Clinical Associations of Human T-Lymphotropic Virus Type 1 Infection in an Indigenous Australian Population

Abstract

IntroductionIn resource-poor areas, infectious diseases may be important causes of morbidity among individuals infected with the Human T-Lymphotropic Virus type 1 (HTLV-1). We report the clinical associations of HTLV-1 infection among socially disadvantaged Indigenous adults in central Australia.Methodology and Principal FindingsHTLV-1 serological results for Indigenous adults admitted 1st January 2000 to 31st December 2010 were obtained from the Alice Springs Hospital pathology database. Infections, comorbid conditions and HTLV-1 related diseases were identified using ICD-10 AM discharge morbidity codes. Relevant pathology and imaging results were reviewed. Disease associations, admission rates and risk factors for death were compared according to HTLV-1 serostatus. HTLV-1 western blots were positive for 531 (33.3%) of 1595 Indigenous adults tested. Clinical associations of HTLV-1 infection included bronchiectasis (adjusted Risk Ratio, 1.35; 95% CI, 1.14–1.60), blood stream infections (BSI) with enteric organisms (aRR, 1.36; 95% CI, 1.05–1.77) and admission with strongyloidiasis (aRR 1.38; 95% CI, 1.16–1.64). After adjusting for covariates, HTLV-1 infection remained associated with increased numbers of BSI episodes (adjusted negative binomial regression, coefficient, 0.21; 95% CI, 0.02–0.41) and increased admission numbers with strongyloidiasis (coefficient, 0.563; 95% CI, 0.17–0.95) and respiratory conditions including asthma (coefficient, 0.99; 95% CI, 0.27–1.7), lower respiratory tract infections (coefficient, 0.19; 95% CI, 0.04–0.34) and bronchiectasis (coefficient, 0.60; 95% CI, 0.02–1.18). Two patients were admitted with adult T-cell Leukemia/Lymphoma, four with probable HTLV-1 associated myelopathy and another with infective dermatitis. Independent predictors of mortality included BSI with enteric organisms (aRR 1.78; 95% CI, 1.15–2.74) and bronchiectasis (aRR 2.07; 95% CI, 1.45–2.98).ConclusionHTLV-1 infection contributes to morbidity among socially disadvantaged Indigenous adults in central Australia. This is largely due to an increased risk of other infections and respiratory disease. The spectrum of HTLV-1 related diseases may vary according to the social circumstances of the affected population.

The prevalence and clinical associations of HTLV‐1 infection in a remote Indigenous community

“…HTLV‐1 was first identified in central Australia in 1988 9 and each of the major recognised complications of HTLV‐1 have since been described in Indigenous residents of this region 3 , 5 , 10 , 11 . HTLV‐1‐associated pulmonary disease is particularly common 6 , 10 , 12 and contributes to the highest reported adult prevalence of bronchiectasis worldwide 6 . An impaired immune response also contributes to HTLV‐1‐associated morbidity by increasing the larval burden of Strongyloides stercoralis in people infected with HTLV‐1 living in resource‐poor areas 1 , 10 .…”

“…HTLV‐1‐associated pulmonary disease is particularly common 6 , 10 , 12 and contributes to the highest reported adult prevalence of bronchiectasis worldwide 6 . An impaired immune response also contributes to HTLV‐1‐associated morbidity by increasing the larval burden of Strongyloides stercoralis in people infected with HTLV‐1 living in resource‐poor areas 1 , 10 . Notwithstanding seropositivity rates that exceed 30% for Indigenous adults admitted to Alice Springs Hospital, 10 there has been no coordinated program to reduce viral transmission among Indigenous Australians.…”

Crusted scabies: a clinical marker of human T‐lymphotropic virus type 1 infection in central Australia

“…As in this case, re‐infection and relapse are common, and failure to effectively manage core transmitters results in a cycle of infection that demoralises communities and carries the attendant risks of secondary bacterial infection 1 , 2 . The risks of complications are particularly high in HTLV‐1‐endemic central Australia, where HTLV‐1 infection is also associated with blood stream infections, strongyloidiasis, pulmonary disease, leukaemia, infective dermatitis and myelopathy 3 . The growing number of life‐threatening sequelae that affect Indigenous Australians with HTLV‐1 infection are a compelling reason to urgently implement a program to control HTLV‐1 transmission among the Indigenous population of central Australia.…”

“…This human retrovirus is endemic to much of Western Australia, South Australia and the NT. In a recent study, 33% of nearly 1600 Indigenous adults tested at Alice Springs Hospital (ASH) were infected 3 …”

Higher human T‐cell leukaemia virus type 1 (HTLV‐1) proviral load is associated with end‐stage kidney disease in Indigenous Australians: Results of a case‐control study in central Australia

“…Little is known about the role of infection and chronic inflammation in our setting. The highest prevalence of ESKD in Australia is found in the western desert of central Australia, which coincides with the highest seropositivity rates for HTLV‐1 infection . This raises the possibility that HTLV‐1 infection contributes to kidney injury in central Australia.…”