Association of a sex-related difference of Strongyloides stercoralis-specific IgG4 antibody titer with the efficacy of treatment of strongyloidiasis.

It is difficult to completely eradicate strongyloidiasis, a human intestinal nematode infection with Strongyloides stercoralis with drugs, especially in males. To find host factors involved in the response to treatment, patients infected with S. stercoralis were examined for S. stercoralis-specific antibody titers and the effect of treatment with albendazole on these titers were determined. The cure rate was slightly but not significantly lower in males than in females (P = 0.108). However, a significantly higher titer of S. stercoralis-specific IgG4 antibody was observed in males than in females (P = 0.0097), and the S. stercoralis-specific IgG4 antibody titer was significantly higher in the male non-cured group than in the cured group (P = 0.035). These results suggest that elevation of the S. stercoralis-specific IgG4 antibody titer is associated with resistance to treatment of S. stercoralis infection, especially in males.