several similar factors were identified, which facilitates the comparison between prevalences. In the study conducted by Segurado [22] in 1997 in the state of São Paulo, a period of approximately 3 years was studied. The study analyzed data from 1063 reactive samples were obtained from serological screening and 2238 samples with indeterminate results were tested by Western Blot 21e. The study confirmed 5 cases of genotyped HTLV-2 through PCR, resulting in a prevalence of 0.001%. In the study carried out by Gomes and Júnior [9] in Ceará in 2011, using data from 5 blood centers located in the state of Ceará were used, and out of 679,610 donors, 351 were reactive in the serological screening for HTLV. Among these, 40 samples were identified as HTLV-2, resulting a prevalence of 0.005%. Additionally, 7 samples were identified as co-infection between HTLV-1 and HTLV-2 using the Western Blot methodology (W.b 2.4) Genelabs Diagnostics (Singapore-Malaysia), a result that was not obtained in the current study. In the 2017 study conducted by Morais [6] in Amazonas, reagent samples for HTLV ELISA were tested using Western Blot. Out of 116 seropositive samples, 5 were identified with HTLV-2, with a prevalence similar to that found in the current study of 0.005. This similarity was observed despite the use of different serological and molecular testing methodologies, indicating that the populations studied were comparable. In the most recent study by Maneschy [21], carried out in Pará in 2021, a total of 453,626 blood donations were analyzed. The study detected 1476 serologically unfit donations by chemiluminescence and 30 donations with HTLV-2 by real-time PCR in the blood donor population of Pará. This represents a prevalence of 0.006%, which is similar to the prevalence found in the current study and the same population.
In the present study, a predominance of females was observed among the samples confirmed with HTLV-2. This profile has been reported in several studies that distinguish the HTLV-2 in Pará [19–21, 28], in Brazil [9, 29–31], and worldwide [27, 32–35]. However, among the referenced studies, only 5 [9, 19, 20, 27, 32] exclusively detected HTLV-2, while the others assessed the prevalence of both HTLV-1 and HTLV-2. Nevertheless, the epidemiological profiles of HTLV-2 and HTLV-1 were consistent with sex, which is likely due to the fact that transmission from men to women is generally more efficient than transmission from women to men [20, 29, 36].
Regarding the other social markers, the age range reported in the current study was 39 to 59 years of age among those infected with HTLV-2. This result directly reflects an individual’s potential for sexual experience or engagement in other risky behaviors. This prevalence among middle-aged individuals has already been reported in other studies with confirmation of HTLV-2 [9, 18, 20, 28, 31, 32, 36, 37]. Marital status is a relevant factor, as indicated by a higher prevalence of HTLV-2 infection among single individuals in the current study and in previous research [17, 24, 28]. This association may be attributed to greater exposure and a higher number of sexual partners, which can increase the risk of HTLV-2 infection as well as other sexually transmitted infections. Education level is a relevant factor in studies conducted among populations infected with HTLV-2 [9, 21, 24, 28, 36]. Individuals with up to a high school education have been shown to have a higher prevalence of infection, possibly due to limited access to information and sex education, which can influence risky behaviors in this population. Lastly, the higher presence of HTLV-2 in the metropolitan area could reveal urbanization of the virus, but this result is likely due to the culture of blood donation being more present in the metropolitan region than in the interior of the state as most of the donations, in general, are from the metropolitan region, and is not a representative of the HTLV-2 prevalence in the regions.
Data regarding co-infection were collected in the current survey. However, for HTLV-2, no other agents (HIV, HBV, HCV) were confirmed to be present in the same sample. This demonstrates an absence of co-infections detected with the virus in the samples analyzed during the studied period, even though the analyzed viruses have similar infection routes.
Conclusion
The molecular prevalence of HTLV-2 found in the blood donor population of the HEMOPA foundation in the state of Pará was found to be 0.005% over the course of the 6-year study. This prevalence is similar to previous studies and is of significant relevance to the general population. It is important to note that the blood donor population is representative of the overall population of Pará, which distinguishes it from other population groups that have been studied.
A limitation of the study to be able to compare the prevalence of HTLV-2 with authors who carried out the same research was the methodological differences that make the comparison of prevalence imprecise.
HTLV-2 is a neglected etiological agent worldwide. Compared to HTLV-1, there is limited information available on the prevalence of the population and the specific epidemiological profile of HTLV-2, both for the general population and for healthcare professionals. Having knowledge about the prevalence of HTLV-2 in hematological and hemotherapy services in Pará can aid in making informed decisions for prophylactic measures concerning the virus.
Author contribution
All authors participated in all stages of article preparation and approval of the final version.
Funding
The authors would like to thank the UNIFAMAZ Extension Research Management Nucleus (NUPEX) for funding the research project.
Declarations
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- 1.Futsch N, Mahieux R, Dutartre H. HTLV-1, the other pathogenic yet neglected human retrovirus: from transmission to therapeutic treatment. Viruses. 2017;10(1):1. doi: 10.3390/v10010001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.González-Alcaide G, Ramos JM, Huamaní C, Mendoza C, Soriano V. human t-lymphotropic virus 1 (htlv-1) and human t-lymphotropic virus 2 (htlv-2): geographical research trends and collaboration networks (1989-2012) Rev Inst Med Trop Sao Paulo. 2016;58:11. doi: 10.1590/S1678-9946201658011. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Martinez MP, Al-Saleem J, Green PL. Comparative virology of HTLV-1 and HTLV-2. Retrovirology. 2019;16(1):21. doi: 10.1186/s12977-019-0483-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Schierhout G, McGregor S, Gessain A, Einsiedel L, Martinello M, Kaldor J. Association between HTLV-1 infection and adverse health outcomes: a systematic review and meta-analysis of epidemiological studies. Lancet Infect Dis. 2020;20(1):133–143. doi: 10.1016/S1473-3099(19)30402-5. [DOI] [PubMed] [Google Scholar]
- 5.Eusebio-Ponce E, Anguita E, Paulino-Ramirez R, Candel FJ. HTLV-1 infection: An emerging risk. Pathogenesis, epidemiology, diagnosis and associated diseases. Rev Esp Quimioter. 2019;32(6):485–496. [PMC free article] [PubMed] [Google Scholar]
- 6.Morais MPE, Gato CM, Maciel LA, Lalwani P, Costa CA, Lalwani JDB. Prevalence of human T-lymphotropic virus type 1 and 2 among blood donors in Manaus, Amazonas State, Brazil. Rev Inst Med Trop Sao Paulo. 2017;21(59):e80. doi: 10.1590/S1678-9946201759080. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Ngoma AM, Omokoko MD, Mutombo PB, Nollet KE, Ohto H. Seroprevalence of human T-lymphotropic virus (HTLV) in blood donors in sub-Saharan Africa: a systematic review and meta-analysis. Vox Sang. 2019;114(5):413–425. doi: 10.1111/vox.12779. [DOI] [PubMed] [Google Scholar]
- 8.Percher F, Jeannin P, Martin-Latil S, Gessain A, Afonso PV, Vidy-Roche A, Ceccaldi PE. Mother-to-child transmission of HTLV-1 epidemiological aspects, mechanisms and determinants of mother-to-child transmission. Viruses. 2016;8(2):40. doi: 10.3390/v8020040. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Gomes FV, Eleutério JJ. HTLV-II in blood donors at the Blood Center Net of Ceará - HEMOCE. Rev Assoc Med Bras (1992) 2011;57(3):309–312. doi: 10.1016/S0104-4230(11)70064-1. [DOI] [PubMed] [Google Scholar]
- 10.Santos EL, Tamegão-Lopes B, Machado LF, Ishak Mde O, Ishak R, Lemos JA, Vallinoto AC. Caracterização molecular do HTLV-1/2 em doadores de sangue em Belém, Estado do Pará: primeira descrição do subtipo HTLV-2b na região Amazônica [Molecular characterization of HTLV-1/2 among blood donors in Belém, State of Pará: first description of HTLV-2b subtype in the Amazon region] Rev Soc Bras Med Trop. 2009;42(3):271–276. doi: 10.1590/s0037-86822009000300007. [DOI] [PubMed] [Google Scholar]
- 11.Rosário VAC, Ricardo I. HTLV-2: an ancient infection among Indian people of Brazilian Amazon Region. Rev Pan-Amaz Saude. 2017;8(2):7–9. [Google Scholar]
- 12.Ishak R, Guimarães Ishak MO, Azevedo VN, Machado LFA, Vallinoto IMC, Queiroz MAF, Costa GLC, Guerreiro JF, Vallinoto ACR. HTLV in South America: origins of a silent ancient human infection. Virus Evol. 2020;6(2):veaa053. doi: 10.1093/ve/veaa053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Stufano A, Jahantigh HR, Cagnazzo F, Centrone F, Loconsole D, Chironna M, Lovreglio P. Work-related human t-lymphotropic virus 1 and 2 (HTLV-1/2) infection: a systematic review. Viruses. 2021;13(9):1753. doi: 10.3390/v13091753. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Medeiros ACM, Vidal LRR, Von Linsingen R, Ferin AN, Bessani Strapasson T, de Almeida SM, Raboni SM, Carvalho NS, Bordignon NM. Confirmatory molecular method for HTLV-1/2 infection in high-risk pregnant women. J Med Virol. 2018;90(5):998–1001. doi: 10.1002/jmv.25014. [DOI] [PubMed] [Google Scholar]
- 15.Caterino-de-Araujo A, Barbosa-Stancioli EF, Alonso Neto JB, Aragón MG, Galvão-Castro B, Ishak R, Rosadas C. Laboratory diagnosis of human T-lymphotropic virus in Brazil: assays, flowcharts, challenges, and perspectives. Rev Soc Bras Med Trop. 2021;2(54):e01752021. doi: 10.1590/0037-8682-0175-2021. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Abreu IN, Lopes FT, Lima CNC, Barbosa ADN, de Oliveira LR, Fujishima MA, Freitas FB, Dos Santos MB, de Lima VN, Cayres-Vallinoto IMV, Castelo-Branco S, da Silva HP, Vallinoto ACR. HTLV-1 and HTLV-2 infection among Warao indigenous refugees in the Brazilian Amazon: challenges for public health in times of increasing migration. Front Public Health. 2022;11(10):833169. doi: 10.3389/fpubh.2022.833169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Ishak R, Harrington WJ, Jr, Azevedo VN, Eiraku N, Ishak MO, Guerreiro JF, Santos SB, Kubo T, Monken C, Alexander S, et al. Identification of human T cell lymphotropic virus type IIa infection in the Kayapo, an indigenous population of Brazil. AIDS Res Hum Retrovir. 1995;11(7):813–821. doi: 10.1089/aid.1995.11.813. [DOI] [PubMed] [Google Scholar]
- 18.Tamegão-Lopes BP, Rezende PR, Maradei-Pereira LM, de Lemos JA. Carga proviral do HTLV-1 e HTLV-2: um método simples através da PCR quantitativa em tempo real [HTLV-1 and HTLV-2 proviral load: a simple method using quantitative real-time PCR] Rev Soc Bras Med Trop. 2006;39(6):548–552. doi: 10.1590/s0037-86822006000600007. [DOI] [PubMed] [Google Scholar]
- 19.Ishak R, Vallinoto AC, Azevedo VN, Ishak MO. Epidemiological aspects of retrovirus (HTLV) infection among Indian populations in the Amazon Region of Brazil. Cad Saude Publica. 2003;19(4):901–914. doi: 10.1590/s0102-311x2003000400013. [DOI] [PubMed] [Google Scholar]
- 20.Braço ILJ, de Sá KSG, Waqasi M, Queiroz MAF, da Silva ANR, Cayres-Vallinoto IMV, Lima SS, de Oliveira Guimarães Ishak M, Ishak R, Guerreiro JF, Vallinoto ACR. High prevalence of human T-lymphotropic virus 2 (HTLV-2) infection in villages of the Xikrin tribe (Kayapo), Brazilian Amazon region. BMC Infect Dis. 2019;19(1):459. doi: 10.1186/s12879-019-4041-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.de Alcântara Maneschy C, do Santos Barile KA, de Castro JA, Palmeira MK, de Castro RB, de Melo Amaral CE. Seroprevalence of the human T lymphotropic virus (HTLV 1 and HTLV 2) in blood donor candidates in the State of Pará, Northern Brazil. Res Soc Dev. 2022;11(4):e1111427082. doi: 10.33448/rsd-v11i4.27082. [DOI] [Google Scholar]
- 22.Segurado AAC, Malaque CMS, Sumita LM, Pannuti CS, Lal RB. Laboratory characterization of human T cell lymphotropic virus types 1 (HTLV-1) and 2 (HTLV-2) infections in blood donors from Sao Paulo, Brazil. Am J Trop Med Hyg. 1997;57(2):142–148. doi: 10.4269/ajtmh.1997.57.142. [DOI] [PubMed] [Google Scholar]
- 23.Colin DD, Alcântara Júnior LC, Santos FL, Uchôa R, Tavares-Neto J. Prevalência da infecção pelo vírus linfotrópico humano de células T e fatores de risco associados à soropositividade em doadores de sangue da cidade de Rio Branco, AC, Brasil (1998-2001) [Seroprevalence of human T cell lymphotropic virus infection and associated factors of risk in blood donors of Rio Branco city, AC, Brazil (1998-2001)] Rev Soc Bras Med Trop. 2003;36(6):677–683. doi: 10.1590/s0037-86822003000600006. [DOI] [PubMed] [Google Scholar]
- 24.Ribeiro IP, Kozlowski AG, Dias de Matos MA, da Costa E, Silva ÁM, Dos Santos Carneiro MA, Vicente ACP, Martins RMB. HTLV-1 and -2 in a first-time blood donor population in Northeastern Brazil: Prevalence, molecular characterization, and evidence of intrafamilial transmission. J Med Virol. 2018;90(10):1651–1657. doi: 10.1002/jmv.25231. [DOI] [PubMed] [Google Scholar]
- 25.Sequeira CG, Tamegão-Lopes BP, Santos EJ, Ventura AM, Moraes-Pinto MI, Succi RC. Descriptive study of HTLV infection in a population of pregnant women from the state of Pará, Northern Brazil. Rev Soc Bras Med Trop. 2012;45(4):453–456. doi: 10.1590/s0037-86822012005000007. [DOI] [PubMed] [Google Scholar]
- 26.Ehrlich GD, Glaser JB, LaVigne K, Quan D, Mildvan D, Sninsky JJ, Kwok S, Papsidero L, Poiesz BJ. Prevalence of human T-cell leukemia/lymphoma virus (HTLV) type II infection among high-risk individuals: type-specific identification of HTLVs by polymerase chain reaction. Blood. 1989;74(5):1658–1664. doi: 10.1182/blood.V74.5.1658.1658. [DOI] [PubMed] [Google Scholar]
- 27.Zunt JR, Tapia K, Thiede H, Lee R, Hagan H. HTLV-2 infection in injection drug users in King County, Washington. Scand J Infect Dis. 2006;38(8):654–663. doi: 10.1080/00365540600617009. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Brito WRDS, Cardoso-Costa GL, Roland Junior LM, Pereira KAS, Lopes FT, Dos Santos BC, de Lima ACR, Abreu IN, Lima CNC, Lima SS, Cayres Vallinoto IMV, Dos Santos EJM, Guerreiro JF, Vallinoto ACR. Prevalence and risk factors for HTLV-1/2 infection in Quilombo remnant communities living in the Brazilian Amazon. Front Public Health. 2022;30(10):871865. doi: 10.3389/fpubh.2022.871865. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Rosadas C, Menezes MLB, Galvão-Castro B, Assone T, Miranda AE, Aragón MG, Caterino-de-Araujo A, Taylor GP, Ishak R. Blocking HTLV-1/2 silent transmission in Brazil: current public health policies and proposal for additional strategies. PLoS Negl Trop Dis. 2021;15(9):e0009717. doi: 10.1371/journal.pntd.0009717. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Machado LFA, Vallinoto ACR, Rosadas C, Taylor GP, Ishak R. Editorial: Prevention and control of human T lymphotropic viruses 1 and 2 (HTLV-1/2) Front Med (Lausanne) 2022;11(9):998431. doi: 10.3389/fmed.2022.998431. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Orletti MPS, Assone T, Sarnaglia GD, Martins ML, Rosadas C, Casseb J, Taylor G, Ferreira-Filho JB, Pereira FEL, Miranda AE. Prevalence of infection by human T cell lymphotropic viruses (HTLV-1/2) in adult population in Vitória-ES. Braz J Infect Dis. 2021;25(5):101631. doi: 10.1016/j.bjid.2021.101631. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Murphy EL, Watanabe K, Nass CC, Ownby H, Williams A, Nemo G. Evidence among blood donors for a 30-year-old epidemic of human T lymphotropic virus type II infection in the United States. J Infect Dis. 1999;180(6):1777–1783. doi: 10.1086/315139. [DOI] [PubMed] [Google Scholar]
- 33.Liu H, Leung P, Glynn S, Murphy EL. Human T-lymphotropic virus type II RFLP subtypes a0 and b4/b5 are associated with different demographic and geographic characteristics in the United States. Virology. 2001;279(1):90–96. doi: 10.1006/viro.2000.0632. [DOI] [PubMed] [Google Scholar]
- 34.Pham D, Nguyen D, Nguyen TA, Tran C, Tran L, Devare S, Tran A, Bhatnagar S. Seroprevalence of HTLV-1/2 among voluntary blood donors in Vietnam. AIDS Res Hum Retrovir. 2019;35(4):376–381. doi: 10.1089/AID.2018.0240. [DOI] [PubMed] [Google Scholar]
- 35.Salehi M, Mostafavi SK, Ghasemian A, Gholami M, Kazemi-Vardanjani A, Rahimi MK. Seroepidemiology of HTLV-1 and HTLV-2 infection in Neyshabur City, North-Eastern Iran, during 2010-2014. Iran Biomed J. 2017;21(1):57–60. doi: 10.6091/.21.1.57. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Alcantara Maneschy C, Dos Santos Barile KA, de Castro JAA, Palmeira MK, de Castro RBH, de Melo Amaral CE. Epidemiological and molecular profile of blood donors infected with HTLV-1/2 in the state of Pará, northern Brazil. Braz J Microbiol. 2021;52(4):2001–2006. doi: 10.1007/s42770-021-00609-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Alencar SP, Souza MC, Fonseca RRS, Menezes CR, Azevedo VN, Ribeiro ALR, Lima SS, Laurentino RV, MDAAP B, Freitas FB, Oliveira-Filho AB, LFA M. Prevalence and molecular epidemiology of human T-Lymphotropic virus (HTLV) infection in people living with HIV/AIDS in the Pará State, Amazon Region of Brazil. Front Microbiol. 2020;11:572381. doi: 10.3389/fmicb.2020.572381. [DOI] [PMC free article] [PubMed] [Google Scholar]