Asthma and current intestinal parasite infection: systematic review and meta-analysis

Parasitic helminths and protozoa: Treasure boxes of disease modifying anti-rheumatic drugs

Parasites generally survive in their hosts by employing various immunomodulation and immune evasion mechanisms. "helminth therapy" is one strategy that harnesses these parasite-specific beneficial properties for the therapeutic treatment of autoimmune and allergic diseases. Although numerous experimental reports have documented the anti-autoimmune activities of parasitic infections and parasite-derived products, the underlying mechanisms remain insufficiently elucidated due to the significant diversity among parasite species and autoimmune conditions. Rheumatoid arthritis (RA) is one of the most prevalent autoimmune disorders, presenting a substantial opportunity for the therapeutic use of parasites as novel disease-modifying antirheumatic drugs (DMARDs). In this paper, we summarize the immunomodulatory properties of parasites, focusing on their anti-arthritic mechanisms, and discuss the potential of parasite-derived products for the treatment of RA.

Helminth-derived molecules: pathogenic and pharmacopeial roles

Parasitic helminths, taxonomically comprising trematodes, cestodes, and nematodes, are multicellular invertebrates widely disseminated in nature and have afflicted people continuously for a long time. Helminths play potent roles in the host through generating a variety of novel molecules, including some excretory/secretory products and others that are involved in intracellular material exchange and information transfer as well as the initiation or stimulation of immune and metabolic activation. The helminth-derived molecules have developed powerful and diverse immunosuppressive effects to achieve immune evasion for parasite survival and establish chronic infections. However, they also improve autoimmune and allergic inflammatory responses and promote metabolic homeostasis by promoting metabolic reprogramming of various immune functions, and then inducing alternatively activated macrophages, T helper 2 cells, and regulatory T cells-mediated immune responses. Therefore, a deeper exploration of the immunopathogenic mechanism and immune regulatory mechanisms of helminth-derived molecules exerted in the host is crucial for understanding host-helminth interactions as well as the development of therapeutic drugs for infectious or non-infectious diseases. In this review, we focus on the properties of helminth-derived molecules to give an overview of the most recent scientific knowledge about their pathogenic and pharmacopeial roles in immune-metabolic homeostasis.

Geohelminths: Use in the Treatment of Selected Human Diseases

Research on the therapeutic use of parasites has been ongoing since the development of the "hygiene hypothesis". Parasites can stimulate the Th2-dependent response and suppress the Th1-dependent response, which is intensified in many diseases, especially allergic and autoinflammatory ones. In this review, we present the types of parasites used in helminth therapy and the range of diseases in which they may be useful. We also present the results of clinical trials conducted so far, which confirm the safety of such therapy and provide promising outcomes.

Presence of Intestinal Parasites in Patients with Chronic Non-Communicable Diseases in Masaya (Nicaragua)

AIMS

A cross-sectional study was conducted in Masaya (Nicaragua) to estimate the prevalence of intestinal parasite (IP) infections in patients with non-communicable diseases (NCDs) and to determine the associations between the types of NCDs and patients' epidemiological characteristics of infection.

METHODS

A total of 157 preserved faecal samples were examined (direct wet mount, formalin/ethyl acetate concentration and modified Ziehl-Neelsen technique). Microscopically positive faecal sample identification was completed by conducting a molecular study.

RESULTS

The total prevalence of IP was 52% in NCD patients. Diabetic patients presented an IP prevalence of 42%. Blastocystis presented the highest prevalence (42%). A molecular analysis of Giardia intestinalis (prevalence of 1.3%) revealed 100% of sub-assemblage BIII and the Entamoeba complex (5%) was identified as E. dispar. Blastocystis ST1 appeared in 44% of those suffering from diabetes and ST3 in 66% of those suffering from hypertension, while ST2 only appeared in those suffering with several NCDs simultaneously. In diabetic patients, the risk of infection is associated with having pets (p = 0.021) and land-floor houses. The risk of infection appears to be statistically related (p = 0.019) in those with several NCDs having received a previous helminthic deworming treatment.

CONCLUSIONS

Coordinated public health activities for IP and NCD screening and diagnosis are crucial to their successful control programmes.

The Association between Migration and Prevalence of Allergic Diseases: A Systematic Review and Meta-Analysis

INTRODUCTION

Allergic diseases remain of concern due to their increasing prevalence worldwide. Intrinsic and environmental risk factors have been implicated in the pathogenesis of allergic disease. Among the possible risk factors, migration has been associated with the manifestation of allergic diseases. We aimed to consolidate the existing evidence, review the hypotheses for the relationship between environmental factors and allergic disease, and provide a direction for future work.

METHODS

This systematic review and meta-analysis complied with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Web of Science database was searched in September 2023 to retrieve publications investigating the relationship between allergic rhinitis (AR), atopic dermatitis (AD), or asthma and the following factors: (i) migrant status (i.e., migrants vs. natives) or (ii) duration since migration among migrants. Risk of bias was assessed using the JBI critical appraisal tool. Details and findings from the included studies were also summarized and meta-analyses were conducted where appropriate.

RESULTS

Fifty studies encompassing an estimated 3,755,248 individuals were reviewed. Articles investigated asthma (n = 46), AR (n = 16), and AD (n = 14). A variety of migration-related factors were also studied: movement of individuals across regions (n = 40), duration since immigration (n = 12), age at immigration (n = 9), and acculturation (n = 2). Migration status was not significantly associated with AD (pooled odds ratio [pOR] = 0.68, 95% confidence interval (CI) = 0.31, 1.49). Although AR prevalence was lower among immigrants than natives (pOR = 0.58, 95% CI = 0.45, 0.74), immigrants who had resided at least 10 years in the destination country had a higher risk of AR than immigrants with a duration of residence of less than 10 years (pOR = 8.36, 95% CI = 4.15, 16.81). Being an immigrant was also associated with a decreased risk of asthma (pOR = 0.56, 95% CI = 0.44, 0.72). Among immigrants, residing in the host country for at least 10 years was associated with increased asthma manifestation (pOR = 1.85, 95% CI = 1.25, 2.73). Immigrants who migrated aged 5 and below did not exhibit a significantly higher likelihood of asthma than migrants who immigrated older than 5 years (pOR = 1.01, 95% CI = 0.68, 1.50).

CONCLUSION

This review was limited by the primarily cross-sectional nature of the included studies. Objective diagnoses of allergic disease, such as using the spirometry of bronchodilator reversibility test for asthma rather than questionnaire responses, could add to the reliability of the outcomes. Furthermore, immigrant groups were mostly nonspecific, with little distinction between their country of origin. Overall, migration appears to be a protective factor for allergic diseases, but the protection subsides over time and the prevalence of allergic diseases among the immigrant group approaches that of the host population.

Controlled Infection of Humans with the Hookworm Parasite Necator americanus to Accelerate Vaccine Development : The Human Hookworm Vaccination/Challenge Model (HVCM)

In this chapter, we describe the scientific, technical, clinical and regulatory aspects of establishing a controlled human hookworm infection (CHHI) model in non-endemic and endemic geographical regions, to facilitate a pathway towards accelerated vaccine development. The success achieved in establishing the CHHI platform specifically allows the Human Hookworm Vaccine Initiative (HHVI) to accelerate its progress by establishing a human hookworm vaccination/challenge model (HVCM) in a hookworm endemic area of Brazil. The HVCM will permit the rapid and robust determination of clinical efficacy in adults, allowing for early selection of the most efficacious human hookworm vaccine (HHV) candidate(s) to advance into later-stage pivotal paediatric clinical trials and reduce the overall number of participants required to assess efficacy (Diemert et al. 2018).

Eosinophilia and potential antibody cross-reactivity between parasites in a child with pinworm and immune dysregulation: a case report

BACKGROUND

Intestinal parasitic infections are common in humans, especially among young children. These conditions are often asymptomatic and self-limiting, and diagnosis is mainly based on the search for ova and parasites in the stools since serology may be biased due to cross reactivity between parasites. Pinworm is common in children and is not usually associated with hypereosinophilia; adhesive-tape test is the gold standard testing for the microscopic detection of Enterobious vermicularis (Ev) eggs.

CASE PRESENTATION

A 13-year-old boy was referred due to a self-resolving episode of vomiting and palpebral oedema after dinner, together with a history of chronic rhinitis, chronic cough, absolute IgA deficiency and Hashimoto's thyroiditis and hypereosinophilia (higher value = 3140/µl). On evaluation we detected only palpable thyroid and hypertrophic nasal turbinates. Food allergy was excluded, but skin prick tests showed sensitization to house dust mites and cat epithelium and spirometry showed a marked obstructive pattern with positive bronchodilation test prompting the diagnosis of asthma for which maintenance inhaled treatment was started. Chest x-ray and abdomen ultrasound were negative. Further blood testing showed positive IgG anti-Echinococcus spp. and Strongyloides stercoralis and positive IgE for Ascaris, while Ev were detected both by the adhesive tape test and stool examination, so that we made a final diagnosis of pinworm infection. Three months after adequate treatment with pyrantel pamoate the adhesive-tape test turned out negative and blood testing showed a normal eosinophil count. The child later developed also type 1 diabetes.

CONCLUSIONS

We suggest the need to investigate for enterobiasis in children with hypereosinophilia and to consider autoimmunity as a potential confounding factor when interpreting serology for helminths.

COVID-19 morbidity in lower versus higher income populations underscores the need to restore lost biodiversity of eukaryotic symbionts

The avoidance of infectious disease by widespread use of 'systems hygiene', defined by hygiene-enhancing technology such as sewage systems, water treatment facilities, and secure food storage containers, has led to a dramatic decrease in symbiotic helminths and protists in high-income human populations. Over a half-century of research has revealed that this 'biota alteration' leads to altered immune function and a propensity for chronic inflammatory diseases, including allergic, autoimmune and neuropsychiatric disorders. A recent Ethiopian study (EClinicalMedicine 39: 101054), validating predictions made by several laboratories, found that symbiotic helminths and protists were associated with a reduced risk of severe COVID-19 (adjusted odds ratio = 0.35; p<0.0001). Thus, it is now apparent that 'biome reconstitution', defined as the artificial re-introduction of benign, symbiotic helminths or protists into the ecosystem of the human body, is important not only for alleviation of chronic immune disease, but likely also for pandemic preparedness.

Association of helminth infestation with childhood asthma: a nested case-control study

OBJECTIVES

The association between helminthiasis and asthma remains inconclusive but can only be investigated in counties where helminthiasis is transitioning from a high to low burden. We investigated this association using data from a childhood respiratory cohort in Sri Lanka.

METHODS

A case-control study was nested within a population-based cohort of children aged 6-14 years in Sri Lanka. The stool samples of 190 children with asthma and 190 children without asthma were analyzed to assess the burden of helminth infestation. Logistic regression models were fitted to investigate the association of gastrointestinal helminth species with asthma.

RESULTS

Helminthiasis in children with and without asthma was 23.3% (n = 44) and 15.3% (n = 23), respectively. Those with asthma were more likely to have helminthiasis (odds ratio 3.7; 95% confidence interval 1.7, 7.7; P = 0.001), particularly with Trichiuris trichura (odds ratio 4.5; 95% confidence interval 1.6, 12.3; P = 0.004). Helminth eggs per gram of feces were not associated with asthma (P >0.05).

CONCLUSION

Our findings demonstrate a positive association between T. trichura infestation and asthma and point to the need to fully characterize this association to understand the likely immunological mechanism that drives it. This association highlights an important public health intervention in countries where these infestations are still prevalent, affecting 24% of the population worldwide.

Multiple overlapping risk factors for childhood wheeze among children in Benin

BACKGROUND

The African continent is currently facing an epidemiological transition characterized by a shift from communicable to non-communicable diseases. Prominent amongst the latter are allergies and asthma. In that context, wheeze has multiple potential contributory factors that could include some of the endemic helminth infections, as well as environmental exposures, such as household air pollution. We sought to determine the relative importance of these risk factors among children in Benin.

METHODS

We included 964 children aged 6-14 years living in the commune of Comé, south-west Benin. All children were participants in the longitudinal monitoring cohort of the DeWorm3 trial designed to evaluate multiple rounds of community mass treatment with albendazole for interruption of the transmission of soil transmitted helminths (STH). We administered a standard ISAAC questionnaire to determine the presence of wheeze. In addition, we assessed exposure to household air pollution and to other potential allergy-inducing factors, dietary intake and anthropometry. Using STH infection status assessed at the pretreatment baseline timepoint, we used multivariate statistical modelling, controlling for covariates, to investigate associations between wheeze and the different factors measured.

RESULTS

The prevalence of wheezing history was 5.2%, of current wheezing was 4.6% and of severe wheezing was 3.1%, while STH infections were found in 5.6% of children. These profiles did not vary as a function of either age or gender. Infection with Ascaris lumbricoides, but not hookworm species, was significantly associated with both current wheeze (adjusted Odds Ratio (aOR) = 4.3; 95% CI [1.5-12.0]) and severe wheeze (aOR = 9.2; 95% CI [3.1-27.8]). Significant positive associations with current wheeze, independent of each other and of STH infection status, were also found for (i) use of open cookstoves (aOR = 3.9; 95% CI [1.3-11.5]), (ii) use of palm cakes for fire lighting (aOR = 3.4; 95% CI [1.1-9.9]), (iii) contact with domestic animals and/or rodents (aOR = 2.5; 95% CI [1.1-6.0]), (iv) being overweight (aOR = 9.7; 95% CI [1.7-55.9]). Use of open cookstoves and being overweight were also independent risk factors for severe wheeze (aOR = 3.9; 95% CI [1.1-13.7]) and aOR = 10.3; 95% CI [1.8-60.0], respectively).

CONCLUSIONS

Children infected with A. lumbricoides appear to be at elevated risk of wheeze. Deworming may be an important intervention to reduce these symptoms. Improving cooking methods to reduce household air pollution, modifying dietary habits to avoid overweight, and keeping animals out of the house are all additional measures that could also contribute to reducing childrens' risk of wheeze. Policymakers in LMIC should consider tailoring public health measures to reflect the importance of these different risk factors.

Allergic asthma manifestations in human and seropositivity to Toxocara, a soil-transmitted helminth of carnivores: A case-control study and scoping review of the literature

Asthma is a common respiratory disease affecting humans. Helminth parasites, including Toxocara species, have been implicated as predisposing factors of asthma. However, various studies present different findings on asthma-Toxocara association. Herein, we investigated the association of asthma manifestations with Toxocara seropositivity in a case-control setting on 248 participants (147 women and 101 men), with 124 healthy individuals as the control group and 124 patients known to have asthma based on the medical records of asthma clinics of Kerman University of Medical Sciences. Consequently, we presented a scoping review of all previous studies carried out on this topic, summarizing current findings and existing knowledge on this issue. Of 248 participants, 31 (12.5%) were Toxocara-seropositive, of which 19 (15.3%) were in the patient group and 12 (9.7%) in the control group. A significant relationship was found between asthma severity and age in Toxocara-seropositive individuals (P < 0.04). We found no significant relationship between asthma and Toxocara seropositivity. We identified 7,724 related records in three major scientific databases, NCBI PubMed, Scopus, and Google Scholar. The review of the literature showed that there are 80 published articles on asthma-Toxocara relationship with contradictory findings. More than half of the studies were performed in only four countries, namely, Brazil, the Netherlands, the United States, and Iran. The study population in 70% of the studies were children, and few studies investigated asthma-Toxocara association in adults. The most common study designs for investigating the association of asthma and Toxocara seropositivity were cross-sectional (35.0%), case-control (27.5%), and animal experimental (12.5%) studies. This study found no significant relationship between asthma manifestations and toxocariasis in a case-control setting. However, a scoping review of the current literature suggests that further experimental and field longitudinal cohort studies are required to elucidate the nature of asthma-Toxocara interaction in humans.

The role of helminths in the development of non-communicable diseases

Non-communicable diseases (NCDs) like cardiovascular disease, chronic respiratory diseases, cancers, diabetes, and neuropsychiatric diseases cause significant global morbidity and mortality which disproportionately affect those living in low resource regions including low- and middle-income countries (LMICs). In order to reduce NCD morbidity and mortality in LMIC it is imperative to understand risk factors associated with the development of NCDs. Certain infections are known risk factors for many NCDs. Several parasitic helminth infections, which occur most commonly in LMICs, have been identified as potential drivers of NCDs in parasite-endemic regions. Though understudied, the impact of helminth infections on the development of NCDs is likely related to helminth-specific factors, including species, developmental stage and disease burden. Mechanical and chemical damage induced by the helminth in combination with pathologic host immune responses contribute to the long-term inflammation that increases risk for NCD development. Robust studies from animal models and human clinical trials are needed to understand the immunologic mechanisms of helminth-induced NCDs. Understanding the complex connection between helminths and NCDs will aid in targeted public health programs to reduce helminth-induced NCDs and reduce the high rates of morbidity that affects millions of people living in parasite-endemic, LMICs globally.

Microbial Dysbiosis Tunes the Immune Response Towards Allergic Disease Outcomes

The hygiene hypothesis has been popularized as an explanation for the rapid increase in allergic disease observed over the past 50 years. Subsequent epidemiological studies have described the protective effects that in utero and early life exposures to an environment high in microbial diversity have in conferring protective benefits against the development of allergic diseases. The rapid advancement in next generation sequencing technology has allowed for analysis of the diverse nature of microbial communities present in the barrier organs and a determination of their role in the induction of allergic disease. Here, we discuss the recent literature describing how colonization of barrier organs during early life by the microbiota influences the development of the adaptive immune system. In parallel, mechanistic studies have delivered insight into the pathogenesis of disease, by demonstrating the comparative effects of protective T regulatory (Treg) cells, with inflammatory T helper 2 (Th2) cells in the development of immune tolerance or induction of an allergic response. More recently, a significant advancement in our understanding into how interactions between the adaptive immune system and microbially derived factors play a central role in the development of allergic disease has emerged. Providing a deeper understanding of the symbiotic relationship between our microbiome and immune system, which explains key observations made by the hygiene hypothesis. By studying how perturbations that drive dysbiosis of the microbiome can cause allergic disease, we stand to benefit by delineating the protective versus pathogenic aspects of human interactions with our microbial companions, allowing us to better harness the use of microbial agents in the design of novel prophylactic and therapeutic strategies.

Concurrent allergy and helminthiasis in underprivileged urban South African adults previously residing in rural areas

This study investigated whether prior exposure to helminths (Ascaris IgE, Ascaris eggs and Trichuris eggs) either in childhood or in adulthood, and residence in rural and resource‐limited urban areas influence allergy outcomes (asthma, rhinitis, IgE atopy and food allergy) in a South African population. Participants historical and present allergies data were collected through questionnaires and clinical record files. Coproscopy and immunoassays (ImmunoCAP^TM Phadiatop, total IgE and allergen‐specific fx3 IgE immunoassays and Ascaris IgE radioallergosorbent [RAST] tests) were used for active helminthiasis and allergy screens respectively. Data were analysed using logistic regression analysis, and models were adjusted for age, gender and locality. High Ascaris IgE was significantly associated with asthma (adjusted odds ratio [aOR] = 2.20, p = .047), IgE atopy (aOR = 18.18, p < .0001) and food allergy (aOR = 14.47, p < .0001). Asthma was significantly less likely among participants with Ascaris eggs (aOR = 0.43, p = .048) and Trichuris eggs (aOR = 0.36, p = .024). The findings of co‐occurrent helminthiasis and allergic disorders in a population that has resided both in rural and peri‐urban informal settlements both oppose and agree with two main notions of the hygiene hypothesis that (i) individuals residing in rural settings with poor sanitation and geohelminth infection are less prone to allergy, and (ii) helminth infections protect against allergy respectively. Further research is warranted.

Fungal allergic sensitisation in young rural Zimbabwean children: Gut mycobiome and seroreactivity characteristics

Background

The prevalence of allergic diseases has increased over the last few decades, with sensitisation to fungal allergens and gut microbiome dysbiosis implicated in this trend. The fungal community in the gut (mycobiome) has yet to be characterised and related to fungal allergic sensitisation. Thus, we characterised the gut mycobiome and related it to fungal sensitisation and seroreactivity among Zimbabwean children. We further determined the effect of host age, sex, Schistosoma haematobium infection and mycobiome composition on fungal sensitisation and seroreactivity.

Methods

Using shotgun metagenomic sequencing, we characterised the gut microbiome of stool samples of 116 preschool aged children (PSAC) (≤5 years old, 57(49.1%) male and 59 (50.9%) female). Sensitisation to common fungi in Zimbabwe was assessed using skin prick tests (SPTs). Allergen-specific IgM, IgA, IgG, IgE and IgG4 antibodies were quantified by ELISA. We analysed the relationship between fungal genera and SPT reactivity by ANOVA; fungal genera and IgE antibody reactivity by linear regression; variation in mycobiome abundance with host and environmental factors by PERMANOVA; SPT reactivity and host and environmental factors by logistic regression; seroreactivity and host and environmental factors by ANOVA.

Results

The mycobiome formed <1% of the sequenced gut microbiome and 228 fungal genera were identified. The most abundant genera detected were Protomyces, Taphrina, and Aspergillus. S.haematobium infection had a significant effect on fungal genera. Prevalence of SPT sensitisation to ≥1 fungal species was 96%, and individuals were frequently sensitised to Saccharomyces cerevisiae. Antibodies were detected in 100% of the population. There was no relationship between mycobiome abundance and IgE titres or IgE/IgG4 ratios for each fungal species; no significant differences between SPT reactivity and abundance of fungal species except for S. cerevisiae; and fungal seroreactivity did not significantly differ with age. There were some sex (m>f for, Epicoccum nigrum and Penicillium chrysogenum) and SPT reactivity -related differences in seroreactivity.

Conclusion

This is the first comprehensive characterisation of gut mycobiome and fungal allergic sensitisation of rural children in Zimbabwe. Although reported allergic disease is low there is a high percentage of sensitisation. Further studies with larger populations are required to understand the role of the mycobiome in allergic diseases.

Exacerbation of allergic asthma by somatic antigen of Echinococcus granulosus in allergic airway inflammation in BALB/c mice

BACKGROUND

There is ample evidence demonstrating a reverse relationship between helminth infection and immune-mediated diseases. Accordingly, several studies have shown that Echinococcus granulosus infection and hydatid cyst compounds are able to suppress immune responses in allergic airway inflammation. Previous studies have documented the ability of hydatid cysts to suppress aberrant Th2 immune response in a mouse model of allergic asthma. However, there is a paucity of research on the effects of protoscoleces on allergic asthma. Thus, this study was designed to evaluate the effects of somatic antigens of protoscoleces in a murine model of allergic airway inflammation.

METHODS

Ovalbumin (OVA)/aluminum hydroxide (alum) was injected intraperitoneally to sensitize BALB/c mice over a period of 0 to 7 days, followed by challenge with 1% OVA. The treatment group received somatic antigens of protoscoleces emulsified with PBS on these days in each sensitization before being challenged with 1% OVA on days 14, 15, and 16. The effects of somatic antigens of protoscoleces on allergic airway inflammation were evaluated by examining histopathological changes, the recruitment of inflammatory cells in the bronchoalveolar lavage, cytokine production in the homogenized lung tissue (IL-4, IL-5, IL-10, IL-17, and IFN-γ), and total antioxidant capacity in serum.

RESULTS

Overall, administration of somatic antigens of protoscoleces exacerbated allergic airway inflammation via increased Th2 cytokine levels in the lung homogenate, recruitment of eosinophils into bronchoalveolar lavage fluid, and pathological changes. In addition, total antioxidant capacity and IFN-γ levels declined following the administration of somatic antigens.

CONCLUSIONS

The results revealed that the co-administration of somatic products of protoscoleces with OVA/alum contributed to the exacerbation of allergic airway inflammation in BALB/c mice. Currently, the main cause of allergic-type inflammation exacerbation is unknown, and further research is needed to understand the mechanism of these interactions.

Tissue-specific immunity in helminth infections

A characteristic feature of host responses to helminth infections is the development of profound systemic and tissue-localised Type 2 immune responses that play critical roles in immunity, tissue repair and tolerance of the parasite at tissue sites. These same Type 2 responses are also seen in the tissue-associated immune-pathologies seen in asthma, atopic dermatitis and many forms of allergies. The recent identification of new subtypes of immune cells and cytokine pathways that influence both immune and non-immune cells and tissues creates the opportunity for reviewing helminth parasite-host responses in the context of tissue specific immunity. This review focuses on the new discoveries of the cells and cytokines involved in tissue specific immune responses to helminths and how these contribute to host immunity against helminth infection and allow the host to accommodate the presence of parasites when they cannot be eliminated.

Helminth infections and allergic diseases: systematic review and meta-analysis of the global literature

INTRODUCTION

There is considerable research interest in the role of helminth infections in the development of allergic diseases. However, findings from previous studies are mixed. Existing systematic reviews of these studies are outdated. We performed a systematic review of the global literature on the association between helminth infections and development and clinical outcomes of allergic diseases.

METHODS

We searched Cochrane Library, MEDLINE, EMBASE, ISI Web of Science, PubMed, Global Index Medicus, Scielo, KoreaMed, Google Scholar, and Lilacs for studies published up to January 2020. We included observational epidemiological studies (cohort, case-control and cross-sectional studies) of children and adults reporting associations between helminth infections and asthma, allergic rhinitis, eczema and atopy. We performed random-effects meta-analysis to summarize the effect estimates.

RESULTS

We included 80 studies with 99,967 participants. In the meta-analyses, we did not observe an overall association between helminth infections and allergic diseases. There was, however, evidence that A. lumbricoides infections was associated with an increased risk of bronchial hyperreactivity in children (RR:1.41, 95%CI: 1.17-1.70; I²=50, p for I²=0.09), and was associated with an increased risk of atopy among helminth-infected adults (RR:1.37, 95%CI: 1.18-1.61; I²=52, p for I²=0.02). We found no study that addressed the association between helminth infection and clinical outcomes of allergic diseases. The overall strength of the underlying evidence was low to moderate.

CONCLUSION

Helminth infections may increase the risk of bronchial hyperreactivity in children and atopy in adults. Well-designed longitudinal cohorts may help clarify potential causal associations between chronic helminth infections and allergic diseases.

Transient Ascaris suum larval migration induces intractable chronic pulmonary disease and anemia in mice

Ascariasis is one of the most common infections in the world and associated with significant global morbidity. Ascaris larval migration through the host’s lungs is essential for larval development but leads to an exaggerated type-2 host immune response manifesting clinically as acute allergic airway disease. However, whether Ascaris larval migration can subsequently lead to chronic lung diseases remains unknown. Here, we demonstrate that a single episode of Ascaris larval migration through the host lungs induces a chronic pulmonary syndrome of type-2 inflammatory pathology and emphysema accompanied by pulmonary hemorrhage and chronic anemia in a mouse model. Our results reveal that a single episode of Ascaris larval migration through the host lungs leads to permanent lung damage with systemic effects. Remote episodes of ascariasis may drive non-communicable lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), and chronic anemia in parasite endemic regions.

Ascariasis is the most common helminth infection and leads to significant global morbidity. Transient Ascaris larval migration through the host’s lungs is essential for larval development but leads to an exaggerated type-2 host immune response. Our work demonstrates that transient Ascaris spp. larval migration through the lungs has significant long-term consequences including changes in lung structure and function as well as vascular damage causing chronic lung disease and anemia. We propose that Ascaris spp. larval migration through the host lungs is a risk factor for the development of chronic lung disease and anemia in parasite-endemic regions globally.

Impact of early life geohelminths on wheeze, asthma and atopy in Ecuadorian children at 8 years

BACKGROUND

Early-life exposures to geohelminths may protect against development of wheeze/asthma and atopy.

OBJECTIVE

To study the effect of maternal geohelminths and infections in children during the first 5 years on atopy, wheeze/asthma and airways reactivity/inflammation at 8 years.

METHODS

Birth cohort of 2404 neonates followed to 8 years in rural Ecuador. Data on wheeze/asthma were collected by questionnaire and atopy by skin prick test (SPT) reactivity to 9 allergens. We measured airways reactivity to bronchodilator, fractional exhaled nitric oxide (FeNO) and nasal eosinophilia. Stool samples were examined for geohelminths by microscopy.

RESULTS

1933 (80.4%) children were evaluated at 8 years. Geohelminths were detected in 45.8% of mothers and 45.5% of children to 5 years. Frequencies of outcomes at 8 years were as follows: wheeze (6.6%), asthma between 5 and 8 years (7.9%), SPT (14.7%), airways reactivity (10%) and elevated FeNO (10.3%) and nasal eosinophilia (9.2%). Any maternal geohelminth was associated with reduced SPT prevalence (OR 0.72). Childhood Trichuris trichiura infections during the first 5 years were associated with reduced wheeze (OR 0.57) but greater parasite burdens with Ascaris lumbricoides at 5 years were associated with increased wheeze (OR 2.83) and asthma (OR 2.60). Associations between maternal geohelminths and wheeze/asthma were modified by atopy. Parasite-specific effects on wheeze/asthma and airways reactivity and inflammation were observed in non-atopic children.

CONCLUSIONS

Our data provide novel evidence for persistent effects of in utero geohelminth exposures on childhood atopy but highlight the complex nature of the relationship between geohelminths and the airways. Registered as an observational study (ISRCTN41239086).

Immunoprotective inference of experimental chronic Trichinella spiralis infection on house dust mites induced allergic airway remodeling

Allergic bronchial asthma is characterized by chronic inflammation of the respiratory airways mediated by T-helper 2 (Th2), Th17 and their cytokines. Although most asthmatic patients suffer from allergic airway remodeling (AAR), aggressive anti-allergic treatment failed to reverse it. The hygiene hypothesis illuminated the counter relationship between allergy and helminthic infections. The immune system is modulated by Trichinella spiralis (T. spiralis) infection to maintain homeostasis. Therefore, this work aimed to investigate the impact of chronic T. spiralis infection on induced AAR in C57BL/6 mice sensitized by house dust mites (HDM) allergens. Forty mice were divided into 3 groups: I (10 healthy mice), IΙ (15 HDM sensitized mice), and ΙΙI (15 T. spiralis chronically infected mice and sensitized with HDM allergens). The assessment aimed to evaluate the effects of regulatory CD4+CD25+FOXP3+ cells (Tregs) and their cytokines comparative to hypersensitivity mediated cytokines. Chronic T. spiralis infection effectively prevented the host's AAR. This result was evidenced by upregulated Tregs in blood by flow cytometric analysis and increased interleukin-10 (IL-10) levels in bronchoalveolar lavage (BAL) by Enzyme linked immunosorbent assay (ELISA) as well as improved lung histopathological changes. Also, serum HDM specific immunoglobulin E (IgE), BAL eosinophils, BAL IL-5 levels, and IL-17 gene expression in lung tissues were significantly reduced in T. spiralis chronically infected mice. In conclusion, the immune response in chronic T. spiralis infection could provide a promising mechanistic tool for protection against AAR, which paves the way for innovative preventive measures of other immunological disorders.

Lack of Consistent Association between Asthma, Allergic Diseases, and Intestinal Helminth Infection in School-Aged Children in the Province of Bengo, Angola

Epidemiological studies have shown conflicting findings on the relationship between asthma, atopy, and intestinal helminth infections. There are no such studies from Angola; therefore, we aimed to evaluate the relationship between asthma, allergic diseases, atopy, and intestinal helminth infection in Angolan schoolchildren. We performed a cross-sectional study of schoolchildren between September and November 2017. Five schools (three urban, two rural) were randomly selected. Asthma, rhinoconjunctivitis, and eczema were defined by appropriate symptoms in the previous 12 months: atopy was defined by positive skin prick tests (SPT) or aeroallergen-specific IgE; intestinal helminths were detected by faecal sample microscopy. In total, 1023 children were evaluated (48.4% female; 57.6% aged 10–14 years; 60.5% urban). Asthma, rhinoconjunctivitis, or eczema were present in 9%, 6%, and 16% of the studies children, respectively. Only 8% of children had positive SPT, but 64% had positive sIgE. Additionally, 40% were infected with any intestinal helminth (A. lumbricoides 25.9%, T. trichiura 7.6%, and H. nana 6.3%). There were no consistent associations between intestinal helminth infections and asthma, allergic diseases, or atopy, except for A. lumbricoides, which was inversely associated with rhinoconjuctivitis and directly associated with aeroallergen-specific IgE. We concluded that, overall, intestinal helminth infections were not consistently associated with allergic symptoms or atopy. Future, preferably longitudinal, studies should collect more detailed information on helminth infections as part of clusters of environmental determinants of allergies.

Prevalence of Respiratory Viral Infections in Children with Asthma in Kermanshah

Background: Asthma is a chronic inflammatory disorder of lung airways, affecting about 300 million people worldwide. Several risk factors are involved in asthma development, such as environmental allergens, genetic susceptibility, and respiratory viral infections. Viral infections induce NF-kB and inflammatory pathways that lead to the production of cytokines, chemokines, and inflammatory proteins and, finally, a reduction of lung volume and function. Objectives: The aim of this study was to evaluate viral infections’ prevalence in children with asthma from 2016 to 2017. Methods: One hundred throat swab samples were collected from asthmatic children. Extraction of RNA and cDNA synthesis were performed to recognize parainfluenza viruses, rhinoviruses, influenza viruses, and respiratory syncytial virus (RSV) using real-time PCR. Also, the associations of age, sex, and other studied factors with asthmatic attacks were evaluated. Results: In this study, 41 viruses were detected, including 21 cases of rhinoviruses (51.22%), 10 cases of parainfluenza (24.39%), seven cases of respiratory syncytial virus (17.07%), and three cases of the influenza virus (7.32%). Regarding seasonal incidence, the prevalence of the viruses was high in autumn and winter, and there was a significant relationship between seasonal incidence and gender. However, there were no statistically significant relationships between the prevalence of the viruses and age or gender. Conclusions: The most important viral causes of childhood asthma in this study were found to be rhinoviruses, followed by parainfluenza. The lowest prevalence was related to the RSV and influenza virus, which the two viruses also showed the lowest seasonal outbreaks. Therefore, it can be said that with an increase in the seasonal incidence of respiratory viruses, the effects of these viruses will be greater on asthma.

Prevalence and psychosocial impact of atopic dermatitis in Bangladeshi children and families

BACKGROUND

Skin conditions are the fourth leading cause of nonfatal disease globally, with atopic dermatitis (AD) a major and rising contributor. Though atopic dermatitis (AD) is rising in prevalence, little is known about its psychosocial effects on children and families in low- and middle-income countries (LMICs).

METHODS

We conducted a community-based, cross-sectional survey of 2242 under-5 children in rural Bangladesh using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire to measure AD prevalence and severity, the Patient-Oriented Eczema Measure (POEM) to measure severity, and the Infants' Dermatitis Quality of Life index (IDQoL) and Dermatitis Family Index (DFI) to measure quality of life.

FINDINGS

Overall AD prevalence in under-five children was 11.9% [95% confidence interval (CI) 10.6-13.3%]. Prevalence was highest in children age 30-35 months [16.2% (95% CI 11.4-21.0)]. IDQoL was significantly higher in males (2.67) vs. females (1.95, p = 0.015), the lowest (3.06) vs. highest (1.63) wealth quintile (p<0.001), and among mothers with < primary (2.41) vs. > secondary (1.43) education (p = 0.039). POEM severity was correlated with IDQoL (r = 0.77, p<0.001) and DFI (r = 0.56, p<0.001). Severe disease as rated by caretakers was correlated with POEM (r = 0.73, p<0.001), IDQoL (r = 0.82, p<0.001) and DFI (r = 0.57, p<0.001).

CONCLUSIONS

Severe AD significantly affects quality of life for children and families in Bangladesh. As access to healthcare expands in LMICs, identification and treatment of both the medical and psychosocial morbidities associated with the disease are needed.

Immunological underpinnings of Ascaris infection, reinfection and co-infection and their associated co-morbidities

Human ascariasis is the most common and prevalent neglected tropical disease and is estimated that ~819 million people are infected around the globe, accounting for 0.861 million years of disability-adjusted life years in 2017. Even with the existence of highly effective drugs, the constant presence of infective parasite eggs in the environment contribute to a high reinfection rate after treatment. Due to its high prevalence and broad geographic distribution Ascaris infection is associated with a variety of co-morbidities and co-infections. Here, we provide data from both experimental models and humans studies that illustrate how complex is the interaction of Ascaris with the host immune system, especially, in the context of reinfections, co-infections and associated co-morbidities.

House dust mite sensitization drives cross-reactive immune responses to homologous helminth proteins

The establishment of type 2 responses driven by allergic sensitization prior to exposure to helminth parasites has demonstrated how tissue-specific responses can protect against migrating larval stages, but, as a consequence, allow for immune-mediated, parasite/allergy-associated morbidity. In this way, whether helminth cross-reacting allergen-specific antibodies are produced and play a role during the helminth infection, or exacerbate the allergic outcome awaits elucidation. Thus, the main objective of the study was to investigate whether house dust mite (HDM) sensitization triggers allergen-specific antibodies that interact with Ascaris antigens and mediate antibody-dependent deleterious effects on these parasites as well as, to assess the capacity of cross-reactive helminth proteins to trigger allergic inflammation in house dust mite presensitized mice. Here, we show that the sensitization with HDM-extract drives marked IgE and IgG1 antibody responses that cross-react with Ascaris larval antigens. Proteomic analysis of Ascaris larval antigens recognized by these HDM-specific antibodies identified Ascaris tropomyosin and enolase as the 2 major HDM homologues based on high sequence and structural similarity. Moreover, the helminth tropomyosin could drive Type-2 associated pulmonary inflammation similar to HDM following HDM tropomyosin sensitization. The HDM-triggered IgE cross-reactive antibodies were found to be functional as they mediated immediate hypersensitivity responses in skin testing. Finally, we demonstrated that HDM sensitization in either B cells or FcγRIII alpha-chain deficient mice indicated that the allergen driven cell-mediated larval killing is not antibody-dependent. Taken together, our data suggest that aeroallergen sensitization drives helminth reactive antibodies through molecular and structural similarity between HDM and Ascaris antigens suggesting that cross-reactive immune responses help drive allergic inflammation.

Epidemiological studies related to the interaction between allergies and helminth infection led to the observations that helped shape the so-called hygiene hypothesis, which generally states that chronic exposure to helminths diminishes the risk of the development of allergic disease. However, there are conflicting studies that have called this particular hypothesis into question, such as, the studies that suggest that infection with the helminth Ascaris lumbricoides is a risk factor for wheezing and atopy or can aggravate the clinical symptoms of asthma. A hypothetical explanation for such phenomenon is the fact that there is a high degree of molecular and structural similarities among helminth antigens with many common allergens, including the house dust mite (HDM). This high degree of homology of certain epitopes shared between helminths and allergens generate cross-react antibodies which may play a role in the pathogenesis or regulation of both conditions. Thus, this study aimed to understand the structural basis for cross-reactive antibodies induced by HDM sensitization. Here, we demonstrate that HDM sensitization drives helminth cross-reactive antibodies through molecular and structural homology between tropomyosins and enolases. This study highlights the pro-allergenic properties of HDM and helminth proteins that share homologous epitopes.

Understanding Asthma and Allergies by the Lens of Biodiversity and Epigenetic Changes

Exposure to different organisms (bacteria, mold, virus, protozoan, helminths, among others) can induce epigenetic changes affecting the modulation of immune responses and consequently increasing the susceptibility to inflammatory diseases. Epigenomic regulatory features are highly affected during embryonic development and are responsible for the expression or repression of different genes associated with cell development and targeting/conducting immune responses. The well-known, "window of opportunity" that includes maternal and post-natal environmental exposures, which include maternal infections, microbiota, diet, drugs, and pollutant exposures are of fundamental importance to immune modulation and these events are almost always accompanied by epigenetic changes. Recently, it has been shown that these alterations could be involved in both risk and protection of allergic diseases through mechanisms, such as DNA methylation and histone modifications, which can enhance Th2 responses and maintain memory Th2 cells or decrease Treg cells differentiation. In addition, epigenetic changes may differ according to the microbial agent involved and may even influence different asthma or allergy phenotypes. In this review, we discuss how exposure to different organisms, including bacteria, viruses, and helminths can lead to epigenetic modulations and how this correlates with allergic diseases considering different genetic backgrounds of several ancestral populations.

Allergen skin test reactivity and asthma are inversely associated with ratios of IgG4/IgE and total IgE/allergen-specific IgE in Ugandan communities

Background

Serum inhibition of allergen‐specific IgE has been associated with competing IgG4 and non‐specific polyclonal IgE. In allergen immunotherapy, beneficial responses have been associated with high IgG4/IgE ratios. Helminths potentiate antibody class switching to IgG4 and stimulate polyclonal IgE synthesis; therefore, we hypothesized a role for helminth‐associated IgG4 and total IgE in protection against atopic sensitization and clinical allergy (asthma) in tropical low‐income countries.

Methods

Among community residents of Ugandan rural Schistosoma mansoni (Sm)–endemic islands and a mainland urban setting with lower helminth exposure, and among urban asthmatic schoolchildren and non‐asthmatic controls, we measured total, Schistosoma adult worm antigen (SWA)–specific, Schistosoma egg antigen (SEA)–specific and allergen (house dust mite [HDM] and German cockroach)–specific IgE and IgG4 by ImmunoCAP^® and/or ELISA. We assessed associations between these antibody profiles and current Sm infection, the rural‐urban environment, HDM and cockroach skin prick test (SPT) reactivity, and asthma.

Results

Total IgE, total IgG4 and SWA‐, SEA‐ and allergen‐specific IgE and IgG4 levels were significantly higher in the rural, compared to the urban setting. In both community settings, both Sm infection and SPT reactivity were positively associated with allergen‐specific and total IgE responses. SPT reactivity was inversely associated with Schistosoma‐specific IgG4, allergen‐specific IgG4/IgE ratios and total IgE/allergen‐specific IgE ratios. Asthmatic schoolchildren, compared with non‐asthmatic controls, had significantly higher levels of total and allergen‐specific IgE, but lower ratios of allergen‐specific IgG4/IgE and total IgE/allergen‐specific IgE.

Conclusions and clinical relevance

Our immuno‐epidemiological data support the hypothesis that the IgG4–IgE balance and the total IgE–allergen‐specific IgE balance are more important than absolute total, helminth‐ or allergen‐specific antibody levels in inhibition of allergies in the tropics.

Prevalence of atopic dermatitis, asthma and rhinitis from infancy through adulthood in rural Bangladesh: a population-based, cross-sectional survey

OBJECTIVE

Describe the pattern of atopic disease prevalence from infancy to adulthood.

DESIGN

Cross-sectional household survey.

SETTING

Community-based demographic surveillance site, Mirzapur, Bangladesh.

PARTICIPANTS

7275 individuals in randomly selected clusters within 156 villages.

PRIMARY AND SECONDARY OUTCOME MEASURES

The 12-month prevalence of atopic dermatitis (by UK Working Party Criteria (UK criteria) and International Study of Asthma and Allergies in Childhood (ISAAC)), asthma and rhinitis (by ISAAC); disease severity (by ISAAC); history of ever receiving a medical diagnosis.

RESULTS

Children aged 2 years had the highest prevalence of atopic dermatitis-18.8% (95% CI 15.2% to 22.4%) by UK criteria and 14.9% (95% CI 11.6% to 18.1%) by ISAAC- and asthma (20.1%, 95% CI 16.4% to 23.8%). Prevalence of rhinitis was highest among 25-29 year olds (6.0%, (95% CI% 4.5 to 7.4%). History of a medical diagnosis was lowest for atopic dermatitis (4.0%) and highest for rhinitis (27.3%) and was significantly associated with severe disease compared with those without severe disease for all three conditions (atopic dermatitis: 30.0% vs 11.7%, p=0.015; asthma; 85.0% vs 60.4%, p<0.001; rhinitis: 34.2% vs 7.3%, p<0.001) and having a higher asset-based wealth score for asthma (29.7% (highest quintile) vs 7.5% (lowest quintile), p<0.001) and rhinitis (39.8% vs 12.5%, p=0.003). Prevalence of having >1 condition was highest (36.2%) at 2 years and decreased with age. Having atopic dermatitis (ISAAC) was associated with significantly increased odds ratios (OR) for comorbid asthma (OR 5.56 (95% CI 4.26 to 7.26)] and rhinitis (3.68 (95% CI 2.73 to 4.96)). Asthma and rhinitis were also strongly associated with each other (OR 8.39 (95% CI 6.48 to 10.86)).

CONCLUSIONS

Atopic disease burden was high in this rural Bangladeshi population. Having one atopic condition was significantly associated with the presence of another. Low incidence of ever obtaining a medical diagnosis highlights an important opportunity to increase availability of affordable diagnosis and treatment options for all age groups.

What Can Parasites Tell Us About the Pathogenesis and Treatment of Asthma and Allergic Diseases

The same mechanisms that enable host defense against helminths also drive allergic inflammation. This suggests that pathomechanisms of allergic diseases represent evolutionary old responses against helminth parasites and that studying antihelminth immunity may provide insights into pathomechanisms of asthma. However, helminths have developed an intricate array of immunoregulatory mechanisms to modulate type 2 immune mechanisms. This has led to the hypothesis that the lack of helminth infection may contribute to the rise in allergic sensitization in modern societies. Indeed, the anti-inflammatory potential of helminth (worm) parasites and their products in allergy and asthma has been recognized for decades. As helminth infections bring about multiple undesired effects including an increased susceptibility to other infections, intended helminth infection is not a feasible approach to broadly prevent or treat allergic asthma. Thus, the development of new helminth-based biopharmaceutics may represent a safer approach of harnessing type 2–suppressive effects of helminths. However, progress regarding the mechanisms and molecules that are employed by helminths to modulate allergic inflammation has been relatively recent. The scavenging of alarmins and the modulation of lipid mediator pathways and macrophage function by helminth proteins have been identified as important immunoregulatory mechanisms targeting innate immunity in asthma and allergy. In addition, by regulating the activation of dendritic cells and by promoting regulatory T-cell responses, helminth proteins can counterregulate the adaptive T helper 2 cell response that drives allergic inflammation. Despite these insights, important open questions remain to be addressed before helminth molecules can be used for the prevention and treatment of asthma and other allergic diseases.

Host-microbiota interactions in immune-mediated diseases

Host-microbiota interactions are fundamental for the development of the immune system. Drastic changes in modern environments and lifestyles have led to an imbalance of this evolutionarily ancient process, coinciding with a steep rise in immune-mediated diseases such as autoimmune, allergic and chronic inflammatory disorders. There is an urgent need to better understand these diseases in the context of mucosal and skin microbiota. This Review discusses the mechanisms of how the microbiota contributes to the predisposition, initiation and perpetuation of immune-mediated diseases in the context of a genetically prone host. It is timely owing to the wealth of new studies that recently contributed to this field, ranging from metagenomic studies in humans and mechanistic studies of host-microorganism interactions in gnotobiotic models and in vitro systems, to molecular mechanisms with broader implications across immune-mediated diseases. We focus on the general principles, such as breaches in immune tolerance and barriers, leading to the promotion of immune-mediated diseases by gut, oral and skin microbiota. Lastly, the therapeutic avenues that either target the microbiota, the barrier surfaces or the host immune system to restore tolerance and homeostasis will be explored.

Exposure to Toxocara spp. and Ascaris lumbricoides infections and risk of allergic rhinitis in children

Background

Substantial experimental studies suggest a role for helminthes infections in the pathogenesis of allergies, but epidemiologic data have been inconsistent. Unlike to asthma, the association between helminthes infection and allergic rhinitis (AR) has been poorly studied. Therefore, we sought to evaluate the association between exposure to Ascaris and Toxocara infections and AR.

Methods

We did an age- and gender-matched case–control study of 81 children with physician-confirmed AR and 101 control subjects in a referral hospital for pediatric diseases in northern Iran. Exposure to Ascaris and Toxocara infections was evaluated by anti-A. lumbricoides- and anti-Toxocara- IgG antibodies using a commercial enzyme-linked immunosorbent assay. Associations were determined using multivariate logistic regression.

Results

Ascaris seropositivity was higher in children with rhinitis than in controls (12.34 vs. 3.96%). Ascaris seropositivity was positively associated with AR in univariate analysis (OR, 3.42; 95% CI 1.03–11.3; P value = 0.035), but this association was not significant after adjustment for potential confounders (OR, 1.85; 95% CI 0.42–8.18). Also Toxocara seropositivity was higher in children with AR than in healthy subjects (3.7% vs. 0.99), indicating non-significant association with AR in both univariate (OR, 3.84; 95% CI 0.39–37.7) and multivariate analyses (OR, 0.8; 95% CI 0.04–15.44).

Conclusion

Our results revealed that AR is not associated with seropositivity to Ascaris and Toxocara infections in general; however, a higher seropositivity rate was found for both parasites in children with AR. More studies with longitudinal design and larger sample size are needed to elucidate this association.

Immunomodulatory properties of Schistosoma mansoni proteins Sm200 and SmKI-1 in vitro and in a murine model of allergy to the mite Blomia tropicalis

The prevalence of allergic diseases in Brazil is one of the biggest in the world. Among these pathologies, we highlight asthma as one of the most importance. Asthma is characterized as a chronic inflammatory disease of airways, associated with hyperresponsiveness. Many environmental factors can trigger asthma symptoms, among them house dust mites can stimulate hypersensitivity type I reaction. The most common in house dust mite, in tropical countries, are Dermatophagoides pteronysinus and Blomia tropicalis. Several studies have shown that helminths, especially Schistosoma mansoni, lead to reduction of symptoms of atopy and allergic diseases. Therefore, the present study aims to evaluate the ability of recombinant S. mansoni proteins Sm200, and SmKI-1 to induce immunomodulation in vitro, using peripheral blood mononuclear cells (PBMCs) from atopic and non-atopic individuals, stimulated or not with B. tropicalis extract, and in vivo, in a murine model of allergy to the mite B. tropicalis. As results, we observed that the fragment called rSm200-3 and the protein rSmKI-1 stood out for their immunomodulatory potential, stimulating IL-10 production by human PBMCs in vitro. When these proteins were associated with B. tropicalis extract, it was observed the reduction of the production of the cytokine IL-5, with a statistically significant difference in non-atopic individual's cells. In vivo, both proteins presented similar results, with a reduction of IL-5 and IL-4 levels in lung homogenates and of serum IgE. SmKI-1 was also able to decrease the levels of EPO in lung homogenates and in BAL. These results showed that both proteins were able to downmodulate Th2 cells on human PBMCs, and in a murine model of allergy. However, SmKI-1 also reduced significantly the levels of EPO in BAL and lungs showing that this protein may be a good candidate to be used as a possible replacement or in conjunction with pharmacotherapy in individuals with unregulated immune response in asthma.

Helminth infections, atopy, asthma and allergic diseases: protocol for a systematic review of observational studies worldwide

INTRODUCTION

Childhood infections, particularly those caused by helminths are considered to be important environmental exposures influencing the development of allergic diseases. However, epidemiological studies focusing on the relationship between helminth infections and risk of allergic diseases, performed worldwide, show inconsistent findings. Previous systematic reviews of observational studies published 10 or more years ago showed conflicting findings for effects of helminths on allergic diseases. Over the past 10 years there has been growing literature addressing this research area and these need to be considered in order to appreciate the most contemporary evidence. The objective of the current systematic review will be to provide an up-to-date synthesis of findings of observational studies investigating the influence of helminth infections on atopy, and allergic diseases.

METHODS AND ANALYSIS

This systematic review protocol was registered at PROSPERO. We will search Cochrane Library, MEDLINE, EMBASE, CINAHL, AMED, ISI Web of Science, WHO Global Health Library, Scielo, IndMed, PakMediNet, KoreaMed, Ichushi for published studies from 1970 to January 2020. Bibliographies of all eligible studies will be reviewed to identify additional studies. Unpublished and ongoing research will also be searched in key databases. There will be no language or geographical restrictions regarding publications. Critical Appraisal Skills Programme quality assessment tool will be used to appraise methodological quality of included studies. A descriptive summary with data tables will be constructed, and if adequate, meta-analysis using random-effects will be performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist will be followed for reporting of the systematic review.

ETHICS AND DISSEMINATION

Since this systematic review will be only based on published and retrievable literature, no ethics approval will be sought. The multidisciplinary team performing this systematic review will participate in relevant dissemination activities. Findings will be presented at scientific meetings and publish the systematic review in international, peer-reviewed, open-access journals.

PROSPERO REGISTRATION NUMBER

CRD42020167249.

A helminth-derived suppressor of ST2 blocks allergic responses

The IL-33-ST2 pathway is an important initiator of type 2 immune responses. We previously characterised the HpARI protein secreted by the model intestinal nematode Heligmosomoides polygyrus, which binds and blocks IL-33. Here, we identify H. polygyrus Binds Alarmin Receptor and Inhibits (HpBARI) and HpBARI_Hom2, both of which consist of complement control protein (CCP) domains, similarly to the immunomodulatory HpARI and Hp-TGM proteins. HpBARI binds murine ST2, inhibiting cell surface detection of ST2, preventing IL-33-ST2 interactions, and inhibiting IL-33 responses in vitro and in an in vivo mouse model of asthma. In H. polygyrus infection, ST2 detection is abrogated in the peritoneal cavity and lung, consistent with systemic effects of HpBARI. HpBARI_Hom2 also binds human ST2 with high affinity, and effectively blocks human PBMC responses to IL-33. Thus, we show that H. polygyrus blocks the IL-33 pathway via both HpARI which blocks the cytokine, and also HpBARI which blocks the receptor.

The Human Microbiome, Conventional Medicine, and Homeopathy

Human health is intimately linked to the ecology and diversity of the human microbiome. Together, the human organism and the human microbiome work as a complex super-organism throughout the human life cycle. Microbiome science provides direct evidence and substantiation of the fundamental principles of homeopathy, including holism, psychosomatics, direction of cure, the Law of Similars, individuality and susceptibility, minimum dose, and homeostasis. Whilst many conventional (allopathic) medical treatments irreversibly damage the ecology of the microbiome and trigger chronic immune dysfunction and inflammation, the future sustainability of the entire field of medicine depends on the ability to recognize these inconvenient biological truths and to embrace a safer approach based on this evidence. Fortunately, one of the oldest forms of clinically verifiable, evidence-based, and ecologically sustainable medicine, that does not harm the microbiome, already exists in the form of homeopathy.

Relevance of the first thousand days of life to the development of wheezing in children aged 6-7 years

INTRODUCTION

The first thousand days of life are a critical stage for the development of respiratory and immune systems. Many events in this period may be associated with wheezing in childhood.

OBJECTIVE

This study aimed to investigate the association between early life determinants and wheezing in children aged 6-7 years.

MATERIALS AND METHODS

Population-based case-control study using early-life related questions. We used the International Study of Asthma and Allergies in Childhood questionnaire to assess wheezing symptoms. Multiple logistic regressions were performed according to a hierarchical framework, considering the complex dynamic of wheezing/asthma and potential interaction between different levels of determination.

RESULTS

A total of 820 children were included, from which 162 reported wheezing symptoms (19.7%). Multivariable analysis identified socioeconomic conditions (OR 2.08, 95% CI 1.08-4.00), family history of asthma (OR 2.28, 95% CI 1.37-3.75), vaginal discharge that required treatment during pregnancy (OR 1.68, 95% CI 1.00-2.83), neonatal hyperbilirubinemia (OR 2.00, 95% CI 1.17-3.42), anemia and intestinal parasitosis in the first two years (OR 2.28, 95% CI 1.22-4.25; OR 1.72, 95% CI 1.02-2.92, respectively) independently associated to wheezing at 6-7 years. Intended pregnancy was associated with reduced wheezing (OR 0.47, 95% CI 0.28-0.77).

CONCLUSIONS

Several factors were associated with wheezing in childhood. Considering that intended pregnancy reduced wheezing and other associated exposures are considered modifiable, these findings may guide the planning of strategies to decrease the susceptibility to asthma symptoms in childhood.

Anthelmintic drugs for treating ascariasis

BACKGROUND

Ascaris lumbricoides is a common infection, and mainly affects children living in low-income areas. Water and sanitation improvement, health education, and drug treatment may help break the cycle of transmission, and effective drugs will reduce morbidity.

OBJECTIVES

To compare the efficacy and safety of anthelmintic drugs (albendazole, mebendazole, ivermectin) for treating people with Ascaris infection.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, three other databases, and reference lists of included studies, without language restrictions, up to 4 July 2019.

SELECTION CRITERIA

Randomized controlled trials (RCT) that compared albendazole, mebendazole, and ivermectin in children and adults with confirmed Ascaris infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, assessed risk of bias, and extracted data from the included trials. A third review author checked the quality of data extraction. We used the Cochrane 'Risk of bias' assessment tool to determine the risk of bias in included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) to compare dichotomous outcomes in treatment and control groups. We used the fixed-effect model for studies with low heterogeneity and the random-effects model for studies with moderate to high heterogeneity. We assessed the certainty of the evidence using the GRADE approach. We used the control rate average to provide illustrative cure rates in the comparison groups.

MAIN RESULTS

We included 30 parallel-group RCTs, which enrolled 6442 participants from 17 countries across Africa, Asia, Central America and the Caribbean, and South America. Participants were from 28 days to 82 years of age, recruited from school, communities, and health facilities. Twenty studies were funded or co-funded by manufacturers, while 10 studies were independent of manufacturer funding. Twenty-two trials had a high risk of bias for one or two domains (blinding, incomplete outcome data, selective reporting). Single dose of albendazole (four trials), mebendazole (three trials) or ivermectin (one trial) was compared to placebo. Parasitological cure at 14 to 60 days was high in all the studies (illustrative cure of 93.0% in the anthelmintic group and 16.1% in the placebo group; RR 6.29, 95% CI 3.91 to 10.12; 8 trials, 1578 participants; moderate-certainty evidence). Single dose of albendazole is as effective as multiple doses of albendazole (illustrative cure of 93.2% with single dose, 94.3% with multiple doses; RR 0.98, 95% CI 0.92 to 1.05; 3 trials, 307 participants; high-certainty evidence); or as single dose of mebendazole (illustrative cure of 98.0% with albendazole, 96.9% with mebendazole; RR 1.01, 95% CI 1.00 to 1.02; 6 trials, 2131 participants; high-certainty evidence). Studies did not detect a difference between a single dose of albendazole and a single dose of ivermectin (cure rates of 87.8% with albendazole, 90.2% with ivermectin; RR 0.99, 95% CI 0.91 to 1.08; 3 trials, 519 participants; moderate-certainty evidence). Across all the studies, failure after single dose of albendazole ranged from 0.0% to 30.3%, mebendazole from 0.0% to 22.2%, and ivermectin from 0.0% to 21.6%. The egg reduction rate (ERR) measured up to 60 days after the treatment was high in all treated groups, regardless of the anthelmintic used (range 96% to 100%). It was not possible to evaluate parasitological cure by classes of infection intensity. No included trials reported complication or serious adverse events. Other adverse events were apparently similar among the compared anthelmintic groups (moderate- to low-certainty evidence). The most commonly reported other adverse events were nausea, vomiting, abdominal pain, diarrhoea, headache, and fever.

AUTHORS' CONCLUSIONS

Single-dose of albendazole, mebendazole, and ivermectin all appeared effective against Ascaris lumbricoides infection, yielding high parasitological cure and large reductions in eggs excreted, with no differences detected between them. The drugs appear to be safe to treat children and adults with confirmed Ascaris infection. There is little to choose between drugs and regimens in terms of cure or adverse events.

Decline in Total Serum IgE and Soluble CD30 in the Context of Soil-Transmitted Helminth Decline in Bolivia

In the Bolivian Chaco, recent surveys documented a dramatic decrease in the prevalence of soil-transmitted helminth (STH) infections as compared with the 1980s after thirty years of preventive chemotherapy (PC). Concomitant immunological rearrangements are expected. Because nematode infections are associated with increased levels of circulating IgE and glycoprotein CD30 soluble form (sCD30), this study aims to evaluate changes in serological markers of T helper (Th)2-cells activity between 1987 (high STH prevalence) and 2013 (low STH prevalence) in rural communities in the Bolivian Chaco area. We collected 151 sera during two different surveys in 1987 (n = 65) and 2013 (n = 86) and measured the concentration of total IgE and sCD30 by immunoassays. We found a statistically significant age-independent decrease in the total IgE (P < 0.0001) and sCD30 (P < 0.0001) from 1987 to 2013. The significant decrease in serological Th2 markers (IgE and sCD30) between 1987 and 2013 is consistent with the drop in STH prevalence in this geographical area during the same period of time. Further studies might elucidate the clinical and epidemiological impact of these serological rearrangements.

Human Toxocara Infection: Allergy and Immune Responses

BACKGROUND

Toxocariasis is a cosmopolitan infection that occurs in various regions worldwide, more frequently in developing countries. Chronic infections with Toxocara species in humans are associated with the production of high levels of specific and non-specific antibodies of all isotypes and IgG subclasses and a cytokine response characterized by the production of Th2 cytokines including IL-4, IL-5 and IL-13 by Peripheral Blood Monocytes (PBMCs) and Leukocytes (PBLs) in whole blood cultures. Other Th2 effector responses are also prominent during infection, reflected by elevated numbers of peripheral blood eosinophils and increased expression of eosinophil degranulation products. The production of IFN-γ by PBMCs/PBLs stimulated with Toxocara-secreted proteins is not prominent in toxocariasis but IL-10 production may be increased in infected individuals. The relationship between Toxocara species with allergic reactions was reported in the recent century. Experimental and epidemiological investigations revealed that toxocariasis with this parasite led to the development of allergic symptoms, such as asthma. However, the findings are conflicting since in other investigations no association between these two immunopathologies has been reported.

CONCLUSION

The present review endeavours to summarize the data on Toxocara species and findings from studies on the relationship of toxocariasis with symptoms and signs of allergy. Furthermore, the mechanisms of immune responses and the factors associated between allergy and Toxocara infection are discussed.

Immunomodulatory effect of Syphacia obvelata in treatment of experimental DSS-induced colitis in mouse model

The ability of helminth parasite infections to manipulate the immune system of their host towards T regulatory responses has been proposed to suppress the inflammatory response. The aim of this study was to investigate the protective and therapeutic effect of Syphacia obvelata in the treatment of experimental DSS -induced colitis. 50 male C57BL/6 mice were divided into 5 groups: healthy uninfected controls, DSS colitis, receiving only S. obv, preventive (S. obv + DSS) and therapeutic group (DSS + S.obv). Colitis intensity was investigated by measuring body weight changes, stool consistency/bleeding and colon length. To evaluate the immune responses induced by this nematode, TNF-α, IL-10, IL-17, IFN-γ and expressing of FoxP3⁺ T cells were measured in mesenteric lymph nodes and Peyer’s patches cells. Mice in preventive and therapeutic groups treated with S. obv egg significantly ameliorated the severity of the DSS colitis, indicated by the reduced disease manifestations, improved histopathological scores correlated with the up regulation of Treg responses and down regulation of proinflammatory cytokines. S. obv can prevention and reverse on-going murine DSS colitis. The data suggest that induction of Tregs and change in cytokine profiles during helminthic therapies were responsible for reversed inflammatory events in IBD.

Classification of Wheezing Children in Rural Bangladesh by Intensity of Ascaris Infection, Total and Specific IgE Levels, History of Pneumonia, and Other Risk Factors

Ascaris lumbricoides is the most common soil-transmitted helminth and infects 447 million people in impoverished areas worldwide. It causes serious morbidity including wheezing and influences various aspects of human immunity, such as type 2 innate lymphoid cells, regulatory T cell function, and acquired immunity. Thus, it is crucial to elucidate its influence on human immunity. We aimed to classify wheezing children based on their Ascaris infection intensity and other risk factors using hierarchical cluster analysis to determine the mechanisms of and the degree to which Ascaris contributes to childhood wheezing in rural Bangladesh. We analyzed relevant data collected in 2001. The participants included 219 5-year-old wheezing children who were randomly selected from 1705 children living in the Matlab Health and Demographic Surveillance area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Hierarchical cluster analysis was conducted using variables of history of pneumonia, total and specific immunoglobulin E levels, Ascaris infection intensity, and parental asthma. Three distinct wheezing groups were identified. Children in Cluster 1 (n = 50) had the highest titers of the total, anti-Ascaris, anti-Dermatophagoides pteronyssinus, and anticockroach IgEs and experienced the fewest episodes of pneumonia. Cluster 2 (n = 114), the largest group, experienced few episodes of pneumonia and had the lowest titers of the total, anti-Ascaris, anti-Dp, and anticockroach IgEs. Cluster 3 (n = 32) consisted of participants with the most episodes of pneumonia and lower titers of the total and specific IgEs. The extremely high prevalence of Ascaris infection found in Clusters 1-3 was 78%, 77%, and 72%, respectively. Childhood wheezing in rural Bangladesh could be divided into three groups, with 26% of wheezing attributable to anti-Ascaris IgE and 16% to history of pneumonia during early childhood, and 58% might have been due to Ascaris infection without elevated anti-Ascaris IgE.

Risk factors for asthma among schoolchildren who participated in a case-control study in urban Uganda

Data on asthma aetiology in Africa are scarce. We investigated the risk factors for asthma among schoolchildren (5–17 years) in urban Uganda. We conducted a case-control study, among 555 cases and 1115 controls. Asthma was diagnosed by study clinicians. The main risk factors for asthma were tertiary education for fathers (adjusted OR (95% CI); 2.32 (1.71–3.16)) and mothers (1.85 (1.38–2.48)); area of residence at birth, with children born in a small town or in the city having an increased asthma risk compared to schoolchildren born in rural areas (2.16 (1.60–2.92)) and (2.79 (1.79–4.35)), respectively; father’s and mother’s history of asthma; children’s own allergic conditions; atopy; and cooking on gas/electricity. In conclusion, asthma was associated with a strong rural-town-city risk gradient, higher parental socio-economic status and urbanicity. This work provides the basis for future studies to identify specific environmental/lifestyle factors responsible for increasing asthma risk among children in urban areas in LMICs.

Asthma is a chronic disease of the airways that leads to breathing difficulty and sometimes death: the condition affects about 235 million people worldwide, especially children. Scientists still do not know exactly what causes asthma, but studies in Europe and North America suggest that individuals born or raised in rural areas are less likely to be affected. However, few studies have examined asthma in African countries, where urbanization is often quickly increasing. Examining the factors associated with the disease as more people move to cities may provide new clues about how asthma emerges, and how to prevent it.

To this end, Mpairwe et al. conducted a study with over 1,670 schoolchildren in Uganda. Those born or raised in rural areas were least likely to have asthma, but the risk doubled among children from small towns, and tripled in those born or who grew up in the city. Children whose parents had a higher education and socioeconomic status had the highest asthma risk, but more work is required to understand why this is the case.

The study by Mpairwe et al. is the first step towards identifying environmental and lifestyle factors associated with increased asthma risk in Africa. Further studies may help scientists to understand how beginning life in a more urban area plays a role in the development of the disease.

Concurrent decreases in the prevalence of wheezing and Ascaris infection among 5-year-old children in rural Bangladesh and their regulatory T cell immunity after the implementation of a national deworming program

INTRODUCTION

Epidemiological research on the prevalence of asthma and helminthic infections in various countries has led to the hypothesis that helminthic infections protect against asthma by suppressing the host's immune response. This study was conducted to elucidate whether decreased Ascaris infection following a national deworming program was associated with increased recurrent wheezing among rural Bangladeshi children and to test their anti-inflammatory immunity.

METHODS

This nested case-control study was conducted from December 2015 to October 2016 in the rural service area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Of the 1800 5-year old children randomly selected for the study, informed consent was obtained from the guardians of 1658 children. Data were collected using a semistructured questionnaire adopted from the International Study of Asthma and Allergies in Childhood and blood samples for the analysis of regulatory T (Treg) cell immune responses and the balance between Th1 and Th2 immunity in Ascaris infections.

RESULTS

A total of 145 children were found to have wheezing, yielding a prevalence rate of 8.7%, which was significantly lower than the rate found in 2001 (16.2%, P < .001); Ascaris infection also decreased from 2001 to 2016. The 127 wheezing children who agreed to participate further were compared to 114 randomly selected never-wheezing children. Wheezing had a significant positive association with antibiotic use, history of pneumonia, parents' history of asthma, and Ascaris infection; children with Ascaris infection were twice as likely to have wheezing (adjusted odds ratio = 2.31, P = .053). Flow cytometry found no significant differences in the rates of Th1, Th2, and CD4 + CD25 + CD127low cells by the wheezing group.

CONCLUSIONS

Ascaris infection had a positive rather than a negative association with wheezing and the rates of wheezing and Ascaris infections both decreased from 2001 to 2016. These findings undermines the hypothesis that such infections provide protection against asthma.

Critical roles of regulatory B and T cells in helminth parasite-induced protection against allergic airway inflammation

The prevalence of allergic asthma and incidences of helminth infections in humans are inversely correlated. Although experimental studies have established the causal relation between parasite infection and allergic asthma, the mechanism of the parasite-associated immunomodulation is not fully elucidated. Using a murine model of asthma and nematode parasite Heligmosomoides polygyrus, we investigated the roles of regulatory B cells (B_reg ) and T cells (T_reg ) in mediation of the protection against allergic asthma by parasite. H. polygyrus infection significantly suppressed ovalbumin (OVA)-induced allergic airway inflammation (AAI) evidenced by alleviated lung histopathology and reduced numbers of bronchoalveolar inflammatory cell infiltration, and induced significant responses of interleukin (IL)-10⁺ B_reg , IL-10⁺ T_reg and forkhead box protein 3 (FoxP3)⁺ T_reg in mesenteric lymph node and spleen of the mice. Adoptive transfer of IL-10⁺ B_reg and IL-10⁺ T_reg cell prevented the lung immunopathology in AAI mice. Depletion of FoxP3⁺ T_reg cells in FoxP3-diphtheria toxin (DT) receptor transgenic mice by diphtheria toxin (DT) treatment exacerbated airway inflammation in parasite-free AAI mice and partially abrogated the parasite-induced protection against AAI. IL-10⁺ B_reg cells were able to promote IL-10⁺ T_reg expansion and maintain FoxP3⁺ T_reg cell population. These two types of T_regs failed to induce CD19⁺ B cells to transform into IL-10⁺ B_reg cells. These results demonstrate that B_reg , IL-10⁺ T_reg and FoxP3⁺ T_reg cells contribute in A discrepant manner to the protection against allergic airway immunopathology by parasiteS. B_reg cell might be a key upstream regulatory cell that induces IL-10⁺ T_reg response and supports FoxP3⁺ T_reg cell population which, in turn, mediate the parasite-imposed immunosuppression of allergic airway inflammation. These results provide insight into the immunological relationship between parasite infection and allergic asthma.

Reflections upon immunological mechanisms involved in fertility, pregnancy and parasite infections

During a pregnancy, the mother accepts her semi-allogeneic fetus with no signs of immunological rejection. Therefore, some modulation of the maternal immune system must occur. Similarly, changes in the host's immune system occurs during infections with parasites. In a study conducted in an endemic area in Bolivia, it has been reported that women infected with either the helminthic parasite roundworm or hookworm were estimated to give birth to either two more, or three fewer, children than uninfected, endemic women, respectively. Immune regulation by helminthic parasites is a rather well-researched concept, but there are few reports on the effects on human fecundity. The current review focuses on mechanisms of possible importance for especially the increased fertility rates in women infected with roundworm. The host immune response to roundworm has been hypothesized to be more favourable for a successful pregnancy because it bears resemblance to the anti-inflammatory immunological responses observed in pregnancy, steering the immunological response away from a pro-inflammatory state that seem to suppress fecundity. Further research into parasitic worm interactions, fertility, and the molecular mechanisms that they unfold may widen our understanding of the immunomodulatory pathways in both helminthic infections and in fertility and pregnancy.

Exposure to Ascaris lumbricoides infection and risk of childhood asthma in north of Iran

BACKGROUND

Asthma and Ascaris lumbricoides infection are common health issues affecting 250 and 700 million people worldwide, respectively. The relationship between ascariasis and asthma is a matter of substantial interest and research.

METHODS

We performed a case-control study to evaluate whether the exposure to Ascaris infection is associated with asthma in children. We also assessed potential risk factors for Ascaris infection and asthma in study area. We enrolled 145 asthmatic children and 115 healthy controls. The Global Initiative for Asthma guideline was used to evaluate asthma symptoms and severity in study participants. Ascaris infection was assessed by the presence of anti-Ascaris IgG ≥ 11 IU/mL measured by enzyme-linked immunosorbent assay.

RESULTS

We have found a significant relationship between exposure to Ascaris and asthma (odds ratio, 2.92; 95% CI 1.04-8.18; P value = 0.034), and this relationship remained significant after adjustment for covariates (adjusted OR, 3.36; 95% CI 1.04-13%; P value = 0.047). Ascaris infection was more frequent in children with mild sustainable asthma (13.2%; 15/113) than in children with moderate sustainable asthma (6.2%, 2/32), although there was a non-significant difference between these groups (OR, 2.3; 95% CI 0.5-10.1; P value = 0.35). Based on results of a multi-regression analysis, contact with soil (OR, 6.7; 95% CI 1.9-23.5), and drinking unsafe water (OR, 4.2; 95% CI 1.2-14.2) were significant risk factors for Ascaris infection in the study area.

CONCLUSION

Results of this study suggest that A. lumbricoides infection might affect susceptibility to asthma in children. These results could be useful in prevention, early diagnosis and management of childhood asthma.

Soil-transmitted helminth parasites and allergy: Observations from Ecuador

There is considerable interest as to potential protective effects of soil-transmitted helminths (STH) against allergy and allergic diseases. Here, we discuss findings of studies done of the effects of STH parasites on atopy and allergic diseases in Ecuador. While cross-sectional studies have consistently shown a reduced prevalence of allergen skin prick test (SPT) reactivity among infected schoolchildren, the removal of these infections by repeated deworming did not affect SPT prevalence over the short-term (ie, 12 months) but may have increased SPT prevalence over the long-term (ie, 15-17 years). In the case of allergic symptoms, cross-sectional studies have generally not shown associations with STH and intervention studies showed no impact on prevalence. However, a birth cohort suggested that early STH infections might reduce wheeze by 5 years. Allergic sensitization to Ascaris, however, explained a significant proportion of wheezing among rural schoolchildren. Studies of the effects of STH on immune and inflammatory responses indicated a potential role of STH in contributing to more robust regulation. The effects of STH on allergy are likely to be determined by history of exposure over the life-course and by interactions with a wide variety of other infectious and non-infectious factors.

Helminths and Asthma: Risk and Protection

Helminth infections may inhibit the development of allergic diseases, including asthma. On the other hand, some helminth species may induce or worsen symptoms of asthma. This article discusses the impact of helminth infections on asthma as well as the potencial of helminth-derived molecules with regulatory characteristics in the prevention or treatment of this disease. The ability to induce regulation has been observed in animal models of asthma or cells of asthmatic individuals in vitro. Potential future clinical applications of helminth antigens or infection for prevention of asthma merit further translational research.