Mortality among inhabitants of an HTLV-I endemic area in Japan

Clinical characteristics and outcomes of infection with human T-lymphotropic virus in a non-endemic area: a single institution study

Introduction

Understanding of human T-lymphotropic virus (HTLV) remains largely based on epidemiologic and clinical data from endemic areas. Globalization has resulted in migration of persons living with HTLV (PLHTLV) from endemic to non-endemic areas, and a rise of HTLV infection in the United States. Yet, due to the historical rarity of this disease, affected patients are often under- and mis-diagnosed. Thus, we sought to characterize the epidemiology, clinical features, comorbidities, and survival of HTLV-1- or HTLV-2-positive individuals identified in a non-endemic area.

Methods

Our study was a single institution, retrospective case-control analysis of HTLV-1 or HTLV-2 patients between 1998 and 2020. We utilized two HTLV-negative controls, matched for age, sex, and ethnicity, for each HTLV-positive case. We evaluated associations between HTLV infection and several hematologic, neurologic, infectious, and rheumatologic covariates. Finally, clinical factors predictive of overall survival (OS) were assessed.

Results

We identified 38 cases of HTLV infection, of whom 23 were HTLV-1 and 15 were HTLV-2 positive. The majority (~54%) of patients in our control group received HTLV testing for transplant evaluation, compared to ~24% of HTLV-seropositive patients. Co-morbidities associated with HTLV, hepatitis C seropositivity were higher in HTLV-seropositive patients compared to controls (OR 10.7, 95% CI = 3.2-59.0, p < 0.001). Hepatitis C and HTLV co-infection resulted in decreased OS, compared to no infection, hepatitis C infection alone, or HTLV infection alone. Patients with any cancer diagnosis and HTLV infection had worse OS compared to patients with cancer or HTLV alone. HTLV-1 positive patients had lower median OS compared to HTLV-2 patients (47.7 months vs. 77.4 months). In univariate analysis, the hazard for 1-year all-cause mortality was increased among patients with HTLV-seropositivity, adult T-cell leukemia, acute myelogenous leukemia, and hepatitis C infection. When corrected, multivariate analysis showed that HTLV seropositivity was no longer associated with 1 year all-cause mortality; however association with AML and hepatitis C infection remained significant.

Conclusion

HTLV-seropositivity was not associated with increased 1 year mortality in multivariate analysis. However, our study is limited by our small patient sample size, as well as the biased patient control population due to selection factors for HTLV testing.

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.

Dichotomy in Fatal Outcomes in a Large Cohort of People Living with HTLV-1 in São Paulo, Brazil

Background: Despite its relatively low incidence of associated diseases, Human T-cell Leukemia Virus-1 (HTLV-1) infection was reported to carry a significant risk of mortality in several endemic areas. HTLV-1-associated diseases, adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraperesis (HAM/TSP), as well as frequent coinfections with human immunodeficiency virus (HIV), hepatitis C virus (HCV), and Strongyloides stercoralis were associated to increased morbidity and mortality of HTLV-1 infection. Objective: To determine the mortality rate and its associated variables from an open cohort started in July 1997 at the HTLV Clinic, Emilio Ribas Institute (IIER), a major infectious disease hospital in São Paulo, Brazil. Methods: Since inception up to September 2018, we admitted 727 HTLV-1-infected individuals, with a rate of 30–50 new admissions per year. All patient data, including clinical and laboratory data, were regularly updated throughout the 21-year period, using a dedicated REDCap database. The Ethical Board of IIER approved the protocol. Results: During 21 years of clinical care to people living with HTLV-1 in the São Paulo region, we recruited 479 asymptomatic HTLV-1-infected individuals and 248 HAM/TSP patients, of which 632 remained under active follow-up. During a total of 3800 person-years of follow-up (maximum follow-up 21.5 years, mean follow-up 6.0 years), 27 individuals died (median age of 51.5 years), of which 12 were asymptomatic, one ATLL patient and 14 HAM/TSP patients. HAM/TSP diagnosis (but neither age nor gender) was a significant predictor of increased mortality by univariate and multivariate (hazard ratio (HR) 5.03, 95% CI [1.96–12.91], p = 0.001) Cox regression models. Coinfection with HIV/HCV was an independent predictor of increased mortality (HR 15.08; 95% CI [5.50–41.32]; p < 0.001), with AIDS-related infections as a more frequent cause of death in asymptomatics (6/13; p = 0.033). HIV/HCV-negative fatal HAM/TSP cases were all female, with urinary tract infection and decubitus ulcer-associated sepsis as the main cause of death (8/14, p = 0.002). Conclusions: All-cause mortality among people living with HTLV-1 in São Paulo differs between asymptomatic (2.9%) and HAM/TSP patients (7.3%), independent of age and gender. We observe a dichotomy in fatal cases, with HAM/TSP and HIV/HCV coinfection as independent risk factors for death. Our findings reveal an urgent need for public health actions, as the major causes of death, infections secondary to decubitus ulcers, and immune deficiency syndrome (AIDS)-related infections, can be targeted by preventive measures.

Association between HTLV-1 infection and adverse health outcomes: a systematic review and meta-analysis of epidemiological studies

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is a human retrovirus that causes a lifelong infection. Several diseases, including an aggressive form of leukaemia, have been designated as associated with HTLV-1, whereby having HTLV-1 is a necessary condition for diagnosis. Beyond these diseases, there is uncertainty about other health effects of HTLV-1. We aimed to synthesise evidence from epidemiological studies on associations between health outcomes and HTLV-1.

METHODS

For this systematic review and meta-analysis, we searched Embase, MEDLINE, MEDLINE In-Process, and Global Health for publications from their inception to July, 2018. We included cohort, case-control, and controlled cross-sectional studies that compared mortality or morbidity between people with and without HTLV-1. We excluded studies of psychiatric conditions, of symptoms or clinical findings only, of people who had undergone blood transfusion or organ transplant, and of population groups defined by a behavioural characteristic putting them at increased risk of co-infection with another virus. We extracted the risk estimates (relative risks [RRs] or odds ratios [ORs]) that reflected the greatest degree of control for potential confounders. We did a random-effects meta-analysis for groups of effect estimates where case ascertainment methods, age groups, and confounders were similar, presenting pooled estimates with 95% CIs and prediction intervals.

FINDINGS

Of the 3318 identified studies, 39 met the inclusion criteria, examining 42 clinical conditions between them. The adjusted risk of death due to any cause was higher in people with HTLV-1 when compared with HTLV-1-negative counterparts (RR 1·57, 95% CI 1·37-1·80). From meta-analysis, HTLV-1 was associated with increased odds of seborrheic dermatitis (OR 3·95, 95% CI 1·99-7·81), Sjogren's syndrome (3·25, 1·85-5·70), and, inversely, with lower relative risk of gastric cancer (RR 0·45, 0·28-0·71). There were a further 14 diseases with significant associations or substantially elevated risk with HTLV-1 from single studies (eczema [children]; bronchiectasis, bronchitis and bronchiolitis [analysed together]; asthma [males]; fibromyalgia; rheumatoid arthritis; arthritis; tuberculosis; kidney and bladder infections; dermatophytosis; community acquired pneumonia; strongyloides hyperinfection syndrome; liver cancer; lymphoma other than adult T-cell leukaemia-lymphoma; and cervical cancer).

INTERPRETATION

There is a broad range of diseases studied in association with HTLV-1. However, the elevated risk for death among people with HTLV-1 is not explained by available studies of morbidity. Many of the diseases shown to be associated with HTLV-1 are not fatal, and those that are (eg, leukaemia) occur too rarely to account for the observed mortality effect. There are substantial research gaps in relation to HTLV-1 and cardiovascular, cerebrovascular, and metabolic disease. The burden of disease associated with the virus might be broader than generally recognised.

FUNDING

Commonwealth Department of Health, Australia.

Human T-Lymphotropic Virus type 1c subtype proviral loads, chronic lung disease and survival in a prospective cohort of Indigenous Australians

Background

The Human T-Lymphotropic Virus type 1c subtype (HTLV-1c) is highly endemic to central Australia where the most frequent complication of HTLV-1 infection in Indigenous Australians is bronchiectasis. We carried out a prospective study to quantify the prognosis of HTLV-1c infection and chronic lung disease and the risk of death according to the HTLV-1c proviral load (pVL).

Methodology/Principal findings

840 Indigenous adults (discharge diagnosis of bronchiectasis, 154) were recruited to a hospital-based prospective cohort. Baseline HTLV-1c pVL were determined and the results of chest computed tomography and clinical details reviewed. The odds of an association between HTLV-1 infection and bronchiectasis or bronchitis/bronchiolitis were calculated, and the impact of HTLV-1c pVL on the risk of death was measured.

Radiologically defined bronchiectasis and bronchitis/bronchiolitis were significantly more common among HTLV-1-infected subjects (adjusted odds ratio = 2.9; 95% CI, 2.0, 4.3). Median HTLV-1c pVL for subjects with airways inflammation was 16-fold higher than that of asymptomatic subjects. There were 151 deaths during 2,140 person-years of follow-up (maximum follow-up 8.13 years). Mortality rates were higher among subjects with HTLV-1c pVL ≥1000 copies per 10⁵ peripheral blood leukocytes (log-rank χ² (2df) = 6.63, p = 0.036) compared to those with lower HTLV-1c pVL or uninfected subjects. Excess mortality was largely due to bronchiectasis-related deaths (adjusted HR 4.31; 95% CI, 1.78, 10.42 versus uninfected).

Conclusion/Significance

Higher HTLV-1c pVL was strongly associated with radiologically defined airways inflammation and with death due to complications of bronchiectasis. An increased risk of death due to an HTLV-1 associated inflammatory disease has not been demonstrated previously. Our findings indicate that mortality associated with HTLV-1c infection may be higher than has been previously appreciated. Further prospective studies are needed to determine whether these results can be generalized to other HTLV-1 endemic areas.

The Human T-Lymphotropic Virus type 1 (HTLV-1) infects up to 20 million people worldwide who predominantly reside in resource-limited areas. The virus is associated with a haematological malignancy (adult T-cell leukaemia/lymphoma, ATL), and inflammatory diseases involving organ systems including the spinal cord, eyes and lungs. Determining the outcomes of infection in most HTLV-1 endemic areas is extremely difficult; however, the virus is highly endemic to central Australia where the Indigenous population has access to sophisticated medical facilities. We prospectively followed a large hospital-based cohort of Indigenous Australian adults that was well characterized with regard to base-line comorbid conditions, HTLV-1 serostatus and HTLV-1 proviral load (pVL). A higher baseline HTLV-1 pVL was strongly associated with an increased risk of airway inflammation (bronchitis/bronchiolitis and bronchiectasis) and death, which most often resulted from complications of bronchiectasis. Increased mortality due to an HTLV-1-associated inflammatory condition has not been demonstrated previously. The morbidity and mortality associated with HTLV-1 infection may therefore be substantially higher than has been assumed from an analysis of cohorts of subjects with adult T-cell leukaemia or HTLV-1-associated myelopathy. These findings have important implications for epidemiological research and for determining health care priorities in resource-limited settings.

HTLV-1 and HIV-2 infection are associated with increased mortality in a rural West African community

Background

Survival of people with HIV-2 and HTLV-1 infection is better than that of HIV-1 infected people, but long-term follow-up data are rare. We compared mortality rates of HIV-1, HIV-2, and HTLV-1 infected subjects with those of retrovirus-uninfected people in a rural community in Guinea-Bissau.

Methods

In 1990, 1997 and 2007, adult residents (aged ≥15 years) were interviewed, a blood sample was drawn and retroviral status was determined. An annual census was used to ascertain the vital status of all subjects. Cox regression analysis was used to estimate mortality hazard ratios (HR), comparing retrovirus-infected versus uninfected people.

Results

A total of 5376 subjects were included; 197 with HIV-1, 424 with HIV-2 and 325 with HTLV-1 infection. The median follow-up time was 10.9 years (range 0.0–20.3). The crude mortality rates were 9.6 per 100 person-years of observation (95% confidence interval 7.1-12.9) for HIV-1, 4.1 (3.4–5.0) for HIV-2, 3.6 (2.9–4.6) for HTLV-1, and 1.6 (1.5–1.8) for retrovirus-negative subjects. The HR comparing the mortality rate of infected to that of uninfected subjects varied significantly with age. The adjusted HR for HIV-1 infection varied from 4.0 in the oldest age group (≥60 years) to 12.7 in the youngest (15–29 years). The HR for HIV-2 infection varied from 1.2 (oldest) to 9.1 (youngest), and for HTLV-1 infection from 1.2 (oldest) to 3.8 (youngest).

Conclusions

HTLV-1 infection is associated with significantly increased mortality. The mortality rate of HIV-2 infection, although lower than that of HIV-1 infection, is also increased, especially among young people.

HTLV-1 in rural Guinea-Bissau: prevalence, incidence and a continued association with HIV between 1990 and 2007

Background

HTLV-1 is endemic in Guinea-Bissau, and the highest prevalence in the adult population (5.2%) was observed in a rural area, Caió, in 1990. HIV-1 and HIV-2 are both prevalent in this area as well. Cross-sectional associations have been reported for HTLV-1 with HIV infection, but the trends in prevalence of HTLV-1 and HIV associations are largely unknown, especially in Sub Saharan Africa. In the current study, data from three cross-sectional community surveys performed in 1990, 1997 and 2007, were used to assess changes in HTLV-1 prevalence, incidence and its associations with HIV-1 and HIV-2 and potential risk factors.

Results

HTLV-1 prevalence was 5.2% in 1990, 5.9% in 1997 and 4.6% in 2007. Prevalence was higher among women than men in all 3 surveys and increased with age. The Odds Ratio (OR) of being infected with HTLV-1 was significantly higher for HIV positive subjects in all surveys after adjustment for potential confounding factors. The risk of HTLV-1 infection was higher in subjects with an HTLV-1 positive mother versus an uninfected mother (OR 4.6, CI 2.6-8.0). The HTLV-1 incidence was stable between 1990-1997 (Incidence Rate (IR) 1.8/1,000 pyo) and 1997-2007 (IR 1.6/1,000 pyo) (Incidence Rate Ratio (IRR) 0.9, CI 0.4-1.7). The incidence of HTLV-1 among HIV-positive individuals was higher compared to HIV negative individuals (IRR 2.5, CI 1.0-6.2), while the HIV incidence did not differ by HTLV-1 status (IRR 1.2, CI 0.5-2.7).

Conclusions

To our knowledge, this is the largest community based study that has reported on HTLV-1 prevalence and associations with HIV. HTLV-1 is endemic in this rural community in West Africa with a stable incidence and a high prevalence. The prevalence increases with age and is higher in women than men. HTLV-1 infection is associated with HIV infection, and longitudinal data indicate HIV infection may be a risk factor for acquiring HTLV-1, but not vice versa. Mother to child transmission is likely to contribute to the epidemic.

Mortality associated with HIV-1, HIV-2, and HTLV-I single and dual infections in a middle-aged and older population in Guinea-Bissau

BACKGROUND

In Guinea-Bissau HIV-1, HIV-2, and HTLV-I are prevalent in the general population. The natural history of HIV/HTLV-I single and dual infections has not been fully elucidated in this population. Previous studies have shown that combinations of these infections are more common in older women than in men. The present study compares mortality associated with HIV-1, HIV-2, and HTLV-I single and dual infections in individuals over 35 years of age within an urban community-based cohort in Guinea-Bissau.

RESULTS

A total of 2,839 and 1,075 individuals were included in the HIV and HTLV-I mortality analyses respectively. Compared with HIV-negative individuals, adjusted mortality rate ratios (MRRs) were 4.9 (95% confidence interval (CI): 2.3, 10.4) for HIV-1, 1.8 (95%CI: 1.5, 2.3) for HIV-2, and 5.9 (2.4, 14.3) for HIV-1/HIV-2 dual infections. MRR for HTLV-I-positive compared with HTLV-I-negative individuals was 1.7 (1.1, 2.7). Excluding all HIV-positive individuals from the analysis, the HTLV-I MRR was 2.3 (1.3, 3.8). The MRR of HTLV-I/HIV-2 dually infected individuals was 1.7 (0.7, 4.3), compared with HIV/HTLV-I-negative individuals. No statistically significant differences were found in retrovirus-associated mortality between men and women.

CONCLUSION

HIV-1-associated excess mortality was low compared with community studies from other parts of Africa, presumably because this population was older and the introduction of HIV-1 into the community recent. HIV-2 and HTLV-I-associated mortality was 2-fold higher than the mortality in uninfected individuals. We found no significant differences between the mortality risk for HIV-2 and HTLV-I single infection, respectively, and HIV-2/HTLV-I dual infection. The higher prevalence of retroviral dual infections in older women is not explained by differential retrovirus-associated mortality for men and women.

Sex-specific mortality from adult T-cell leukemia among carriers of human T-lymphotropic virus type I

Perinatal infection with human T-lymphotropic virus type I (HTLV-I) is considered a risk factor for adult T-cell leukemia (ATL). Incidence of ATL in Japan is generally higher in males compared with females, perhaps partly due to an earlier average age of infection among males. We estimated sex-specific ATL mortality among perinatally-infected HTLV-I carriers in the prospective Miyazaki Cohort Study in Japan. Based on the approximated proportion of perinatally-infected carriers, the relative risk (RR) of ATL for males compared with females was calculated. Six ATL deaths (4 males, 2 females) occurred among the 550 HTLV-I carriers in the cohort during 13 years of follow-up. The overall ATL mortality was 190.5 (95% CI 51.9-487.7) per 10(5) person-years for males and 51.7 (6.3-186.8) per 10(5) person-years for females (age-standardized RR = 3.9, p=0.02). By approximating the number of persons who acquired infection perinatally, the estimated mortality among those perinatally-infected HTLV-I carriers was 209.1 (57.0-535.2) per 10(5) person-years for males and 60.9 (7.4-219.9) per 10(5) person-years for females (age-standardized RR = 3.7, p=0.02). The adjusted RR changed minimally from the unadjusted RR, suggesting that earlier age of infection alone is unlikely the explanation for the male predominance in ATL. Based on the small number of cases available for analysis, aspects of gender itself appear to play a role in the development of this malignancy.

Evaluation of adult T-cell leukemia/lymphoma incidence and its impact on non-Hodgkin lymphoma incidence in southwestern Japan

The incidence of adult T-cell leukemia/lymphoma (ATL) and its impact on that of total non-Hodgkin lymphoma (NHL) were evaluated in Nagasaki, an area in southwestern Japan where human T-cell lymphotropic virus type I (HTLV-I) is endemic. The first study area comprised 4 towns located on the K Islands, which had a population of 26,870 in 1990. The overall HTLV-I seroprevalence estimated from the serologic survey of 18,485 subjects was 16.2%. By using the data from the Nagasaki Prefectural Cancer Registry (NPCR) and reviewing clinical and laboratory information, we identified 40 cases of ATL and 35 cases of other NHL diagnosed between 1985 and 1995. The crude annual incidence of ATL among 100,000 HTLV-I carriers aged 30 or older was estimated at 137.7 for men and 57.4 for women, with a significant sex difference after adjustment for age (rate ratio = 2.50, 95% confidence interval 1.32-4.73). The cumulative risk from 30 to 79 years of age was estimated at approximately 6.6% for men and 2.1% for women. Among the entire population, ATL accounted for 51 to 59% of the total NHL incidence, showing the strong impact of HTLV-I infection. The second study area comprised the whole of Nagasaki Prefecture (total population in 1990 = 1.56 million). Between 1985 and 1995, 989 cases of ATL and 1,745 cases of other NHL were registered in the NPCR. The world age-standardized annual incidence rate of ATL per 100,000 persons aged 30 or older was estimated at 10.5 for men and 6.0 for women, which accounted for approximately 37 to 41% of the total NHL incidence.

Human T-lymphotropic virus type-I infection, antibody titers and cause-specific mortality among atomic-bomb survivors

There have been few longitudinal studies on the long-term health effects of human T-lymphotropic virus type-I (HTLV-I) infection. The authors performed a cohort study of HTLV-I infection and cause-specific mortality in 3,090 atomic-bomb survivors in Nagasaki, Japan, who were followed from 1985-1987 to 1995. The prevalence of HTLV-I seropositivity in men and women was 99/1,196 (8.3%) and 171/1,894 (9.0%), respectively. During a median follow-up of 8.9 years, 448 deaths occurred. There was one nonfatal case of adult T-cell leukemia/lymphoma (incidence rate = 0.46 cases/1,000 person-years; 95% confidence interval [CI] 0.01-2.6). After adjustment for sex, age and other potential confounders, significantly increased risk among HTLV-I carriers was observed for deaths from all causes (rate ratio [RR] = 1.41), all cancers (RR = 1.64), liver cancer (RR = 3.04), and heart diseases (RR = 2.22). The association of anti-HTLV-I seropositivity with mortality from all non-neoplastic diseases (RR = 1.40) and chronic liver diseases (RR = 5.03) was of borderline significance. Possible confounding by blood transfusions and hepatitis C/B (HCV/HBV) viral infections could not be precluded in this study. However, even after liver cancer and chronic liver diseases were excluded, mortality rate was still increased among HTLV-I carriers (RR = 1.32, 95% CI 0.99-1.78), especially among those with high antibody titers (RR = 1.56, 95% CI 0.99-2.46, P for trend = 0.04). These findings may support the idea that HTLV-I infection exerts adverse effects on mortality from causes other than adult T-cell leukemia/lymphoma. Further studies on confounding by HCV/HBV infections and the interaction between HCV/HBV and HTLV-I may be required to analyze the increased mortality from liver cancer and chronic liver diseases.

Screening for human T cell leukaemia/lymphoma virus among blood donors in Sweden: cost effectiveness analysis

OBJECTIVE

To analyse the cost effectiveness of a national programme to screen blood donors for infection with the human T cell leukaemia/lymphoma virus.

DESIGN

Three models for calculating the costs and benefits of screening were developed. The first model analysed the cost of continuously testing all donations; the second analysed the cost of initially testing new blood donors and then retesting them after five years; the third analysed the cost of testing donors only at the time of their first donation. Patients who had received blood components from donors confirmed to be infected with the virus were offered testing.

SETTING

Sweden.

MAIN OUTCOME MEASURES

Prevalence of infection with the virus among blood donors, the risk of transmission of the virus, screening costs, and the outcome of infection.

RESULTS

648 497 donations were tested for the virus; 1625 samples tested positive by enzyme linked immunosorbent assay. 6 were confirmed positive by western blotting. The prevalence of infection with the virus was 2/100 000 donors. 35 patients who had received blood infected with the virus were tested; 3 were positive. The cost of testing every donation was calculated to be $3.02m (1.88m pounds); this is 18 times higher than the cost of testing new donors only, and only 1 additional positive donor would be discovered in 7 years. Regardless of the model used, screening was estimated to prevent only 1 death every 200 years at a minimum cost of $36m (22.5m pounds).

CONCLUSION

Based on these estimates the Swedish National Board of Health and Welfare decided that only new blood donors would be screened for infection with the virus.

Decreased survival of HTLV-I carriers in leprosy patients from the Democratic Republic of the Congo: a historical prospective study

In this historical prospective study using sera stored for 22 years, we investigated the effect of HTLV-I infection on survival in a population of leprosy patients in the Democratic Republic of the Congo (formerly Zaire). We also determined the distribution of HTLV-I by subpopulation, age, and gender. Stored sera taken from a population of leprosy patients and controls in 1969 were tested for HTLV-I. Follow-up survival data on these patients were obtained in 1991. The sera collected in 1969 from 520 individuals was used to determine the prevalence of HTLV-I. Included in this number were 328 patients resident in the sanatorium. Survival and other data were available for 327 of these. A multivariate survival analysis using a logistic regression model was performed to evaluate the influence of HTLV-I status, age, type of leprosy, gender, duration of hospitalization, and ethnic group on survival. The overall prevalence of HTLV-I among the 520 individuals in the prevalence study was 34%, with 37.4% in the leprosy group and 25.2% in the control group (p < 0.01). Multivariate analysis using logistic regression showed that females of the Mongo and Ngombe ethnic group taken together were significantly more likely to be infected than the other groups (OR = 3.67, 95% CI: 2.14 to 6.30). A comparison of the death rates directly standardized for age and sex showed that the rate was significantly higher for HTLV-I positive (5.5/100 person-years of observation) compared with HTLV-I negative (3.6/100 person-years of observation). A survival analysis using the Cox model showed a risk ratio of 1.4 (CI: 1.04 to 1.89) for those infected with HTLV-I. An increase in the death rate was associated with HTLV-I infection in leprosy inpatients. The decreased survival associated with HTLV-I infection may result from an increased susceptibility to a variety of diseases.