Epidemiology, treatment, and prevention of human T-cell leukemia virus type 1-associated diseases

Abstract

Human T-cell leukemia virus type 1 (HTLV-1), the first human retrovirus to be discovered, is present in diverse regions of the world, where its infection is usually neglected in health care settings and by public health authorities. Since it is usually asymptomatic in the beginning of the infection and disease typically manifests later in life, silent transmission occurs, which is associated with sexual relations, breastfeeding, and blood transfusions. There are no prospects of vaccines, and screening of blood banks and in prenatal care settings is not universal. Therefore, its transmission is active in many areas such as parts of Africa, South and Central America, the Caribbean region, Asia, and Melanesia. It causes serious diseases in humans, including adult T-cell leukemia/lymphoma (ATL) and an incapacitating neurological disease (HTLV-associated myelopathy/tropical spastic paraparesis [HAM/TSP]) besides other afflictions such as uveitis, rheumatic syndromes, and predisposition to helminthic and bacterial infections, among others. These diseases are not curable as yet, and current treatments as well as new perspectives are discussed in the present review.

FIG. 1.

Geographic distribution of HTLV-1 in countries where the disease is endemic. The stars emphasize high-prevalence areas. The country boundaries shown in the map are not coincidental with the areas of endemicity, reflecting the cluster nature of HTLV infection. (Adapted from reference .)

FIG. 2.

MRIs showing thoracic cord atrophy (white arrow) in a patient with HAM/TSP.

FIG. 3.

Brain MRI performed with 1.5-T equipment (sagittal T2 weighted; axial FLAIR, T1- and T2-weighted images). (Top) T1-weighted images following venous paramagnetic contrast at three planes. (Bottom) T2-weighted MRI of the brain reveals punctate nodular discrete hyperintense foci without a mass effect in the periventricular and subcortical white matter. These lesions do not increase.