Co-infection with Ascaris lumbricoides modulates protective immune responses against Giardia duodenalis in school Venezuelan rural children

Giardia duodenalis stimulates protective immune responses in rural children. However, co-infection of Ascaris lumbricoides may modulate these responses affecting the resistance against G. duodenalis in rural Venezuelan children. [Display omitted] ▶ We studied the effect of A. lumbricoides co- infection on the course of giardiasis. ▶ A group of 251 rural and 70 urban school children was evaluated. ▶ Moderate A. lumbricoides intensities correlated with a high prevalence of giardiasis. ▶G. duodenalis stimulated TH2/TH1 immunity only in Ascaris lightly infected children. ▶ Moderate worm burdens decreased G. duodenalis immunity favoring recurrent infection. We evaluated the effect of Ascaris lumbricoides on Giardia duodenalis infection and TH1/TH2 type immune mechanisms toward this parasite in 251 rural parasitized and 70 urban non-parasitized school children. The children were classified according to light (0–5000eggs/gfaeces) or moderate (>5001–50,000eggs/gfaeces) A. lumbricoides infection. Anti G. duodenalis skin hyper-reactivity, IgE, IgG, IL-13, IFN γ, IL6 and IL-10 levels were compared among G. duodenalis infected and non-infected children according to light or moderate A. lumbricoides infection. It was found that 62% of the A. lumbricoides moderately infected children were co-infected by G. duodenalis compared to 45% of the lightly infected group. After treatment, 42% of the A. lumbricoides moderately group were infected with G. duodenalis compared to 11% of their lightly counterparts, being A. lumbricoides IL-10 levels higher (p0.0001), suggesting that co-infection with A. lumbricoides may affect both TH1 and TH2 type immunity against G. duodenalis that may play an important role in the susceptibility to the infection after chemotherapy in children from en