Laboratory diagnosis of human T-lymphotropic virus in Brazil: assays, flowcharts, challenges, and perspectives

Abstract INTRODUCTION We present a data analysis and review of recent studies regarding the laboratory diagnosis of human T-lymphotropic virus 1 and 2 (HTLV-1/2) infections in Brazil. METHODS Target populations, available diagnostic serological assays (screening and complementary tests), molecular assays (in-house), causes of false-positive and false-negative results, and flowcharts were analyzed. RESULTS A table presents the target populations, two diagnostic flowcharts (depending on laboratory infrastructure and study population), and recent research that may improve how HTLV-1/2 is diagnosed in Brazil. CONCLUSIONS: Our results support the implementation of public policies to reduce HTLV-1/2 transmission and its associated diseases.

Provirus Mutations of Human T-Lymphotropic Virus 1 and 2 (HTLV-1 and HTLV-2) in HIV-1-Coinfected Individuals

Provirus mutations of human T-lymphotropic virus 1 (HTLV-1), mostly the lack of the 5= long terminal repeat (LTR) genomic region, have been described and associated with severe adult T cell leukemia/lymphoma (ATLL), non-sense point mutations with low proviral load, and Western blotting indeterminate results. Until now, no information concerning provirus mutations of HTLV-2 and its consequences, as well as those of HTLV-1/2 in HIV-coinfected individuals, had been described. Therefore, we searched for these mutations in provirus samples of 44 HIV/HTLV-1- and 25 HIV/HTLV-2-coinfected individuals. Using protocols well established for amplification and sequencing of segments of the LTR, env, and tax regions, we searched for defective type 1 particles that retain LTRs and lack internal sequences and type 2 particles that lack the 5=LTR region. In addition, using as references the prototypes ATK (HTLV-1) and Mo (HTLV-2), we searched for point mutations in the LTR and synonyms and nonsynonymous mutations and non-sense mutations in env and tax regions. Defective HTLV-1 and HTLV-2 provirus type 1 or 2 was detected in 31.8% of HIV/HTLV-1- and 32.0% of HIV/HTLV-2-coinfected individuals. Synonymous and nonsynonymous mutations were identified mostly in HTLV-2 and associated with lower levels of specific antibodies. No non-sense mutations that resulted in premature termination of Env and Tax proteins were detected. On the contrary, mutation in the stop codon of Tax2a produced a long protein characteristic of the HTLV-2c subtype. The clinical significance of these mutations in coinfected individuals remains to be defined, but they confirmed the lower sensitivity of serological and molecular diagnostic tests in HIV/HTLV-1/2 coinfections. IMPORTANCE HTLV-1 and HTLV-2 are endemic to Brazil, and they have different effects in HIV/AIDS disease progression. HIV/HTLV-1 has been described as accelerating the progression to AIDS and death, while HIV/HTLV-2 slows the progression to AIDS. Provirus mutations of HTLV-1 were implicated in severe leukemia development and in problems in the diagnosis of HTLV-1; in contrast, provirus mutations of HTLV-2 had not been confirmed and associated with problems in HTLV-2 diagnosis or disease outcome. Nevertheless, data obtained here allowed us to recognize and understand the false-negative results in serologic and molecular tests applied for HTLV-1 and HTLV-2 diagnosis. Defective proviruses, as well as synonymous and nonsynonymous mutations, were associated with the diagnosis deficiencies. Additionally, since HIV-1 and HTLV-1 infect the same cells (CD4 positive), the production of HIV-1 pseudotypes with HTLV-1 envelope glycoprotein during HIV/HTLV-1 coinfection cannot be excluded. Defective provirus of HTLV-2 and Tax2c is speculated to influence progression to AIDS. (AU)

Diagnósticos de enfermagem em pessoas soropositivas pelo vírus linfotrópico t humano / Diagnósticos de enfermería en personas seropositivas por virus linfotrópicos t humanos / Nursing diagnoses in seropositive people by human t lymphotropic virus

Objetivo identificar diagnósticos de enfermagem em pessoas sintomáticas e soropositivas para o vírus linfotrópico T humano. Método pesquisa documental, realizada nos prontuários de pessoas soropositivas para o vírus linfotrópico T humano, cadastradas no Centro de Testagem e Aconselhamento de um município do interior do estado da Bahia. A análise dos registros foi realizada com base na Taxonomia II da NANDA-I 2018-2020. Resultados foram identificados 13 diagnósticos de enfermagem distribuídos em 5 domínios: Conforto; Eliminação e Troca; Atividade e repouso; Autopercepção; Enfrentamento/Tolerância ao estresse. Os diagnósticos mais prevalentes foram: Dor crônica, em 21 (100%) dos soropositivos, Incontinência urinária em nove (43%), e Deambulação prejudicada em 8 (38%). Conclusão a identificação dos diagnósticos em pessoas sintomáticas e soropositivas para o vírus linfotrópico T humano fornece subsídios para a construção de planos de cuidados de enfermagem específicos.

Objetivo identificar los diagnósticos de enfermería en personas sintomáticas y seropositivas para el virus linfotrópico T humano. Método investigación documental, realizada en los registros médicos de personas seropositivas para el virus linfotrópico T humano, registradas en el Centro de Pruebas y Asesoramiento de un municipio en el interior del estado de Bahía. El análisis de los registros se realizó sobre la base de la Taxonomía II de NANDA-I 2018-2020. Resultados se identificaron 13 diagnósticos de enfermería, distribuidos en cinco dominios: Confort; Eliminación e Intercambio; Actividad y descanso; Auto-percepción; Afrontamiento/tolerancia al estrés. Los diagnósticos más frecuentes fueron: Dolor crónico, en 21 (100%) de individuos seropositivos, incontinencia urinaria en nueve (43%) y deterioro de la ambulación en 8 (38%). Conclusión la identificación de diagnósticos en personas sintomáticas y seropositivas para el virus linfotrópico T humano proporciona apoyo para la construcción de planes específicos de cuidados de enfermería.

Objective to identify nursing diagnoses in symptomatic and seropositive people for the human T lymphotropic virus. Method documentary research, carried out with the medical records of people seropositive for the human T lymphotropic virus, registered at the Testing and Counseling Center of a municipality in inland Bahia state. The analysis of the records was performed based on Taxonomy II of NANDA-I 2018-2020. Results 13 nursing diagnoses were identified, distributed in five domains: Comfort; Elimination and Exchange; Activity and rest; Self-perception; Coping/Stress Tolerance. The most prevalent diagnoses were: Chronic Pain, in 21 (100%) of seropositive individuals, urinary incontinence in nine (43%), and Impaired ambulation in 8 (38%). Conclusion the identification of diagnoses in symptomatic and seropositive people for the human T lymphotropic virus provides support for the construction of specific nursing care plans.

Seroprevalencia de los virus linfotrópicos de células T humanas de tipos I y II en donantes del Banco de Sangre del Hospital Pablo Tobón Uribe, entre 2014 y 2015 / HTLV-I/II seroprevalence in blood donors of Hospital Pablo Tobón Uribe Blood Bank during the period 2014-2015

Resumen Introducción . El virus linfotrópico humano de células T (HTLV) es un retrovirus del cual se conocen varios tipos, entre ellos el HTLV-I y el HTLV-II, los cuales son de importancia clínica por ser los causantes de diferentes enfermedades, como la leucemia y el linfoma de células T del adulto, la paraparesia espástica tropical y la mielopatía asociada al HTLV. Objetivo . Obtener la prevalencia de las reacciones presuntiva y confirmatoria de los virus HTLV-I y HTLV-II en los donantes del Banco de Sangre del Hospital Pablo Tobón Uribe de Medellín, entre el 2014 y el 2015. Materiales y métodos . La información se obtuvo de la base de datos del Banco de Sangre del Hospital Pablo Tobón Uribe. Se analizaron la edad, el sexo y el lugar de procedencia y de residencia de los donantes, así como la reacción en la prueba de tamización (ELISA) y en la prueba confirmatoria (inmunoblot). Resultados . La población de donantes estudiados incluyó a 6.275 hombres y 8.148 mujeres, para un total de 14.423 donantes reclutados entre el 1° de marzo de 2014 y el 30 de junio de 2015. De ellos, 25 resultaron positivos para HTLV-I o HTLV-II en la prueba de tamización (ELISA). En la prueba confirmatoria (inmunoblot), nueve (36 %) pacientes fueron positivos para el HTLV-I o HTLV-II , y de ellos ocho (32 %) lo fueron para el HTLV-I y uno (4 %) para el HTLV-II; la seroprevalencia global fue de 0,06 % (IC95% 0,10-0,25). Conclusiones . Los hallazgos del estudio concordaron con los de estudios similares en áreas no endémicas del país y con los de los estudios consultados a nivel internacional.

Abstract Introduction: The human-T cell lymphotropic virus is a retrovirus with various types known so far. HTLV-I and HTLV-II are of clinically importance as they cause different diseases such as adult T-cell leukemia/lymphoma, tropical spastic paraparesis, and human T-lymphotropic virus type I-associated myelopathy (HAM). Objective: To estimate the prevalence of presumptive and confirmatory reactivity to HTLV-I/II in blood donors of Hospital Pablo Tobón Uribe Blood Bank between 2014 and 2015. Materials and methods: The information was obtained from the Hospital Pablo Tobón Uribe Blood Bank database. We analyzed age, sex, place of origin, and place of residence of donors, and the reactivity using the screening test (ELISA) as well as the confirmatory test (immunoblot). Results: The donor population studied included 6,275 men and 8,148 women, for a total of 14,423 donors recruited between March 1, 2014, and June 30, 2015. Of all tested donors, 25 were positive for HTLV-I/II by the screening test (ELISA). After performing the confirmatory test (immunoblot), only nine patients were positive for HTLV-I/II (36%), of whom eight were reactive to HTLV-I (32%) and one to HTLV-II (4%), for a global seroprevalence of 0.06% (CI 95%: 0.10-0.25). Conclusions: Our findings were consistent with those found in similar studies in non-endemic areas of the country and with those from studies at international level reported in the literature.

Desafios no diagnóstico da infecção pelos Vírus Linfotrópicos de Células T Humanas do tipo 1 e tipo 2 (HTLV-1 e HTLV-2) em pacientes infectados com o HIV-1 / Challenges in the diagnosis of Human T-Cell Lymphotropic Virus type 1 and type 2 (HTLV-1 and HTLV-2) infection in patients infected with HIV-1

Desde a década de 90 o Instituto Adolfo Lutz de São Paulo (IAL) tem realizado o diagnóstico da infecção por Vírus Linfotrópicos de Células T Humanas dos tipos 1 e 2 (HTLV-1 e HTLV-2) e, desde então, têm sido reportadas as dificuldades principalmente no diagnóstico de HTLV-2, em especial em pacientes infectados pelo HIV-1. O presente trabalho teve como objetivo avaliar várias técnicas de diagnóstico disponíveis no momento atual (kits comerciais e testes in house) e estabelecer o melhor algoritmo para ser empregado no diagnóstico de pacientes infectados pelo HIV-1. A população analisada foi composta por dois grupos provenientes de Serviços de Assistência Especializados em HIV/AIDS de São Paulo: um pioneiro [Grupo 1 (G1), n=1.608] e outro com histórico mais recente [Grupo 2 (G2), n=1.383]. Ambos os grupos foram formados, na maioria, por indivíduos do sexo masculino... (AU).

Since the 90 decade, the Instituto Adolfo Lutz (IAL) has performed the diagnosis of Human T-cell Lymphotropic Virus type 1 and type 2 (HTLV-1 and HTLV-2), and thenceforth the difficulties in diagnosing HTLV-2 have been reported, mostly in HIV-infected patients. The present study aimed at evaluating the several diagnostic techniques currently available (commercial kits and in-house assays), and to establish the best algorithm to be employed for diagnosing HTLV-1/-2 in patients infected with HIV-1. The study population was composed by two patient groups attended at HIV/AIDS specialized services care in São Paulo: the pioneer one [Group 1 (G1), n=1,608], and the other with the most recent historical health setting [Group 2 (G2), n=1,383. The majority of the both groups were composed by male patients...(AU).

Seroprevalence of HTLV-1/2 among blood donors in the state of Maranhao, Brazil

Background: Infection with human T-lymphotropic virus 1 or 2 (HTLV-1/2) is a major health problem. There is a public health policy defining measures for state hematology and hemotherapy centers in Brazil, in order to avoid virus transmission through blood donors. Objective: This study aimed to evaluate the seroprevalence of HTLV -1/2 in blood donors in the State of Maranhão, Brazil, during routine blood unit screening. Methods: Screening tests of blood donors using the enzyme-linked immunosorbent assay (ELISA) to detect seropositivity for HTLV-1/2 performed at the Hematology and Hemotherapy Center of the State of Maranhão (HEMOMAR) between July of 2003 and December of 2009 were retrospectively evaluated. Results: Of the 365,564 blood donors, 561 (0.15%) were HTLV-1/2-positive, of whom 72 (12.8%) performed the confirmatory test (Western blot). In donors who had a confirmatory test, 53 (73.6%) were positive. The ages of the infected individuals ranged from 18 to 65 years; 305 (54%) were aged over 40 years. Among the infected individuals, 309 (55%) were male, 399 (71%) were mixed-race, and 259 (46%) were single. Co-infections were frequently found, especially with hepatitis B (in 68.6% of the cases). Conclusion: The results obtained will contribute to the planning and implementation of control measures by the epidemiological surveillance agency of Maranhão, and will also contribute to reducing morbidity. The high seropositivity in a small sample in donors who had confirmatory tests indicates the need for confirmatory tests for all donors who initially test as seropositive. .

Prevalence of human T-cell lymphotropic virus types 1 and 2 in blood donors of the Caruaru Blood Center (Hemope)

BACKGROUND: There is difficulty in gathering data on the prevalence of human T-cell lymphotropic virus in blood donors as confirmatory testing is not mandatory in Brazil. This suggests there may be an underreporting of the prevalence. OBJECTIVE: To estimate the prevalence of human T-cell lymphotropic virus types 1 and 2 in donors of a blood bank in Caruaru, Brazil. METHODS: This was an observational, epidemiological, descriptive, longitudinal and retrospective study with information about the serology of donors of the Caruaru Blood Center, Fundação de Hematologia e Hemoterapia de Pernambuco (Hemope) from May 2006 to December 2010. The data were analyzed using the Excel 2010 computer program (Microsoft Office(r)). RESULTS: Of 61,881 donors, 60 (0.096%) individuals were identified as potential carriers of human T-cell lymphotropic virus types 1 and 2. Of these, 28 (0.045%) were positive and 32 (0.051%) had inconclusive results in the serological screening. Forty-five (0.072%) were retested; 17 were positive (0.027%) and 3 inconclusive (0.005%). After confirmatory tests, 8 were positive (0.013%). Six (75%) of the confirmed cases were women. CONCLUSION: Epidemiological surveys like this are very important in order to create campaigns to attract donors and reduce the costs of laboratory tests. .

Detección de virus linfotrópico de células T humano-I/II en pacientes con enfermedades de transmisión sexual de Santiago / Human T-lymphotropic virus I/II detection in Chilean patients from Sexually Transmitted Diseases clinics

Background: The human T-lymphotropic virus I (HTLV-I) causes spastic para-paresis and adult T-cell leukemia/lymphoma. It can be sexually transmitted and is highly prevalent in Central and South America. Aim: To study HTLV-I/IIprevalence in serum samples obtained from two Sexually Transmitted Diseases (STD) clinics. Material and Methods: Two hundred serum samples were randomly chosen from two reference STD centers of Santiago. The presence of specific HTLV I/II antibodies was detected by indirect immunofluorescence. Results: The analyzed samples came from participants aged 14 to 70 years. Forty nine percent were women and 76% were heterosexual. Only one of the 200 samples was positive (0.5%) and it came from a 70 year-old woman, housewife, with a stable single partner, a history of recurrent genital ulcers, VDRL (-) and positive serology for herpes simplex virus. Conclusions: The prevalence of HTLV-I found in this group is similar to that demonstrated in other populations in Chile, except for aboriginal populations, and similar to international STD studies. Our data is consistent with the low transmissibility by sexual contact.

Piomiosite tropical em paciente com lúpus eritematoso sistêmico e infecção por HTLV 1/2 / Tropical pyomyositis in a patient with systemic lupus erythematosus and HTLV 1/2 infection

A piomiosite tropical (PT) é uma doença infecciosa da musculatura esquelética, de etiologia bacteriana, incomum, e muitas vezes associada a situações de imunodeficiência. O envolvimento de musculatura pélvica profunda, como o músculo ilíaco, é uma condição ainda mais incomum. A associação de lúpus eritematoso sistêmico (LES) e PT é pouco relatada na literatura. Como o LES é uma situação de imunodepressão tanto pela doença em si como pelas medicações utilizadas no seu tratamento, esses pacientes tornam-se grupo de risco para o desenvolvimento de infecções, como PT. A infecção pelo HTLV está cada vez sendo mais identificada e associada a patologias nas quais autoimunidade está implicada, como é o caso do LES. Os autores descrevem um caso de PT de localização no músculo ilíaco em paciente portadora de LES, insuficiência renal crônica, em hemodiálise, além de portadora do vírus HTLV 1/2, internada no Hospital Heliópolis, em São Paulo, Brasil.

Tropical pyomyositis (TP) is an unusual infectious disease of skeletal muscles, caused by bacteria, and often associated with immunodeficiency conditions. The involvement of deep pelvic muscles, such as the iliac muscle, is even rarer. The association of systemic lupus erythematosus (SLE) and PT is seldom reported in the literature. Because SLE involves a state of immunosuppression resulting from both the disease itself and its medicamentous treatment, SLE patients are at higher risk for developing infections, such as PT. Infection by HTLV 1/2 is increasingly identified and associated with autoimmune diseases, such as SLE. This is a case report of PT in the pelvic muscles of a female patient with SLE, chronic kidney failure, on hemodialysis, and HTLV1/2 infection, admitted to the Hospital Heliópolis, in the city of São Paulo, Brazil.

Geographic distribution of human T-lymphotropic virus types 1 and 2 among mothers of newborns tested during neonatal screening, Minas Gerais, Brazil / Distribución geográfica del virus linfotrópico de células T humanas tipos 1 y 2 en madres de recién nacidos estudiados en el tamizaje neonatal en Minas Gerais, Brasil

OBJECTIVE: To evaluate the geographic distribution of human T-lymphotropic virus types 1 and 2 (HTLV-1/2) in the State of Minas Gerais, Brazil, in puerperal women whose newborns were tested for HTLV-1/2 during neonatal screening, and to overlap seropositivity with social and economic status determinants. METHODS: During September-November 2007, the dry-blood samples taken from newborns on filter paper for routine screening were also tested for maternal IgG anti-HTLV-1/2 antibodies. For reactive samples, the mothers of the newborns had blood drawn to test for these viruses. RESULTS: The study analyzed 55 293 specimens taken from newborns. Of these, 52 (9.4 per 10 000) were reactive and 42 mothers (7.6 per 10 000) were confirmed with HTLV-1/2 infection. HTLV-1/2 geographic distribution was heterogeneous, with a tendency to be higher in the North and North-East parts of Minas Gerais. The highest rates of seropositivity were observed in Vale do Mucuri (55.9 per 10 000) and in Jequitinhonha (16.0 per 10 000), overlapping with the State's worst social and economic indicators. CONCLUSIONS: To our knowledge this was the first time that neonatal screening for HTLV-1/2 was performed in Brazil. This model could be used in other areas with high HTLV-1/2 prevalence rates. The detection of carrier mothers can enable intervention measures, such as providing infant formula to newborns, to be implemented expeditiously to reduce vertical transmission.

OBJETIVOS: Evaluar la distribución geográfica del virus linfotrópico de células T humanas tipos 1 y 2 (HTLV-1/2) en el estado de Minas Gerais (Brasil), en mujeres puérperas en cuyos recién nacidos se analizó la presencia del HTLV-1/2 durante las pruebas neonatales de detección sistemática, y superponer la seropositividad con determinantes del estado socioeconómico. MÉTODOS: Entre septiembre y noviembre de 2007, en las muestras de sangre seca extraída a los recién nacidos en papel de filtro para un tamizaje sistemático, se analizaron también los anticuerpos maternos de tipo IgG anti-HTLV-1/2. En el caso de las muestras reactivas, se extrajo la sangre de las madres de los recién nacidos para realizar pruebas de detección de estos virus. RESULTADOS: En el estudio se analizaron 55 293 muestras extraídas de los recién nacidos. De estas, 52 (9,4 por 10 000) fueron reactivas y en 42 madres (7,6 por 10 000) se confirmó la infección por el HTLV-1/2. La distribución geográfica del HTLV-1/2 fue heterogénea, con una tendencia a ser mayor en el norte y el noreste de Minas Gerais. Las tasas más elevadas de seropositividad se observaron en Vale do Mucuri (55,9 por 10 000) y en Jequitinhonha (16,0 por 10 000), superponiéndose con los peores indicadores socioeconómicos del estado. CONCLUSIONES: Esta fue la primera vez que se realizó un tamizaje neonatal para el HTLV-1/2 en Brasil. Este modelo podría usarse en otras regiones con tasas de prevalencia altas del HTLV-1/2. La detección de las madres portadoras puede permitir la aplicación rápida de medidas de intervención, como por ejemplo, el suministro de leche maternizada a los recién nacidos, a fin de reducir la transmisión vertical.

Introdução da reação em cadeia da polimerase em tempo real no algoritmo de testes laboratoriais para o diagnóstico de infecção por HTLV-1 e HTLV-2 / Use of the real-time polymerase chain reaction in the HTLV-1 and HTLV-2 infections diagnostic testing algorithm

Em vista das dificuldades encontradas no diagnóstico de infecção por vírus linfotrópicos de células T humanas dos tipos 1 e 2 (HTLV-1 e HTLV-2) no Instituto Adolfo Lutz (IAL) de São Paulo, foi proposto o presente estudo que objetivou avaliar o valor do cut-off dos testes de triagem sorológica e os algoritmos de testes laboratoriais, dando ênfase ao emprego da reação em cadeia da polimerase (PCR) como teste confirmatório. Do total de 3.271 amostras de sangue provenientes da rotina diagnóstica dos anos de 1998 a 2010: (a) 2.312 amostras de soro (1998-2006) foram empregadas para estabelecer o melhor valor de cut-off para os ensaios imunoenzimáticos (EIAs) usando a análise ROC (receiving operating characteristics); (b) 313 amostras de sangue (2009) foram analisadas por algoritmo de duas coletas seqüências de sangue; (c) 73/959 amostras de sangue reagentes na triagem sorológica (2007-2010) foram empregadas no estudo comparativo de sensibilidade e custo dos testes confirmatórios de Western blot (WB), PCR convencional (tax e pol) e PCR em tempo real (pol). As PCRs foram otimizadas usando DNA extraído de linhagens celulares infectadas por HTLV-1 (C91-PL) e por HTLV-2 (BBF) e realizada pesquisa de gene da albumina humana como controle endógeno. Os resultados da análise ROC mostraram que um ajuste no valor do cut-off dos EIAs de 3ª geração aumentou a especificidade desses ensaios em 7,8%, sem alterar significativamente a sua sensibilidade. O algoritmo de coleta seqüencial de sangue se mostrou inadequado sendo mais apropriada a coleta única em tubo contendo anticoagulante. Os resultados do ensaio confirmatório de WB mostraram que este foi mais sensível (90,56%) do que a PCR convencional (77,36%) e a PCR em tempo real (79,25%), provavelmente pela pequena carga proviral de HTLV-1 e HTLV-2 presente no sangue, principalmente de portadores assintomáticos. Todavia, as técnicas de PCR se mostraram úteis na elucidação de amostras com padrão indeterminado à análise pelo WB, sendo os ensaios sorológicos e moleculares complementares. Concluindo, em vista da PCR em tempo real ser um teste rápido, seguro, de menor custo e de fácil execução, ele pode ser aplicado como primeiro teste confirmatório de infecção por HTLV-1 e HTLV-2 seguido do WB (AU).

Taking into account the difficulties in diagnosing the human T-cell lymphotropic virus type 1 and type 2 (HTLV-1 and HTLV-2) in Instituto Adolfo Lutz of São Paulo, the present study was conducted aiming at evaluating the cut-off values of screening enzyme immunoassays (EIAs) and the tests algorithms, emphasizing the use of polymerase chain reaction (PCR) as confirmatory assay. Of 3,271 blood samples routinely analyzed from 1998 to 2010: (a) 2,312 serum samples (1998-2006) were assessed for the best cutoff value by using the receiving operating characteristics analyses (ROC); (b) 313 blood samples (2009) were tested following the algorithm which employs two sequential blood collection, and (c) 73/959 blood samples (2007-2010) showing reactive results on screening testing were employed for comparative analysis of serologic (Western blot ­ WB) and molecular confirmatory assays [PCR (tax and pol) and real time PCR (pol)]. The PCRs were optimized using the cells lines infected with HTLV-1 (C91-PL) and HTLV-2 (BBF), and the human albumin gene. The ROC analysis showed that an adjustment of the cut-off value in the third generation EIAs increased their specificity in 7.8%. The use of the sequential blood collection algorithm for serological diagnosis was completely inefficient and a unique blood collection in an anticoagulantcontaining tube seems to be the most appropriate. The WB confirmatory assay resulted to be more sensitive (90.56%) than the standard PCRs (77.36%) and the real-time PCR (79.25%), probably owing to the low HTLV-1 and HTLV-2 proviral load in asymptomatic carriers' blood. However, the PCRs were able in elucidating the samples with indeterminate WB profile, thereby standing the serologic and molecular assays as complementary tests. In conclusion, because of the low cost, rapidity, reliability and easiness to perform, the real-time PCR could be used as the first confirmatory assay for performing the HTLV-1 and HTLV-2 diagnosis, followed by the WB technique (AU).