HTLV-I and HTLV-II infections in volunteer blood donors and high-risk groups in Lebanon

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.

Human T-lymphotropic virus and transfusion safety: does one size fit all?

Human T-cell leukemia viruses (HTLV-1 and HTLV-2) are associated with a variety of human diseases, including some severe ones. Transfusion transmission of HTLV through cellular blood components is undeniable. HTLV screening of blood donations became mandatory in different countries to improve the safety of blood supplies. In Japan and Europe, most HTLV-infected donors are HTLV-1 positive, whereas in the United States a higher prevalence of HTLV-2 is reported. Many industrialized countries have also introduced universal leukoreduction of blood components, and pathogen inactivation technologies might be another effective preventive strategy, especially if and when generalized to all blood cellular products. Considering all measures available to minimize HTLV blood transmission, the question is what would be the most suitable and cost-effective strategy to ensure a high level of blood safety regarding these viruses, considering that there is no solution that can be deemed optimal for all countries.

Emerging infectious threats to the blood supply: seroepidemiological studies in iran - a review

SUMMARY

The risk of transfusion-transmitted infections has been greatly reduced by improvements in donor screening and testing. However, newly recognized blood-borne infectious agents can be threats to blood safety. In order to evaluate the prevalence some of these agents in blood donors, a systematic review was conducted. Data were obtained from published papers related to HGV, Torque Teno virus (TTV), HTLV, West Nile virus (WNV) and SEN virus (SEN-V). Based on these studies, the prevalence of HGV varied from 1 to 8.6% for anti-E2 and from 0 to 4.8% for HGV RNA. The prevalence of TTV DNA and HTLV-I varied from 2.7 to 79.5% and from 0.013 to 2.3%, respectively. The WNV-specific IgM antibody and WNV RNA are negative in blood donors. Prevalence rates of SEN-V in Iranian blood donors range from 23 to 90.8%. Consequences of these infectious agents for blood safety are different. Thus, the need to perform laboratory screening as well as effectiveness and efficiency of laboratory tests depend on pathogenicity level and epidemiological conditions of emerging infections. However, being prepared based on the current level of risk and interventions to reduce the risk can be effective in reducing the potential threat for blood supply.

Epidemiological Aspects and World Distribution of HTLV-1 Infection

The human T-cell leukemia virus type 1 (HTLV-1), identified as the first human oncogenic retrovirus 30 years ago, is not an ubiquitous virus. HTLV-1 is present throughout the world, with clusters of high endemicity located often nearby areas where the virus is nearly absent. The main HTLV-1 highly endemic regions are the Southwestern part of Japan, sub-Saharan Africa and South America, the Caribbean area, and foci in Middle East and Australo-Melanesia. The origin of this puzzling geographical or rather ethnic repartition is probably linked to a founder effect in some groups with the persistence of a high viral transmission rate. Despite different socio-economic and cultural environments, the HTLV-1 prevalence increases gradually with age, especially among women in all highly endemic areas. The three modes of HTLV-1 transmission are mother to child, sexual transmission, and transmission with contaminated blood products. Twenty years ago, de Thé and Bomford estimated the total number of HTLV-1 carriers to be 10-20 millions people. At that time, large regions had not been investigated, few population-based studies were available and the assays used for HTLV-1 serology were not enough specific. Despite the fact that there is still a lot of data lacking in large areas of the world and that most of the HTLV-1 studies concern only blood donors, pregnant women, or different selected patients or high-risk groups, we shall try based on the most recent data, to revisit the world distribution and the estimates of the number of HTLV-1 infected persons. Our best estimates range from 5-10 millions HTLV-1 infected individuals. However, these results were based on only approximately 1.5 billion of individuals originating from known HTLV-1 endemic areas with reliable available epidemiological data. Correct estimates in other highly populated regions, such as China, India, the Maghreb, and East Africa, is currently not possible, thus, the current number of HTLV-1 carriers is very probably much higher.

Adult T-cell leukemia/lymphoma in the Middle East: first report of two cases from Lebanon

BACKGROUND

Adult T-cell leukemia/lymphoma (ATL) is an aggressive lymphoproliferative disorder caused by human T-cell leukemia virus type I (HTLV-I). HTLV-I is endemic in southern Japan, the Caribbean, Central and South America, certain areas of Africa, and the southeastern United States. In the Middle East, North East Iran, particularly the region of Mashhad, has been recognized as an endemic region.

CASE REPORTS

In this report, the first two cases of ATL diagnosed in Lebanon are described. The first patient of Lebanese origin presented with acute ATL. The second patient of Romanian origin developed acute ATL in early relapse after autologous transplantation for ATL. Both patients had lymphocytosis, severe hypercalcemia, and CD25+ T-cell immunophenotype on peripheral blood. In both patients, HTLV-I serology was positive by enzyme-linked immunosorbent assay and confirmed by Western blot and HTLV-I oncoprotein Tax expression was documented in the leukemic cells. Upon screening, seven direct family members of the first patient were HTLV-I positive; four of them were regular blood donors.

CONCLUSIONS

Screening blood donors for HTLV-I seropositivity is not currently performed in Lebanon. A large screening study in Lebanon is needed to confirm whether South Lebanon is a new endemic region for HTLV-I infection and to recommend mandatory screening of blood donors for HTLV-I infection.

Is seroprevalence of HTLV-I/II among blood donors in Lebanon relevant?

Human T-cell lymphotropic virus type I (HTLV-I) is associated with certain hematologic and neurologic disorders. Seroprevalence studies demonstrated that the distribution of HTLV-I is heterogeneous worldwide and not specific to 1 region. Because blood is one of the major routes of transmission of the virus, blood banks of several countries routinely screen all blood donations for HTLV-I. The aim of the present study was to assess the seroprevalence rate of HTLV-I/II antibodies among Lebanese blood donors. Between August 2001 and March 2002, consecutive blood samples of 3529 blood donors were collected at blood banks of 4 major hospitals in Lebanon. Initial enzyme-linked immunosorbent assay (ELISA) screening resulted in 23 (0.7%) positive samples, of which 12 (0.3%) were reconfirmed positive by ELISA. Further analysis by Western blot resulted in 2 (0.06%) positive samples, of which 1 tested positive for HTLV-I by PCR (0.028%). Although its very low prevalence among Lebanese blood donors does not support routine screening of Lebanese blood donors for HTLV-I, screening of blood donors from other nationalities may be exercised, especially those from HTLV-I endemic areas.

Infection with hepatitis B and C viruses and human retroviruses (HTLV-I and HIV) among high-risk Lebanese patients

Three groups of Lebanese patients (haemophiliacs, patients on cycled cancer chemotherapy who were regularly receiving blood transfusions, and intravenous drug users) and a control group of healthy blood donors were checked for markers of infection with hepatitis viruses (B and C) and human retroviruses (HIV and HTLV-I). Compared with the controls, all three groups of patients were more likely to be seropositive for antibody to hepatitis C virus (anti-HCV), and the haemophiliacs and cancer patients (but not the relatively young drug users) were more likely to be seropositive for hepatitis B virus (HBV). All the haemophiliacs and cancer patients found to be carrying the surface antigen of HBV (HBsAg) and/or to be seropositive for anti-HCV had given the same result when tested before the screening of blood and blood products for HBsAg and anti-HCV became routine practice in Lebanon (a decade before the present study). The four intravenous drug users (IVDU) found seropositive for HBV (two cases) or anti-HCV (two cases) had seroconverted in the 2 years prior to the present study. In addition to highlighting the problem of HCV infection among IVDU, the present results emphasise the need for the careful screening of donated blood for all blood-borne viruses, and for the exclusive use of disposable equipment in the management of cancer patients. The anti-HBV vaccination of IVDU is recommended but only the results of further clinical evaluation will show whether the similar vaccination of patients on cycled cancer chemotherapy is of value. Although none of the patients or controls was found positive for anti-HIV-1, anti-HIV-2 or anti-HTLV-I, the routine screening of blood and blood products for these viruses (particularly for HIV) should remain mandatory.