Environmental determinants of total IgE among school children living in the rural Tropics: importance of geohelminth infections and effect of anthelmintic treatment

Abstract

Background: The environmental factors that determine the elevated levels of polyclonal IgE observed in populations living in the Tropics are poorly understood but may include geohelminth infections. We investigated the association between geohelminth infections and total IgE levels in school children in rural tropical Ecuador, and assessed the effect on IgE of repeated anthelmintic treatments over a period of 12 months. The study was nested within a clusterrandomized study that randomized 68 schools to receive either 400 mg of albendazole every 2 months over a year or no treatment. We studied random samples of children completing follow-up and representing four groups stratified by the presence of geohelminth infection at baseline and treatment allocation. We measured levels of total IgE and anti-A. lumbricoides IgG (used as a measure of past and current geohelminth infectious exposure) in blood samples collected at the start of the study and after 12 months.

Immune Profile of Honduran Schoolchildren with Intestinal Parasites: The Skewed Response against Geohelminths

“…Such findings are consistent with observations in studies conducted in Nigeria [47, 48], Ecuador [49], Venezuela [50], Spain [26], and Brazil [41, 51, 52]. Helminth-induced IgE is mostly characterized by a nonspecific polyclonal stimulation with only a small fraction of parasite-specific IgE.…”

“…Other researchers have made the same observation [49, 51, 56]. Some studies have shown that specific IgE levels reflect the parasite infection intensity; therefore, higher specific antibody levels would be expected in lightly infected individuals when compared with those heavily infected [57].…”

Ascaris lumbricoides infection in urban schoolchildren: Specific IgE and IL-10 production

“…12 These last authors suggested that this condition may be due to the continuous re-stimulation by evolving forms of the worm or that particularly in persons with an atopic genetic disposition and so, in this context, the higher levels of anti-Ascaris IgE would seem to reflect not only a marker of previous infection, but also a protective factor. 12,23 In fact, some studies have used the anti-Ascaris IgG isotype (not IgE) as a marker for chronic infections, 11,24 whereas some protective functions of the specific IgE molecule seem to contribute to the immunity of the host against different stages of the life cycle of the parasite (alterations in intestinal mobility and mucus production, associated to Th2 cytokines responses (IL-4, IL-13) and mast cell activation. 25,26 Furthermore, an analysis of the isotypic profile against antigenic molecules of A. lumbricoides demonstrates that in both non-infected patients and those with a low parasitic load, there were higher levels of specific IgE, thus suggesting a protective role for this immunoglobulin isotype.…”

Temporal Changes in Total Serum Immunoglobulin E Levels in East German Children and the Effect of Potential Predictors

“…IgE levels in a comparable group of children in West Germany were clearly lower (geometric mean 20.3 kU/l) [25]. In contrast, the geometric mean of total IgE in a study of schoolchildren in rural Ecuador was as high as 1,004 kU/l [26]. …”