BACKGROUND:It has been hypothesized that helminth infections increase HIV susceptibility by enhancing systemic immune activation and hence contribute to elevated HIV-1 transmission in sub-Saharan Africa.OBJECTIVE:To study systemic immune activation and HIV-1 co-receptor expression in relation to different helminth infections and in response to helminth treatment.METHODS:HIV-negative adults with (n = 189) or without (n = 57) different helminth infections, as diagnosed by Kato-Katz, were enrolled in Mbeya, Tanzania. Blinded to helminth infection status, T cell differentiation (CD45RO, CD27), activation (HLA-DR, CD38) and CCR5 expression was determined at baseline and 3 months after Albendazole/Praziquantel treatment. Plasma cytokine levels were compared using a cytometric bead array.RESULTS:Trichuris and Ascaris infections were linked to increased frequencies of "activated" CD4 and/or CD8 T cells (p<0.05), whereas Hookworm infection was associated with a trend towards decreased HLA-DR+ CD8 T cell frequencies (p = 0.222). In Trichuris infected subjects, there was a linear correlation between HLA-DR+ CD4 T cell frequencies and the cytokines IL-1β and IL-10 (p<0.05). Helminth treatment with Albendazole and Praziquantel significantly decreased eosinophilia for S. mansoni and Hookworm infections (p<0.005) but not for Trichuris infection and only moderately modulated T cell activation. CCR5 surface density on memory CD4 T cells was increased by 1.2-fold during Trichuris infection (p-value: 0.053) and reduced after treatment (p = 0.003).CONCLUSIONS:Increased expression of T cell activation markers was associated with Trichuris and Ascaris infections with relatively little effect of helminth treatment.