Higher human T-lymphotropic Virus Type 1 Subtype C Proviral Loads Are Associated With Bronchiectasis in Indigenous Australians: Results of a Case-Control Study

Lloyd Einsiedel, Olivier Cassar, Emma Goeman, Tim Spelman, Virginia Au, Saba Hatami, Sheela Joseph, Antoine Gessain

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    Background: We previously suggested that infection with the human T-lymphotropic virus type 1 (HTLV-1) subtype C is associated with bronchiectasis among Indigenous Australians. Bronchiectasis might therefore result from an HTLV-1-mediated inflammatory process that is typically associated with a high HTLV-1 proviral load (PVL). Human T-lymphotropic virus type 1 PVL have not been reported for Indigenous Australians. 

    Methods: Thirty-six Indigenous adults admitted with bronchiectasis from June 1, 2008, to December 31, 2009 were prospectively recruited and matched by age, sex, and ethno-geographic origin to 36 controls. Case notes and chest high-resolution computed tomographs were reviewed, and pulmonary injury scores were calculated. A PVL assay for the HTLV-1c subtype that infects Indigenous Australians was developed and applied to this study. Clinical, radiological, and virological parameters were compared between groups and according to HTLV-1 serostatus. 

    Results: Human T-lymphotropic virus type 1 infection was the main predictor of bronchiectasis in a multivariable model (adjusted risk ratio [arr], 1.84; 95% confidence interval [CI], 1.19-2.84; P =.006). moreover, the median HTLV-1c PVL(interquartile range) for cases was > 100-fold that of controls (cases, 0.319 [0.007, 0.749]; controls, 0.003 [0.000, 0.051] per 100 peripheral blood lymphocytes; P=.007), and HTLV-1c PVL were closely correlated with radiologically determined pulmonary injury scores (spearman's rho = 0.7457; P=.0000). other predictors of bronchiectasis were positive strongyloides serology (aRR, 1.69; 95% CI, 1.13-2.53) and childhood skin infections (aRR, 1.62; 95% CI, 1.07-2.44). Bronchiectasis was the major predictor of death (aRR, 2.71; 95% CI, 1.36-5.39; P =.004). 

    Conclusions: These data strongly support an etiological association between HTLV-1 infection and bronchiectasis in a socially disadvantaged population at risk of recurrent lower respiratory tract infections.

    Original languageEnglish
    Article numberofu023
    Number of pages8
    JournalOpen Forum Infectious Diseases
    Issue number1
    Publication statusPublished - 28 May 2014

    Bibliographical note

    © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/by-nc-nd/3.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com.


    • Australia
    • Bronchiectasis
    • HTLV-1
    • HTLV-1 proviral load
    • Indigenous
    • Pulmonary disease
    • Strongyloides stercoralis


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