Sensitization to common aeroallergens in a population of young adults in a sub-Saharan Africa setting: a cross-sectional study

Factors associated with sensitisation to selected aero-allergens in children and adolescents with asthma followed up at Laquintinie Hospital Douala, Cameroon

INTRODUCTION

In spite of the substantial impact of pediatric asthma on healthcare resources, there is a notable dearth of research focusing on allergen sensitization specifically in children and adolescents with asthma in Cameroon, with existing studies primarily concentrating on adult populations. We, therefore, set out to determine factors associated with sensitization to selected aero-allergens in children and adolescents with asthma followed up at Laquintinie Hospital Douala, Cameroon.

METHODOLOGY

We conducted a cross-sectional analytical study on patients aged 2-17 years followed up for pediatric asthma at Laquintinie Hospital Douala for 8 months (January to August 2023). Skin prick tests were performed using selected standardized aeroallergens extracts. Factors associated with sensitization were determined using multivariable logistic regression analysis. The threshold for significance was set at p < .05.

RESULTS

In total, 126 children and adolescents with asthma were recruited, 50.79% of whom were male with an average age of 8.00 ± 3.99 years. Eight out of 10 patients (83.52%) were sensitized to common aero-allergens (20.59% monosensitized and 79.41% polysensitized). The most common aero-allergens found were the dust mites Dermatophagoïdes pteronyssinus (81.37%), Blomia tropicalis (67.64%) and Dermatophagoïdes farinae (52.94%) followed by Blatella species (25.49%). The factors independently associated with sensitization in our population were the personal history of allergic rhinitis in the patient [adjusted odds ratio, aOR: 4.07 (95% confidence interval, CI: 1.41-11.76), b = 0.54, p = .009], chest tightness at rest [aOR: 5.92 (95% CI: 1.08-32.38), b = 0.87, p = .040), and age above 5 years [aOR: 4.65 (95% CI: 1.47-14.69), b = 0.59, p = .009).

CONCLUSION

Sensitization to multiple aeroallergens is common in children and adolescents with asthma, especially for dust mites and cockroaches. Factors associated with sensitization are patients aged >5 years, chest tightness at rest, and a personal history of allergic rhinitis.

Immunogenetics and pharmacogenetics of allergic asthma in Africa

Asthma is a common chronic condition in children and in an African setting is often highly prevalent in urban areas as compared to rural areas. Asthma is a heritable disease and the genetic risk is often exacerbated by unique localised environmental factors. The Global Initiative for Asthma (GINA) recommendation for the control of asthma includes inhaled corticosteroids (ICS) alone or together with short-acting β₂-agonists (SABA) or long-acting β₂-agonists (LABA). While these drugs can relieve asthma symptoms, there is evidence of reduced efficacy in people of African ancestry. Whether this is due to immunogenetics, genomic variability in drug metabolising genes (pharmacogenetics) or genetics of asthma-related traits is not well defined. Pharmacogenetic evidence of first-line asthma drugs in people of African ancestry is lacking and is further compounded by the lack of representative genetic association studies in the continent. In this review, we will discuss the paucity of data related to the pharmacogenetics of asthma drugs in people of African ancestry, mainly drawing from African American data. We will further discuss how this gap can be bridged to improve asthma health outcomes in Africa.

Impact of Chronic Rhinosinusitis with Nasal Polyposis on IL-12 and IL-8

Introduction

The pathophysiology of Chronic Rhinosinusitis is coordinated by distinct inflammatory reactions in different individuals. Inflammatory environments with a predominance of Th2 lymphocytes tend also to be rich in eosinophils. These environments are common during the formation of nasal polyps associated with aspirin intolerance, which is also marked by an increase in inflammatory mediators, especially IL-4, IL-5, and IL-13. Despite the significance of these inflammatory mediators, the relevance of IL-12 subunits' presence within eosinophilic nasal polyps, however, has been less studied. The current study aims to evaluate the presence of IL-12 subunits, IL-12p40 and IL-12p70, in eosinophilic nasal polyps and their correlations with IL-8 presence.

Materials and Methods

We compared the concentrations of IL-8, IL12p40, and IL12p70 among samples of eosinophilic nasal polypoid tissue, eosinophilic nasal polypoid tissue associated with aspirin intolerance, and healthy nasal mucosa, using an indirect immunoassay (ELISA) kit.

Results

When compared to healthy nasal mucosa, there was a lower concentration of IL-8 in Chronic Rhinosinusitis with Nasal Polyp (CRSwNP) tissue. Aspirin Intolerant polypoid tissue also presented a lower concentration of IL-12 subunits compared to healthy nasal mucosa. There was no significant correlation between IL-8 and IL-12 in the eosinophilic polypoid conditions.

Conclusion

In CRSwNP, there is a reduction in IL-8 and IL-12 subunits compared to control, with a lack of correlation between IL-12 and IL-8. The lack of correlation can be justified by a type two inflammatory storm environment.

Sensitization and Clinical Characteristics of Congolese Children with Vernal Keratoconjunctivitis in Kinshasa

BACKGROUND

Data on the sensitization pattern and clinical characteristics of pediatric vernal keratoconjunctivitis (VKC) are scary in Central Africa. This chronic form of allergic conjunctivitis affects the quality of school life and work productivity. There is no study that shows the breadth of vernal keratoconjunctivitis in our setting.

PURPOSE

To describe the clinical characteristics of vernal keratoconjunctivitis in Kinshasa, to evaluate the sensitization profile and associated factors.

METHODS

A total of 400 children with vernal keratoconjunctivitis underwent a clinical examination and a skin prick test (SPT) for 10 allergens. Dermatophagoides pteronyssinus, Blomia tropicalis and cockroach were the most common allergens in 52, 1 %, 18, 8% and 13% respectively among sensitized children and 66, 4% showed polysensitization.

RESULTS

The main symptoms were itchy eyes 45%, brownish discoloration conjunctiva 17%, red eyes 12, 2%, eyelids rubbing 11, 5%, tearing 8, 7% and photophobia 5, 5%.The limbic form was predominant with 54%, followed by palpebral form 26% and mixed form 20%. The most common complications were superficial punctate keratitis 17, 2%, shield ulcer 1, 5%, corneal plaque 1, 3% and corneal erosion 1%.

CONCLUSION

This study outlines that 34, 5% of children attending the outpatient Ophthalmology Department in two hospitals of Kinshasa for vernal keratoconjunctivitis disease had a positive skin prick test to at least one allergen, in particular for Dermatophagoides pteronyssinus, Blomia tropicalis and cockroach.

Association between allergic sensitization and intestinal parasite infection in schoolchildren in Gqeberha, South Africa

Background

Inconsistent data exist regarding the influence of parasitic infection on the prevalence of allergic sensitization and disorders.

Objective

To investigate the impact of geohelminth and protozoan infections on sensitization patterns and allergic symptoms of children living in low‐income communities in Gqeberha, South Africa.

Methods

In a cross‐sectional study, 587 schoolchildren aged 8–12 years were recruited in June 2016 and screened for reactivity to common allergens by skin prick tests (SPTs) and for parasitic infections by stool examination. Additionally, questionnaires were completed to record allergic symptoms the children may have experienced.

Results

Positive SPTs were found in 237/587 children (40.4%), and about one‐third of whom were polysensitized. Sensitizations were most frequently detected against the house dust mites (HDM) Dermatophagoides spp. (31.9%) and Blomia tropicalis (21.0%). Infections with geohelminths (Ascaris lumbricoides, Trichuris trichiura) were found in 26.8% and protozoan infections (Giardia intestinalis, Cryptosporidia spp.) in 13.9% of study participants. Mixed logistic regression analyses revealed negative associations between parasite infection and sensitization to Blomia tropicalis (OR: 0.54, 95% CI 0.33–0.89) and to Dermatophagoides spp. (OR 0.65, 95% CI 0.43–0.96), and between protozoan infection and allergic sensitization to any aeroallergen, although these associations were not significant when adjusted for false discovery. Geohelminth infection and intensity of geohelminth infection were both associated with reduced risk of polysensitization (OR 0.41, 95% CI 0.21–0.86), and this association remained significant with adjustment for false discovery. Reported respiratory symptoms were associated with HDM sensitization (ORs from 1.54 to 2.48), but not with parasite infection.

Conclusions and clinical relevance

Our data suggest that geohelminth infection and high geohelminth infection intensity are associated with a reduced risk of polysensitization.

The most common allergens according to skin prick test: The role of wheal diameter in clinical relevancy

The skin prick test (SPT) could be applied as a useful in vivo method for the detection of sensitization in epidemiological and diagnostic studies if the wheal size is ideally evaluated. We focused on SPT wheal size to identify sensitization pattern to common inhalant and food allergens. In this cross-sectional study, SPT results were obtained from a total of 972 allergic patients. Common allergen extracts for SPT were selected according to the type of allergic diseases, and the geographical pattern. SPT with food allergens was performed for patients with atopic dermatitis (AD) and chronic urticaria (CU). A total of 461 male (47.4%) and 511 female (52.6%) participated in this study (median age: 31 years). The majority of individuals were affected with allergic rhinitis (AR) (n = 624) and asthma (n = 224); while 129 and 67 patients suffered from AD and CU, respectively. The most common aeroallergens were Russian thistle (52.1%) and lamb's quarter (50.7%) with the largest wheal diameter. The wheal size of lamb's quarter was significantly different between patients with asthma and AR (P<.001). In addition, a significant difference was detected in wheal diameter in response to the Russian thistle between patients with AR and AD (P = .001). Shrimp (23.6%) and Peanut (22.5%) caused the most common food sensitization in patients with AD and CU. Having in mind the most common weed pollens including the Russian thistle and lamb's quarter, preventive strategies, such as, removing unwanted weeds or preventing them from growing, avoidance, and specific immunotherapy may be crucial for better disease control.

Sensitisation to aeroallergens in relation to asthma and other allergic diseases in Angolan children: a cross-sectional study

INTRODUCTION AND OBJECTIVES

In Africa, few studies of sensitisation profiles have been performed in children or adolescents and, in Angola, there are none. The objectives of the present study were to assess the sensitisation profile of Angolan schoolchildren and to determine the relationship between that pattern, sociodemographic factors, asthma and other allergic diseases.

MATERIALS AND METHODS

Cross-sectional, observational study in 5-14-year-old children, performed between September and November 2017, in the Province of Bengo, Angola. Five schools (15%) were randomly selected in the geographical area of the study: three from an urban area, and two from a rural area. Data were collected using the Portuguese versions of the ISAAC questionnaires for children and adolescents, regarding asthma, rhinitis and eczema. Skin prick tests (SPT) were performed with a battery of 12 aeroallergens. Stools were assessed for the presence of helminths. Descriptive statistics were used, as well as univariate calculation of odds ratios.

RESULTS

Sensitisation to aeroallergens was low (8%) and most sensitised children were asymptomatic. Most frequent sensitisations involved house dust mites, cockroach or fungi, and a high proportion of children (78.1%) were monosensitised. No relationship was detected between sensitisations and asthma, rhinitis or eczema. Place of residence, gender, age or helminthic infection did not affect the probability of having positive SPTs.

CONCLUSIONS

The most frequent sensitisations in children from Bengo Province in Angola involve house dust mites, followed by cockroach and fungi. No relationship was found between atopic sensitisation and asthma or other allergic diseases.

Prevalence of common sensitizing aeroallergens in Egyptian asthmatic patients

Background

Aeroallergens and food allergens play a key role in the pathogenesis of asthma; they are the target for future immunotherapy worldwide. Food allergens have been studied often in Egypt, but data are defective concerning the prevalent Egyptian aeroallergens that can be affected by the climatic conditions in Egypt. So, our study aimed to explore the dominant sensitizing aeroallergens in Egyptian patients with bronchial asthma.

Methods

Cross-sectional study performed on 122 Egyptian asthmatic patients. Sera from all patients were examined by enzyme allegro sorbent test (EAST) method for specific IgE to a panel of 18 inhaled allergens.

Results

Positive specific IgE to aeroallergens was detected in 43.44% of our patients. German cockroach (18.9%) was the most frequent sensitizing aeroallergen amongst our asthmatic patients, followed by the fungal allergens (15.57%) and house dust mites (HDMs) (13.93%).

Conclusion

German cockroach, fungi, and house dust mite are the chief sensitizing aeroallergens in Egyptian asthmatic patients.

Environmental Health Research in Africa: Important Progress and Promising Opportunities

The World Health Organization in 2016 estimated that over 20% of the global disease burden and deaths were attributed to modifiable environmental factors. However, data clearly characterizing the impact of environmental exposures and health endpoints in African populations is limited. To describe recent progress and identify important research gaps, we reviewed literature on environmental health research in African populations over the last decade, as well as research incorporating both genomic and environmental factors. We queried PubMed for peer-reviewed research articles, reviews, or books examining environmental exposures and health outcomes in human populations in Africa. Searches utilized medical subheading (MeSH) terms for environmental exposure categories listed in the March 2018 US National Report on Human Exposure to Environmental Chemicals, which includes chemicals with worldwide distributions. Our search strategy retrieved 540 relevant publications, with studies evaluating health impacts of ambient air pollution (n=105), indoor air pollution (n = 166), heavy metals (n = 130), pesticides (n = 95), dietary mold (n = 61), indoor mold (n = 9), per- and polyfluoroalkyl substances (PFASs, n = 0), electronic waste (n = 9), environmental phenols (n = 4), flame retardants (n = 8), and phthalates (n = 3), where publications could belong to more than one exposure category. Only 23 publications characterized both environmental and genomic risk factors. Cardiovascular and respiratory health endpoints impacted by air pollution were comparable to observations in other countries. Air pollution exposures unique to Africa and some other resource limited settings were dust and specific occupational exposures. Literature describing harmful health effects of metals, pesticides, and dietary mold represented a context unique to Africa. Studies of exposures to phthalates, PFASs, phenols, and flame retardants were very limited. These results underscore the need for further focus on current and emerging environmental and chemical health risks as well as better integration of genomic and environmental factors in African research studies. Environmental exposures with distinct routes of exposure, unique co-exposures and co-morbidities, combined with the extensive genomic diversity in Africa may lead to the identification of novel mechanisms underlying complex disease and promising potential for translation to global public health.

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.

Detection and identification of dust mite allergens in the air conditioning filters in Chandigarh, India

Modern lifestyle with the increasing use of air conditioner (AC) has been linked with breathing difficulties, irritation, dryness, and other symptoms. Hence, dust mites were isolated from AC filters, which causes allergic diseases. A total of 95 dust samples were collected from AC filters from hospitals, guest house, office, school, and homes in Chandigarh, India. The highest concentration of dust mites was detected from hospitals (9/g), offices (7/g), households (6/g), guest houses (3/g), and schools (0/g). Based on the morphology of dust mites observed under a light microscope, Dermatophagoides and Acarus species were found most common. Indoor air quality was also monitored to find out their relation with dust mites present in AC filters. Further, the respiratory health status of indoor facility users was also assessed using a standard questionnaire as a study tool. It was seen that 55.3% of male among the total respondents were having an allergy and only 44.7% of the females had an allergy. The allergy among the male respondents (55.3%) was significantly more (p < 0.05) in comparison with female respondents (44.7%). Some of the respondents also reported a family history of rhinitis (31.9%), asthma (12.8%), recurrent urticaria (6.4%), and conjunctivitis (6.4%). Interestingly, 23.4% of study participants reported that they get disturbed by the use of AC and house dust was found to be the most triggering factor in enhancing the symptoms of allergy. Thus, it is recommended that air conditioner filters should be cleaned regularly to prevent the accumulation of the dust mites and related allergens on filter dust.

Allergy and immunology in Africa: Challenges and unmet needs

The tremendous increase in allergy in the African continent cannot simply be explained by the change in public hygiene. There are many "prehygiene" communities with sewage-contaminated water supplies, helminth infestations, bare footedness, and poor housing, and still there is a high prevalence of allergic disease. Africans can be exposed to many risk factors facilitating severe asthma and wheezing, including airborne viruses, smoke, indoor dampness, cockroaches, and poor access to health care. Although the reporting on food allergy is inadequate to perform systematic reviews or meta-analyses, the available data suggest that food allergy is underdiagnosed. The rate of new HIV infections in high-prevalence settings in Africa remains unacceptably high. Although the annual number of new HIV infections in Sub-Saharan Africa has decreased lately, new HIV infections in the Middle East and North Africa region have increased; however, the current prevalence of 0.1% is still among the lowest globally. Africa is densely populated, and consanguineous mating is high in some areas of North and Sub-Saharan Africa. This allows for emergence of many autosomal recessive primary immunodeficiency diseases. There is urgent need for the establishment of primary immunodeficiency disease registries, stem cell transplantation facilities, and neonatal screening programs. To address these expanding problems and perform local cutting-edge research, Africans need to be empowered by motivated governments, dedicated funds, and compassionate scientific partnership.