Epidemiological and clinical interaction between HTLV-1 and Strongyloides stercoralis.
Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.
Carvalho
E M
EM
Federal University of Bahia, Hospital Universitário Prof. Edgard Santos, Serviço de Imunologia, Salvador-BA, Brazil. edgar@ufba.br
Da Fonseca Porto
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D000818:Animals; D015490:HTLV-I Infections / Q000150:complications* / Q000453:epidemiology* / Q000276:immunology / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000276:immunology / Q000472:pathogenicity; D006801:Humans; D017171:Strongyloides stercoralis / Q000276:immunology / Q000472:pathogenicity; D013322:Strongyloidiasis / Q000150:complications* / Q000453:epidemiology* / Q000276:immunology / Q000469:parasitology