Infection with human T-lymphotropic virus types-1 and -2 (HTLV-1 and -2): Implications for blood transfusion safety

Prevalence of human T-cell lymphotropic virus-1/2 in Canada over 33 years: A unique contribution of blood donors to public health surveillance

OBJECTIVES

Estimate HTLV-1/2 (human T-cell lymphotropic viruses) prevalence in Canadian blood donors and the association of demographic variables with infection and their corresponding risk factors.

METHODS

First-time blood donors in all Canadian provinces (except Quebec) from 1990 to 2022 were included. Blood samples were tested for HTLV-1/2 by enzyme-linked immunoassay, confirmed by Western blot. Multivariable logistic regression with year, age group, sex, region, neighbourhood material deprivation, and ethnocultural composition indices predicted HTLV-1/2. Since 2005, all HTLV-1/2-positive donors (cases) were invited to participate in a risk factor interview, and 4 non-positive donors (controls per case) were matched for age, sex, and region. Case-control predictors of HTLV-1/2 were analyzed using logistic regression.

RESULTS

There were 3,085,554 first-time donors from 1990 to 2022. HTLV-1/2 prevalence remained low (12 per 100,000 in 2022, 95% CI 6.4-23.5). The odds ratios predicting HTLV-1/2 were higher in females (2.0, 95% CI 1.5-2.6), older age groups (50 + ; 6.3, 95% CI 4.3-9.2), British Columbia and Ontario, those materially deprived (1.9, 95% CI 1.2-2.9), and those in ethnocultural neighbourhoods (7.5, 95% CI 3.2-17.3). Most HTLV-1/2 in Ontario was HTLV-1, whereas in British Columbia half were HTLV-2. Forty-three of 149 (28.8%) cases and 172 of 413 (41.6%) controls completed an interview. The strongest predictor of HTLV-1/2 in case-control analysis was birth in a high-prevalence country (OR 39.8, 95% CI 7.8-204.3) but about 50% of HTLV-1 and 90% of HTLV-2 were Canadian-born.

CONCLUSION

HTLV-1/2 prevalence is low in blood donors. High-prevalence country of birth accounts for about half of HTLV-1; HTLV-2 positives are usually Canadian-born. HTLV-1/2 transmission likely occurs overseas and within Canada.

Detection of early phase human T-cell leukemia virus type 1 and 2 infection with an improved confirmatory test

BACKGROUND

Human T-cell leukemia virus type 1 (HTLV-1) is a blood-borne virus, and mandatory testing of donated blood for HTLV-1 antibodies has been adopted by Japanese Red Cross blood centers since 1986. A confirmatory line immunoassay was initiated in 2019 for individuals who were seroreactive in the screening test. This decreased the incidence of indeterminate individuals, however, donors with indeterminate results are not informed of their HTLV-1 seroreactivity and they can continue to donate blood.

OBJECTIVES

To clarify the characteristics of indeterminate line immunoassay results among Japanese blood donors.

STUDY DESIGN

Of 759,259 blood donors in the Kyushu district of Japan, an area endemic for HTLV-1, 101 cases were classified as indeterminate by line immunoassay testing. We examined these cases using alternative secondary antibodies, anti-human-Ig (IgG/IgM/IgA) and -IgM antibodies, to detect the early phase of HTLV infection.

RESULTS

Using anti-human-Ig and -IgM antibodies, HTLV infection status was confirmed in 37 individuals (HTLV-1-positive, 2; HTLV-positive, 27; HTLV-negative, 8). Among the remaining 64 indeterminate individuals, we identified one HTLV-2-infected 18-year-old female. A previous blood donation from this individual showed a negative anti-HTLV screening test result (signal-to-cutoff ratio = 0.1). Therefore, this case was considered to be an HTLV-2 seroconversion case.

CONCLUSIONS

These results indicate that the procedure for diagnosing HTLV infection should be reconsidered and that an accurate detection system for the early phase of HTLV infection is urgently needed for public health in Japan. Moreover, the issue of HTLV-2 infection needs a higher profile in Japan.

Comparison of two new HTLV-I/II screening methods, Abbott Alinity i rHTLV-I/II and Diasorin LIAISON® XL murex recHTLV-I/II, to Abbott architect rHTLVI/II assay

BACKGROUND

Diagnosis of Human T-cell Lymphotropic Virus (HTLV) types I and II infection requires sequencial testing with firstly a screening using an Enzyme immunoassay followed by a confirmatory test.

OBJECTIVES

To compare the performances of the Alinity i rHTLV-I/II (Abbott®) and LIAISON® XL murex recHTLV-I/II serological screening tests to the ARCHITECT rHTLVI/II test followed if positive by HTLV BLOT 2.4, MP Diagnostics as the reference.

STUDY DESIGN

119 serum samples from 92 known HTLV-I infected patients and 184 from uninfected patients with HTLV were analyzed in parallel with, Alinity i rHTLV-I/II, LIAISON® XL murex recHTLV-I/II and ARCHITECT rHTLVI/II.

RESULTS

Alinity i rHTLV-I/II and LIAISON® XL murex recHTLV-I/II exhibited a total agreement with ARCHITECT rHTLVI/II for both positive and negative samples. Both tests are suitable alternatives for HTLV screening.

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

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

HTLV-1/2 Infection in Blood Donors from a Non-Endemic Area (Catalonia, Spain) between 2008 and 2017: A 10-Year Experience

Human T-cell lymphotropic virus type 1 and 2 (HTLV-1/2) screening is not mandatory in Spanish blood banks. In Catalonia, selective screening was introduced in 2008, followed by universal screening in 2011. We present herein a 10-year experience of HTLV testing in blood donors. HTLV-1/2 selective screening was performed using Ortho-Clinical Diagnostics HTLV-I/HTLV-II Ab-Capture ELISA between February 2008 and May 2009, then Abbott Prism HTLV-I/ HTLV-II assay until December 2010. Abbott Architect rHTLV-I/II assay was then used for HTLV-1/2 universal screening in pooled samples. INNO-LIA HTLV I/II Score (Fujirebio) and in-house HTLV-1/2 proviral DNA real-time PCR were used in reactive samples. Follow-up was offered to confirm HTLV-1/2 donors in Vall d’Hebron Hospital. Between 2008 and 2017, 51 blood donors were confirmed HTLV positive (46 HTLV-1, 4 HTLV-2 and 1 HTLV) out of 2,114,891 blood donations (1 in 41,468). Sixty-nine percent were female, median age was 40 years and most were born in Latin America (69%), followed by Europe (25%), Africa (4%) and Asia (2%). Screening of relatives and partners identified 12 additional HTLV-1 cases. Lookback studies did not show any HTLV-1/2 transmission. HTLV infections found in blood donors mirror epidemiological changes in the population of Spain. Consequently, HTLV should be considered a potential risk for recipients and calls for the design of optimal strategies to ensure transfusion safety.

HTLV-1-related adult T-cell leukemia/lymphoma: insights in early detection and management

PURPOSE OF REVIEW

Adult T-cell leukemia-lymphoma (ATL) is an aggressive mature T-cell malignancy that arises in approximately 5% of carriers of human T-lymphotropic virus type 1 (HTLV-1), but this risk is not random among carriers. We describe recent advance in pathogenesis, risk factors and for early detection of ATL.

RECENT FINDINGS

Unraveling ATL molecular genetics has shed light on pathogenesis and provides insights into novel therapeutic targets. Moreover, an important step in improving outcomes is identifying asymptomatic carriers who are at high risk of progression to ATL, which has traditionally relied on quantifying the proviral load (PVL). This can be done by quantifying oligoclonality- and in particular the expanded clone- with molecular and flow cytometric techniques, that can be applied to a clinical setting. Studies using these methods have shown that carriers with oligoclonal populations are at an increased risk of transformation, beyond that that predicted by PVL alone.

SUMMARY

There is an urgent unmet need for developing novel therapies in ATL in order to improve survival. Recent advances in the molecular and epigenetic landscape of ATL, and the early detection of disease offer the potential to intervene early, before disease becomes aggressive, and to offer tailored therapeutic strategies.

Epidemiological evidence of nosocomial and zoonotic transmission of HTLV-1 in a large survey in rural population of central Africa

BACKGROUND

Central Africa is one of the largest areas of high endemicity for human T-cell leukaemia virus (HTLV-1). However, no preventive measures are yet implemented to reduce its transmission, which can be sexual, from mother-to-child, or through contaminated blood products. Rare zoonotic transmissions from non-human primates (NHPs) have also been reported in this region. Here, we investigated the HTLV-1 prevalence and associated risk factors in a rural population in Cameroon.

METHODS

From 2019 to 2021, we performed a cross-sectional survey in the Eastern region of Cameroon. HTLV-1 infection was first screened by ELISA, then tested by Western blot and envelope gene targeted polymerase chain reaction. Risk factors associated with HTLV-1 infection were identified by logistic regression on univariable and multivariable analyses.

RESULTS

Among 3,400 participants, HTLV-1 prevalence was 1.1% (95%CI 0.7-1.5). Factors independently associated with HTLV-1 infection were: Pygmy ethnicity (adjusted odd ratio ORa, 2.9, 95%CI 1.3-6.2), history of surgery (ORa 6.3, 95%CI 2.2-17.8) and NHP bite (ORa 6.6, 95%CI 2.2-19.8).

CONCLUSIONS

These results suggest both iatrogenic and zoonotic transmission of HTLV-1 in Cameroon. Further studies are needed to assess the risk of nosocomial transmission of HTLV-1, to guide public health authorities in implementing preventive measures to control HTLV-1 transmission.

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.

Molecular fusion events in carcinogenic organisms: a bioinformatics study for the detection of fused proteins between viruses, bacteria and eukaryotes

Molecular fusion events have a prominent role in the initial steps of carcinogenesis. In this study, a bioinformatics analysis was performed between four organisms that are known to induce cancer development in humans: two viruses, Human Herpesvirus 4, and Human T-cell leukaemia virus, one bacterium, Helicobacter Pylori, and one trematode, Schistosoma mansoni. The annotated proteomes from these organisms were analysed using the SAFE software to identify protein fusion events, which may provide insight into protein function similarities and possible merging events during the course of evolution. Based on the results, five fused proteins with very similar functions were detected, whereas proteins with different functions that might act in the same molecular complex or biochemical pathway were not found. Thus, this study analysed the above four well-known cancer-related organisms with de novo bioinformatics programs and provided useful information on protein fusion events, hopefully leading to deeper understanding of carcinogenenesis.

Updates on the Epidemiology of the Human T-Cell Leukemia Virus Type 1 Infection in the Countries of the Eastern Mediterranean Regional Office of the World Health Organization with Special Emphasis on the Situation in Iran

Background: The epidemiology and prevalence of the Human T-cell leukemia virus type-1 (HTLV-1) infection represent a recommended priority by global health agencies. An in-depth revision to update the status of this infection in countries including those of the Eastern Mediterranean Regional Office (EMRO) of the World Health Organization is hence required. Methods: Ninety-seven studies evaluating the HTLV-1 infection in low- and high-risk populations in EMRO countries were retrieved from the international electronic databases and were used to assess the epidemiological status of the infection in these countries. Results: Most epidemiologic reports were published from Iran, with more than 50% of Iranian prisoners and around 4% of healthy individuals reported to have the infection. In Egypt, a considerable prevalence of the virus spans around 1.11% of blood donors. Foci of HTLV-1 infection are also present in some countries and require a careful epidemiological evaluation. In the other EMRO countries, a lower prevalence that does not exceed 1% was reported. Conclusion: The epidemiology and prevalence of HTLV-1 in the EMRO countries require a tight revision and update. Published studies reveal a scarce distribution of the virus in the African countries of EMRO, while a lower prevalence is denoted in the Asian countries of EMRO, except in Iran, where the prevalence is high.

Association of the rs4143815 polymorphism of PDL1 gene with HTLV-1 infection and proviral load in asymptomatic blood donors in northeast Iran

Obviously, genetic differences, including mutations and polymorphisms, can play an important role in viral infections, So in this case-control study, which contained 81 Human T-cell leukemia virus type 1(HTLV-1) asymptomatic carriers (ACs) and 162 healthy controls (HCs), the rs4143815 polymorphism of PDL1 gene investigated. This polymorphism is the site of miR-570 binding and it can influence immune system responses. The rs4143815 polymorphism was evaluated by allele-specific polymerase chain reaction (AS-PCR) and proviral load (PVL) levels by quantitative real-time PCR (q PCR). The results demonstrated that C allele (p=0.027) and CC genotype (p=0.031) of rs4143815 polymorphism was significantly higher in ACs than HCs group also, the PVL in ACs with C allele (p=0.020) was higher significantly. Thus, the rs4143815 polymorphism can play a vital role in HTLV-1 infection. This article is protected by copyright. All rights reserved.

Brazilian Protocol for Sexually Transmitted Infections 2020: human T-cell lymphotropic virus (HTLV) infection

This article addresses the Human T-lymphotropic virus (HTLV). This subject comprises the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health. HTLV-1/2 infection is a public health problem globally, and Brazil has the largest number of individuals living with the virus. HTLV-1 causes several clinical manifestations of neoplasm (adult T-cell leukemia/lymphoma) and inflammatory nature, such as HTLV-1-associated myelopathy and other manifestations such as uveitis, arthritis, and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health authorities professionals regarding viral transmission, diagnosis, treatment, and monitoring of individuals living with HTLV-1 and 2 in Brazil.

HTLV-1/2 transmission can occur through blood transfusion and derivatives, injectable drug use, organ transplantation, unprotected sexual intercourse, and vertical transmission.

[Brazilian Protocol for Sexually Transmitted Infections 2020: human T cell lymphotropic virus (HTLV) infection]

This manuscript is related to the chapter about human T-cell lymphotropic virus (HTLV) that is part of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Health Ministry. HTLV-1/2 infection is a worldwide public health problem and Brazil has the largest number of individuals living with the virus. HTLV-1 causes a variety of clinical manifestations of a neoplastic nature, such as adult leukemia/T-cell lymphoma, and also of an inflammatory nature, such as HTLV-1-associated myelopathy, as well as other manifestations such as uveitis, arthritis and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health service managers and workers regarding virus transmission modes, diagnosis, treatment and monitoring of individuals living with HTLV-1 and 2 in Brazil.

Screening for Human T-Cell Lymphotropic Virus (HTLV) in Pregnant Women in the Peruvian Amazon and Systematic Review with Meta-Analysis of HTLV Infection in Peru

Background. Human T-cell lymphotropic virus type 1 (HTLV-1) is responsible for tropical spastic paraparesis and HTLV-1-associated leukemia/lymphoma. The infection is endemic in some areas of Peru, but its prevalence in the Peruvian Amazon is not well established. We aimed to assess the seroprevalence of HTLV-1 infection in pregnant women in the Peruvian Amazon. Moreover, we performed a systematic literature review and meta-analysis of the seroprevalence of HTLV infection in Peru. (2) Methods. This is a prospective cross-sectional study involving pregnant women attending health centers in the city of Iquitos, Peru, in May and June 2019. The presence of antibodies against HTLV-1 was assessed using ELISA (HTLV I + II ELISA recombinant v.4.0, Wiener lab, Rosario, Argentina). Positive cases were confirmed by Western Blot and HTLV-1 proviral load. (3) Results. The study included 300 pregnant women with a mean age of 26 years (standard deviation [SD] 6.4). Five patients were diagnosed with HTLV-1 infection (prevalence 1.7%, 95% confidence interval (CI) 0.7% to 3.8%). Pregnant women with HTLV-1 infection were discretely younger (mean age 22.6 [SD 22.6] vs 26.8 [SD 6.3]; p = 0.128). None of the five women had been transfused, and all were asymptomatic. Two (40%) also had a positive serology for Strongyloides, but larvae were not detected in any of the parasitological stool studies. The systematic review component identified 40 studies, which showed that the prevalence of HTLV infection in the general population was 2.9% (95% CI 1.2% to 5.3%) and in women of childbearing age, 2.5% (95% CI 1.2% to 4.0%). (4) Conclusion. The prevalence of HTLV-1 in the Peruvian Amazon basin is about 1.7%, indicating an endemic presence. Screening for HTLV-1 in prenatal care is warranted.

Challenges in transfusion-transmitted infection screening in Sub-Saharan Africa

In Sub-Saharan Africa, high clinical demand for transfusion faces endemic bloodborne infections and limited resources. Blood screening for transfusion-transmitted bloodborne pathogens is the cornerstone of blood safety. Although there have been substantial improvements over the years, challenges in transfusion-transmitted infection screening that have been identified repeatedly long ago still need to be addressed. Affordability and sustainability of state-of-the-art quality assessed serological and molecular assays, and associated confirmation strategies remain of real concern. In addition, limited resources and infrastructures hamper the development of adequate facilities, quality management, and staff qualification, and exacerbate shortage of reagents and equipment maintenance. It is also important to maintain effort in constituting pools of repeat voluntary non-remunerated donors. Alternative strategies for blood screening that take into account local circumstances might be desirable but they should rely on appropriate field evaluation and careful economic assessment rather than dogma established from high-resource settings.

Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger

Human T-cell lymphotropic virus type 1 (HTLV-1) infects 5-10 million people worldwide and is the causative agent of adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as other inflammatory diseases. A major concern is that the most majority of individuals with HTLV-1 are asymptomatic carriers and that there is limited global attention by health care officials, setting up potential conditions for increased viral spread. HTLV-1 transmission occurs primarily through sexual intercourse, blood transfusion, intravenous drug usage, and breast feeding. Currently, there is no cure for HTLV-1 infection and only limited treatment options exist, such as class I interferons (IFN) and Zidovudine (AZT), with poor prognosis. Recently, small membrane-bound structures, known as extracellular vesicles (EVs), have received increased attention due to their potential to carry viral cargo (RNA and proteins) in multiple pathogenic infections (i.e., human immunodeficiency virus type I (HIV-1), Zika virus, and HTLV-1). In the case of HTLV-1, EVs isolated from the peripheral blood and cerebral spinal fluid (CSF) of HAM/TSP patients contained the viral transactivator protein Tax. Additionally, EVs derived from HTLV-1-infected cells (HTLV-1 EVs) promote functional effects such as cell aggregation which enhance viral spread. In this review, we present current knowledge surrounding EVs and their potential role as immune-modulating agents in cancer and other infectious diseases such as HTLV-1 and HIV-1. We discuss various features of EVs that make them prime targets for possible vehicles of future diagnostics and therapies.

HTLV-2 infection in Manaus, Brazil: first description of HTLV-2c subtype in an urban area of the Western Amazon region

INTRODUCTION

We investigated the prevalence of human T-cell lymphotropic virus types 1 and 2 (HTLV-1/2) infection in patients with hematological diseases from the western Amazon region of Brazil.

METHODS

Samples from 306 patients were submitted for the molecular diagnosis of HTLV-1/2 infection by real time PCR (qPCR), with amplification, sequencing, and phylogenetic analysis of the long terminal repeat (LTR) region.

RESULTS

A 29-year-old male carrier of sickle cell anemia with a history of multiple blood transfusions was diagnosed with the HTLV-2c subtype.

CONCLUSIONS

This study describes the first known occurrence of HTLV-2c in the urban area of Brazil's western Amazon region.

First case of molecularly identified and genetically characterized human T-cell leukemia virus type 2 infection in a pregnant woman in non-endemic Japan

Human T-cell leukemia virus type 2 (HTLV-2) is non-endemic in Japan unlike the related HTLV type 1. Previously, although HTLV-2-seropositivity was identified via western blotting in one male blood donor in Japan, there have been no reports of HTLV-2 provirus detection by nucleic acid testing. In this report, one Japanese pregnant woman was clinically diagnosed as being HTLV-2-infected with a line immunoassay for specific antibodies after primary testing through prenatal screening in Japan. In genomic DNA of her peripheral blood mononuclear cells, HTLV-2 proviral genome was detected by nucleic acid testing (three methods) with quantitative polymerase chain reaction. The full-genome sequence of this strain was successfully determined. The identified virus was interestingly characterized as a presumed progenitor of subtypes a and c by recombination region and phylogenetic tree analyses. In conclusion, the present infection is, to our knowledge, the first case of molecularly identified and genetically characterized HTLV-2 infection found via prenatal screening in non-endemic Japan.

Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid and Accurate Confirmatory Diagnosis of HTLV-1/2 Infection

Laboratory diagnosis of human T-lymphotropic viruses (HTLV) 1 and 2 infection is performed by serological screening and further confirmation with serological or molecular assays. Thus, we developed a loop-mediated isothermal nucleic acid amplification (LAMP) assay for the detection of HTLV-1/2 in blood samples. The sensitivity and accuracy of HTLV-1/2 LAMP were defined with DNA samples from individuals infected with HTLV-1 (n = 125), HTLV-2 (n = 19), and coinfected with HIV (n = 82), and compared with real-time polymerase chain reaction (qPCR) and PCR-restriction fragment length polymorphism (RFLP). The overall accuracy of HTLV-1/2 LAMP (95% CI 74.8-85.5%) was slightly superior to qPCR (95% CI 69.5-81.1%) and similar to PCR-RFLP (95% CI 79.5-89.3%). The sensitivity of LAMP was greater for HTLV-1 (95% CI 83.2-93.4%) than for HTLV-2 (95% CI 43.2-70.8%). This was also observed in qPCR and PCR-RFLP, which was associated with the commonly lower HTLV-2 proviral load. All molecular assays tested showed better results with samples from HTLV-1/2 mono-infected individuals compared with HIV-coinfected patients, who present lower CD4 T-cell counts. In conclusion, HTLV-1/2 LAMP had similar to superior performance than PCR-based assays, and therefore may represent an attractive alternative for HTLV-1/2 diagnosis due to reduced working time and costs, and the simple infrastructure needed.

Prevalence and trends of transfusion transmissible infections among blood donors in the State of Qatar, 2013-2017

BACKGROUND

Millions of lives around the world are being saved annually through blood transfusion. However, blood transfusion is among the essential vehicles for transmitting infections. The overall prevalence of Transfusion Transmissible Infections among blood donors differs around the world, reflecting the variation in the prevalence of these infections. This study aims to assess the prevalence and trends of Transfusion Transmissible Infections among blood donors in Qatar.

METHODS

This is a cross-sectional study utilizing donation records of 5 years from January 2013 to December 2017. We included in the study results for all screening and confirmatory tests for Hepatitis B Virus, Hepatitis C Virus, Human T-lymphotropic Virus-I/II, Syphilis and Malaria.

RESULTS

Among the 190,509 donations received at the donation centre during the study period, about 91% of donations were received from males and 9% from females. The overall positivity rate for all tests was 1.87, 2.23, 1.78, 2.31, 2.67% for the years 2013 through 2017, with an increasing yearly trend by 6% each year. The overall positivity rates for Hepatitis C Virus, Human T-lymphotropic Virus-I/II, Hepatitis B Virus, Syphilis and Malaria (2013-2017) were 0.60, 0.18, 0.30, 0.43 and 0.20%, respectively.

CONCLUSION

The overall positivity rate of all tests combined for the Transfusion Transmissible Infections demonstrated a gradually increasing trend from 2013 to 2017. However, the trend for each infection (Hepatitis C Virus, Hepatitis B Virus, Syphilis and Malaria) was fluctuating except for Human T-lymphotropic Virus-I/II, which was increasing. Supporting the development of effective prevention and control strategies requires further comprehensive investigations for better estimation of the burden of these infections.

Hospital admissions in individuals with HTLV-1 infection in Spain

OBJECTIVE

To examine the clinical burden and disease spectrum, as well as time trends for human T-cell leukemia virus type 1 (HTLV-1) and HTLV type 2 (HTLV-2) hospital admissions.

DESIGN

Retrospective, observational study using the Spanish National Hospital Discharge Database.

METHODS

Information for the diagnostic codes HTLV-1 and HTLV-2 using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) was retrieved from the national public registry since 1997--2015.

RESULTS

From a total of 66 462 136 nationwide hospital admissions recorded during the study period, 135 included HTLV diagnosis, being HTLV-1 in 115 (85.2%) and HTLV-2 in 20 (14.8%). The overall hospital admission rate because of HTLV was 2.03 per million, without significant yearly changes. First admissions represented 104 (77%) whereas 31 (23%) were re-admissions. The median in-hospital stay for HTLV patients was 9 days. In-hospital death occurred in 11 (8.1%). The median age of individuals with HTLV admission was 48 years and 60 (44.4%) were women. HTLV was recorded as the main diagnosis in 20%. The most frequent clinical conditions recorded alongside HTLV diagnosis were myelopathy (61; 45.2%), leukemia/lymphoma (30; 22.2%), solid organ transplantation (14; 10.4%) and child delivery (7; 5.2%).

CONCLUSION

The rate of HTLV diagnosis in hospitalized patients in Spain is low, roughly of two per million admissions. Despite continuous large immigrant flows from HTLV-1 endemic areas, no significant rising in hospitalizations because of HTLV-1 associated illnesses were noticed during the last two decades. Classical clinical complications of HTLV-1 infection, such as myelopathy and lymphoma account for more than two-thirds of cases.

High prevalence of human T-cell leukemia virus type-1b genotype among blood donors in Gabon, Central Africa

BACKGROUND

The African continent is considered to be the largest endemic area of HTLV‐1 infection, with at least several million infected individuals. Systematic screening of blood donors can prevent the transmission of HTLV‐1 in blood. Gabon is one of the countries with the highest prevalence of HTLV‐1 worldwide, and yet the routine testing of blood donors has still not been introduced.

METHODS

All blood donations collected between April and July 2017 at the Centre National de Transfusion Sanguine of Gabon were studied. Plasma samples were screened by ELISA for the presence of HTLV‐1/2 antibodies. Western blot (WB) and polymerase chain reaction (PCR) tests were used for confirmation.

RESULTS

In total, 3123 blood donors were tested, including 1740 repeat and 1378 first‐time blood donors (FTBDs). Of them, 132 samples tested positive for HTLV‐1/2 by ELISA (4.2%). WB and PCR confirmed HTLV‐1 infection for 23 individuals. The overall prevalence of HTLV‐1 was 0.74% [95% CI 0.47%‐1.10%], 1% in FTBD, and 0.5% in repeat donors. Age and sex‐adjusted prevalence was five‐fold lower in FTBD than in the general adult population of rural areas of Gabon. All detected HTLV‐1 strains belonged to the central African HTLV‐1b genotype but were highly diverse.

CONCLUSION

We report an overall prevalence of HTLV‐1 of 0.74%, one of the highest values reported for blood donors in Africa. Given the high risk of HTLV‐1 transmission in blood, it is necessary to conduct cost‐effectiveness studies to determine the need and feasibility of implementing screening of HTLV‐1 in blood donors in Gabon.

The challenge of describing the epidemiology of HTLV in the Amazon region of Brazil

HTLV-1 was the first described human retrovirus and was soon found to be associated with severe clinical diseases, including a devastating lymphoma/leukemia and other inflammatory diseases. Although HTLV-2 is not usually pathogenic, it is widely distributed among native Indian populations in Brazil, particularly in the Amazon region of the country. Presently, HTLV spreads mainly by the sexual route and from mother to child, and virus persistence is an active biological factor aiding its transmission. Recently, the use of illicit drugs has been shown to be an additional risk factor, showing the influence of new habits on the epidemiology of HTLV in the region. Despite the detection of the virus in several different populations in the Amazon region of Brazil for almost 30 years, the exact prevalence of HTLV-1/2 is not well defined. The original biases in sampling and the selection of epidemiologically unsuitable populations were commonly repeated in most prevalence studies, generating unreliable and conflicting figures that do not represent the actual prevalence of HTLV. The improvements in clinical and laboratory facilities have resulted in the description of several clinical manifestations that were previously unknown in the region. The extent of the spread of the virus must be defined in this region, which is the largest geographical area of the country. As prophylaxis advances toward the use of vaccines against HTLV-1, it is important to determine who is at risk of being infected and developing a disease to successfully implement preventive measures, particularly as proposals are made to eradicate the virus among humans.

Blood Transfusion-Associated Infections in the Twenty-First Century: New Challenges

Blood transfusions are vital components of modern medical treatment to which there is no viable alternative despite efforts to create artificial blood. Each year thousands of lives are saved by blood transfusions in every country of the world. However, blood and blood products can result in significant adverse events including immunologic reactions, infections, inefficacy, and others which can sometimes result in death and severe disability. Thus, the sustainability of safe blood systems and costs are considered to be at crisis level. In industrialized countries, the risk of transfusion-transmitted infections such as HIV, syphilis, hepatitis viruses B and C are very low [generally [<1 in a million units], but in developing countries [especially in Africa] blood safety is still not assured. Compounding the problem of blood/product safety with respect to infectious agents are new emerging infectious microbes that are not being routinely tested for in blood that are donated. This chapter reviews the infectious risk of blood transfusions, types, mode and geographic variation, and the methods being used by blood services to attenuate and prevent these risks.

Updates in lymph node and skin pathology of adult T-cell leukemia/lymphoma, biomarkers, and beyond

Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell lymphoproliferative disorder associated with the human T lymphotropic virus (HTLV-1) infection. ATLL predominantly affects individuals within HTLV-1 endemic areas such as Japan, areas of Africa, South America, and the Caribbean. HTLV-1 preferentially infects CD4+ T-cells, and several genetic hits must occur before ATLL develops. ATLL is classically divided into four clinical variants based on manifestations of disease: acute, chronic, lymphomatous, and smouldering. As of 2019, a new subtype has been described: lymphoma type of ATL, extranodal primary cutaneous. In this review, emphasis will be taken to describe the common clinicopathologic manifestations of the disease, advances in biomarker discovery, mutational landscape and targeted therapeutic approaches to treat this highly aggressive and frequently lethal type of T-cell lymphoma.

Characterization of peripheral blood mononuclear cells isolated using two kinds of leukocyte filters

OBJECTIVE

The objective of this study was to compare the activity and biological function of leukocytes isolated using apheresis platelet leukoreduction system chambers (LRSC), whole blood leukoreduction filters (LRF), and leukocytes in unfiltered peripheral whole blood (WB).

METHODS

Peripheral blood mononuclear cells (PBMCs) and granulocytes were obtained by density gradient centrifugation using recovery filters and WB. Flow cytometry was used to detect the activity, phenotype, and apoptosis ratio of each cell subtype.

RESULTS

The proportion of lymphocytes obtained from PBMCs was similar when using the two different filters as compared to traditional isolation; however, there were significant differences between the monocytes and granulocytes. The phenotypic frequency of lymphocytes was similar, but the apoptosis rate of lymphocytes from the two filters was slightly higher. Additionally, monocytes isolated via the three sources were able to be induced into dendritic cells expressing specific molecules; Granulocytes isolated from the LRF showed a lower purity and a higher level of apoptosis than granulocytes isolated from the WB.

CONCLUSION

Compared with WB, the PBMCs isolated from the filters used in our blood center had no statistical difference in their activity and biological function, but they did differ in the proportion and quantity of monocytes and granulocytes. Our results show that the two filters can be used as an alternative method to collect leukocytes, which solves the problem of an insufficient blood supply for clinical and basic science research. Thus, these filters have significant value beyond their practical use in clinics.

Flow cytometric methodology for the detection of de novo human T-cell leukemia virus -1 infection in vitro: A tool to study novel infection inhibitors

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MT-2 cells express more Tax, gp46 and p19 than HUT102′s.

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HUT78 cells express higher levels of the HTLV-1 permissive receptors neuropilin and GLUT-1 than CEM or JURKAT.

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Irradiation does not eliminate all MT-2 donor cells in HTLV-1 co-culture protocols.

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Flow cytometry and Lt-4 anti-tax antibody can detect de novo HTLV-1 infection at early time points.

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Cytochalasin B and sodium valproate inhibit HTLV-1 infection at early time points.

Methodology to detect and study de novo human T-cell leukemia virus (HTLV)-1 infection is required to further our knowledge of the viruses’ mechanisms of infection and to study potential therapeutic interventions. Whilst methodology currently exists, utilisation of an anti-Tax antibody to detect de novo Tax expression in permissive cells labelled with cell tracker allowing for the detection by flow cytometry of new infection after co-culture with donor cell lines productively infected with HTLV-1 is an alternative strategy. Using this methodology, we have been able to detect de novo infection of the T cell line HUT78 following co-culture with the productively infected HTLV-1 donor cell line MT-2 and to confirm that infection can be effectively blocked with well characterised infection inhibitors. This methodology will benefit experimental studies examining HTLV infection in vitro and may aid identification of therapeutic agents that block this process.

Comparative virology of HTLV-1 and HTLV-2

Human T cell leukemia virus type 1 (HTLV-1) was the first discovered human retrovirus and the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Shortly after the discovery of HTLV-1, human T-cell leukemia virus type 2 (HTLV-2) was isolated from a patient with hairy cell leukemia. Despite possession of similar structural features to HTLV-1, HTLV-2 has not been definitively associated with lymphoproliferative disease. Since their discovery, studies have been performed with the goal of highlighting the differences between HTLV-1 and HTLV-2. A better understanding of these differences will shed light on the specific pathogenic mechanisms of HTLV-1 and lead to novel therapeutic targets. This review will compare and contrast the two oldest human retroviruses with regards to epidemiology, genomic structure, gene products, and pathobiology.

Prevalence of human T-cell lymphotropic virus type-1 infection among blood donors in mainland China: a systematic review and meta-analysis of the last 20 years

Background: The southeastern coastal area of China has a high prevalence of HTLV-1 infection among blood donors. However, the estimation of HTLV-1 prevalence on a national and regional level is little known. The aim of this study is to understand and explore the estimation of HTLV-1 infection prevalence among blood donors on a national and regional level in mainland China by using a systematic review and meta-analysis. Study design and methods: All relevant publications of the past two decades (1998-2017), which were reported in both English and Chinese languages, were adopted and systematically assessed. The estimation of prevalence and its 95% confidence interval (CI) at the level of provinces/municipalities and overall were estimated using meta-analysis method. Results: From the 327 studies searched, 60 met the inclusion criteria. These were from 18 provinces and four municipalities and included 1,420,079 blood donors. The overall estimation of the HTLV-1 prevalence in blood donors was 0.169‰, and its 95% CI was 0.121‰-0.240‰. Conclusion: A disproportionate distribution of HTLV-1 infection among blood donors in different provinces/municipalities regarding its prevalence has been reported. This study recommends developing appropriate HTLV-1 screening strategies of blood donors in various regions of China considering regional prevalence, and cost-effectiveness.

Health economic implications of testing blood donors in South Africa for HTLV 1 & 2 infection

BACKGROUND AND OBJECTIVES

Currently, HTLV screening is not performed in South Africa (SA). This report describes an economic assessment (budget impact and cost-effectiveness) of implementing different HTLV screening strategies.

METHODS

A modified version of the Alliance of Blood Operators risk-based decision-making framework was used to assess the risk and consequences of HTLV in the blood supply in SA. We developed a deterministic model of the cost and consequences of four screening strategies: none, universal, all donors once and first time donors only assuming a transfusion-transmission (TT) efficiency of 10% and a manifestation of clinical disease of 6%.

RESULTS

Unscreened blood results in 3·55 symptomatic TT-HTLV cases and a total healthcare cost of Rand (R)3 446 950 (US Dollars (USD)229 800) annually. Universal screening would cost R24 000 000 (USD1 600 000) per annum and prevent 3·54 (99·8%) symptomatic TT-HTLV cases in the first year and 0·55 (98·4%) symptomatic TT-HTLV cases in the second year at a cost per TT-HTLV prevented of R6 780 000 (USD450 000) in year one and R43 254 000 (USD2 890 000) in year two. Screening all donors once would cost R16,200,000 (USD1 080 000) or R4 600 000 (USD306 000) per symptomatic TT-HTLV infection prevented in year one. Total costs decrease to R5 100 000 (USD340 000) in year 2 but the cost per TT-HTLV prevented increases to R10 700 000 (USD713 333).

CONCLUSION

This analysis contributed to the decision not to implement HTLV screening as the healthcare budget and particularly the budget for blood transfusion in SA is insufficient to provide appropriate treatment. Arguably, available resources can be more efficiently utilized in other healthcare programs.

Evaluation of Elecsys HTLV-I/II assay in comparison with ARCHITECT rHTLV-I/II assay with Korean samples

BACKGROUND

The seroprevalence rate of human T-lymphotropic virus I and II (HTLV-I/II) in Korean blood donors has been known as 0.004%, and HTLV-I/II Ab screening test has been performed since 2008 in Korea. Korea Ministry of Food and Drug Safety (MFDS) approved two chemiluminescent microparticle immunoassays (CMIA) for testing HTLV-I/II antibody, ABBOTT PRISM HTLV-I/HTLV-II and ARCHITECT rHTLV-I/II. A multicenter performance evaluation study in Europe and Japan was carried out with the new electrochemiluminescence immunoassay (ECLIA) for HTLV-I/II antibody detection, Elecsys HTLV-I/II assay which launched in 2017, but not in Korea. We aimed to evaluate the clinical performance of Elecsys HTLV-I/II assay in comparison with ARCHITECT rHTLV-I/II for the detection of HTLV-I/II antibody with Korean samples.

METHODS

For sensitivity evaluation, 100 HTLV-I/II-positive Korean standards from Korean Red Cross and two HTLV-II-positive samples that were purchased from Seracure were used. For the specificity, 500 potential donor specimens from Korea University Hospital healthcare center were used. All the samples were simultaneously analyzed by the two HTLV-I/II assays, Elecsys HTLV-I/II assay and ARCHITECT rHTLV-I/II assay.

RESULTS

Elecsys HTLV-I/II assay and ARCHITECT rHTLV-I/II assay showed a complete agrement. Elecsys HTLV-I/II assay showed 100% sensitivity (95% CI: 96.38-100.0) and specificity (95% CI: 99.26-100.0).

CONCLUSIONS

Elecsys HTLV-I/II assay is as reliable as ARCHITECT rTHLV-I/II assay, and can be used as a screening test for HTLV-I/II in Korea.

Molecular biology of human T cell leukemia virus

Human T cell leukemia virus type 1 (HTLV-1) is a horizontally transmitted virus infection of CD4+ lymphocytes which causes adult T cell leukemia-lymphoma (ATLL) and HTLV-associated myelopathy (HAM). The viral genome encodes two oncoproteins, transactivator protein (Tax) and helix basic zipper protein (HBZ), which are considered tumor initiator and maintenance factors, respectively. Tax is the primary inducer of clonal infected T cell expansion, and genetic instability. The immune response to Tax results in the selection of cells with little or no Tax expression, which have undergone genetic and epigenetic alterations that promote T cell activation, proliferation, and resistance to apoptosis. This selection of malignant cells occurs over several decades in 5% of infected individuals. Novel insights into the molecular details of each of these events has led to targeted therapies for ATLL.

The prevalence of human T-lymphotropic virus type 1 & 2 (HTLV-1/2) in South African blood donors

BACKGROUND AND OBJECTIVES

Donated blood is not currently screened for human T-cell lymphotropic virus (HTLV) in South Africa. Several small studies have detected HTLV-1 in South Africa, but prevalence by geographic region or population group is unavailable.

MATERIALS AND METHODS

We performed a large seroprevalence study of South African blood donors during 3 months in 2013. All geographic regions except the Western Cape were included, and Black and Coloured (local term for mixed race) donors were oversampled. Identity-unlinked plasma samples were screened with the Abbott Prism HTLV-1/2 assay, and repeatedly reactive samples were tested by the Inno-LIA HTLV-1/2 Score confirmatory assay. Odds ratios were calculated with multivariable logistic regression.

RESULTS

Of 46 752 donors tested, 133 (0·28%) were initially reactive, 111 (0·24%) repeatedly reactive and 57 (0·12%) confirmed positive for HTLV-1; none were HTLV-2 positive. Prevalence was 0·062% weighted to annual blood donations but highly concentrated in the Black population group (OR = 20·24 CI: 2·77-147·88); higher in females than males (OR = 1·81 CI: 1·06-3·08); and in donors aged >50 years compared to ages 16-19 (OR = 6·4 CI: 2·95-13·86). After controlling for age, sex and population group, there was no difference in prevalence between new and repeat blood donors or among geographic regions within South Africa.

CONCLUSIONS

We conclude that HTLV-1 infection is widespread among the Black population of South Africa and its epidemiology is similar to other endemic areas. Because South Africa is increasing its recruitment of Black blood donors, the implications for blood screening require further consideration.

Clinical Presentation of Individuals With Human T-Cell Leukemia Virus Type-1 Infection in Spain

Background

Although only 8%–10% of persons infected with human T-cell leukemia virus type 1 (HTLV-1) may develop virus-associated diseases lifelong, misdiagnosis of asymptomatic infected carriers frequently leads to late diagnoses.

Methods

A nationwide HTLV-1 register was created in Spain in 1989. A total of 351 infected persons had been reported by the end of 2017. We examined all new HTLV-1 diagnoses during the last decade and compared their clinical presentation.

Results

A total of 247 individuals with HTLV-1 infection had been reported in Spain since year 2008. The incidence has remained stable with 20–25 new diagnoses yearly. Women represented 62%. Only 12% were native Spaniards, most of whom were foreigners from Latin America (72.5%). Up to 57 (23%) individuals presented clinically with HTLV-1-associated conditions, including subacute myelopathy (n = 24; 42.1%), T-cell lymphoma (n = 19; 33.3%), or Strongyloides stercoralis infestation (n = 8; 14%). Human T-cell leukemia virus type 1 diagnosis had been made either at blood banks (n = 109; 44%) or at clinics (n = 138; 56%). It is interesting to note that Spaniards and especially Africans were overrepresented among patients presenting with HTLV-1-associated illnesses, suggesting that misdiagnosis and late presentation are more frequent in these populations compared to Latin Americans.

Conclusions

Given that 23% of new HTLV-1 diagnoses in Spain are symptomatic, underdiagnosis must be common. Although screening in blood banks mostly identifies asymptomatic Latin American carriers, a disproportionately high number of Spaniards and Africans are unveiled too late, that is, they already suffer from classic HTLV-1 illnesses.

Human T-cell lymphotropic virus type I and II seroprevalence among volunteer blood donors in Thailand

Human T-cell lymphotrophic virus type I and II (HTLV-I/II) are closely related but distinct retroviruses that can infect humans. Both the viruses can be transmitted via transfusion of contaminated blood components. HTLV pre-transfusion screening is not mandatory in Thailand until now. Current epidemiological data for HTLV prevalence is still lacking since the past surveys were done more than a decade ago. The main objective of this study was to determine the seroprevalence of HTLV-I/II among voluntary blood donors in Thailand. 11,057 volunteer blood donors were screened for HTLV-I/II antibodies using the ARCHITECT rHTLV-I/II chemiluminescent immunoassay (CLIA). Initial-reactive (IR)  samples were subjected to repeat duplicate testing and were also sent for confirmatory testing at Korean Red Cross Society (KRC), Seoul or National Serology Reference Laboratories (NRL), Australia using alternate HTLV serological assays and immunoblot and/or specific nucleic acid testing respectively. Out of 11,057 plasma samples, 10,080 were low-risk seronegative donors and 977 were first-time/high-risk donors. Twenty of 24 IR samples were repeatedly reactive (RR) in low-risk seronegative donors group. On confirmatory testing of these 24 IR by immunoblot, 13 indeterminate and 11 negative results were observed. One out of 977 samples from first-time/high-risk donors was RR for anti-HTLV-I/II antibodies. This sample was co-reactive for HBsAg, but negative for HTLV by EIA or in-house HTLV-I qPCR. The ARCHITECT rHTLV-I/II assay exhibited a specificity of 99.93% in low-risk donors and 99.90% among high-risk donors. This study concluded that HTLV-I/II prevalence is low among blood donors in Thailand. But periodic surveillance should be continually conducted to ensure high blood safety standards in the country.

Blood transfusion safety in sub-Saharan Africa: A literature review of changes and challenges in the 21st century

BACKGROUND

Access to a safe, adequate blood supply has proven challenging in sub-Saharan Africa, where systemic deficiencies spanning policy, collections, testing, and posttransfusion surveillance have long been recognized. Progress in transfusion safety in the early 2000s was in large part due to intervention by the World Health Organization and other foreign governmental bodies, coupled with an influx of external funding.

STUDY DESIGN AND METHODS

A review of the literature was conducted to identify articles pertaining to blood safety in sub-Saharan Africa from January 2009 to March 2018. The search was directed toward addressing the major elements of the blood safety chain, in the countries comprising the World Health Organization African region. Of 1380 articles, 531 met inclusion criteria and 136 articles were reviewed.

RESULTS

External support has been associated with increased recruitment of voluntary donors and expanded testing for the major transfusion-transmitted infections (TTIs). However, the rates of TTIs among donors remain high. Regional education and training initiatives have been implemented, and a tiered accreditation process has been adopted. However, a general decline in funding for transfusion safety (2009 onwards) has strained the ability to maintain or improve transfusion-related services. Critical areas of need include data collection and dissemination, epidemiological surveillance for TTIs, donor recruitment, quality assurance and oversight (notably laboratory testing), and hemovigilance.

CONCLUSION

Diminishing external support has been challenging for regional transfusion services. Critical areas of deficiency in regional blood transfusion safety remain. Nonetheless, substantive gains in education, training, and accreditation suggest durable gains in regional capacity.

Revisiting human T-cell lymphotropic virus types 1 and 2 infections among rural population in Gabon, central Africa thirty years after the first analysis

HTLV-1 infection is considered as highly endemic in central Africa. Thirty years ago, a first epidemiological study was performed in Gabon, central Africa, and revealed that the prevalence varied from 5.0 to 10.5%. To evaluate current distribution of HTLVs in Gabon, 4.381 samples were collected from rural population living in 220 villages distributed within the 9 provinces of country. HTLVs prevalence was determined using two ELISA tests and positive results were confirmed by Western Blot. The overall HTLV-1 seroprevalence was of 7.3% among the rural Gabonese population; with 5.4% for men and 9.0% for women. Prevalence of HTLV-1 differed by province, ranging from 2.3% to 12.5% into the rain forest. Being a woman older than 51 years represented a high risk for HTLV-1 acquisition. Hospitalization, operation/surgery, transfusion and medical abortion or fever, arthritis and abdominal pain are also significant risk factors. In addition, 0.1% of samples were found as HTLV-2 positive, while 12.0% had an indeterminate HTLV serological pattern. HTLV-3 and HTLV-4 were not found. Phylogenetic analysis was performed on 87 samples and demonstrated that HTLV-1 present in Gabon belongs mostly to subtype B, however the rare subtype D was also found. Altogether, our results demonstrate that almost thirty years after the first epidemiological study prevention of HTLVs infection is still an issue in Gabon.

Risk factors for HTLV-1 infection in Central Africa: A rural population-based survey in Gabon

BACKGROUND

Human T-Lymphotropic Virus type 1 (HTLV-1) is a human oncoretrovirus that infects at least 5 to 10 million people worldwide and is associated with severe diseases. Africa appears as the largest HTLV-1 endemic area. However, the risk factors for the acquisition of HTLV-1 remain poorly understood in Central Africa.

METHODS

We conducted an epidemiological survey between 2013 and 2017, in rural areas of 6 provinces of Gabon, in a rainforest environment. Epidemiological data were obtained and blood samples were collected after informed consent. Plasma were screened for HTLV-1 antibodies by ELISA and the positive samples were then tested by Western blot (WB). Genomic DNA derived from buffy-coat was subjected to two semi-nested PCRs amplifying either HTLV-1 env gene or LTR region fragments.

RESULTS

We recruited 2,060 individuals over 15 years old, including 1,205 men and 855 women (mean age: 49 years). Of these, 299 were found to be ELISA HTLV-1/2 seropositive. According to WB criteria, 136 were HTLV-1 (6.6%), 25 HTLV-1/2 (1.2%) and 9 HTLV seroreactive (0.4%). PCR results showed that 146 individuals were positive for at least one PCR: 104 for the env gene and 131 for the LTR region. Based on both serological and molecular results, 179 individuals were considered infected with HTLV-1, leading to an overall prevalence of 8.7%. The distribution of HTLV-1 infection was heterogeneous across the country. Based on multivariable analyses, female gender, increasing age, ethnicity (Pygmy) and multiple hospitalizations (more than 5 times) were found to be independent risk factors for HTLV-1 infection. Furthermore, a non-human primate bite appeared to be marginally associated with a higher risk of HTLV-1 infection.

CONCLUSION

Based on state-of-the-art serological and molecular methods, we have demonstrated that rural adult populations in Gabon are highly endemic for HTLV-1. Our results regarding risk factors should lead to public health actions aiming to reduce HTLV-1 transmission.

Moderate endemicity of the human T-lymphotropic virus infection in the metropolitan region of Belém, Pará, Brazil

INTRODUCTION

The spread of the HTLV infection in families living in the metropolitan area of Belém, Pará, Brazil, and the lack of studies in the general population requires studies to better understand its prevalence in the region.

METHODS

An anti-HTLV-1/HTLV-2 antibodies test was carried out on random adults in public places in Belém between November 2014 and November 2015. A proviral DNA test detected if the person was infected, and then a clinical evaluation and an intrafamilial investigation were carried out.

RESULTS

Of the 1059 individuals being investigated, 21 (2.0%) had seroreagent samples, 15 (1.4%) had HTLV-1, 5 (0.5%) had HTLV-2, and proviral DNA was undetectable in one case. The mean age of the infected people (57.2) was higher than that of those that were uninfected (46.2) (p = 0.0010). The prevalence of infection increased with age, especially in individuals with a family income equal to or less than a minimum wage. Intrafamilial transmission seems to have occurred in all of the families being studied. Among the patients with HTLV-1, 30% (3/10) already had some symptom related to the infection.

DISCUSSION

The increase in prevalence rates according to age may be due to late seroconversion of a previously acquired infection, or the cumulative risk of new infections, especially in women.

CONCLUSION

There was a moderate prevalence of the HTLV infection among adult individuals from the metropolitan area of Belém, with a predominance of HTLV-1. This infection was associated with low income and increasingly older women. It also presented intrafamily spread and negligence in the diagnosis of associated diseases.

Re-emergence of human T-lymphotropic viruses in West Africa

Human T-lymphotropic viruses (HTLV) are Deltaretroviruses that infect millions of individuals worldwide via the same transmission routes as HIV. With the aim of exposing the possible re-emergence of HTLV in West Africa since discovery, a systematic review was carried out, focusing on the distribution of the virus types and significance of frequent indeterminate reports, while highlighting the need for mandatory routine blood screening. Capturing relevant data from discovery till date, sources searched were Google Scholar, CrossRef, NCBI (PubMed), MEDLINE, Research Gate, Mendeley, abstracts of Conferences and Proceedings, organization websites and reference lists of selected papers. A total of 2626 references were initially retrieved using search terms: Worldwide prevalence of HTLV, HTLV in Africa, HTLV in West Africa, HTLV subtypes, HTLV 3 and 4 in Africa, HTLV of African origin, HTLV seroindeterminate results, Spread of HTLV. These references were rigorously trimmed down to 76. Although evidence shows that HTLV is still endemic in the region, West Africa lacks recent epidemiological prevalence data. Thorough investigations are needed to ascertain the true cause of indeterminate Western Blot results. It is imperative that routine screening for HTLVs be mandated in West African health care facilities.

Infectious Complications of Transfusion of Blood Components

Transfusions are lifesaving but are not without some risks. During the middle of the last century, infectious complications were common from transfusions. By the mid 1980s the risk of transfusion transmission of infections became much lower. With the advent of emerging diseases, however, infectious risks became more prominent for a period of time. Now we live in a time where death from transfusion transmission is 10%–15% of all transfusion-associated deaths and is the lowest in history. As the risks are identified and new screens or processes are put in place, the associated transfusion transmission of infection will continue to have reducing risks and blood supply will continue to be safer still.

HTLV-1, the Other Pathogenic Yet Neglected Human Retrovirus: From Transmission to Therapeutic Treatment

Going back to their discovery in the early 1980s, both the Human T-cell Leukemia virus type-1 (HTLV-1) and the Human Immunodeficiency Virus type-1 (HIV-1) greatly fascinated the virology scene, not only because they were the first human retroviruses discovered, but also because they were associated with fatal diseases in the human population. In almost four decades of scientific research, both viruses have had different fates, HTLV-1 being often upstaged by HIV-1. However, although being very close in terms of genome organization, cellular tropism, and viral replication, HIV-1 and HTLV-1 are not completely commutable in terms of treatment, especially because of the opposite fate of the cells they infect: death versus immortalization, respectively. Nowadays, the antiretroviral therapies developed to treat HIV-1 infected individuals and to limit HIV-1 spread among the human population have a poor or no effect on HTLV-1 infected individuals, and thus, do not prevent the development of HTLV-1-associated diseases, which still lack highly efficient treatments. The present review mainly focuses on the course of HTLV-1 infection, from the initial infection of the host to diseases development and associated treatments, but also investigates HIV-1/HTLV-1 co-infection events and their impact on diseases development.

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.

Human T-lymphotropic virus type 1 infection and disease in Spain

: Human T-lymphotropic virus type 1 (HTLV-1) infection is a neglected disease despite roughly 15 million people are chronically infected worldwide. Lifelong less than 10% of carriers develop life-threatening diseases, mostly a subacute myelopathy known as tropical spastic paraparesis (TSP) and a lymphoproliferative disorder named adult T-cell leukemia (ATL). HTLV-1 is efficiently transmitted perinatally (breastfeeding), sexually (more from men to women) and parenterally (transfusions, injection drug user (IDU), and transplants). To date there is neither prophylactic vaccine nor effective antiviral therapy. A total of 327 cases of HTLV-1 infection had been reported at the HTLV-1 Spanish registry until December 2016, of whom 34 had been diagnosed with TSP and 25 with ATL. Overall 62% were Latin American immigrants and 13% were persons of African origin. The incidence of HTLV-1 in Spain has remained stable for nearly a decade with 20-25 new cases yearly. Of the 21 newly diagnosed HTLV-1 cases during year 2016, one was a native Spaniard pregnant woman, and four presented with symptomatic disease, including three with ATL and one with TSP. Underdiagnosis of HTLV-1 in Spain must be high (iceberg model), which may account for the disproportionate high rate of symptomatic cases (almost 20%) and the late recognition of preventable HTLV-1 transmissions in special populations, such as newborns and transplant recipients. Our current estimate is of 10 000 persons living with HTLV-1 infection in Spain. Given the large flux of immigrants and visitors from HTLV-1 endemic regions to Spain, the expansion of HTLV-1 screening policies is warranted. At this time, it seems worth recommending HTLV testing to all donor/recipient organ transplants and pregnant women regardless place of birth. Although current leukoreduction procedures largely prevent HTLV-1 transmission by blood transfusions, HTLV testing of all first-time donors should be cost-effective contributing to unveil asymptomatic unaware HTLV-1 carriers.

Emerging Infectious Diseases and Blood Safety: Modeling the Transfusion-Transmission Risk

While the transfusion-transmission (TT) risk associated with the major transfusion-relevant viruses such as HIV is now very low, during the last 20 years there has been a growing awareness of the threat to blood safety from emerging infectious diseases, a number of which are known to be, or are potentially, transfusion transmissible. Two published models for estimating the transfusion-transmission risk from EIDs, referred to as the Biggerstaff-Petersen model and the European Upfront Risk Assessment Tool (EUFRAT), respectively, have been applied to several EIDs in outbreak situations. We describe and compare the methodological principles of both models, highlighting their similarities and differences. We also discuss the appropriateness of comparing results from the two models. Quantitating the TT risk of EIDs can inform decisions about risk mitigation strategies and their cost-effectiveness. Finally, we present a qualitative risk assessment for Zika virus (ZIKV), an EID agent that has caused several outbreaks since 2007. In the latest and largest ever outbreak, several probable cases of transfusion-transmission ZIKV have been reported, indicating that it is transfusion-transmissible and therefore a risk to blood safety. We discuss why quantitative modeling the TT risk of ZIKV is currently problematic.

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During the last 20 years there has been a growing awareness of the threat to blood safety from emerging infectious diseases (EIDs), a number of which are known to be, or are potentially, transfusion-transmissible.

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The transfusion-transmission risk of EID agents can be estimated by risk modeling which can form an important part of risk assessments and inform decisions regarding risk mitigation strategies.

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We describe and compare the methodological principles of two published risk models for estimating the transfusion transmission risk of EIDs.

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We use Zika virus as a case study to demonstrate that reliable risk modeling for EID agents can be problematic due to the uncertainty of the input parameters.

Evaluation of Sensitivity and Specificity Performance of Elecsys HTLV-I/II Assay in a Multicenter Study in Europe and Japan

Screening of blood for human T-cell lymphotropic virus type 1 and type 2 (HTLV-1 and -2, respectively) is important to diagnose and prevent infection and ensure the safety of blood supplies. The Elecsys HTLV-I/II assay is a newly developed, electrochemiluminescence screening assay for the detection of HTLV-1/2 infection. The sensitivity and specificity of the Elecsys HTLV-I/II assay were determined using well-characterized HTLV-1/2-positive serum and plasma samples and routine diagnostic and blood donor samples expected to be HTLV negative, respectively. These results were compared with those for at least one of the following CE-marked assays at seven independent laboratories and the Roche Diagnostics facility in Penzberg, Germany: Abbott Architect rHTLV-I/II, Ortho Avioq HTLV-I/II Microelisa system, Abbott Prism HTLV-I/HTLV-II, and DiaSorin Murex HTLV I+II. Fujirebio INNO-LIA HTLV-I/II Score was used as a confirmatory assay. The Elecsys HTLV-I/II, Abbott Architect rHTLV-I/II, and Abbott Prism HTLV-I/HTLV-II assays detected all HTLV-1/2-positive samples (sensitivity, 100%). Sensitivity for Ortho Avioq HTLV-I/II was 98.63%. The Elecsys HTLV-I/II assay had a specificity of 99.95% in blood donor samples, which was comparable to results for the other assays (range, 99.91 to 100%). In routine diagnostic samples, the specificity of the Elecsys HTLV-I/II assay was 99.83%, compared with 99.70% for Abbott Architect rHTLV-I/II. Specificity for the Elecsys HTLV-I/II assay in potentially cross-reactive samples was 100%, compared with 99.0% for Ortho Avioq HTLV-I/II and 99.2% for DiaSorin Murex HTLV I+II. The Elecsys HTLV-I/II assay has the sensitivity and specificity to support its use as a routine screening assay for detecting HTLV infection.