Human T-Lymphotropic Virus 1: Clinical Aspects of a Neglected Infection among Indigenous Populations

This chapter discusses the clinical manifestations of human T-lymphotropic virus 1 (HTLV-1) in two neglected indigenous populations: the Aboriginal people of central Australia and the Quechua Amerindians of the southern Andes in Peru. The vast majority of the 10 million to 20 million HTLV-1-infected people worldwide, therefore, live in the developing world, and even there, infection is associated with lower socioeconomic status. Among indigenous people in Peru, prolonged breast-feeding is also probably the most important route of transmission. The remainder of the chapter focuses on HTLV-1-associated conditions that might be relevant to resource-poor areas. The major clinical manifestations of HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) are spastic weakness of the lower limbs, urinary and sexual dysfunction, constipation, and back pain. Although a brief report from Papua New Guinea also failed to find an association between HTLV-1 and tuberculosis, a study performed in Port Moresby, included no control group, and did not report background prevalence rates. Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy of HTLV-1-infected CD4 lymphocytes. Clinical characteristics include lymphadenopathy, hepatosplenomegaly, skin lesions, hypercalcemia, lytic bone lesions, and presentation with opportunistic infections, including Pneumocystis jirovecii pneumonia. Monoclonal integration of HTLV-1 has been found in as many as 39% of Strongyloides stercoralis-infected HTLV-1-seropositive patients, and two patients in this study subsequently developed ATL. Conversely, case reports suggest that treating S. stercoralis reduces the number of clones and Tax mRNA transcription and may lead to remission of chronic ATL in some patients.