Impairment of Host Immune Response Against Strongyloides Stercoralis by Human T Cell Lymphotropic Virus Type 1 Infection

A large-scale study was undertaken to clarify the prevalence rate of strongyloidiasis in Okinawa, Japan and to evaluate the relationship between strongyloidiasis and infection with human T cell lymphotropic virus type 1 (HTLV-1). The prevalence rate of Strongyloides stercoralis and HTLV-1 infection were 6.3% and 14.0%, respectively. Among 2,185 patients more than 50 years of age, the rate of S. stercoralis infection was significantly higher in patients with HTLV-1 infection compared with patients without HTLV-1 infection. In 252 patients treated with ivermectin, serum IgE levels and peripheral eosinophil counts were significantly lower in HTLV-1 co-infected patients compared with patients without HTLV-1 infection. In addition, the anthelmintic effect was significantly lower in patients with HTLV-1 infection compared with patients without HTLV-1 infection. Our prospective study demonstrated a prevalence rate for strongyloidiasis and HTLV-1 infections, and clearly demonstrated that co-infection with HTLV-1 impaired the immune response against S. stercoralis.