HTLV‐1 modifies the clinical and immunological response to schistosomiasis
The immunological response in HTLV‐1 infected individuals is characterized by a prominent Type‐1 cytokine response with high production of IFN‐γ and TNF‐α. In contrast, helminthic infections and in particular chronic schistosomiasis are associated with a predominant production of IL‐4, IL‐5, IL‐10 and IL‐13. Liver fibrosis is the main pathological finding in schistosomiasis that occurs after many years of infection. This pathology is T cell dependent but the immune response mechanisms are not completely understood. The North‐east region of Brazil is endemic for both HTLV‐1 and schistosomiasis. In the present study the immune response, clinical severity, and therapeutic response to praziquantel of patients with schistosomiasis coinfected with HTLV‐1 were compared with patients infected only with S. mansoni. Patients with HTLV‐1 and S. mansoni had lower levels of IL‐5 (P < 0·05) and higher levels of IFN‐γ (P < 0·05) in cultures stimulated with S. mansoni antigen and decreased S. mansoni antigen specific IgE levels when compared with patients with schistosomiasis without HTLV‐1 coinfection. Liver fibrosis was mild in all HTLV‐1 coinfected patients and efficacy of praziquantel was lower in patients dually infected than in patients infected only with S. mansoni.