Effects of helminth co-infections on atopy, asthma and cytokine production in children living in a poor urban area in Latin America

Abstract

BackgroundHelminths are modulators of the host immune system, and infections with these parasites have been associated with protection against allergies and autoimmune diseases. The human host is often infected with multiple helminth parasites and most studies to date have investigated the effects of helminths in the context of infections with single parasite or types of parasites (e.g. geohelminths). In this study, we investigated how co-infections with three nematodes affect markers of allergic inflammation and asthma in children. We selected Ascaris lumbricoides and Trichuris trichiura, two parasites that inhabit the human intestine and Toxocara spp (Toxocara canis and/or T. cati), intestinal roundworms of dogs and cats that cause systemic larval infection in humans. These parasites were selected as the most prevalent helminth parasites in our study population.Results36.4% of children were infected with one parasite; 12.7% with 2 and 5.2% with 3. Eosinophilia >4% and >10% was present in 74.3% and 25.5% of the children, respectively. Total IgE > 200 IU/mL, sIgE ≥ 0.70 kU/L and SPT positivity were present in 59.7%, 37.1% and 30% of the children, respectively. 22.7% had recent asthma (12.0% non-atopic and 10.7% atopic). Helminth infections were associated in a dose-dependent way to decrease in the prevalence of SPT and increase in eosinophilia, total IgE, and the production of the regulatory cytokine IL-10 by unstimulated peripheral blood leukocytes. No association with asthma was observed.ConclusionsHelminth co-infections in this population were associated with increased markers of the Th2 immune response, and with a host immune regulatory phenotype that may suppress allergic effector responses such as immediate hypersensitivity reactions in the skin.

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

“…STH infections have been largely associated with eosinophilia, especially in early stages of infection, when larval migration occurs. The association between eosinophilia and STH in the present study is consistent with results from previous work conducted in Honduras [39, 40] and other countries such as Brazil [41, 42], Philippines [43], Indonesia [44], and Spain [26]. …”

Enteroparasites, Respiratory Allergy and Other Signs and Symptoms in Childs and Youth Population of Recôncavo of Bahia – Brazil

“…In the city of Salvador-BA, a study using the ISAAC quiz (round 2) analyzed 1,445 children living in poor neighborhoods of the city, where high prevalences of helminths such as A scaris lumbricoides and low prevalence of allergic manifestations were found, suggesting helminth protection (48) and corroborating with the study done by Cardoso et al (49), in the same city.…”

Allergens of <b><i>Blomia tropicalis</i></b>: An Overview of Recombinant Molecules

“…Recent studies have also evaluated the cross-reactivity between rBlo t 5 and the group 21 allergens, as well as with crude extracts of B. tropicalis and Ascaris lumbricoides [12,53]. The latter allergen source should be considered in tropical regions due to the high prevalence of helminth infections [54,55,56], which could possibly interfere with the serodiagnosis of mite allergy [57,58]. Interestingly, Carvalho et al [12] showed that rBlo t 5 and rBlo t 21 are less cross-reactive with A. lumbricoides crude extracts than with extracts of B. tropicalis , suggesting that these 2 recombinant allergens might represent markers for the diagnosis of B. tropicalis- sensitized patients.…”