Bronchiectasis is associated with human T-lymphotropic virus 1 infection in an Indigenous Australian population

High level of genomic divergence in orf-I p12 and hbz genes of HTLV-1 subtype-C in Central Australia

BACKGROUND

Human T cell lymphotropic virus type 1 (HTLV-1) infection remains a largely neglected public health problem, particularly in resource-poor areas with high burden of communicable and non-communicable diseases, such as some remote populations in Central Australia where an estimated 37% of adults are infected with HTLV-1. Most of our understanding of HTLV-1 infection comes from studies of the globally spread subtype-A (HTLV-1a), with few molecular studies reported with the Austral-Melanesian subtype-C (HTLV-1c) predominant in the Indo-Pacific and Oceania regions.

RESULTS

Using a primer walking strategy and direct sequencing, we constructed HTLV-1c genomic consensus sequences from 22 First Nations participants living with HTLV-1c in Central Australia. Phylogenetic and pairwise analysis of this subtype-C proviral gDNA showed higher levels of genomic divergence in comparison to previously published HTLV-1a genomes. While the overall genomic homology between subtypes was 92.5%, the lowest nucleotide and amino acid sequence identity occurred near the 3' end of the proviral genome coding regulatory genes, especially overlapping hbz (85.37%, 77.46%, respectively) and orf-I product p12 (82.00%, 70.30%, respectively). Strikingly, the HTLV-1c genomic consensus sequences uniformly showed a defective translation start codon for the immune regulatory proteins p12/p8 encoded by the HTLV-1A orf-I. Deletions in the proviral genome were detected in many subjects, particularly in the structural gag, pol and env genes. Similarly, using a droplet digital PCR assay measuring the copies of gag and tax per reference host genome, we quantitatively confirmed that provirus retains the tax gene region at higher levels than gag.

CONCLUSIONS

Our genomic analysis of HTLV-1c in Central Australia in conjunction with earlier Melanesian HTLV-1c sequences, elucidate substantial differences with respect to the globally spread HTLV-1a. Future studies should address the impact these genomic differences have on infection and the regionally distinctive frequency of associated pulmonary disease. Understanding the host and virus subtype factors which contribute to the differential morbidity observed, is crucial for the development of much needed therapeutics and vaccine strategies against this highly endemic infection in remote First Nations communities in Central Australia.

High HTLV-1 Proviral Load Predates and Predicts HTLV-1-Associated Disease: Literature Review and the London Experience

Human T cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects lymphocytes and causes severe diseases. HTLV-1 proviral load (PVL), i.e., the number of host cells that carry HTLV-1 proviral DNA integrated into their genome, can be measured in peripheral blood mononuclear cells (PBMCs) using quantitative polymerase chain reaction. In this narrative review, we discuss the usefulness of HTLV-1 PVL quantification and share our experience acquired during more than 30 years of follow-up of people living with HTLV-1 in the UK. Patients with HTLV-1-associated myelopathy have higher PVL than those with asymptomatic infection. This is consistent across studies in different countries. High PVL predates symptom onset for both inflammatory and proliferative diseases. High PVL is essential but not sufficient for the development of HTLV-1-associated diseases. Therefore, PVL quantification can be used to support the care of people living with HTLV-1 by identifying those most at risk of HTLV-1-associated diseases.

Comprehensive Insight into the Functional Roles of NK and NKT Cells in HTLV-1-Associated Diseases and Asymptomatic Carriers

Human T cell leukemia virus type 1 (HTLV-1) is the first human oncogenic retrovirus to be discovered and causes two major diseases: a progressive neuro-inflammatory disease, termed HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), and an aggressive malignancy of T lymphocytes known as adult T cell leukemia (ATL). Innate and acquired immune responses play pivotal roles in controlling the status of HTLV-1-infected cells and such, the outcome of HTLV-1 infection. Natural killer cells (NKCs) are the effector cells of the innate immune system and are involved in controlling viral infections and several types of cancers. The ability of NKCs to trigger cytotoxicity to provide surveillance against viruses and cancer depends on the balance between the inhibitory and activating signals. In this review, we will discuss NKC function and the alterations in the frequency of these cells in HTLV-1 infection.

Bronchiectasis among Indigenous adults in the Top End of the Northern Territory, 2011-2020: a retrospective cohort study

OBJECTIVES

To assess the prevalence of bronchiectasis among Aboriginal and Torres Strait Islander (Indigenous) adults in the Top End of the Northern Territory, and mortality among Indigenous adults with bronchiectasis.

STUDY DESIGN

Retrospective cohort study.

SETTING, PARTICIPANTS

Aboriginal and Torres Strait Islander adults (18 years or older) living in the Top End Health Service region of the NT in whom bronchiectasis was confirmed by chest computed tomography (CT) during 1 January 2011 - 31 December 2020.

MAIN OUTCOME MEASURES

Prevalence of bronchiectasis, and all-cause mortality among Indigenous adults with CT-confirmed bronchiectasis - overall, by sex, and by health district - based on 2011 population numbers (census data).

RESULTS

A total of 23 722 Indigenous adults lived in the Top End Health Service region in 2011; during 2011-2020, 459 people received chest CT-confirmed diagnoses of bronchiectasis. Their median age was 47.5 years (interquartile range [IQR], 39.9-56.8 years), 254 were women (55.3%), and 425 lived in areas classified as remote (93.0%). The estimated prevalence of bronchiectasis was 19.4 per 1000 residents (20.6 per 1000 women; 18.0 per 1000 men). The age-adjusted prevalence of bronchiectasis was 5.0 (95% CI, 1.4-8.5) cases per 1000 people in the Darwin Urban health area, and 18-36 cases per 1000 people in the three non-urban health areas. By 30 April 2023, 195 people with bronchiectasis had died (42.5%), at a median age of 60.3 years (IQR, 50.3-68.9 years).

CONCLUSION

The prevalence of bronchiectasis burden among Indigenous adults in the Top End of the NT is high, but differed by health district, as is all-cause mortality among adults with bronchiectasis. The socio-demographic and other factors that contribute to the high prevalence of bronchiectasis among Indigenous Australians should be investigated so that interventions for reducing its burden can be developed.

The Respiratory Microbiome in Paediatric Chronic Wet Cough: What Is Known and Future Directions

Chronic wet cough for longer than 4 weeks is a hallmark of chronic suppurative lung diseases (CSLD), including protracted bacterial bronchitis (PBB), and bronchiectasis in children. Severe lower respiratory infection early in life is a major risk factor of PBB and paediatric bronchiectasis. In these conditions, failure to clear an underlying endobronchial infection is hypothesised to drive ongoing inflammation and progressive tissue damage that culminates in irreversible bronchiectasis. Historically, the microbiology of paediatric chronic wet cough has been defined by culture-based studies focused on the detection and eradication of specific bacterial pathogens. Various 'omics technologies now allow for a more nuanced investigation of respiratory pathobiology and are enabling development of endotype-based models of care. Recent years have seen substantial advances in defining respiratory endotypes among adults with CSLD; however, less is understood about diseases affecting children. In this review, we explore the current understanding of the airway microbiome among children with chronic wet cough related to the PBB-bronchiectasis diagnostic continuum. We explore concepts emerging from the gut-lung axis and multi-omic studies that are expected to influence PBB and bronchiectasis endotyping efforts. We also consider how our evolving understanding of the airway microbiome is translating to new approaches in chronic wet cough diagnostics and treatments.

The emerging association between bronchiectasis and systemic sclerosis: assessing prevalence and potential causality

BACKGROUND

Bronchiectasis has been observed in association with systemic sclerosis (SSc). Theorised aetiology includes aspiration related to oesophageal dysmotility, immunosuppressant medication use and the direct effect of collagen deposition on airway calibre.

AIMS

To detail bronchiectasis prevalence in an SSc population who have had a high-resolution computed tomography (HRCT) of the thorax. We assessed whether oesophageal dysmotility, demographic variables, SSc duration or subclass were associated with bronchiectasis.

METHODS

Participants in the Australian Scleroderma Cohort Study (ASCS) with a HRCT were included. The ASCS provided demographic and clinical data. HRCT studies were reviewed for bronchiectasis, oesophageal dilatation and interstitial lung disease (ILD). Traction bronchiectasis associated with ILD was recorded as a separate entity to bronchiectasis. Oesophageal dysmotility was defined by symptoms and/or oesophageal dilatation.

RESULTS

Of the 256 participants, 16.4% (n = 42) had bronchiectasis. Logistic regression analysis revealed no significant association between bronchiectasis and oesophageal dysmotility (observed in 95.7%), any demographic variable, SSc duration or subclass. A negative association between bronchiectasis and ILD was observed (P = 0.009; odds ratio 0.322; 95% confidence intervals 0.137-0.756).

CONCLUSION

Those with SSc appear to have an increased risk for bronchiectasis. Since bronchiectasis was not more frequent in participants with a longer duration of SSc, we hypothesise that its development is not related to immunosuppression alone. Oesophageal dysmotility was almost universal in our population such that its effect on bronchiectasis development could not be concluded. A negative association between bronchiectasis and ILD reflects that bronchiectasis occurring alongside ILD was recorded as a separate entity.

Research on HTLV-1 and HTLV-2 in Latin America and the Caribbean over the last ten years

Worldwide, Human T-lymphtropic virus-1 and 2 (HTLV-1 and 2) infects approximately more than 10 million people, mostly occurring in hyperendemic areas such as the region of Latin America and the Caribbean (LAC). A comprehensive bibliographic exploration of original articles published on the Web of Science Core Collection database over the last 10 years was done. A bibliometric analysis was performed using the bibliometrix package in RStudio and VOSviewer. A total of 519 articles published in 194 journals were identified along the 10 years studied. In 2012 the peak number of publications was identified and the average number of citations per document was 1.33. Galvao-Castro B was the author with the greatest number of publications. Aids Research and Human Retroviruses was the most productive journal, and the study by Bangham CRM was the most cited. Brazil was the country with most corresponding authors that had the most publications and the most significant number of total citations. Infections and HTLV-1 were the most used keywords. In conclusion, according to the current quantitative analysis, there is a need for more significant promotion of research on HTLV-1 and 2 among the scientific community of LAC.

HTLV-I associated bronchioloalveolar disorder (HABA): disease concept and differential diagnosis of an unsolved disease entity

INTRODUCTION

Human T-cell leukemia virus type 1 (HTLV-I) associated bronchioloalveolar disorder (HABA) is a chronic and progressive bronchiolar/alveolar disorder related to HTLV-1 infection. Clinical knowledge and guidance are lacking for the diagnosis and management of this condition.

AREAS COVERED

This work aimed to review the latest information and challenges regarding HABA diagnosis and treatment.

EXPERT OPINION

HABA is an immune-mediated state induced by HTLV-1. For diagnosis of HABA, other infectious diseases and pulmonary infiltration of adult T-cell leukemia should be excluded by investigations such as computed tomography (CT), transbronchial biopsy, and bronchoalveolar lavage fluid (BALF) analysis. Typical CT findings in HABA include diffuse panbronchiolitis-like or bronchiectasis patterns, whereas cases with other abnormalities, including interstitial pneumonia, have also been reported. A high rate of polyclonal CD4+ and CD25+ lymphocytes is detected in BALF of patients with HABA, reflecting the infiltration of HTLV-1 infected T-cells in the lung. Current treatment options are not HABA specific, and include corticosteroids, macrolide antibiotics, and pirfenidone. Mitigation of the adverse effects of HTLV-1 infection requires the establishment of diagnostic criteria for the disease, screening programs for HABA in HTLV-1 infected individuals, and the development of effective disease treatment strategies.

Prevalence and Risk Factors for HTLV-1/2 Infection in Quilombo Remnant Communities Living in the Brazilian Amazon

Human T-lymphotropic viruses 1 and 2 (HTLV-1 and HTLV-2) are retroviruses that originated on the African continent and dispersed throughout other continents through human migratory flows. This study describes the prevalence of HTLV-1 and HTLV-2 infection in residents of 11 quilombo remnant communities in the state of Pará, Brazil, and the associated risk factors. A total of 859 individuals (334 men and 525 women), aged between 7 and 91 years, participated in the study. All subjects answered a questionnaire with questions on sociodemographic characteristics and on risk factors associated with HTLV infection, and blood samples were collected and separated into plasma and leukocytes. An immunoenzymatic assay (ELISA; Murex HTLV-I+II, DiaSorin, Dartford, UK) was used as a screening test, and positive samples were subjected to line immunoassay confirmatory tests (Inno-LIA HTLV I/II Score FUJIREBIO) and DNA extraction for subsequent real-time PCR to differentiate the viral type. Four of the 859 individuals were seropositive for HTLV. HTLV-1 infection was confirmed in one individual from the Itamoari community (0.92%), and HTLV-2 infection was confirmed in two individuals from São Benedito (3.17%) and in one individual from Arimandeua (2.22%). Blood transfusion was the only risk factor associated with HTLV infection in this study. This study reports the occurrence of HTLV-1 and HTLV-2 in quilombo remnant communities in the state of Pará. Considering the African origin of the virus and its introduction into Brazil from the slave trade, the continued evaluation of quilombola communities in the state of Pará is essential to better characterize the distribution of infections in these populations and to create public health policies for the control of the spread of the virus and associated diseases.

Reflections on Some of the Exceptional Features of HTLV-1 and HTLV-1 Research: A Perspective

The report is not a review or a summary. In a manner, it is a perspective but an unusual one. It looks back to the years my colleagues and I (RG) began preparing for human retroviruses (beginning in 1970), how they evolved, and attempts to bring to light or simply to emphasize many exceptional characteristics of a retrovirus known as HTLV-1 and some fortuitous coincidences, with emphasis on the needs of the field. These events cover over one half a century. We have had many reviews on HTLV-1 disease, epidemiology, and basic aspects of its replication, genome, gene functions, structure, and pathogenesis, though continued updates are needed. However, some of its truly exceptional features have not been highlighted, or at least not in a comprehensive manner. This article attempts to do so.

Transcriptional regulators of human oncoviruses: structural and functional implications for anticancer therapy

Transcription is often the first biosynthetic event of viral infection. Viruses produce preferentially viral transcriptional regulators (vTRs) essential for expressing viral genes and regulating essential host cell proteins to enable viral genome replication. As vTRs are unique viral proteins that promote the transcription of viral nucleic acid, vTRs interact with host proteins to suppress detection and immune reactions to viral infection. Thus, vTRs are promising therapeutic targets that are sequentially and structurally distinct from host cell proteins. Here, we review vTRs of three human oncoviruses: HBx of hepatitis B virus, HBZ of human T-lymphotropic virus type 1, and Rta of Epstein–Barr virus. We present three cunningly exciting and dangerous transcription strategies that make viral infections so efficient. We use available structural and functional knowledge to critically examine the potential of vTRs as new antiviral-anticancer therapy targets. For each oncovirus, we describe (i) the strategy of viral genome transcription; (ii) vTRs’ structure and binding partners essential for transcription regulation; and (iii) advantages and challenges of vTR targeting in antiviral therapies. We discuss the implications of vTR regulation for oncogenesis and perspectives on developing novel antiviral and anticancer strategies.

Human T-Cell Lymphotropic Virus Type 1 and Strongyloides stercoralis Co-infection: A Systematic Review and Meta-Analysis

Background

The distribution of human T cell lymphotropic virus type 1 (HTLV-1) overlaps with that of Strongyloides stercoralis. Strongyloides stercoralis infection has been reported to be impacted by co-infection with HTLV-1. Disseminated strongyloidiasis and hyperinfection syndrome, which are commonly fatal, are observed in HTLV-1 co-infected patients. Reduced efficacy of anti-strongyloidiasis treatment in HTLV-1 carriers has been reported. The aim of this meta-analysis and systematic review is to better understand the association between HTLV-1 and S. stercoralis infection.

Methods

PubMed, Embase, MEDLINE, Global Health, Healthcare Management Information Consortium databases were searched. Studies regarding the prevalence of S. stercoralis, those evaluating the frequency of mild or severe strongyloidiasis, and treatment response in people living with and without HTLV-1 infection were included. Data were extracted and odds ratios were calculated. Random-effect meta-analysis was used to assess the pooled OR and 95% confidence intervals.

Results

Fourteen studies were included after full-text reviewing of which seven described the prevalence of S. stercoralis and HTLV-1. The odds of S. stercoralis infection were higher in HTLV-1 carriers when compared with HTLV-1 seronegative subjects (OR 3.2 95%CI 1.7–6.2). A strong association was found between severe strongyloidiasis and HTLV-1 infection (OR 59.9, 95%CI 18.1–198). Co-infection with HTLV-1 was associated with a higher rate of strongyloidiasis treatment failure (OR 5.05, 95%CI 2.5–10.1).

Conclusion

Strongyloides stercoralis infection is more prevalent in people living with HTLV-1. Co-infected patients are more likely to develop severe presentation and to fail treatment. Screening for HTLV-1 and Strongyloides sp. should be routine when either is diagnosed.

Refining the risk of HTLV-1-associated myelopathy in people living with HTLV-1: identification of a HAM-like phenotype in a proportion of asymptomatic carriers

Up to 3.8% of human T-lymphotropic virus type-1 (HTLV-1)-infected asymptomatic carriers (AC) eventually develop HTLV-1-associated myelopathy (HAM). HAM occurs in patients with high (> 1%) HTLV proviral load (PVL). However, this cut-off includes more than 50% of ACs and therefore the risk needs to be refined. As HAM is additionally characterised by an inflammatory response to HTLV-1, markers of T cell activation (TCA), β₂-microglobulin (β₂M) and neuronal damage were accessed for the identification of ACs at high risk of HAM. Retrospective analysis of cross-sectional and longitudinal routine clinical data examining differences in TCA (CD4/CD25, CD4/HLA-DR, CD8/CD25 & CD8/HLA-DR), β₂M and neurofilament light (NfL) in plasma in ACs with high or low PVL and patients with HAM. Comparison between 74 low PVL ACs, 84 high PVL ACs and 58 patients with HAM revealed a significant, stepwise, increase in TCA and β₂M. Construction of receiver operating characteristic (ROC) curves for each of these blood tests generated a profile that correctly identifies 88% of patients with HAM along with 6% of ACs. The 10 ACs with this 'HAM-like' profile had increased levels of NfL in plasma and two developed myelopathy during follow-up, compared to none of the 148 without this viral-immune-phenotype. A viral-immuno-phenotype resembling that seen in patients with HAM identifies asymptomatic carriers who are at increased risk of developing HAM and have markers of subclinical neuronal damage.

Computed tomography with 6-year follow-up demonstrates the evolution of HTLV-1 related lung injuries: A cohort study

Previous observational studies have demonstrated the development of pulmonary impairments in human T-lymphotropic virus type 1 (HTLV-1) infected individuals. The main observed lesions due to chronic inflammation of viral infection in situ are bronchiectasis and lung-scarring injuries. This lung inflammation may be the causal agent of restrictive and obstructive lung diseases, primarily in tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP-HAM) patients. We conducted a prospective cohort study to compare spirometry and high-resolution computed tomography (HRCT) findings among 28 HTLV-1-carrier patients over the course of 6 years (2014–2019) (male/female: 7/21; mean age: 54.7 ± 9.5, range: 41–68 years). Chest HRCT exams revealed the development and evolution of lung lesions related to TSP-HAM: including centrilobular nodules, parenchymal bands, lung cysts, bronchiectasis, ground-glass opacity, mosaic attenuation, and pleural thickening. Spirometry exams showed maintenance of respiratory function, with few alterations in parameters suggestive of obstructive and restrictive disorders primarily in individuals with lung lesions and TSP-HAM. The findings of the present study indicate that pulmonary disease related to HTLV-1 is a progressive disease, with development of new lung lesions, mainly in individuals with TSP-HAM. To improve clinical management of these individuals, we recommend that individuals diagnosed with PET-MAH undergo pulmonary evaluation.

Very high prevalence of infection with the human T cell leukaemia virus type 1c in remote Australian Aboriginal communities: Results of a large cross-sectional community survey

Infection with the human T cell leukaemia virus type 1 (HTLV-1) subtype C is endemic among Aboriginal people in central Australia. To provide insights into the risk factors for transmission, we conducted the first large-scale, community-based prevalence study in seven remote Aboriginal communities. Residents >2 years old were invited to participate in the study between August 2014 and June 2018. HTLV-1 infection was defined as a positive western blot (WB) test or a positive HTLV-1 PCR. 720 community residents participated in the study (children <15 years, 142; adults, 578). Prevalences for children and adults were 3.5% (5/142) and 36.8% (213/578), respectively, reaching 49.3% (106/215) for those older than 45 years. A wide range of proviral loads were measured for both asymptomatic and symptomatic participants with no difference within groups according to age or gender; however, median PVL was 1.34 log10 higher for symptomatic participants. The adult prevalence of HTLV-1 infection in central Australia is the highest reported worldwide. Sexual contact is likely to be the predominant mode of transmission.

Clinical, Radiological and Functional Characteristics of Pulmonary Diseases among HTLV-1 Infected Patients without Prior Active Tuberculosis Infection

The lifelong infection with the human T lymphotropic virus type 1 (HTLV-1) has been associated with a variety of clinical manifestations; one of the less-explored is HTLV-1-associated pulmonary disease. Imaging of lung damage caused by the HTLV-1 hyperinflammatory cascade can be similar to sequelae from TB infection. Our study aims to describe the pulmonary lesions of HTLV-1-positive patients without past or current active TB and evaluate pulmonary function. We found that nine out of fourteen patients with no known TB disease history presented bronchiectasis, mainly found bilaterally while five presented pulmonary fibrosis. A normal pattern was found in most patients with a pulmonary functional test. Furthermore, there was no association between the PVL and the chest-CT scan findings, nor with spirometry results. However, the sample size was insufficient to conclude it.

How I treat adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive T-cell malignancy that arises in a proportion of individuals who are long-term carriers of human T-lymphotropic virus type 1. The median survival of aggressive subtypes is 8 to 10 months; with chemotherapy-based approaches, overall survival has remained largely unchanged in the ∼35 years since ATL was first described. Through the use of 4 representative case studies, we highlight advances in the biological understanding of ATL and the use of novel therapies such as mogamulizumab, as well as how they are best applied to different subtypes of ATL. We discuss the implementation of molecular methods that may guide diagnosis or treatment, although we accept that these are not universally available. In particular, we acknowledge discrepancies in treatment between different countries, reflecting current drug licensing and the difficulties in making treatment decisions in a rare disease, with limited high-quality clinical trial data.

Comparison of Profiles of First Nations and Non-First Nations Children With Bronchiectasis Over Two 5-Year Periods in the Northern Territory, Australia

BACKGROUND

Although the burden of bronchiectasis is recognized globally, pediatric data are limited, particularly on trends over the years. Also, no published data exists regarding whether vitamin D deficiency or insufficiency and human T-cell lymphotropic virus type 1 (HTLV-1) infection, both found to be related to severe bronchiectasis in First Nations adults, also are important in children with bronchiectasis.

RESEARCH QUESTION

Among children with bronchiectasis, (1) have the clinical and BAL profiles changed between two 5-year periods (period 1, 2007-2011; period 2, 2012-2016) and (b) are vitamin D deficiency or insufficiency, HTLV-1 infection, or both associated with radiologic severity of bronchiectasis?

STUDY DESIGN AND METHODS

We analyzed the data from children with bronchiectasis prospectively enrolled at Royal Darwin Hospital, Australia, at the first diagnosis; that is, no child was included in both periods. Data collected include demographics, BAL, bloods, and high-resolution CT scan of the chest evaluated using the Bhalla and modified Bhalla scores.

RESULTS

The median age of the 299 children was 2.2 years (interquartile range, 1.5-3.7 years). One hundred sixty-eight (56%) were male and most were First Nations (92%). Overall, bronchiectasis was high over time, particularly among First Nations children. In the later period, numbers of non-First Nations children more than tripled, but did not reach statistical significance. In period 2 compared with period 1, fewer First Nations children demonstrated chronic cough (period 1, 61%; period 2, 47%; P = .03), were younger, First Nations children were less likely to have received azithromycin (period 1, 42%; period 2, 21%; P < .001), and the BAL fluid of First Nations children showed lower Haemophilus influenzae and Moraxella catarrhalis infection. HTLV-1 infection was not detected, and vitamin D deficiency or insufficiency did not correlate with severity of bronchiectasis.

INTERPRETATION

Bronchiectasis remains high particularly among First Nations children. Important changes in their profiles that arguably reflect improvements were present, but overall, the profiles remained similar. Although vitamin D deficiency was uncommon, its role in children with bronchiectasis requires further evaluation. HTLV-1 infection was nonexistent and is unlikely to play any role in First Nations children with bronchiectasis.

Human T-cell leukaemia virus type 1 associated pulmonary disease: clinical and pathological features of an under-recognised complication of HTLV-1 infection

The lung is one of several organs that can be affected by HTLV-1 mediated inflammation. Pulmonary inflammation associated with HTLV-1 infection involves the interstitium, airways and alveoli, resulting in several clinical entities including interstitial pneumonias, bronchiolitis and alveolitis, depending on which structures are most affected. Augmentation of the inflammatory effects of HTLV-1 infected lymphocytes by recruitment of other inflammatory cells in a positive feedback loop is likely to underlie the pathogenesis of HTLV-1 associated pulmonary disease, as has been proposed for HTLV-1 associated myelopathy. In contrast to the conclusions of early case series, HTLV-1 associated pulmonary disease can be associated with significant parenchymal damage, which may progress to bronchiectasis where this involves the airways. Based on our current understanding of HTLV-1 associated pulmonary disease, diagnostic criteria are proposed.

HTLV-I and Strongyloides in Australia: The worm lurking beneath

Strongyloidiasis and HTLV-I (human T-lymphotropic virus-1) are important infections that are endemic in many countries around the world with an estimated 370 million infected with Strongyloides stercoralis alone, and 5-10 million with HTVL-I. Co-infections with these pathogens are associated with significant morbidity and can be fatal. HTLV-I infects T-cells thus causing dysregulation of the immune system which has been linked to dissemination and hyperinfection of S. stercoralis leading to bacterial sepsis which can result in death. Both of these pathogens are endemic in Australia primarily in remote communities in Queensland, the Northern Territory, and Western Australia. Other cases in Australia have occurred in immigrants and refugees, returned travellers, and Australian Defence Force personnel. HTLV-I infection is lifelong with no known cure. Strongyloidiasis is a long-term chronic disease that can remain latent for decades, as shown by infections diagnosed in prisoners of war from World War II and the Vietnam War testing positive decades after they returned from these conflicts. This review aims to shed light on concomitant infections of HTLV-I with S. stercoralis primarily in Australia but in the global context as well.

Epidemiology and Microbiology of Severe Community-Acquired Pneumonia in Central Australia: A Retrospective Study

BACKGROUND

Severe community-acquired pneumonia (SCAP) has high mortality and morbidity.

AIMS

To describe the epidemiology and microbiology of SCAP in Central Australia.

METHODS

A retrospective epidemiological study describing the characteristics, incidence rates (IR) and microbiological aetiology of SCAP in Central Australia. Adult patients admitted to Alice Springs Hospital Intensive Care Unit (ICU) between 2011-2014 that fitted the IDSA/ATS definition of SCAP were included. Medical records were reviewed and compared between Indigenous and non-Indigenous patients. Primary outcomes were incidence rate and microbiological aetiology of SCAP. Secondary outcomes were 30-day mortality, and ICU and hospital length of stay (LoS).

RESULTS

A total of 185 patents were included (156 Indigenous, 29 non-Indigenous). The overall SCAP IR per 1000 person-years was 3.24 (3.75 Indigenous and 1.87 non-Indigenous) with an IR difference of 2.71 after adjustment (p<0.001). Those aged ≥50 had an IR 74.8% higher than those younger. Male IR was 50% higher than females. There was a significant difference between Indigenous and non-Indigenous groups for age (48 vs. 64 years), but not for 30-day mortality (7.7% vs. 10.3%), ICU LoS (4.8 vs. 4.6 days) and hospital LoS (10.9 vs. 15.1 days), respectively. Likely causative pathogen(s) were identified in 117 patients; Streptococcus pneumoniae was the most common pathogen (28.2%), followed by Haemophilus influenzae (19.7%), Influenza A/B (16.2%) and Staphylococcus aureus (14.5%).

CONCLUSION

A high incidence of SCAP was observed in Central Australia, disproportionately affecting the Indigenous population. Prevention strategies are imperative, as well as early identification of SCAP and appropriate empiric antibiotic regimens. This article is protected by copyright. All rights reserved.

Human T-cell lymphotropic virus type-1: a lifelong persistent infection, yet never truly silent

Human T-cell lymphotropic virus type-1 (HTLV-1) has a large global burden and in some key communities, such as Indigenous Australians living in remote areas, greater than 45% of people are infected. Despite HTLV-1 causing serious malignancy and myelopathic paraparesis, and a significant association with a range of inflammatory comorbidities and secondary infections that shorten lifespan, few biomedical interventions are available. HTLV-1 starkly contrasts with other blood-borne sexually transmitted viral infections, such as, HIV, hepatitis B virus, and hepatitis C virus, with no antiviral treatments that reduce virus-infected cells, no rapid diagnostics or biomarker assays suitable for use in remote settings, and no effective vaccine. We review how the replication strategies and molecular properties of HTLV-1 establish a long-term stealthy viral pathogenesis through a fine-tuned balance of persistence, immune cell dysfunction, and proliferation of proviral infected cells that collectively present robust barriers to treatment and prevention. An understanding of the nature of the HTLV-1 provirus and opposing actions of viral-coded negative-sense HBZ and positive-sense regulatory proteins Tax, p12 and its cleaved product p8, and p30, is needed to improve the biomedical tools for preventing transmission and improving the long-term health of people with this lifelong infection.

Pulmonary Disease Is Associated With Human T-Cell Leukemia Virus Type 1c Infection: A Cross-sectional Survey in Remote Aboriginal Communities

Background

The human T-cell leukemia virus type 1 (HTLV-1) subtype c is endemic to central Australia. We report the first large-scale, community-based, health survey of HTLV-1 and its disease associations in this setting.

Methods

Aboriginal community residents aged &gt;2 years in 7 remote communities were invited to do a health survey that included a questionnaire, spirometry, and clinical examination by a physician blinded to HTLV-1 status, clinical records, and spirometry results. Blood was drawn for HTLV-1 serology and proviral load (PVL). Pulmonary disease was assessed clinically and spirometrically and, where records were available, radiologically after the clinical assessment. Associations between specific diseases and HTLV-1 status were determined using logistic regression, adjusting for available confounders.

Results

Overall, 579 residents (164 children aged 3–17 years; 415 adults) were examined (37.7% of the estimated resident population). HTLV-1 prevalences for children and adults were 6.1% and 39.3%, respectively. No associations were found between HTLV-1 and any assessed clinical condition among children. Chronic pulmonary disease and gait abnormalities were more common among adults with HTLV-1 infection. Adjusted odds ratios among participants with PVL ≥1000 per 105 peripheral blood leukocytes were 7.08 (95% confidence interval [CI], 2.67–18.74; P &lt; .001), 9.81 (95% CI, 3.52–27.35; P &lt; .001), and 14.4 (95% CI, 4.99–41.69; P &lt; .001) for clinically defined chronic pulmonary disease, moderate-severe expiratory airflow limitation, and radiologically determined bronchiectasis/bronchiolitis, respectively, and 5.21 (95% CI, 1.50–18.07; P = .009) for gait abnormalities.

Conclusions

In the first study of HTLV-1 disease associations based on community recruitment and blinded assessment, HTLV-1 infection was strongly associated with pulmonary disease and gait abnormalities.

Functional properties and sequence variation of HTLV-1 p13

Human T cell leukemia virus type-1 (HTLV-1) was the first retrovirus found to cause cancer in humans, but the mechanisms that drive the development of leukemia and other diseases associated with HTLV-1 infection remain to be fully understood. This review describes the functional properties of p13, an 87-amino acid protein coded by HTLV-1 open reading frame II (orf-II). p13 is mainly localized in the inner membrane of the mitochondria, where it induces potassium (K⁺) influx and reactive oxygen species (ROS) production, which can trigger either proliferation or apoptosis, depending on the ROS setpoint of the cell. Recent evidence indicates that p13 may influence the cell’s innate immune response to viral infection and the infected cell phenotype. Association of the HTLV-1 transcriptional activator, Tax, with p13 increases p13’s stability, leads to its partial co-localization with Tax in nuclear speckles, and reduces the ability of Tax to interact with the transcription cofactor CBP/p300. Comparison of p13 sequences isolated from HTLV-1-infected individuals revealed a small number of amino acid variations in the domains controlling the subcellular localization of the protein. Disruptive mutations of p13 were found in samples obtained from asymptomatic patients with low proviral load. p13 sequences of HTLV-1 subtype C isolates from indigenous Australian patients showed a high degree of identity among each other, with all samples containing a pattern of 5 amino acids that distinguished them from other subtypes. Further characterization of p13’s functional properties and sequence variants may lead to a deeper understanding of the impact of p13 as a contributor to the clinical manifestations of HTLV-1 infection.

Molecular epidemiology, genetic variability and evolution of HTLV-1 with special emphasis on African genotypes

Human T cell leukemia virus (HTLV-1) is an oncoretrovirus that infects at least 10 million people worldwide. HTLV-1 exhibits a remarkable genetic stability, however, viral strains have been classified in several genotypes and subgroups, which often mirror the geographic origin of the viral strain. The Cosmopolitan genotype HTLV-1a, can be subdivided into geographically related subgroups, e.g. Transcontinental (a-TC), Japanese (a-Jpn), West-African (a-WA), North-African (a-NA), and Senegalese (a-Sen). Within each subgroup, the genetic diversity is low. Genotype HTLV-1b is found in Central Africa; it is the major genotype in Gabon, Cameroon and Democratic Republic of Congo. While strains from the HTLV-1d genotype represent only a few percent of the strains present in Central African countries, genotypes -e, -f, and -g have been only reported sporadically in particular in Cameroon Gabon, and Central African Republic. HTLV-1c genotype, which is found exclusively in Australo-Melanesia, is the most divergent genotype. This reflects an ancient speciation, with a long period of isolation of the infected populations in the different islands of this region (Australia, Papua New Guinea, Solomon Islands and Vanuatu archipelago). Until now, no viral genotype or subgroup is associated with a specific HTLV-1-associated disease. HTLV-1 originates from a simian reservoir (STLV-1); it derives from interspecies zoonotic transmission from non-human primates to humans (ancient or recent). In this review, we describe the genetic diversity of HTLV-1, and analyze the molecular mechanisms that are at play in HTLV-1 evolution. Similar to other retroviruses, HTLV-1 evolves either through accumulation of point mutations or recombination. Molecular studies point to a fairly low evolution rate of HTLV-1 (between 5.6E−7 and 1.5E−6 substitutions/site/year), supposedly because the virus persists within the host via clonal expansion (instead of new infectious cycles that use reverse transcriptase).

Noninvasive Detection of Antibodies to Human T-Cell Lymphotropic Virus Types 1 and 2 by Use of Oral Fluid

Human T-lymphotropic viruses type 1 and 2 (HTLV-1/2) are prevalent in endemic clusters globally, and HTLV-1 infects at least 5 to 10 million individuals. Infection can lead to inflammation in the spinal cord, resulting in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or adult T cell leukemia/lymphoma (ATL). Obtaining venous blood for serological screening, typically performed using enzyme immunoassays (EIAs), is invasive, sometimes socially unacceptable, and has restricted large-scale seroprevalence studies. Collecting oral fluid (OF) is a noninvasive alternative to venesection. In this study, an IgG antibody capture EIA was developed and validated to detect anti-HTLV-1/2 IgG in OF. OF and plasma specimens were obtained from seropositive HTLV-1/2-infected patients attending the National Centre for Human Retrovirology (n = 131) and from HTLV-1/2-uninfected individuals (n = 64). The assay showed good reproducibility and high diagnostic sensitivity (100%) and specificity (100%) using both OF and plasma. The Murex HTLV I+II commercial assay was evaluated and did not detect anti-HTLV-1/2 IgG in 14% (5/36) of OF specimens from seropositive donors. The reactivities of OF and plasma in the IgG capture correlated strongly (r = 0.9290) and were not significantly affected by delayed extraction when held between 3°C and 45°C for up to 7 days to simulate field testing. The use of OF serological screening for HTLV-1/2 infection could facilitate large-scale seroprevalence studies, enabling active surveillance of infection on a population level.

Predictors of non-cystic fibrosis bronchiectasis in Indigenous adult residents of central Australia: results of a case-control study

The human T-cell leukaemia virus type 1 (HTLV-1) is associated with pulmonary inflammation. Indigenous Australians in central Australia have a very high prevalence of HTLV-1 infection and we hypothesised that this might contribute to high rates of bronchiectasis in this population. 80 Indigenous adults with confirmed bronchiectasis, each matched by age, sex and language to two controls without bronchiectasis, were recruited. Case notes and chest imaging were reviewed, HTLV-1 serology and the number of peripheral blood leukocytes (PBLs) infected with HTLV-1 (pro-viral load (PVL)) were determined, and radiological abnormality scores were calculated. Participants were followed for a mean±sd of 1.14±0.86 years and causes of death were determined. Median (interquartile range) HTLV-1 PVL for cases was 8-fold higher than controls (cases 213.8 (19.7-3776.3) copies per 105 PBLs versus controls 26.6 (0.9-361) copies per 105 PBLs; p=0.002). Radiological abnormality scores were higher for cases with HTLV-1 PVL ≥1000 copies per 105 PBLs and no cause of bronchiectasis other than HTLV-1 infection. Major predictors of bronchiectasis were prior severe lower respiratory tract infection (adjusted OR (aOR) 17.83, 95% CI 4.51-70.49; p<0.001) and an HTLV-1 PVL ≥1000 copies per 105 PBLs (aOR 12.41, 95% CI 3.84-40.15; p<0.001). Bronchiectasis (aOR 4.27, 95% CI 2.04-8.94; p<0.001) and HTLV-1 PVL ≥1000 copies per 105 PBLs (aOR 3.69, 95% CI 1.11-12.27; p=0.033) predicted death. High HTLV-1 PVLs are associated with bronchiectasis and with more extensive radiological abnormalities, which may result from HTLV-1-mediated airway inflammation.

Impact of host immunity on HTLV-1 pathogenesis: potential of Tax-targeted immunotherapy against ATL

Human T-cell leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other inflammatory diseases. There is no disease-specific difference in viral strains, and it is unclear how HTLV-1 causes such different diseases manifesting as lymphoproliferation or inflammation. Although some progress has been made in therapies for these diseases, the prognosis for ATL is still dismal and HAM/TSP remains an intractable disease. So far, two regulatory proteins of HTLV-1, Tax and HBZ, have been well studied and shown to have pleiotropic functions implicated in viral pathogenesis. Tax in particular can strongly activate NFκB, which is constitutively activated in HTLV-1-infected cells and considered to contribute to both oncogenesis and inflammation. However, the expression level of Tax is very low in vivo, leading to confusion in understanding its role in viral pathogenesis. A series of studies using IL-2-dependent HTLV-1-infected cells indicated that IL-10, an anti-inflammatory/immune suppressive cytokine, could induce a proliferative phenotype in HTLV-1-infected cells. In addition, type I interferon (IFN) suppresses HTLV-1 expression in a reversible manner. These findings suggest involvement of host innate immunity in the switch between lymphoproliferative and inflammatory diseases as well as the regulation of HTLV-1 expression. Innate immune responses also affect another important host determinant, Tax-specific cytotoxic T lymphocytes (CTLs), which are impaired in ATL patients, while activated in HAM/TSP patients. Activation of Tax-specific CTLs in ATL patients after hematopoietic stem cell transplantation indicates Tax expression and its fluctuation in vivo. A recently developed anti-ATL therapeutic vaccine, consisting of Tax peptide-pulsed dendritic cells, induced Tax-specific CTL responses in ATL patients and exhibited favorable clinical outcomes, unless Tax-defective ATL clones emerged. These findings support the significance of Tax in HTLV-1 pathogenesis, at least in part, and encourage Tax-targeted immunotherapy in ATL. Host innate and acquired immune responses induce host microenvironments that modify HTLV-1-encoded pathogenesis and establish a complicated network for development of diseases in HTLV-1 infection. Both host and viral factors should be taken into consideration in development of therapeutic and prophylactic strategies in HTLV-1 infection.

High prevalence of pulmonary findings in computed tomographies of HTLV-1-infected patients with and without adult-T cell leukemia/lymphoma - implications for staging

Lung involvement has been reported in HTLV-1 carriers and in patients with ATLL. Whether there are differences in the pattern of lung involvement between ATLL and HTLV carriers in North American patients is unknown. We aimed to compare CT pulmonary findings among patients with HTLV-1 infection with and without ATLL. Among 140 patients with HTLV-1 diagnosis, 97 had CT chest available. Of these, 72 (74.2%) had ATLL and 25 (25.8%) did not have ATLL. CT chest abnormalities were present in 90 (92.8%) participants (94.4% in ATLL; 88% in non-ATLL). Higher rates of lymphadenopathy (69.4% versus 24%, p < .01) and lower rates of bronchiectasis (25% versus 48%, p = .04) were seen in ATLL compared to non-ATLL. Our study supports that staging of lung involvement in ATLL should consider HTLV-associated pulmonary findings as not all CT chest abnormalities necessarily represent malignant infiltration.

HTLV-1 is rare in Far North Queensland despite a significant burden of classically associated diseases

Human T-lymphotropic virus type 1 (HTLV-1) is hyperendemic amongst Indigenous Australians living in Central Australia. The epidemiology of the disease is poorly defined in other parts of Australia, despite a high prevalence of classically associated conditions. All HTLV-1 serology tests requested through public health facilities in Far North Queensland (FNQ) from January 1999 to December 2016 were reviewed. The person's age, sex, ethnicity, location, rationale for testing and result were recorded. There were 444 tests performed in 409 people; 217 (53%) were male; 171 (42%) identified as Indigenous Australians. Testing increased over time and was performed throughout the region, suggesting increasing awareness of the disease. Testing occurred in patients with haematological, neurological, dermatological and respiratory complaints, but only four (1%) had proven infection. Three of these individuals were in the same family and two were asymptomatic. One of the two symptomatic seropostive individuals had recurrent scabies infection, the other T-cell lymphoma. HTLV-1 infection is extremely uncommon in FNQ. The high rates of bronchiectasis and other associated conditions that are seen in the region are more likely to be addressed by public health policies focusing on the socioeconomic determinants of health.

Isolated Neurogenic Bladder Associated With Human T-Lymphotropic Virus Type 1 Infection in a Renal Transplant Patient From Central Australia: A Case Report

BACKGROUND

Human T-lymphotropic virus type 1 (HTLV-1) is endemic amongst the Aborigines of the Northern Territory of Australia. HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been associated with this infection. In general population, isolated neurogenic bladder dysfunction in HTLV-1-infected individuals without HAM/TSP has been reported, and the HTLV-1 proviral load has been found to be higher in such patients compared with asymptomatic carriers. In solid organ transplantation, few cases of HAM/TSP have been reported worldwide, but not an isolated neurogenic bladder.

CASE

A 50-year-old indigenous women from Alice Springs with end stage renal disease secondary to diabetic nephropathy with no prior history of bladder dysfunction received a cadaveric renal allograft following which she developed recurrent urinary tract infections. The recipient was seropositive for HTLV-1 infection. HTLV-1 status of donor was not checked. Urodynamic studies revealed stress incontinence and detrusor overactivity without urethral intrinsic sphincter deficiency. She had no features of myelopathy. There was elevation of the serum and cerebrospinal fluid HTLV-1 proviral load. The magnetic resonance imaging myelogram was normal. Pyelonephritis was diagnosed based on clinical features, positive cultures, and renal allograft biopsy. Continuous suprapubic catheter drainage helped preventing further episodes of allograft pyelonephritis in spite of chronic colonization of the urinary tract.

CONCLUSION

Isolated bladder dysfunction is a rare manifestation of HTLV-1 infection and is probably associated with high proviral loads. This may adversely affect renal allograft and patient outcomes.

The Role of the Immune Response in the Pathogenesis of Bronchiectasis

Bronchiectasis is a prevalent respiratory condition characterised by permanent and abnormal dilation of the lung airways (bronchi). There are a large variety of causative factors that have been identified for bronchiectasis; all of these compromise the function of the immune response to fight infection. A triggering factor may lead to the establishment of chronic infection in the lower respiratory tract. The bacteria responsible for the lower respiratory tract infection are usually found as commensals in the upper respiratory tract microbiome. The consequent inflammatory response to infection is largely responsible for the pathology of this condition. Both innate and adaptive immune responses are activated. The literature has highlighted the central role of neutrophils in the pathogenesis of bronchiectasis. Proteases produced in the lung by the inflammatory response damage the airways and lead to the pathological dilation that is the pathognomonic feature of bronchiectasis. The small airways demonstrate infiltration with lymphoid follicles that may contribute to localised small airway obstruction. Despite aggressive treatment, most patients will have persistent disease. Manipulating the immune response in bronchiectasis may potentially have therapeutic potential.

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.

Bronchiectasis in indigenous and non-indigenous residents of Australia and New Zealand

BACKGROUND AND OBJECTIVE

Bronchiectasis not associated with cystic fibrosis is an increasingly recognized chronic lung disease. In Oceania, indigenous populations experience a disproportionately high burden of disease. We aimed to describe the natural history of bronchiectasis and identify risk factors associated with premature mortality within a cohort of Aboriginal Australians, New Zealand Māori and Pacific Islanders, and non-indigenous Australians and New Zealanders.

METHODS

This was a retrospective cohort study of bronchiectasis patients aged >15 years at three hospitals: Alice Springs Hospital and Monash Medical Centre in Australia, and Middlemore Hospital in New Zealand. Data included demographics, ethnicity, sputum microbiology, radiology, spirometry, hospitalization and survival over 5 years of follow-up.

RESULTS

Aboriginal Australians were significantly younger and died at a significantly younger age than other groups. Age- and sex-adjusted all-cause mortality was higher for Aboriginal Australians (hazard ratio (HR): 3.9), and respiratory-related mortality was higher for both Aboriginal Australians (HR: 4.3) and Māori and Pacific Islander people (HR: 1.7). Hospitalization was common: Aboriginal Australians had 2.9 admissions/person-year and 16.9 days in hospital/person-year. Despite Aboriginal Australians having poorer prognosis, calculation of the FACED score suggested milder disease in this group. Sputum microbiology varied with Aspergillus fumigatus more often isolated from non-indigenous patients. Airflow obstruction was common (66.9%) but not invariable.

CONCLUSIONS

Bronchiectasis is not one disease. It has a significant impact on healthcare utilization and survival. Differences between populations are likely to relate to differing aetiologies and understanding the drivers of bronchiectasis in disadvantaged populations will be key.

Lymphocytic focus score is positively related to airway and interstitial lung diseases in primary Sjögren's syndrome

OBJECTIVE

Although high-resolution computed tomography (HRCT) is useful for the characterization of minute morphological changes in the lungs, no study has investigated risk factors for lung involvement detected by HRCT in patients with Sjögren's syndrome with or without respiratory symptoms. The aim of the current study was to investigate risk factors for lung involvement in patients with primary Sjögren's syndrome detected by HRCT, with a particular focus on airway and interstitial lung diseases.

METHODS

We performed a retrospective cohort study of patients with primary Sjögren's syndrome and investigated risk factors for lung involvement detected by HRCT. A total of 101 patients with primary Sjögren's syndrome with initial HRCT examinations were enrolled.

RESULTS

Higher age, dry mouth, and higher labial gland biopsy focus scores (≥4) were risk factors for airway diseases (odds ratio [OR] 1.064 confidence interval [CI] 1.026-1.102, OR 8.795 CI 2.317-33.378 and OR 3.261 CI 1.100-9.675, respectively) in the multivariable analysis. Higher age, male sex, and higher labial gland biopsy focus scores (≥4) were risk factors for interstitial lung diseases (OR 1.078 CI 1.032-1.127, OR 12.178 CI 1.121-132.307 and OR 3.954 CI 1.423-10.987, respectively) in the multivariable analysis. The presence of anti-T-lymphotropic virus type 1 antibodies was significantly more common in patients with airway diseases.

CONCLUSIONS

This study showed significant associations of labial gland biopsy focus scores and dry mouth with pulmonary manifestations in patients with primary Sjögren's syndrome. Focus scores as well as dry mouth may reflect lymphoproliferative activity in the lungs in patients with primary Sjögren's syndrome.

2017 international meeting of the Global Virus Network

The Global Virus Network (GVN) was established in 2011 to strengthen research and responses to emerging viral causes of human disease and to prepare against new viral pandemics. There are now 40 GVN Centers of Excellence and 6 Affiliate laboratories in 24 countries. The 2017 meeting was held from September 25–27 in Melbourne, Australia, and was hosted by the Peter Doherty Institute for Infection and Immunity and the Institut Pasteur. This report highlights the recent accomplishments of GVN researchers in several important areas of medical virology, including the recent Zika epidemic, infections by human papillomavirus, influenza, HIV, hepatitis C, HTLV-1, and chikungunya viruses, and new and emerging viruses in the Australasia region. Plans for the 2018 meeting also are noted.

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The GVN is an international research network comprised of 40 Centers of Excellence and 6 Affiliates in 24 countries.

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The 2017 Global Virus Network (GVN) Meeting was held in Melbourne, Australia from September 25–27.

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New data were presented on various aspects of medical virology, therapies, and emerging viruses in the Australasia region.

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International collaboration is critical to developing new and effective viral vaccines and therapeutics.

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The 2018 international GVN meeting will be held on November 28–30 in Annecy, France.

Human T Cell Leukemia Virus Type 1: Persistence and Pathogenesis

Human T cell leukemia virus type 1 (HTLV-1), also known as human T lymphotropic virus type 1, was the first exogenous human retrovirus discovered. Unlike the distantly related lentivirus HIV-1, HTLV-1 causes disease in only 5-10% of infected people, depending on their ethnic origin. But whereas HIV-1 infection and the consequent diseases can be efficiently contained in most cases by antiretroviral drug treatment, there is no satisfactory treatment for the malignant or inflammatory diseases caused by HTLV-1. The purpose of the present article is to review recent advances in the understanding of the mechanisms by which the virus persists in vivo and causes disabling or fatal diseases.

CT Chest and pulmonary functional changes in patients with HTLV-associated myelopathy in the Eastern Brazilian Amazon

The aim of this study was to compare computed tomography (CT) scans of chest and lung function among patients with Human T-Lymphotropic Virus Type 1 (HTLV) with and without HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). In this cross-sectional study performed between January 2013 and June 2016, we included 48 patients with HAM/TSP (19 women and 11 men) and without HAM/TSP (12 women and 6 men). We compared CT findings and lung functions of these groups. Patients who had HAM/TSP had abnormal CT findings (P = 0.000), including more frequent bronchiectasis (P = 0.049), parenchymal bands (P = 0.007), interlobular septal thickening (P = 0.035), and pleural thickening (P = 0.009). In addition, neither patients with HAM/TSP (9/30; 30%) nor the controls (0/18; 0%) had obstructive or restrictive lung disease (P = 0.009). HTLV diagnosis should be considered in all patients with abnormal CT findings in whom no other cause is apparent. It is important to remember that lung disease increases the rates of morbidity and mortality in developing countries.

Turning a blind eye: HTLV-1-associated uveitis in Indigenous adults from Central Australia

PURPOSE

We describe the first two cases of HTLV-1 associated uveitis to be associated with HTLV-1c subtype infection.

METHODS

Case report.

RESULTS

Uveitis was demonstrated in two Indigenous Australian men, both of whom had high HTLV-1c proviral loads in peripheral blood. Visual outcomes were poor in each case.

CONCLUSION

Clinicians should be aware of HTLV-1c infection as a cause of uveitis in Australia, and HTLV-1 serology should be included in the basic uveitis work-up in HTLV-1-endemic areas.

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

OBJECTIVE

Hospital and laboratory data indicate that human T-lymphotropic virus type 1 (HTLV-1) is endemic to central Australia, but no community-based studies of its prevalence or disease burden have been reported. We determined the prevalence rates of HTLV-1 infection and of HTLV-1-associated diseases in a remote Indigenous community.

SETTING

A remote Northern Territory community.

DESIGN

All residents were asked to complete a health survey and offered a limited clinical examination, together with serological tests for HTLV-1 and Strongyloides, and HTLV-1 proviral load (PVL) assessment.

MAIN OUTCOME MEASURES

HTLV-1 seropositivity rates; HTLV-1 PVL (copies/105 peripheral blood leucocytes [PBL]); presentation with HTLV-1-related clinical disease.

RESULTS

HTLV-1 serostatus was determined for 97 of 138 residents (70%). The prevalence of HTLV-1 infection was significantly higher among adults (30 of 74 people tested) than children (1 of 23; P = 0.001). Nine of 30 HTLV-1-positive adults had a clinical syndrome that was potentially attributable to HTLV-1 infection (chronic lung disease, seven; symptomatic strongyloidiasis, two). The median HTLV-1 PVL was significantly higher for adults with chronic lung disease than for those who were asymptomatic (chronic lung disease, 649 copies/105 PBL [IQR, 162-2220]; asymptomatic adults, 40 copies/105 PBL [IQR, 0.9-229]; P = 0.017). Ten of 72 adults tested were seropositive for Strongyloides (six of 28 HTLV-1-positive participants and four of 44 HTLV-1-negative participants; P = 0.17), as were three of 15 children tested; the three children were HTLV-1-negative.

CONCLUSION

The prevalence of HTLV-1 infection and the rate of disease potentially attributable to HTLV-1 were high among adults in this remote community.

The Epidemiology of Chronic Suppurative Lung Disease and Bronchiectasis in Children and Adolescents

In the modern era, the global burden of childhood chronic suppurative lung disease (CSLD) remains poorly captured by the literature. What is clear, however, is that CSLD is essentially a disease of poverty. Disadvantaged children from indigenous and low- and middle-income populations had a substantially higher burden of CSLD, generally infectious in etiology and of a more severe nature, than children in high-income countries. A universal issue was the delay in diagnosis and the inconsistent reporting of clinical features. Importantly, infection-related CSLD is largely preventable. A considerable research and clinical effort is needed to identify modifiable risk factors and socioeconomic determinants of CSLD and provide robust evidence to guide optimal prevention and management strategies. The purpose of this review was to update the international literature on the epidemiology, etiology, and clinical features of pediatric CSLD.

Heart Failure in Minority Populations - Impediments to Optimal Treatment in Australian Aborigines

Chronic heart failure (CHF) among Aboriginal/Indigenous Australians is endemic. There are also grave concerns for outcomes once acquired. This point is compounded by a lack of prospective and objective studies to plan care. To capture the essence of the presented topic it is essential to broadly understand Indigenous health. Key words such as ‘worsening’, ‘gaps’, ‘need to do more’, ‘poorly studied’, or ‘future studies should inform’ occur frequently in contrast to CHF research for almost all other groups. This narrative styled opinion piece attempts to discuss future directions for CHF care for Indigenous Australians. We provide a synopsis of the problem, highlight the treatment gaps, and define the impediments that present hurdles in optimising CHF care for Indigenous Australians.

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.

Pediatric bronchiectasis: No longer an orphan disease

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Human T-lymphotropic virus-1 serology in the Northern Territory: 2008-2011

A retrospective observational study of human T-lymphotropic virus-1 (HTLV-1) serology requests made to the Northern Territory Government Pathology Service (NTGPS) between 2008 and 2011, was undertaken to review aspects of HTLV-1 sero-epidemiology and performance of the assays. A total of 5686 HTLV-1 serology requests, representing 3555 individual patients, were received during the study period; 368 HTLV-1 confirmed positive serology results were identified from the 3555 individual patients included in the sample. There was a distinct difference in the performance of the two antibody assays in use during this period, with the Serodia particle agglutination having a 5.7% indeterminate positivity rate compared to 18.1% indeterminate positivity rate of the Abbott HTLV 1/2 assay. We believe this is partially a serological anomaly related to current Australian western blot positive interpretative criteria, rather than false positive screening assay results.The majority (99.7%) of positive results occurred in Indigenous patients. The HTLV-1 positive rate varied geographically from a regional high of 51.7%, and falling inversely with distance from Central Australia. Patients with positive serology had a mean age of 49.9 (±13.9) years, with positivity occurring equally in males and females.

High prevalence of bronchiectasis is linked to HTLV-1-associated inflammatory disease

Background

Human T-lymphotropic virus type 1 (HTLV-1), a retrovirus, is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukaemia/lymphoma (ATLL). The reported association with pulmonary disease such as bronchiectasis is less certain.

Methods

A retrospective case review of a HTLV-1 seropositive cohort attending a national referral centre. The cohort was categorised into HTLV-1 symptomatic patients (SPs) (ATLL, HAM/TSP, Strongyloidiasis and HTLV associated inflammatory disease (HAID)) and HTLV-1 asymptomatic carriers (ACs). The cohort was reviewed for diagnosis of bronchiectasis.

Result

34/246 ACs and 30/167 SPs had been investigated for respiratory symptoms by computer tomography (CT) with productive cough +/- recurrent chest infections the predominant indications. Bronchiectasis was diagnosed in one AC (1/246) and 13 SPs (2 HAID, 1 ATLL, 10 HAM/TSP) (13/167, RR 19.2 95 % CI 2.5-14.5, p = 0.004) with high resolution CT. In the multivariate analysis ethnicity (p = 0.02) and disease state (p < 0.001) were independent predictors for bronchiectasis. The relative risk of bronchiectasis in SPs was 19.2 (95 % CI 2.5-14.5, p = 0.004) and in HAM/TSP patients compared with all other categories 8.4 (95 % CI 2.7-26.1, p = 0.0002). Subjects not of African/Afro-Caribbean ethnicity had an increased prevalence of bronchiectasis (RR 3.45 95 % 1.2-9.7, p = 0.02).

Conclusions

Bronchiectasis was common in the cohort (3.4 %). Risk factors were a prior diagnosis of HAM/TSP and ethnicity but not HTLV-1 viral load, age and gender. The spectrum of HTLV-associated disease should now include bronchiectasis and HTLV serology should be considered in patients with unexplained bronchiectasis.

Inflammatory manifestations of HTLV-1 and their therapeutic options

Human T lymphotropic virus type 1 (HTLV-1) is one of the most intriguing retroviruses infecting humans. Most commonly, infection remains undetected, since it does not cause obvious harm, yet in 4-9% of patients, this infection can be devastating, causing adult T-cell leukemia/lymphoma and/or HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). This review concentrates on all inflammatory aspects of HTLV-1 infection: HAM/TSP, HTLV-1 associated uveitis, HTLV-1 associated conjunctivitis, sicca syndrome and interstitial keratitis, HTLV-1 associated Sjögren's syndrome, Hashimoto's thyroiditis and Graves' disease, HTLV-1 associated pulmonary disease, infective dermatitis associated with HTLV-1, HTLV-1 associated inflammatory myositis and HTLV-1 associated arthritis. With the exception of HAM/TSP treatment, studies of these conditions are sparse and even for HAM/TSP, the level of evidence is limited. While control or elimination of infection remains a goal, most therapy beyond symptomatic management is directed at the immune response to HTLV-1.