Is Human T Cell Lymphotropic Type 1 (HTLV-1)-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) Syndrome a Neglected Disease?

Abstract

Human T cell lymphotropic type 1 (HTLV-1) was the first human retrovirus discovered and has been associated mainly with two illnesses [1], an inflammatory disease named HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and a neoplastic condition called adult T cell leukemia/lymphoma (ATL) [2]. Although this virus has worldwide distribution, Japan, Africa, the Caribbean basin, and South America are considered to be endemic areas [3]. It has been estimated that 10–20 million people are infected with this virus [4], but the majority are asymptomatic and probably not aware of their serological status. There is no accurate number of HAM/TSP or ATL cases since these diseases are not considered reportable by the World Health Organization (WHO), although Japan reports approximately 800 cases of ATL yearly [5]. In 1985, Roman et al. used the term tropical spastic paraparesis (TSP) for the first time, modifying the term “tropical spastic paraplegia” as used in South India in 1969, because only a few cases were completely paraplegic [6]. In the same year, it was found that almost 60% of patients with TSP were also positive for HTLV-1 compared with 4% of the controls, which suggested, for the first time, the neurotropism of human retroviruses [7]. In 1986, Osame et al. coined the term HTLV-1-associated myelopathy (HAM) [8]. In 1988, the WHO recommended “that the disease be known by the acronym HAM/TSP for the time being.” Thus, it seems that in endemic areas, about 60% of tropical spastic paraparesis cases are identified as HAM/TSP [7]. The rest are myelopathies probably caused by nutrition problems, intoxication, and unknown causes [6],[9]. HAM/TSP has an estimated incidence ranging from 0.25% to 1% after 30–40 years of incubation [9]. The onset of disease is 40 years of age, with predominance in women [10]. Several factors have been ascribed as potentials for clinical outcome, such as high HTLV-1 proviral load, genetic background, routes of transmission (i.e., breastfeeding or transfusion), and high antibody titers [11]. Despite the publication of several reviews regarding the pathogenesis or molecular biology of HTLV-1 [12],[13], few studies have addressed treatment for the diseases caused by this virus. Thus, this article will focus on the reason why HAM/TSP should be considered a neglected tropical disease. To illustrate our viewpoint, we present one case of HAM/TSP in which several important issues are raised as singularities of the problem. A 29-year-old black woman born in Bahia in northeast Brazil has been living in Sao Paulo city for several years. When she was 20, she began complaining of lumbar pain and parestesis, initially in one leg and then in both, in addition to miccional urgency and constipation. After 3 years of illness and several visits to doctors, including basic and intermediate complexity level services, she was referred to our service as a suspected case of HTLV-1 disease. The diagnosis of HAM/TSP was confirmed. The patient was using a wheelchair most of the time. Pulse therapy with methylprednisolone was administered three to four times per year, with programmed hospitalization for at least 5 days. Her husband abandoned her, and she lives with her two children in a small one-bedroom house in an area difficult to reach by car. Her only income is the government minimum wage (US$250.00/month), and she is unable to attend a facility for physical therapy. She depends on her friends or relatives to bring her to the clinic appointments.