High Ratio of Human T Cell Lymphotropic Virus Transmission and Prevalence of Human T Cell Lymphotropic Virus Type 1-Associated Diseases in Brazilian Family Groups Followed Up by the GIPH Cohort.

A silent spread of human T cell lymphotropic virus type 1 (HTLV-1) has been occurring for thousands of years, with a high prevalence in some regions due to the sexual and vertical transmission and formation of family clusters. The time from HTLV-1 infection until the onset of virus-associated diseases is extremely long, approximately one to three decades. In this study, we evaluated intrafamilial HTLV-1 transmission and associated diseases in 1,204 individuals enrolled and followed up by the GIPH cohort between 1997 and 2017. The family groups (n = 43) were composed of 279 individuals who were tested for HTLV-1/human T cell lymphotropic virus type 2 (HTLV-2) and were classified as two groups according to the index case: blood donor (blood donors referred to the GIPH cohort) and nondonor (individuals referred to the GIPH cohort by other health services). The observed rates of HTLV-1 transmission and associated diseases among the relatives were high. Of 236 family members and sexual partners tested for HTLV, 104 (44.1%) were confirmed as having HTLV infection, with 36.7% of relatives whose index case was blood donors and 56.9% of relatives with nondonor index cases. At least one case of HTLV-1-associated myelopathy was observed in 42.9% of the families with intrafamilial transmission of HTLV-1. Brazil is an endemic area for HTLV-1/2 and has implemented mandatory universal screening of blood donors for HTLV-1/2 since 1993. However, the lack of public health services offer diagnosis for HTLV to the general population and pregnant women in the country makes it difficult to identify infected people, and contributes to the silent spread of the virus.

Vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation may reveal subclinical alterations in human T-cell lymphotropic virus type 1-associated myelopathy.

BACKGROUND: Vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation (galvanic-VEMP) evaluates the motor spinal cord and identifies subclinical myelopathies. We used galvanic-VEMP to compare spinal cord function in individuals infected with human T-cell lymphotropic virus type 1 (HTLV-1) from asymptomatic status to HTLV-1-associated myelopathy (HAM). METHODOLOGY/PRINCIPAL FINDINGS: This cross-sectional study with 122 individuals included 26 HTLV-1-asymptomatic carriers, 26 individuals with possible HAM, 25 individuals with HAM, and 45 HTLV-1-seronegative individuals (controls). The groups were similar regarding gender, age, and height. Galvanic stimuli (duration: 400 ms; intensity: 2 mA) were applied bilaterally to the mastoid processes and VEMP was recorded from the gastrocnemius muscle. The electromyographic parameters investigated were the latency and amplitude of the short-latency (SL) and medium-latency (ML) responses. While SL and ML amplitudes were similar between groups, SL and ML latencies were delayed in the HTLV-1 groups compared to the control group (p<0.001). Using neurological examination as the gold standard, ROC curve showed an area under the curve of 0.83 (p<0.001) for SL and 0.86 (p<0.001) for ML to detect spinal cord injury. Sensibility and specificity were, respectively, 76% and 86% for SL and 79% and 85% for ML. Galvanic-VEMP disclosed alterations that were progressive in HTLV-1-neurological disease, ranging from SL delayed latency in HTLV-1-asymptomatic carriers, SL and ML delayed latency in possible HAM group, to absence of VEMP response in HAM group. CONCLUSIONS/SIGNIFICANCE: The worse the galvanic-VEMP response, the more severe the myelopathy. Galvanic-VEMP alteration followed a pattern of alteration and may be a prognostic marker of progression from HTLV-1-asymptomatic carrier to HAM.

HTLV-1 proviral load in cerebrospinal fluid may not be a good marker to differentiate asymptomatic carriers with high proviral load in blood from HAM/TSP patients.

An elevated human T cell leukemia virus type 1 (HTLV-1) proviral load (PVL) is an important risk factor for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), although there is a considerable frequency of asymptomatic carriers (AC) with high PVL in blood. Our objective was to evaluate whether PVL quantified in cerebrospinal fluid (CSF) is helpful to distinguish AC from HAM when AC have high PVL in blood (ACH). ACH (n = 7) were characterized to have high PVL in blood by quantification of samples collected over time (mean 7 years). HAM patients (n = 14) also had analyzed blood samples collected at different times (mean 9 years). Comparing paired CSF and blood samples of each individual, CSF PVL mean was 4.7-fold higher than blood PVL in the ACH group and 10.8-fold in the HAM group. CSF PVL was significantly greater than blood PVL in the HAM group (p = 0.004), but not in the ACH group. Important to highlight, CSF PVL was not significantly different between the ACH and the HAM groups. These results suggested that significantly higher PVL in CSF than in blood is a hallmark of HAM/TSP patients, but this is also true for asymptomatic carriers with high PVL in blood, thus reducing its usefulness as a marker for HAM/TSP. A greater number of ACH should be analyzed, but whether they will eventually develop HAM/TSP or why they have not developed the disease are still questions to be clarified. Longitudinal studies are necessary to answer these questions.

Long-term follow-up of HTLV-1 proviral load in asymptomatic carriers and in incident cases of HAM/TSP: what is its relevance as a prognostic marker for neurologic disease?

HTLV-1 proviral load (pvl) is an important risk marker for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), but its value as prognostic marker is not well defined. Long-term prospective cohort studies are necessary to clarify this question. Here, we analyzed HTLV-1 pvl in the peripheral blood of 82 asymptomatic carriers (AC; 351 samples), 12 HAM/TSP patients (HAM; 46 samples), and six incident cases of HAM/TSP (iHAM), with serial samples collected before (n = 10) and after (n = 20) the disease onset. The mean interval of follow-up was 10 years in the AC group and 8 years in HAM and iHAM groups. pvl was not significantly different between the first and last measurements in the three groups, but there was a trend to decrease over time. Coefficient of variation of pvl was significantly lower in the AC group than in HAM (p = 0.015) and iHAM (p = 0.022) patients. AC and HAM individuals showed a significant and strong positive correlation between the first and last measurements of pvl, but not iHAM subjects. All individuals who developed HAM/TSP during the follow-up had high pvl level (>1 %) before the onset of disease, but a typical increase in pvl was not observed in that period. The data suggest that there is a trend to reach an equilibrium plateau of pvl over time, characteristic of each individual. A significant rate of AC keeps high pvl levels for a long time without developing clinical symptoms associated to HTLV-1 infection. Thus, serial quantification of pvl in the peripheral blood does not seem to be a good prognostic marker for HAM/TSP.

Electrophysiological analysis shows dizziness as the first symptom in human T cell lymphotropic virus type-associated myelopathy/tropical spastic paraparesis.

Dizziness is a symptom in human T cell lymphotropic virus type-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and may occur due to vestibulospinal tract dysfunction. This tract can be assessed by an electrophysiological test called vestibular-evoked myogenic potential (VEMP). The aim was to correlate the result of VEMP generated by acoustic stimuli and dizziness in individuals with human T cell lymphotropic virus type 1 (HTLV-1)-asymptomatic infection and HAM/TSP. VEMP was recorded from the sternocleidomastoid muscle of 60 HTLV-1-negative adults (60±8 years) and 60 individuals infected with HTLV-1, 30 being asymptomatic (59±8 years) and 30 with HAM/TSP (59±8 years). In all groups, 90% of the participants were women. VEMP was generated by acoustic stimuli (short tone bursts), with an intensity of 118 dBHL and band-pass filter from 10 Hz to 1,500 Hz, and presented 200 stimuli at a frequency of 1,000 Hz with a record time of 60 ms. Of 60 HTLV-1-negative individuals, 14 (23%) reported dizziness; VEMP was normal in all. In the HTLV-1-asymptomatic group, 11(37%) complained of dizziness (p=0.31); VEMP was altered in four (40%) subjects with dizziness and in one (5%) without dizziness (p=0.00). In the group with HAM/TSP, dizziness was reported by 17 (57%) subjects (p=0.002); VEMP was altered in 11 (64%) with dizziness and in 5 (38%) without dizziness (p=0.15). Dizziness without an apparent etiology in HTLV-1-asymptomatic carriers deserves attention in terms of a possible subclinical spinal cord involvement that can be clarified through spinal electrophysiological tests. Damage of the vestibulospinal tract seems to occur in the early stages of HAM/TSP.

Incidence of human T cell lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis in a long-term prospective cohort study of initially asymptomatic individuals in Brazil.

The incidence of human T cell lymphotropic virus type 1 (HLTV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is not well defined in the literature. Several studies have reported different incidence rates, and recent publications suggest a higher incidence and prevalence of HAM/TSP. The interdisciplinary HTLV Research Group (GIPH) is a prospective open cohort study of individuals infected with HTLV-1/2. This study describes the demographic data and HAM/TSP incidence rate observed in 181 HTLV-1-seropositive individuals and compares the results with previous reports in the literature. HAM/TSP was diagnosed on the basis of the World Health Organization diagnostic criteria and De Castro-Costa et al. [Proposal for diagnostic criteria of tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). AIDS Res Hum Retroviruses 2006;22:931-935]. Seven HAM/TSP incident cases were observed during the follow-up. The HAM/TSP incidence density was 5.3 cases per 1,000 HTLV-1-seropositive cases per year (95% confidence interval: 2.6-10.9), with a mean follow-up of 7±4 years (range: 1 month to 15 years). HAM/TSP was more frequent in women in their 40s and 50s with probable infection via the sexual route. The HAM/TSP incidence density among HTLV-1-seropositive cases observed in the present study is higher than that in previous studies. HAM/TSP may be underdiagnosed in countries like Brazil where HTLV infection is prevalent. Orientation and prevent transmission of HTLV programs are needed. Currently, preventing HTLV-1 transmission is the most effective way to reduce the impact of HAM/TSP on society.

Strong correlation between tax and HBZ mRNA expression in HAM/TSP patients: distinct markers for the neurologic disease.

BACKGROUND: HTLV-1 proviral load is a risk marker for HAM/TSP, but it is insufficient to determine the disease outcome. HTLV-1 Tax and HBZ proteins have been implicated in HAM/TSP pathogenesis in inducing cell proliferation and cytotoxic T lymphocytes response. OBJECTIVES: To quantify the expression of tax and HBZ mRNA in asymptomatic carriers (AC) and HAM patients, and to investigate their association with HAM/TSP. STUDY DESIGN: We quantified the expression of HTLV-1 tax and HBZ mRNA in 37 AC and 26 HAM patients classified according to proviral load as low (AC(L) and HAM(L): <1% infected cells) or high (AC(H) and HAM(H): >1%). RESULTS: The AC(L) subgroup showed the lowest frequency of individuals expressing tax mRNA in comparison with AC(H), HAM(L) and HAM(H), and tax mRNA load normalized by proviral load was significantly lower in the AC(L). In turn, normalized HBZ mRNA expression was similar in all subgroups. Both tax and HBZ mRNA expression were moderately correlated with proviral load in AC (r=0.6, p<0.001) and were weaker in HAM (r=0.4, p<0.05). In contrast, the correlation between tax and HBZ mRNA load was moderate in AC (r=0.5, p=0.001) and was much stronger in HAM (r=0.8, p<0.001). In addition, HBZ mRNA load, but not tax, was significantly associated with motor disability in HAM patients (p=0.036). CONCLUSIONS: The expression of tax mRNA seems to be best to estimate the risk of HAM/TSP, whereas HBZ mRNA appears to be a surrogate marker to disease progression, indicating that they have important but distinct roles in HAM/TSP pathogenesis.

Monitoring the HTLV-1 proviral load in the peripheral blood of asymptomatic carriers and patients with HTLV-associated myelopathy/tropical spastic paraparesis from a Brazilian cohort: ROC curve analysis to establish the threshold for risk disease.

Human T-lymphotropic virus 1 (HTLV-1) infection is associated with HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which affects approximately 5% of carriers. High proviral load is a risk marker for HAM/TSP, although there is an overlap of proviral load levels in peripheral blood between asymptomatic carriers and HAM/TSP patients. In this study, receiver operating characteristic curve analysis was used to define a set point of HTLV-1 proviral load that better indicates an increased risk for HAM/TSP. Proviral load was quantified in 75 asymptomatic carriers and 78 HAM/TSP patients in a Brazilian cohort. The cut-off of proviral load was defined as 114 copies/10(4) cells, with 78.2% sensitivity to identify true HAM/TSP patients. The mean proviral load levels were not significantly different between males and females with the same clinical status, and there was no significant correlation between proviral load and age at blood sampling, age at the onset of illness, or duration of disease. In HAM/TSP patients, proviral load was significantly higher in wheelchair-bound patients than in individuals able to walk without support and in those with the worst spinal cord injuries. Follow-up of HTLV-1-infected individuals showed that proviral load was more stable in asymptomatic carriers than in HAM/TSP patients. In a cohort study, periodically quantifying proviral load in asymptomatic carriers is necessary to identify those at risk for developing neurological disease, and it is necessary for HAM/TSP patients to monitor spinal injury and progression to walking disability. The measure of proviral load in clinical practice implicates the definition of the cut-off of proviral load and its validation during follow-up.

[Human T cell lymphotropic virus (HTLV-1): when to suspect infection?].

Human T-cell lymphotropic virus (HTLV) infections have occurred for thousands of years. However, knowledge about their pathogenesis is recent. The virus is endemic in several regions around the world. In Brazil, it is present in all states at varying prevalence rates and it has been estimated that around 2.5 million Brazilians are infected. Genetic and immunological parameters of the host are the most important determinants of the clinical manifestations associated with infection. These can be divided into three categories: neoplastic, inflammatory and infectious. HTLV-associated myelopathy (HAM/TSP) and adult T-cell leukemia/lymphoma (ATLL) were the first diseases to be related to this retrovirus. More recently, countless other diseases have been correlated with the virus. The objective of this review is to provide an update on epidemiological, pathophysiologic, therapeutic and, primarily, diagnostic knowledge about HTLV, in order to encourage etiologic suspicion of HTLV in all its diverse clinical manifestations, which are currently rarely associated with this agent.

O vírus linfotrópico de células T humanos tipo 1 (HTLV-1): quando suspeitar da infecção?: [revisão] / Human T cell lymphotropic virus (HTLV)1: when should infection be suspected?: [review]

A infecção pelo vírus linfotrópico de células T humanas (HTLV) ocorre há milhares de anos. No entanto, o conhecimento sobre a sua patogênese é recente. Esse vírus é endêmico em várias regiões do mundo. No Brasil encontra-se presente em todos os estados, com prevalências variadas, sendo estimado cerca de 2,5 milhões de infectados. Fatores genéticos e imunológicos do hospedeiro são os principais responsáveis pelas manifestações clínicas associadas, que podem ser divididas em três categorias: neoplásicas, inflamatórias e infecciosas. Destacam-se a mielopatia associada ao HTLV (HAM/TSP) e a leucemia/linfoma de células T do adulto (ATLL) como as primeiras doenças associadas a esse retrovírus. Posteriormente, inúmeras outras doenças têm sido correlacionadas a esse vírus. Esta revisão atualiza conhecimentos epidemiológicos, fisiopatológicos, terapêuticos e principalmente diagnósticos do HTLV. O objetivo é permitir a suspeita etiológica do HTLV em suas diversas manifestações clínicas, hoje pouco correlacionadas com este agente.

Human T Lymphotropic Virus (HTLV) infection has occurred for thousands of years. However, knowledge about this pathogenesis is recent. This virus is endemic worldwide. In Brazil it is present throughout the country , with different prevalence and about 2 5 million infected. Genetic and immunologic characteristics of the host are chiefly responsible for clinically associated manifestations which may be: neoplasic, inflammatory and infectious diseases. HTLV associated myelopathy (TSP/ HAM) and adult T cell leukemia/lymphoma (ATL) stand out as the first diseases associated to this retrovirus. Further, several diseases have been correlated to this virus. This review updates epidemiologic, physiopathologic, therapeutic and diagnostic knowledge of HTLV. The purose is to orient suspicion of HTLV etiology and several clinically associated manifestations, which currenty are seldom correlated with this virus.