HTLV-I infection among prostitutes and pregnant women in Kinshasa, Zaïre: how important is high-risk sexual behavior?

Geographic distribution, clinical epidemiology and genetic diversity of the human oncogenic retrovirus HTLV-1 in Africa, the world's largest endemic area

The African continent is considered the largest high endemic area for the oncogenic retrovirus HTLV-1 with an estimated two to five million infected individuals. However, data on epidemiological aspects, in particular prevalence, risk factors and geographical distribution, are still very limited for many regions: on the one hand, few large-scale and representative studies have been performed and, on the other hand, many studies do not include confirmatory tests, resulting in indeterminate serological results, and a likely overestimation of HTLV-1 seroprevalence. For this review, we included the most robust studies published since 1984 on the prevalence of HTLV-1 and the two major diseases associated with this infection in people living in Africa and the Indian Ocean islands: adult T-cell leukemia (ATL) and tropical spastic paraparesis or HTLV-1-associated myelopathy (HAM/TSP). We also considered most of the book chapters and abstracts published at the 20 international conferences on HTLV and related viruses held since 1985, as well as the results of recent meta-analyses regarding the status of HTLV-1 in West and sub-Saharan Africa. Based on this bibliography, it appears that HTLV-1 distribution is very heterogeneous in Africa: The highest prevalences of HTLV-1 are reported in western, central and southern Africa, while eastern and northern Africa show lower prevalences. In highly endemic areas, the HTLV-1 prevalence in the adult population ranges from 0.3 to 3%, increases with age, and is highest among women. In rural areas of Gabon and the Democratic Republic of the Congo (DRC), HTLV-1 prevalence can reach up to 10-25% in elder women. HTLV-1-associated diseases in African patients have rarely been reported in situ on hospital wards, by local physicians. With the exception of the Republic of South Africa, DRC and Senegal, most reports on ATL and HAM/TSP in African patients have been published by European and American clinicians and involve immigrants or medical returnees to Europe (France and the UK) and the United States. There is clearly a huge underreporting of these diseases on the African continent. The genetic diversity of HTLV-1 is greatest in Africa, where six distinct genotypes (a, b, d, e, f, g) have been identified. The most frequent genotype in central Africa is genotype b. The other genotypes found in central Africa (d, e, f and g) are very rare. The vast majority of HTLV-1 strains from West and North Africa belong to genotype a, the so-called 'Cosmopolitan' genotype. These strains form five clades roughly reflecting the geographic origin of the infected individuals. We have recently shown that some of these clades are the result of recombination between a-WA and a-NA strains. Almost all sequences from southern Africa belong to Transcontinental a-genotype subgroup.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

HTLV-1 and Co-infections

Human T lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes lifelong T-cell infection in humans, impacting the host immune response. This virus causes a range of clinical manifestations, from inflammatory conditions, including neuronal damage (HTLV-1 associated myelopathy, HAM) to life-threatening leukemia (adult T-cell leukemia, ATL). Human T lymphotropic virus type 1 is also associated with increased risk of all-cause mortality, but the mechanisms remain unclear. As a blood-borne and sexually transmitted infection (STI), HTLV-1 shares transmission routes to many other pathogens and although it has worldwide distribution, it affects mainly those in low- and middle-income tropical areas, where the prevalence of other infectious agents is high. These factors contribute to a high incidence of co-infections in people living with HTLV-1 (PLHTLV). This comprehensive review addresses the impact of HTLV-1 on several co-infections and vice-versa. There is evidence of higher rates of HTLV-1 infection in association with other blood borne (HCV, HBV) and sexually transmitted (Syphilis, Chlamydia, HPV, HSV) infections but whether this represents increased susceptibility or opportunity is unclear. Higher frequency of Mycobacterium tuberculosis (MTb) and Mycobacterium leprae (M. leprae) is observed in PLHTLV. Reports of opportunistic infections and high frequency of crusted scabies in patients with HTLV-1 points to immune impairment in those individuals. Human T lymphotropic virus type 1 may influence the persistence of pathogens, exemplified by the higher rates of Schistosoma mansoni and Strongyloides stercoralis (St. stercoralis) treatment failure observed in PLHTLV. This retrovirus is also associated with increased tuberculosis (TB) severity with some evidence pointing to a deleterious impact on leprosy outcome as well. These findings are supported by immune alterations observed in those co-infected individuals. Although the role of HTLV-1 in HCV outcome is debatable, most data indicate that HTLV may negatively impact the clinical course of hepatitis C. Co-infections may also influence the risk of developing HTLV-1 associated disease, but data are still limited. The impact of HTLV-1 on the response to more common infections, might contribute to the increased mortality rate of HTLV-1. Large scale prospective controlled studies on the prevalence and impact of HTLV-1 in co-infections and vice-versa are needed. Human T lymphotropic virus type 1 impact in public health is broad. Measures to increase awareness and to prevent new infections are needed.

Human T-cell lymphotropic virus type 1 transmission dynamics in rural villages in the Democratic Republic of the Congo with high nonhuman primate exposure

The Democratic Republic of the Congo (DRC) has a history of nonhuman primate (NHP) consumption and exposure to simian retroviruses yet little is known about the extent of zoonotic simian retroviral infections in DRC. We examined the prevalence of human T-lymphotropic viruses (HTLV), a retrovirus group of simian origin, in a large population of persons with frequent NHP exposures and a history of simian foamy virus infection. We screened plasma from 3,051 persons living in rural villages in central DRC using HTLV EIA and western blot (WB). PCR amplification of HTLV tax and LTR sequences from buffy coat DNA was used to confirm infection and to measure proviral loads (pVLs). We used phylogenetic analyses of LTR sequences to infer evolutionary histories and potential transmission clusters. Questionnaire data was analyzed in conjunction with serological and molecular data. A relatively high proportion of the study population (5.4%, n = 165) were WB seropositive: 128 HTLV-1-like, 3 HTLV-2-like, and 34 HTLV-positive but untypeable profiles. 85 persons had HTLV indeterminate WB profiles. HTLV seroreactivity was higher in females, wives, heads of households, and increased with age. HTLV-1 LTR sequences from 109 persons clustered strongly with HTLV-1 and STLV-1 subtype B from humans and simians from DRC, with most sequences more closely related to STLV-1 from Allenopithecus nigroviridis (Allen's swamp monkey). While 18 potential transmission clusters were identified, most were in different households, villages, and health zones. Three HTLV-1-infected persons were co-infected with simian foamy virus. The mean and median percentage of HTLV-1 pVLs were 5.72% and 1.53%, respectively, but were not associated with age, NHP exposure, village, or gender. We document high HTLV prevalence in DRC likely originating from STLV-1. We demonstrate regional spread of HTLV-1 in DRC with pVLs reported to be associated with HTLV disease, supporting local and national public health measures to prevent spread and morbidity.

Emerging sexually transmitted viral infections: Review of human T-lymphotropic virus-1 disease

Human T-lymphotropic virus-1 is a preventable sexually transmitted infection. In the majority of people it is asymptomatic, remaining undiagnosed and thereby contributing to its silent transmission. When it does manifest it causes significant morbidity and mortality. This review summarises the existing evidence for its role in sexual transmission and offers suggestions for those working in the area of sexual health. This is the third part of a series looking at novel sexually transmitted infections.

Prevalence and Molecular Epidemiology of Human T-Lymphotropic Virus Type 1 among Women Attending Antenatal Clinics in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Human T-cell lymphotropic virus type 1 (HTLV-1) imposes a substantial disease burden in sub-Saharan Africa (SSA), which is arguably the world's largest endemic area for HTLV-1. Evidence that mother-to-child transmission persists as a major mode of transmission in SSA prompted us to estimate the pooled prevalence of HTLV-1 among pregnant women throughout the region. We systematically reviewed databases including EMBASE, MEDLINE, Web of Science, and the Cochrane Database of Systemic Reviews from their inception to November 2018. We selected studies with data on HTLV-1 prevalence among pregnant women in SSA. A random effect meta-analysis was conducted on all eligible data and heterogeneity was assessed through subgroup analyses. A total of 18 studies, covering 14,079 pregnant women, were selected. The evidence base was high to moderate in quality. The pooled prevalence, per 100 women, of the 18 studies that screened HTLV-1 was 1.67 (95% CI: 1.00-2.50), a figure that masks regional variations. In Western, Central, Southern, and Eastern Africa, the numbers were 2.34 (1.68-3.09), 2.00 (0.75-3.79), 0.30 (0.10-0.57), and 0.00 (0.00-0.21), respectively. The prevalence of HTLV-1 infection among pregnant women in SSA, especially in Western and Central Africa, strengthens the case for action to implement routine screening of pregnant women for HTLV-1. Rigorous studies using confirmatory testing and molecular analysis would characterize more accurately the prevalence of this infection, consolidate the evidence base, and further guide beneficial interventions.

Human T-Lymphotropic Virus type 1 infection in an Indigenous Australian population: epidemiological insights from a hospital-based cohort study

Background

The Human T Lymphotropic Virus type 1 (HTLV-1) subtype C is endemic to central Australia where each of the major sequelae of HTLV-1 infection has been documented in the socially disadvantaged Indigenous population. Nevertheless, available epidemiological information relating to HTLV-1c infection is very limited, risk factors for transmission are unknown and no coordinated program has been implemented to reduce transmission among Indigenous Australians. Identifying risk factors for HTLV-1 infection is essential to direct strategies that could control HTLV-1 transmission.

Methods

Risk factors for HTLV-1 infection were retrospectively determined for a cohort of Indigenous Australians who were tested for HTLV-1 at Alice Springs Hospital (ASH), 1st January 2000 to 30th June 2013. Demographic details were obtained from the ASH patient management database and the results of tests for sexually transmitted infections (STI) were obtained from the ASH pathology database.

Results

Among 1889 Indigenous patients whose HTLV-1 serostatus was known, 635 (33.6 %) were HTLV-1 Western blot positive. Only one of 77 (1.3 %) children tested was HTLV-1 infected. Thereafter, rates progressively increased with age (15–29 years, 17.3 %; 30–49 years, 36.2 %; 50–64 years, 41.7 %) reaching 48.5 % among men aged 50–64 years. In a multivariable model, increasing age (OR, 1.04; 95 % CI, 1.03–1.04), male gender (OR, 1.41; 95 % CI, 1.08–1.85), residence in the south (OR, 10.7; 95 % CI, 7.4–15.6) or west (OR, 4.4; 95 % CI, 3.1–6.3) of central Australia and previous STI (OR, 1.42; 95 % CI, 1.04–1.95) were associated with HTLV-1 infection. Infection was acquired by three of 351 adults who were tested more than once during the study period (seroconversion rate, 0.24 (95 % CI = 0.18–2.48) per 100 person-years).

Conclusions

This study confirms that HTLV-1 is highly endemic to central Australia. Although childhood infection was documented, HTLV-1 infection in adults was closely associated with increasing age, male gender and STI history. Multiple modes of transmission are therefore likely to contribute to high rates of HTLV-1 infection in the Indigenous Australian population. Future strategies to control HTLV-1 transmission in this population require careful community engagement, cultural understanding and Indigenous leadership.

Seroprevalence of HTLV-1 and HTLV-2 amongst mothers and children in Malawi within the context of a systematic review and meta-analysis of HTLV seroprevalence in Africa

OBJECTIVES

Human T-lymphotropic virus (HTLV)-1 causes T-cell leukaemia and myelopathy. Together with HTLV-2, it is endemic in some African nations. Seroprevalence data from Malawi are scarce, with no reports on associated disease incidence. HTLV seroprevalence and type were tested in 418 healthy mothers from Malawi. In addition, we tested the sera of 534 children to investigate mother-to-child transmission. To provide context, we conducted a systematic review and meta-analysis of HTLV seroprevalence in African women and children.

METHODS

Stored samples from a previous childhood cancer and BBV study were analysed. ELISA was used for HTLV screening followed by immunoblot for confirmation and typing. Standard methods were used for the systematic review.

RESULTS

HTLV seroprevalence was 2.6% (11/418) in mothers and 2.2% (12/534) in children. Three mothers carried HTLV-1 alone, seven had HTLV-2 and one was dually infected. Three children carried HTLV-1 alone, seven had HTLV-2 and two were dually infected. Only two corresponding mothers of the 12 HTLV-positive children were HTLV positive. The systematic review included 66 studies of women and 13 of children conducted in 25 African countries. Seroprevalence of HTLV-1 varied from 0 to 17% and of HTLV-2 from 0 to 4%.

CONCLUSIONS

In contrast to findings from other studies in Africa, the seroprevalence of HTLV-2 was higher than that of HTLV-1 in Malawi and one of the highest for the African region. The lack of mother-child concordance suggests alternative sources of infection among children. Our data and analyses contribute to HTLV prevalence mapping in Africa.

Sexual transmission of human T-cell lymphotropic virus type 1

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in many parts of the world and is primarily transmitted through sexual intercourse or from mother to child. Sexual transmission occurs more efficiently from men to women than women to men and might be enhanced by sexually transmitted diseases that cause ulcers and result in mucosal ruptures, such as syphilis, herpes simplex type 2 (HSV-2), and chancroid. Other sexually transmitted diseases might result in the recruitment of inflammatory cells and could increase the risk of HTLV-1 acquisition and transmission. Additionally, factors that are associated with higher transmission risks include the presence of antibodies against the viral oncoprotein Tax (anti-Tax), a higher proviral load in peripheral blood lymphocytes, and increased cervicovaginal or seminal secretions. Seminal fluid has been reported to increase HTLV replication and transmission, whereas male circumcision and neutralizing antibodies might have a protective effect. Recently, free virions were discovered in plasma, which reveals a possible new mode of HTLV replication. It is unclear how this discovery might affect the routes of HTLV transmission, particularly sexual transmission, because HTLV transmission rates are significantly higher from men to women than women to men.

Analysis of duration of risk behaviour for key populations: a literature review

Background

The objective of this paper is to review literature in order to calculate regional estimates of the average duration of time individuals maintain a specific high-risk behaviour.

Methods

The review targeted the key populations of female sex workers (FSW), male clients of female sex workers (MCFSW), people who inject drugs (injecting drug users (IDU)) and high-risk men who have sex with men (MSM). To be included in the review the study had to provide information on (1) the time a person spent at risk until death or cessation of the risk behaviour, (2) the percentage of the sample who initiated the risk behaviour in less than a year or (3) the mean or median duration of the behaviour from a representative sample.

Results

49 papers were found for the FSW population describing the period of time FSW stay in sex work to be between 2.9 years (Asia) and 12 years (Latin America). Eight papers were found for MCFSW showing the duration of the risk behaviour in this category varying from 4.6 years in Africa to 32 years in Asia. 86 papers were reviewed for the population of IDU showing that the average time a person injects illegal drugs varies from 5.6 years (Africa) to 21 years (South America). No information was found for duration of high-risk behaviour among MSM; instead, the definitions found in the literature for high- and low-risk behaviour among MSM were described.

Conclusions

There is high variability of estimates of duration of high-risk behaviours at regional level. More research is needed to inform models and prevention programmes on the average duration of time individuals maintain a specific high-risk behaviour.

Epidemiological Aspects and World Distribution of HTLV-1 Infection

The human T-cell leukemia virus type 1 (HTLV-1), identified as the first human oncogenic retrovirus 30 years ago, is not an ubiquitous virus. HTLV-1 is present throughout the world, with clusters of high endemicity located often nearby areas where the virus is nearly absent. The main HTLV-1 highly endemic regions are the Southwestern part of Japan, sub-Saharan Africa and South America, the Caribbean area, and foci in Middle East and Australo-Melanesia. The origin of this puzzling geographical or rather ethnic repartition is probably linked to a founder effect in some groups with the persistence of a high viral transmission rate. Despite different socio-economic and cultural environments, the HTLV-1 prevalence increases gradually with age, especially among women in all highly endemic areas. The three modes of HTLV-1 transmission are mother to child, sexual transmission, and transmission with contaminated blood products. Twenty years ago, de Thé and Bomford estimated the total number of HTLV-1 carriers to be 10-20 millions people. At that time, large regions had not been investigated, few population-based studies were available and the assays used for HTLV-1 serology were not enough specific. Despite the fact that there is still a lot of data lacking in large areas of the world and that most of the HTLV-1 studies concern only blood donors, pregnant women, or different selected patients or high-risk groups, we shall try based on the most recent data, to revisit the world distribution and the estimates of the number of HTLV-1 infected persons. Our best estimates range from 5-10 millions HTLV-1 infected individuals. However, these results were based on only approximately 1.5 billion of individuals originating from known HTLV-1 endemic areas with reliable available epidemiological data. Correct estimates in other highly populated regions, such as China, India, the Maghreb, and East Africa, is currently not possible, thus, the current number of HTLV-1 carriers is very probably much higher.

Performance of absolute CD4+ count in predicting co-infection with human T-lymphotropic virus type 1 in antiretroviral-naïve HIV-infected patients

Early identification of patients co-infected with HIV and human T-lymphotropic virus type 1 (HTLV-1) is essential to improve care, as CD4+ T-cell counts have been revealed to be an unreliable laboratory parameter to monitor HIV infection in co-infection. Unfortunately, HTLV-1 testing is not currently available in sub-Saharan Africa. We conducted this study to determine the performance of absolute CD4+ T-cell count estimation in guiding the clinical suspicion of co-infection. A cross-sectional survey was conducted in antiretroviral-naïve HIV (AN-HIV) patients attending an HIV outpatient clinic in Maputo city, Mozambique. Seven hundred and one AN-HIV patients were enrolled in the study. The prevalence of HTLV-1 co-infection was 4.5% (95% confidence interval [CI] 3.0–6.0%). Logistic regression analysis showed that CD4+ T-cell count was an independent predictor of co-infection ( P value: 0.000). The performance of absolute CD4+ T-cell counts in predicting co-infection was higher in symptomatic HIV patients when compared with asymptomatic HIV patients. The best performance was achieved with the cut-off of CD4+ count of 500 cells/mm3, which gave sensitivity, specificity, positive and negative predictive values of 54.2%, 87.2%, 24.0% and 96.2%, respectively. In conclusion, our data provide evidence that the absolute CD4+ T-cell count is of moderate accuracy in guiding the clinical suspicion of co-infection in AN-HIV and its implementation could improve the care provided to a significant number of HIV patients in Mozambique.

Seroprevalence of human T-cell lymphotropic virus type I among pregnant women in Accra, Ghana

Infection with human T-cell lymphotropic virus type I (HTLV-I) occurs mainly in Japan, Central and West Africa and the Caribbean Basin. Although antibody to HTLV-I has been reported among pregnant women in several endemic countries, there is no information regarding the seroprevalence in pregnant Ghanaian women. The reported seroprevalence of HTLV-I among healthy Ghanaian blood donors is between 0.5 and 4.2 %. Therefore, this study was conducted to determine the seroprevalence of HTLV-I among pregnant women attending the antenatal clinic at the 37 Military Hospital, Accra, Ghana, between the months of January and December 2003. The presence of antibodies specific for HTLV-I/II was tested using a particle agglutination test (PAT) kit and confirmed by Western blotting (WB). Of the 960 sera tested, HTLV-I/II antibodies were detected in 24 samples using the PAT kit. WB results indicated that, of the 24 positive PAT specimens, 20 specimens (83.3 %) were HTLV-I positive, one (4.2 %) was HTLV-II positive, two (8.3 %) were HTLV positive and one (4.2 %) was indeterminate. Therefore, the overall seroprevalence of HTLV-I was 2.1 %. Seroprevalence increased with age, suggesting sexual contact as the primary mode of transmission among women of childbearing age, rather than breastfeeding during infancy. The seroprevalence of 2.1 % reported here for HTLV-I in pregnant women in Accra is comparable to that of human immunodeficiency virus among the same population. In conclusion, the results indicate that HTLV-I is prevalent among asymptomatic Ghanaian pregnant women and thus there is a need to consider introducing antenatal screening for HTLV-I in Ghana.

Dual infections with HIV-1, HIV-2 and HTLV-I are more common in older women than in men in Guinea-Bissau

OBJECTIVES

To investigate the association between the three human retroviruses, HIV-1, HIV-2 and HTLV-I.

DESIGN

Community-based follow-up studies of retrovirus infections in two cohorts.

METHODS

A total of 2057 individuals aged 35 years and over were eligible for inclusion. Participants were interviewed and had a blood sample drawn. Samples were analysed for HIV-1, HIV-2 and HTLV infections. Uni- and multivariate analyses that included behavioural and socio-economic factors were performed using logistic regression and Poisson regression models.

RESULTS

A total of 1686 individuals participated with a blood sample in the HIV prevalence analyses and 1581 individuals participated in the HTLV-I prevalence analyses. The overall prevalence was 2.1% for HIV-1, 13.5% for HIV-2 and 7.1% for HTLV-I. Comparing the < 45 year age group with 45+ year age groups, the female : male (F : M) prevalence ratio increased with age for all three retroviruses. Dual infections were more common in women than in men. Assuming independent distribution of the viruses, the observed prevalence of dual infections in women was significantly higher than expected, while the prevalence was not increased in men. The prevalence of dual infections increased with age in women, the odds ratio (OR) being 3.4 [95% confidence interval (CI), 1.0-11.3] for any combination of dual infection, while the prevalence decreased with age in men (OR, 0.3; 95% CI, 0.1-2.0) (test of interaction, P = 0.033). Control for behavioural factors did not modify these patterns.

CONCLUSIONS

The pattern of increased prevalence among older women could have public health implications; women of older age groups should be regarded as a potential vulnerable group and included in HIV/AIDS prevention programmes.

Prevalences of HTLV-1 infection and associated risk determinants in an urban population in Guinea-Bissau, West Africa

OBJECTIVE

To assess the prevalence and modes of transmission of HTLV-1 infection in an adult population in Bissau, and to evaluate possible interactions between the pattern of spread of HTLV-1 and HIV-1/HIV-2.

DESIGN AND METHODS

Univariate and multivariate analyses were used to evaluate gender-and age-specific HTLV-1 prevalences as well as associated risk determinants in an adult population based on a serosurvey comprising 2127 individuals from 304 randomly selected houses in Bissau.

RESULTS

Using stringent Western blot criteria, the overall seroprevalence of HTLV-1 was 3.6%, 2.2% among men and 4.7% among women, respectively. One individual was seropositive to HTLV-2. The prevalence of HTLV-1, which increased with age in both genders, however more markedly among women, was >4 times higher (9.4%) among older individuals (>44 years of age) than among younger individuals (2.4%). Blood transfusion and HIV-2 seropositivity were independently associated with HTLV-1 seropositivity in men. Among women, both HIV-2 seropositivity and HIV-1 seropositivity were significant risk determinants. Having had sexual partners was associated with a fivefold increased risk among women but did not reach significance.

CONCLUSION

The adult population of Guinea-Bissau has a higher prevalence of HTLV-1 than reported from most other countries in West Africa. The gender-and age-specific pattern of spread of HTLV-1 closely resembles that observed for HIV-2, another retrovirus prevalent to the region. The close correlation between HTLV-1 and HIV-2 most likely reflects the shared risk factors related to sexual behavior. The implication of the high percentage of double infections in this population needs to be determined.

Human T-lymphotropic virus type I among blood donors from Guadeloupe: donation, demographic, and biologic characteristics

BACKGROUND

Epidemiologic data on human T-lymphotropic virus type I (HTLV-I) in Guadeloupe (French West Indies) are scant.

STUDY DESIGN AND METHODS

From January 1989 to December 1996, 59,426 blood donors were screened by enzyme immunoassay for antibodies to HTLV-I. All repeatedly reactive samples were confirmed by Western blot. Temporal trends in HTLV-I seropositivity rates were examined during the study period. A multivariate analysis of donation, demographic, and biologic characteristics was performed.

RESULTS

Of the screened blood donors, 195 were confirmed as seropositive, for an overall prevalence of 0.33 percent (95% CI 0.28-0.38). A marked decrease in overall HTLV-I prevalence with time (from 0.47% in 1989 to 0.13% in 1996) was observed, which can be explained mainly by the decreasing percentage of recruited new donors during the study period. Four independent risk factors for HTLV-I were identified: new donor status (odds ratio [OR] 12.5), female sex (OR 1.7), increasing age (30-39 years: OR, 2.4; 40-49 years: OR, 3.7; >50 years: OR 6.6), and positive antibodies to hepatitis B virus core antigen (OR, 1.7). Selection of specific locations for blood collection was inversely associated with HTLV-I (OR 0.5).

CONCLUSION

New donor status, advancing age, female sex, and positivity for hepatitis B virus core antibodies were the major factors associated with HTLV-I infection in Guadeloupe.