HTLV-1 - HTLV-1, a single-stranded RNA retrovirus is endemic in several regions of the world and is the etiologic agent of severe specific diseases like adult T-cell leukae- mia/lymphoma, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and infective dermatitis

The leprosy spectrum is directly associated with the host immune response to Mycobacterium leprae antigens, which will determine not only the clinical type of disease, but also whether the development of the leprosy reactions (LRs) will occur (Rea & Modlin 1991). Therefore besides being a chronic infection, leprosy can also be regarded as an immunological disease. The leprosy spectrum comprises at one end the tuberculoid pole where cell-mediated immunity against M. leprae leads to few lesions and non-contagious disease. The other pole is represented by lepromatous disease characterized by infiltrated and disseminated lesions with high bacterial load, due to host cellular anergy against Hansen’s bacilli. The borderline forms are associated with unstable immunity leading to mixed and ever changing clinical manifestations (Ridley & Joplin 1966, Rea & Modlin 1991). Several coinfections in leprosy patients (LPs) may contribute to leprosy’s clinical manifestations due to interference with the host immune response, either by depressing cellular immunity or amplifying inflammatory pathways (Seghal & Sharma 1998, Motta et al. 2010). Therefore, it is possible that viral coinfections may modify leprosy outcome and could be associated with more disseminated disease or a higher incidence of LRs. The purpose of this review is to summarize the evidence for a role of specific viral coinfections like human T cell lymphotrophic virus type 1 (HTLV-1), hepatitis B virus (HBV) and hepatitis C virus (HCV) in leprosy.