HTLV-I seroprevalence in the Sultanate of Oman

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.

Discrepancy between human T-cell lymphotropic virus type I screening test and confirmatory tests in non-endemic areas

AIM

The purpose of this study was to examine the seroprevalence of human T-lymphotropic virus (HTLV)-I among pregnant women at our institution in Tokyo, Japan, which is a non-endemic area, and to investigate the results of Western blotting among pregnant women who had obtained positive results from a screening test.

MATERIAL AND METHODS

The seroprevalence of HTLV-I was retrospectively reviewed in 11,352 pregnant women who gave birth at the National Center for Child Health and Development in Tokyo, Japan, between 2002 and 2009. For the screening test, a chemiluminescent enzyme immunoassay was performed followed by a confirmatory Western blot test.

RESULTS

The overall positive rate for the screening test was 0.33% (37/11,352). Western blot testing was performed in 36 of these 37 cases. Only nine patients (25%) were positive for HTLV-I by Western blot testing, seven patients (19%) were indeterminate, and 20 patients (56%) were negative.

CONCLUSIONS

In this study (carried out in a non-endemic area), the percentage of patients with a positive result from the screening test who were confirmed to be true carriers was significantly low, differing from endemic areas.

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.

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

A serosurvey for Human T-cell Lymphotropic virus type 1 (HTLV-I)/HTLV-II was conducted in 1,900 blood donors, 120 pregnant women and 436 high-risk group patients in Beirut, Lebanon. One of the 1,900 blood donors was anti-HTLV-I/II-seroreactive on screening by enzyme immunoassay (EIA) but was indeterminate by Western blot and negative by polymerase chain reaction. None of the other 556 subjects studied was seroreactive by EIA. The credibility of the zero prevalence of HTLV-I/II infection among the Lebanese blood donors is supported by the absence of seroreactivity of antibodies in the multiply transfused patients. It seems therefore that the prevalence of HTLV-I/II appears to be less than 1 in 2,456 in the Lebanese population and hence, HTLV-I/II infection does not appear to require routine screening in Lebanon.

Descriptive epidemiology of de novo acute leukaemia in the Sultanate of Oman

A hospital-based epidemiological study of de novo acute leukaemia was carried out in the Sultanate of Oman, a sparsely populated Arabian Gulf country which has undergone rapid and dramatic socio-economic changes recently. A total of 65/99 Omanis (66%) were diagnosed as acute lymphoblastic leukaemia (ALL) and 34/99 (34%) as acute myeloid leukaemia (AML). Trends and peak values in age-specific incidence rates for ALL are generally in line with those of Western countries. The proportion of T-ALL cases is however higher than that in Caucasian populations but lower than in many non-white populations. AML frequency particularly in childhood is similar to that observed in many African countries.