Detection of a major gene predisposing to human T lymphotropic virus type I infection in children among an endemic population of African origin

How Can We Prevent Mother-to-Child Transmission of HTLV-1?

The perception of human T-cell leukemia virus type 1 (HTlV-1) infection as a "silent disease" has recently given way to concern that its presence may be having a variety of effects. HTLV-1 is known to cause adult T-cell leukemia (ATL), an aggressive cancer of peripheral CD4 T cells; however, it is also responsible for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Most patients develop ATL as a result of HTLV-1 mother-to-child transmission. The primary route of mother-to-child transmission is through the mother's milk. In the absence of effective drug therapy, total artificial nutrition such as exclusive formula feeding is a reliable means of preventing mother-to-child transmission after birth, except for a small percentage of prenatal infections. A recent study found that the rate of mother-to-child transmission with short-term breastfeeding (within 90 days) did not exceed that of total artificial nutrition. Because these preventive measures are in exchange for the benefits of breastfeeding, clinical applications of antiretroviral drugs and immunotherapy with vaccines and neutralizing antibodies are urgently needed.

Mother-to-Child Transmission of Human T-Cell Leukemia Virus Type 1: Mechanisms and Nutritional Strategies for Prevention

Approximately 95% of mother-to-child transmission (MTCT) of human T-cell leukemia virus type-1 (HTLV-1) is derived from prolonged breastfeeding, which is a major cause of adult T-cell leukemia (ATL). Exclusive formula feeding (ExFF) is therefore generally used to prevent MTCT. A recent cohort study revealed that 55% of pregnant carriers chose short-term breastfeeding for ≤3 months in Japan. Our meta-analysis showed that there was no significant increase in the risk of MTCT when breastfeeding was carried out for ≤3 months compared with ExFF (pooled relative risk (RR), 0.72; 95% confidence interval (CI), 0.30-1.77), but there was an almost threefold increase in risk when breastfeeding was carried out for up to 6 months (pooled RR, 2.91; 95% CI, 1.69-5.03). Thus, short-term breastfeeding for ≤3 months may be useful in preventing MTCT. Breastmilk is the best nutritional source for infants, and any approach to minimizing MTCT by avoiding or limiting breastfeeding must be balanced against the impact on the child's health and mother-child bonding. To minimize the need for nutritional interventions, it is necessary to identify factors that predispose children born to carrier mothers to MTCT and thereby predict MTCT development with a high degree of accuracy.

Risk factors associated with HTLV-1 vertical transmission in Brazil: longer breastfeeding, higher maternal proviral load and previous HTLV-1-infected offspring

HTLV-1 is transmitted primarily either through sexual intercourse or from mother to child. The mother/child pairs were classified as seroconcordant or serodiscordant. We analyzed mother to child transmission (MTCT) according to sociodemographic, clinical and epidemiological characteristics of the mother, child's gender and duration of breastfeeding. Between June 2006 and August 2016 we followed 192 mothers with HTLV-1 infection (mean age 41 years old), resulting in 499 exposed offspring, 288 (57.7%) of whom were tested for HTLV-1, making up the final sample for the study, along with their 134 respective mothers. Among the tested mother/child pairs, 41 (14.2%) were HTLV-1 positive, highlighted that seven of 134 family clusters concentrated 48.8% of positive cases. Variables associated with a positive child: breastfeeding duration ≥12 months, maternal PVL ≥100 copies/104 PBMC, mother's age at delivery >26 years old, and HTLV-1 in more than one child of the same mother. In a multiple logistic regression, breastfeeding ≥12 months, higher maternal PVL and ≥2 previous HTLV-1-infected children remained independently associated with the outcome. Thus, high maternal PVL and breastfeeding beyond 12 months were independently associated with MTCT of the HTLV-1 infection. Our results reinforce the need for both prenatal HTLV screening in endemic areas and for advising mothers on breastfeeding.

Retrospective study of a cohort of adult patients with hematological malignancies in a tropical area

AIM: To review the characteristics of hematological malignancies in tropical areas, and to focus on the specific difficulties regarding their management.

METHODS: This is a retrospective narrative review of cases of patients with hematological malignancies. All medical files of patients with malignant disease whose treatment was coordinated by the Hemato-Oncology service of the Cayenne Hospital in French Guiana between the 1^st of January 2010 and the 31^st of December 2012 were reviewed. Clinical data were extracted from the medical files and included: Demographic data, comorbidities, serological status for human immunodeficiency virus, human T-lymphotropic virus 1 (HTLV1), hepatitis B virus and hepatitis C virus infections, cytology and pathology diagnoses, disease extension, treatment, organization of disease management, and follow-up. The subgroup of patients with hematological malignancies and virus-related malignancies were reviewed. Cases involving patients with Kaposi sarcoma, and information on solid tumor occurrence in virus-infected patients in the whole patient population were included. Since the data were rendered anonymous, no informed consent was obtained from the patients for this retrospective analysis. Data were compiled using EXCEL^® software, and the data presentation is descriptive only. The references search was guided by the nature of the data and discussion.

RESULTS: In total, the clinical files of 594 patients (pts) were reviewed. Hematological malignancies were observed in 87 patients, and Kaposi sarcoma in 2 patients. In total, 70 patients had a viral infection, and 34 of these also had hematological malignancies. The hematological diagnoses were: Multiple myeloma in 27 pts, lymphoma (L) in 43 pts, myeloproliferative disorders in 17 pts and Kaposi sarcoma in two patients. The spectrum of non-Hodgkin lymphomas (NHL) was: Burkitt L (1 pt), follicular L (5 pts), chronic lymphocytic leukemia (5 pts), high-grade NHL (9 pts), mucosa-associated lymphoid tissue NHL (4 pts), T-cell lymphoma (4 pts), Adult T-cell lymphoma-leukemia (ATL)/lymphoma/leukemia (12 pts); three patients had Hodgkin disease. The spectrum of myeloproliferative diseases was: Chronic myelogenous leukemia (8 pts), thrombocytemia (5 pts) and acute leukemia (4 pts). There were no polycythemia vera, myelosclerosis, and myelodysplastic diseases. This appears to be due to bias in the recruitment process. The most important observations were: The specificity of HTLV1- related ATL malignancies, and the high incidence of virus infections in patients with hematological malignancies. Further, we noted several limitations regarding the treatment and organization of disease management. These were not related to the health care organization, but were due to a lack of board-certified hemato-oncology specialists, a lack of access to diagnostic tools (e.g., cytogenetic and molecular diagnosis, imaging techniques), the unavailability of radiotherapy, and the physical distance from mainland France. Yet the geography and cultures of the country also contributed to the encountered difficulties. These same limitations are seen in tropical countries with low and intermediate household incomes, but they are amplified by economic, social, and cultural issues. Thus, there is often little access to diagnostic procedures, adequate clinical management, and an unavailability of suitable medical treatments. Programs have been developed to establish centers of excellence, training in pathology diagnosis, and to provide free access to treatment.

CONCLUSION: Management of hematological malignancies in tropical areas requires particular skills regarding specific features of these diseases and in terms of the affected populations, as well as solid public health policies.

Mother-to-Child Transmission of HTLV-1 Epidemiological Aspects, Mechanisms and Determinants of Mother-to-Child Transmission

Human T-cell Lymphotropic Virus type 1 (HTLV-1) is a human retrovirus that infects at least 5-10 million people worldwide, and is the etiological agent of a lymphoproliferative malignancy; Adult T-cell Leukemia/Lymphoma (ATLL); and a chronic neuromyelopathy, HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP), as well as other inflammatory diseases such as infective dermatitis and uveitis. Besides sexual intercourse and intravenous transmission, HTLV-1 can also be transmitted from infected mother to child during prolonged breastfeeding. Some characteristics that are linked to mother-to-child transmission (MTCT) of HTLV-1, such as the role of proviral load, antibody titer of the infected mother, and duration of breastfeeding, have been elucidated; however, most of the mechanisms underlying HTLV-1 transmission during breast feeding remain largely unknown, such as the sites of infection and cellular targets as well as the role of milk factors. The present review focuses on the latest findings and current opinions and perspectives on MTCT of HTLV-1.

Predictive factors of HTLV1-HIV coinfections in French Guiana

French Guiana, the French territory most affected by human immunodeficiency virus (HIV) (1.3% of pregnant women), is also endemic for human T lymphotropic virus 1 (HTLV1). The objective of this study was to determine if the HTLV1/HIV coinfected patients had particular characteristics. All HIV-infected patients having a computerized medical file containing an HTLV1 serology were included: there were 1,333 HIV monoinfections and 76 HTLV1/VIH coinfections. The prevalence of HTLV1/HIV coinfections was 5.39%. Women (odds ratio [OR] = 1.91[1.13-3.24]), subjects > 40 years of age, and patients of Surinamese origin (OR = 2.65 [1.25-5.61]) were overrepresented among the coinfected. CD4 count at the time of diagnosis and viral loads were higher among coinfected patients. The clinical stage was not significantly different between the two groups. The number of CD4 cells was not higher among the coinfected, unlike most reports from the literature. Prevalence of HTLV1 among HIV-infected patients is high in French Guiana, and physicians seem to omit the prescription of serology for this potentially serious coinfection.

A major locus on chromosome 3p22 conferring predisposition to human herpesvirus 8 infection

Infection with human herpesvirus 8 (HHV-8), the etiological agent of Kaposi's sarcoma, has been shown to display strong familial aggregation, in countries in which HHV-8 infection is endemic. We investigated 40 large families (608 subjects aged one to 88 years) living in an isolated area of Cameroon in which HHV-8 is highly endemic. We performed a two-step genetic analysis for HHV-8 infection status (HHV-8+/HHV-8- determined by immunofluorescence) consisting of an initial segregation analysis followed by a model-based genome-wide linkage analysis. Overall HHV-8 seroprevalence was 60%, increasing with age. Segregation analysis provided strong evidence for a recessive major gene conferring predisposition to HHV-8 infection. This gene is predicted to have a major effect during childhood, with almost all homozygous predisposed subjects (∼7% of the population) becoming infected by the age of 10. Linkage analysis was carried out on the 15 most informative families, corresponding to 205 genotyped subjects. A single region on chromosome 3p22 was significantly linked to HHV-8 infection (LOD score=3.83, P=2.0 × 10(-5)). This study provides the first evidence that HHV-8 infection in children in endemic areas has a strong genetic basis involving at least one recessive major locus on chromosome 3p22.

The imprint of the Slave Trade in an African American population: mitochondrial DNA, Y chromosome and HTLV-1 analysis in the Noir Marron of French Guiana

Background

Retracing the genetic histories of the descendant populations of the Slave Trade (16^th-19^th centuries) is particularly challenging due to the diversity of African ethnic groups involved and the different hybridisation processes with Europeans and Amerindians, which have blurred their original genetic inheritances. The Noir Marron in French Guiana are the direct descendants of maroons who escaped from Dutch plantations in the current day Surinam. They represent an original ethnic group with a highly blended culture. Uniparental markers (mtDNA and NRY) coupled with HTLV-1 sequences (env and LTR) were studied to establish the genetic relationships linking them to African American and African populations.

Results

All genetic systems presented a high conservation of the African gene pool (African ancestry: mtDNA = 99.3%; NRY = 97.6%; HTLV-1 env = 20/23; HTLV-1 LTR = 6/8). Neither founder effect nor genetic drift was detected and the genetic diversity is within a range commonly observed in Africa. Higher genetic similarities were observed with the populations inhabiting the Bight of Benin (from Ivory Coast to Benin). Other ancestries were identified but they presented an interesting sex-bias. Whilst male origins spread throughout the north of the bight (from Benin to Senegal), female origins were spread throughout the south (from the Ivory Coast to Angola).

Conclusions

The Noir Marron are unique in having conserved their African genetic ancestry, despite major cultural exchanges with Amerindians and Europeans through inhabiting the same region for four centuries. Their maroon identity and the important number of slaves deported in this region have maintained the original African diversity. All these characteristics permit to identify a major origin located in the former region of the Gold Coast and the Bight of Benin; regions highly impacted by slavery, from which goes a sex-biased longitudinal gradient of ancestry.

[HTLV 1/2 infection: prenatal performance as a disease control strategy in State of Mato Grosso do Sul]

In this study, the prevalence of HTLV 1/2 infection among pregnant women in the State of Mato Grosso do Sul was estimated by means of the ELISA, Western Blot and PCR techniques, in blood samples collected by peripheral venous puncture. 116,689 pregnant women were examined and 153 were diagnosed as presenting HTLV 1/2 infection, with prevalence of 0.13%. Among these 153 pregnant women, 133 (86.9%) had type 1 and 20 (11.1%) had type 2; 73.2% were black, brown or indigenous; about 90% performed domestic activities; and 75.8% (116/153) had been to school for seven years or less. The 153 pregnant women had 172 pregnancies during the study period and 164 pregnancies were followed. Out of pregnancies that were followed, 6.7% (11/164) evolved to abortion, 26.8% (41/153) reported previous abortions and 31.7% (13/41) had had more than two abortions. Comorbidities were found in 17% (26/153), among whom 3.3% (5/153) had HIV (p<0.000002). The authors emphasize the importance of identifying pregnant women with HTLV 1/2 infection, as a strategy for disease control and prevention.

[Analysis of the ethical issues raised by a ten-year epidemiology program in French Guiana: limitations of the current legal framework and solutions adopted]

BACKGROUND

This paper discusses the ethical aspects of a large research program in virology, conducted since 1994 and which has evolved in parallel with the elaboration of bioethics laws in France. This research, which involved the collection of a considerable amount of epidemiological data in the field, focused on epidemiological determinants (mother to child transmission, genetic susceptibility/resistance) of the human oncogenic retrovirus human T cell lymphotropic virus type 1 (HTLV-1). Data were collected from a specific population (Noirs Marrons) living in remote areas in French Guiana (South America). This ethnic group of African descent is highly endemic for HTLV-1 and associated adult T cell leukemia/lymphoma. The population has lived for two centuries on either side of the Maroni river, which constitutes the frontier between French Guiana and Surinam. The low socioeconomic and education levels of a large part of this population are mainly explained by a recent housing/residence fixation on the French side of the Maroni river. It is also linked to significant immigration from Surinam due to the civil war, which lasted for five years in the late 1990s, in this country. Conducting epidemiological surveys in this peculiar context illustrates the limitations of the available current legal framework in France for such studies. Indeed, several important ethical issues arose concerning not only individual and population benefits, but also specificities of the given information and of the informed consent. Another question concerns individual information feed-back in such a context of persistent viral infection, with a very low disease incidence, in a population with a relatively low education level. The goal of this work was mainly to report several of the ethical issues encountered and to discuss possible ways of achieving better information deliver and consent procedures in such a context. Indeed, these procedures should include new ideas and regulations promoting a real partnership, in order to conduct long-term epidemiological studies in populations with a low education level.

Human genetics of infectious diseases: a unified theory

Since the early 1950s, the dominant paradigm in the human genetics of infectious diseases postulates that rare monogenic immunodeficiencies confer vulnerability to multiple infectious diseases (one gene, multiple infections), whereas common infections are associated with the polygenic inheritance of multiple susceptibility genes (one infection, multiple genes). Recent studies, since 1996 in particular, have challenged this view. A newly recognised group of primary immunodeficiencies predisposing the individual to a principal or single type of infection is emerging. In parallel, several common infections have been shown to reflect the inheritance of one major susceptibility gene, at least in some populations. This novel causal relationship (one gene, one infection) blurs the distinction between patient-based Mendelian genetics and population-based complex genetics, and provides a unified conceptual frame for exploring the molecular genetic basis of infectious diseases in humans.

A major susceptibility locus for HTLV-1 infection in childhood maps to chromosome 6q27

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is a human oncoretrovirus causing adult T-cell leukemia/lymphoma and chronic neuromyelopathy. We previously showed by segregation analysis that a dominant gene controls HTLV-1 infection through breast-feeding in children of African origin. Here, we report the mapping of this locus by a genome-wide linkage analysis based on the genetic model provided by segregation analysis. Five pedigrees of African origin with HTLV-1 seropositive children were included in the study. Significant evidence for linkage (LOD score of 3.36, P=0.00004) was obtained for chomosomal region 6q27 when using the robust analysis including only HTLV-1-infected subjects. When HTLV-1 seronegative children born to infected mothers were added in the analysis, a maximum LOD score of 2.79 (P=0.0002) was obtained for chomosome 2p25. This result was mostly due to the largest pedigree of our sample, which alone gave a LOD score of 2.90 (P=0.00013). We further excluded the role of exonic variants of two candidate genes located in the linked regions, CCR6 (chemokine receptor 6) in 6q27 and ID2 (inhibitor of DNA binding 2) in 2p25. Our results, mapping a major susceptibility locus to chromosome 6q27 and suggesting genetic heterogeneity with another locus at 2p25, pave the way to the determination of the molecular basis of predisposition to HTLV-1 infection in children.

Sendai virus-induced alterations in lung structure/function correlate with viral loads and reveal a wide resistance/susceptibility spectrum among mouse strains

The Paramyxoviridae family includes some of the most important and ubiquitous disease-causing viruses of infants and children, most of which cause significant infections of the respiratory tract. Evidence is accumulating in humans that genetic factors are involved in the severity of clinical presentation. As a first step toward the identification of the genes involved, this study was undertaken to establish whether laboratory mouse strains differ in susceptibility to Sendai virus, the murine counterpart of human type-1 parainfluenza virus which, historically, has been used extensively in studies that have defined the basic biological properties of paramyxoviruses in general. With this purpose in mind, double-chamber plethysmography data were collected daily for 7 days after inoculation of Sendai virus in six inbred strains of mice. In parallel, histological examinations and lung viral titration were carried out from day 5 to day 7 after inoculation. Pulmonary structure/function values closely reflected the success of viral replication in the lungs and revealed a pattern of continuous variation with resistant, intermediate, and susceptible strains. The results unambiguously suggest that BALB/c (resistant) and 129Sv (susceptible) strains should be used in crossing experiments aimed at identifying the genes involved in resistance to Paramyxoviridae by the positional cloning approach.

Cellular immune response to HTLV-1

There is strong evidence at the individual level and the population level that an efficient cytotoxic T lymphocyte (CTL) response to HTLV-1 limits the proviral load and the risk of associated inflammatory diseases such as HAM/TSP. This evidence comes from host population genetics, viral genetics, DNA expression microarrays and assays of lymphocyte function. However, until now there has been no satisfactory and rigorous means to define or to measure the efficiency of an antiviral CTL response. Recently, methods have been developed to quantify lymphocyte turnover rates in vivo and the efficiency of anti-HTLV-1 CTLs ex vivo. Data from these new techniques appear to substantiate the conclusion that variation between individual hosts in the rate at which a single CTL kills HTLV-1-infected lymphocytes is an important determinant, perhaps the decisive determinant, of the proviral load and the risk of HAM/TSP. With these experimental data, it is becoming possible to refine, parameterize and test mathematical models of the immune control of HTLV-1, which are a necessary part of an understanding of this complex dynamic system.

Global epidemiology of HTLV-I infection and associated diseases

Epidemiologic aspects of human T-lymphotropic virus type I (HTLV-I) infection have been thoroughly studied over the course of approximately 25 years since its first description. The geographic distribution of the virus has been defined, with Japan, Africa, Caribbean islands and South America emerging as the areas of highest prevalence. The reasons for HTLV-I clustering, such as the high ubiquity in southwestern Japan but low prevalence in neighboring regions of Korea, China and eastern Russia are still unknown. The major modes of transmission are well understood, although better quantitative data on the incidence of transmission, and on promoting/inhibiting factors, are needed. Epidemiologic proof has been obtained for HTLV-I's causative role in major disease associations: adult T-cell leukemia (ATL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-associated uveitis and infective dermatitis. However, more and better studies are needed for other apparent disease outcomes such as rheumatologic, psychiatric and infectious diseases. Since curative treatment of ATL and HAM/TSP is lacking and a vaccine is unavailable, the social and financial cost for the individual, his/her family and the health system is immense. For this reason, public health interventions aimed at counseling and educating high-risk individuals and populations are of paramount importance.

Clinical characteristics of patients in Peru with human T cell lymphotropic virus type 1-associated tropical spastic paraparesis

BACKGROUND

Human T cell lymphotropic virus type 1 (HTLV-1) is associated with tropical spastic paraparesis (TSP). Peru is an area of endemicity for HTLV-1.

METHODS

All patients with suspected cases of TSP referred to our institute (Institute of Tropical Medicine Alexander von Humboldt, Lima, Peru) from 1989 through 2002 were interviewed and tested for HTLV-1. All patients with positive results were evaluated by an expert physician. Disease progression was defined as "rapid" if the time between TSP onset and inability to walk unaided was <2 years.

RESULTS

Among 165 patients enrolled, the symptoms and signs most frequently found were spasticity (in 97.5% of patients), hyperreflexia (95.4%), lower limb paresthesia (90.2%), pyramidal signs (82.6%), urinary complaints (82.0%), and lumbar pain (79.0%). Rapid progression was present in 21.5% of patients; mean age at TSP onset was higher among these patients than among slow progressors (P<.001). Severe spasticity, diminished vibratory sensation, and tremor were found more frequently among rapid progressors, compared with slow progressors.

CONCLUSIONS

HTLV-1--associated TSP is frequently diagnosed in areas of HTLV-1-endemicity. A subgroup of patients experiences rapid disease progression.

Human T-cell leukaemia/lymphoma virus type 1-associated infective dermatitis in Africa: a report of five cases from Senegal

BACKGROUND

Infective dermatitis (ID) is a rare dermatological condition of childhood that has been linked to human T-cell leukaemia/lymphoma virus type 1 (HTLV-1). Most cases have been reported in the Caribbean. Although several million people are estimated to be infected by HTLV-1 in sub-Saharan Africa, no case of ID has been reported in this area.

OBJECTIVES

To identify and to describe cases of HTLV-1-associated ID in Senegal, West Africa.

METHODS

Over a 3-year period, a serological test for HTLV-1 was performed at a dermatological centre in Dakar, Senegal, in children who presented with a picture suggestive of ID. Complementary haematological, immunological and virological investigations were performed in infected children and in their mothers.

RESULTS

Five patients with typical HTLV-1-associated ID were identified, of ages 17, 5, 4, 3 and 3 years; two patients belonged to the same family. They all presented with repeated flares of superinfected dermatitis involving typical sites of ID (mainly the scalp, external ears, nares and eyelids), associated with nasal discharge, and less commonly with a nonspecific papular rash on the face or trunk. Although oral antibiotic therapy always gave effective control of the symptoms, recurrences were constant. A persisting dry dermatitis of the retroauricular folds was common between flares. Infection in the oldest patient was associated with a chronic adult T-cell leukaemia/lymphoma. The mothers of three patients, and the grandmother of another, were all infected by HTLV-1 strains belonging to the Cosmopolitan molecular subtype, with a perfect nucleotide identity of long-terminal repeat and env gp21 genomic regions within each family.

CONCLUSIONS

We present the clinical and virological features of the first reported African cases of HTLV-1-associated ID. When compared with data from the Caribbean, infectious features seemed particularly prominent. ID appears to be overlooked in sub-Saharan Africa, where it might be easily confused with common pyoderma. Breast feeding appears to be the origin of HTLV-1 contamination of the children.

The human model: a genetic dissection of immunity to infection in natural conditions

Tremendous progress has been achieved in developmental, cellular and molecular immunology in the past 20 years, largely due to studies using the mouse as a model system and the arrival of molecular genetics. Immunology is now faced with a difficult challenge. What are the functions of the individual cells and molecules in achieving immunity to infection? Renewed interest in animal models of disease has provided considerable insight in this area, but such models of infection suffer from the inherent limitation of being experimental. In humans, the complex host-environment interaction occurs in natural, as opposed to experimental, conditions. The human model is therefore an indispensable complement to animal models, as it allows an observational genetic dissection of immunity to infection.

Human T-cell Lymphotropic Virus types I and II (HTLV-I/II) in French Guiana: clinical and molecular epidemiology

We review here the epidemiological studies performed by our group on human retrovirus HTLV-I and HTLV-II infections and the associated diseases in French Guiana since 1984. French Guiana is an overseas French administrative district located between Brazil and Surinam. Its population is characterized by a large variety of ethnic groups, including several populations of African origin and various populations of Amerindian origin. Several epidemiological studies of large samples of pregnant women and in remote villages showed that HTLV-I is highly endemic in this area but is restricted to groups of African origin, especially the Noir-Marrons. In this endemic population, the results of segregation analysis in a genetic epidemiological study were consistent with the presence of a dominant major gene predisposing to HTLV-I infection, especially in children. In contrast, HTLV-II infection appears to be rare in French Guiana, having been found in only a few individuals of Brazilian origin. From a molecular point of view, the HTLV-I strains present in the Noir-Marrons, Creoles and Amerindians appear to originate from Africa, as they belong to the large cosmopolitan molecular subtype A.