Allergic Symptoms, Atopy, and Geohelminth Infections in a Rural Area of Ecuador

Laboratorio de Investigaciones, Hospital Pedro Vicente Maldoonado, Pichincha Provinece, Ecuador.
American Journal of Respiratory and Critical Care Medicine (Impact Factor: 13). 08/2003; 168(3):313-7. DOI: 10.1164/rccm.200211-1320OC
Source: PubMed


Geohelminth infections may affect the expression of allergic disease. To investigate the relationship between geohelminth infections, atopy, and symptoms of allergic disease, we studied 4433 schoolchildren from 71 schools in a rural tropical area in Ecuador. Information was collected on allergic symptoms, allergen skin test reactivity, and presence of geohelminth infections. Allergic symptoms were of low prevalence (2.1% had recent wheeze), but prevalence of skin test reactivity was relatively high (18.2%). The presence of geohelminth infections was protective against allergen skin test reactivity (odds ratio 0.62, 95% confidence interval 0.50-0.76, p < 0.001) and symptoms of exercise-induced wheeze (odds ratio 0.59, 95% confidence interval 0.40-0.87, p = 0.008) but not against other wheeze symptoms or symptoms of allergic rhinitis or atopic eczema. Infection intensity with Ascaris lumbricoides or Trichuris trichiura was associated with a reduction in the prevalence of allergen skin test reactivity but not with allergic symptoms. There was no evidence of interactions between geohelminth infection and allergen skin test reactivity on the risks of allergic symptoms. The results suggest that geohelminth infections do not explain the low prevalence of allergic symptoms in the study population.

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Available from: Philip J Cooper, May 02, 2015
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    • "In addition to the problems described above with the use of whole allergenic extracts in the immunodiagnosis of allergic diseases, there is another factor that should be considered by the companies that commercialize these products: the common association of B. tropicalis sensitization with helminth infection in tropical and undeveloped regions of the world. It is in fact believed that about 1.5 billion people worldwide are infected with A. lumbricoides[10,29]. Salvador city, where the donors of the sera used in the present work live, is one helminth parasite endemic areas in Brazil, having high prevalence of A. lumbricoides, Trichuris trichiura and Toxocara spp (Toxocara canis and Toxocara cati) infections. "
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    ABSTRACT: Background Blomia tropicalis is a dust mite and an important source of allergens in tropical regions. Up to now, the assays to diagnose atopy to this mite use whole body extract as antigens. However, anti-B. tropicalis IgE antibodies cross-react with Ascaris lumbricoides antigens, hindering the diagnosis of allergy to this mite. In this study, B. tropicalis recombinant allergens were evaluated with the purpose of developing an immunodiagnostic assay for allergy to this mite with greater specificity than those commercially available. Methods Two B. tropicalis allergens (Blo t 5 and Blo t 21) were cloned into a plasmidial expression vector, expressed in Escherichia coli and purified by affinity chromatography. Sixty-three sera containing anti-B. tropicalis extract (BtE) IgE antibodies were used to investigate IgE reactivity to the recombinant Blot 5 and 21 allergens. Inhibition assays with 20 sera pre-adsorbed with A. lumbricoides extract were performed using rBlo t 5, rBlo t 21, and BtE as antigens. All the assays were carried using indirect ELISA. Results Eighty-two point nine percent and 80.0% of the sera with anti-BtE antibodies from 35 children reacted with rBlo t 5 and rBlo t 21, respectively, whereas 92.8% and 89.3% of the 28 sera with anti-BtE antibodies from adult asthma patients reacted with the same allergens, and 96.4% of these sera reacted with a mixture of rBlo t 5 and rBlo t 21. In an inhibition ELISA, the absorption of sera by A. lumbricoides extract affected less the reaction with rBlo t 5 and rBlo t 21 than with BtE. Conclusions The rBlo t 5 and rBlo t 21 allergens contain important epitopes recognized by IgE antibodies of individuals allergic to B. tropicalis antigens. Moreover, the assays using the recombinant allergens had lower IgE cross-reactivity with A. lumbricoides antigens, a fact which would confers higher specificity to serodiagnostic assays than the crude mite extract. However, additional recombinant allergens should be evaluated in order to reach the same sensitivity of the commercially available assays based on mite extract.
    Full-text · Article · Feb 2013 · BMC Immunology
    • "Although no association between SPT response and A. lumbricoides infection was found in asthmatic individuals [39], a recent study showed that the presence of A. lumbricoides infection is able to reduce the prevalence of positive SPT response but do not affect the prevalence of asthma [8]. Overall, helminth infection is associated with reduced risk of asthma or atopy in regions with high frequency of parasite infections [7, 11, 13], whereas in areas with low endemicity, A. lumbricoides infection is associated with increased risk of atopy and asthma [40, 41]. Although A. lumbricoides is a recognized cause of tropical pulmonary eosinophilia, chronic infection induces a regulatory immune response which includes interleukin-10- and transforming growth factor-β-secreting cells [42, 43]. "
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    ABSTRACT: Protective factors associated with atopy or asthma in rural areas include socioeconomic level, overcrowding, and helminth infection. However, little epidemiological information was originated from schistosomiasis areas. This study aimed to investigate factors associated with asthma in a schistosomiasis endemic area. A questionnaire was used to obtain information on demographics, socioeconomic, and environmental features. The ISAAC questionnaire was used to identify individuals with asthma. Parasitological exam was done in all participants and skin prick test to aeroallergens in all asthmatics. Prevalence of Schistosoma mansoni infection was 57.4% and Ascaris lumbricoides, 30.8%. Asthma was found in 13.1% of the population, and 35.1% of them had a positive SPT. Active and passive smoking was positively associated with asthma, whereas A. lumbricoides was negatively associated. In a schistosomiasis hyperendemic region, current infection with A. lumbricoides is protective against asthma. However, we cannot rule out the involvement of S. mansoni infection in this process.
    No preview · Article · Aug 2012 · Journal of Parasitology Research
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    • "It is well established that atopy is a strong risk factor for developing allergic disease in people living in industrialized countries [20], whereas a consistent relationship has not been demonstrated in studies done in developing regions [21-23]. One drawback of this study is that, we could not perform skin prick test on these children as a measure of allergic sensitization but rather relied on serum sIgE levels. "
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    ABSTRACT: The effect of helminth infections on allergic diseases is still inconclusive. Furthermore, the effect of helminth infections on childhood allergic diseases in a tropical area where prevalence of helminth infections has undergone dramatic changes is not well documented. To investigate the relationship between allergic diseases and helminth infection in a cohort of schoolchildren in an area that has undergone dramatic changes in intensity of helminth infections. Children attending grade 5 were recruited from 17 schools in Western Province of Sri Lanka. They were assessed for allergic diseases using the International Study of Asthma and Allergies in Childhood questionnaire. Their serum total IgE (tIgE) and allergen-specific IgE (sIgE) for five common aeroallergens were measured by ImmunoCAP® method and stools were examined for the presence of helminth infections. A total of 640 children (mean age 10 years) were recruited to the study. Of them, 33.7% had evidence of allergic disease and 15.5% had helminth infections. Majority of infections (68.9%) were of low intensity. A significant relationship between allergic disease and helminth infections was not observed, however, a trend toward protective role of helminth infections against allergic diseases was noted. Multivariate analysis showed helminth infections to be an independent predictor of high tIgE levels whereas allergic disease was not. Allergic sensitization (atopy) was a significant risk factor for allergic disease only among non-infected children (odds ratio 3.025, p = 0.022) but not in infected children. The ratio of sIgE to tIgE was higher in non-infected children. Though not significant, a reduced risk of allergy in helminth-infected children was observed in this population. A Decrease in intensity of helminth infections may have contributed to the reduced capacity of immune-modulation by helminths in this paediatric population.
    Full-text · Article · Apr 2012
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