Asthma, Airway Symptoms and Rhinitis in Office Workers in Malaysia: Associations with House Dust Mite (HDM) Allergy, Cat Allergy and Levels of House Dust Mite Allergens in Office Dust

Insights into uncovered public health risks. The case of asthma attacks among archival workers: a cross-sectional study

Objective

To ascertain the prevalence of asthma attacks among archivists and identify the associated occupational factors in this understudied professional population.

Methods

We conducted a cross-sectional, questionnaire-based study among 1,002 archival workers. A multiple logistic regression was conducted to identify the association between asthma attacks and occupational exposures. The Strobe Protocol was applied.

Results

999 workers were included in the final analysis with the asthma prevalence of 33.3%. Main factors associated with asthma attacks (OR [95% CI]) were the presence of chemically irritating odors (2.152 [1.532-3.024]), mold odors (1.747 [1.148-2.658]), and insects (1.409[1.041-1.907]). A significant synergistic effect was observed between chemical irritants and mold, the odds ratio was 7.098 (95% CI, 4.752-10.603).

Conclusion

There was a high prevalence of asthma attacks among archival workers, an under-studied population. Chemical irritants, molds and insects were associated with their asthma attacks. Notably, this study's data analysis has revealed a strong synergy (OR = 7.098) between chemical odors and molds in the workplace. While the existing international literature on this specific interaction remains somewhat limited, previous studies have already demonstrated the potential for chemical irritants, such as sulfur dioxide and ozone, to synergistically interact with inhalable allergens, including fungi, molds and dust mites. Consequently, this interaction seems to exacerbate asthma symptoms and perpetuate untreated exposure. Furthermore, in damp and damaged buildings, the presence of microbial components, such as cellular debris or spores released during fungal growth can trigger an inflammatory response, potentially served as a shared pathway for the development of asthma among individuals exposed to these hazardous factors.

Comparison of the efficacy of combined budesonide and fexofenadine versus combined fluticasone propionate and fexofenadine on the expression of class-4 semaphorins and their receptors in the peripheral blood cells of patients with allergic rhinitis

Background

Allergic rhinitis (AR) is a common immunoglobulin (Ig) E-mediated disease. This study aimed to evaluate the gene expression levels of class 4 semaphorins and their receptors in AR patients before and after treatment with budesonide and fexofenadine (B/F) compared to fluticasone propionate and fexofenadine (FP/F).

Methods

In this study, 29 AR patients (age 34.4 ± 1.2 years, 18 men and 11 women) were treated with B/F, and 24 AR patients (age 32.8 ± 1.9 years, 15 men and 9 women) were treated with FP/F for one month. Before and after treatment, peripheral blood samples were taken from patients. The expression levels of SEMA4A, SEMA4C, SEMA4D, Plexin-B2, and Plexin-D1 genes were measured using the qPCR method. In addition, the serum levels of IgE were measured using an enzyme-linked immunosorbent assay (ELISA).

Results

The expression levels of SEMA4A (P = 0.011), 4C (P = 0.017), Plexin-B2 (P = 0.0005), and Plexin-D1 (P = 0.008) remarkably increased in AR patients treated with B/F. Our results show a significant reduction in the gene expression levels of SEMA4A (P = 0.002), 4C (P = 0.014), 4D (P = 0.003), Plexin-B2 (P = 0.033), and Plexin-D1 (P = 0.035) after treatment with FP/F. The serum levels of IgE increased in FP/F treated group (P = 0.017) and conversely decreased in the treated group with B/F (P = 0.019). Moreover, the percentages of eosinophils were reduced in both FP/F and B/F groups (P = 0.015 and P = 0.0001, respectively).

Conclusion

In conclusion, concomitant use of fexofenadine and fluticasone propionate reduced SEMA4A, 4C, 4D, Plexin-B2, and Plexin-D1, while the SEMA4A, 4C, Plexin-B2, and Plexin-D1 gene expression levels were increased in the patient group treated with B/F.

House dust mite allergy in Malaysia: review of research gaps in the current scenario and the way forward

The prevalence of house dust mite (HDM) allergy, especially in Asian countries with rapid urbanization, has been increasing. House dust mites thrive in places with relatively high humidity. With the combination of climate change, naturally high humidity, and urbanization, tropical countries like Malaysia are becoming a hotspot for HDM allergy fast. With a previously reported sensitization rate of between 60 and 80%, it is a worrying trend for Malaysia. However, due to incomplete and out-of-date data, as seen by the limited study coverage in the past, these numbers do not paint a complete picture of the true HDM allergy scene in Malaysia. This review briefly discusses the HDM fauna, the HDM sensitization rate, the common diagnosis and therapeutic tools for HDM allergy in Malaysia, and makes suggestions for possible improvements in the future. This review also highlights the need of more comprehensive population-based prevalence studies to be done in Malaysia, encompassing the three main HDMs-Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis-as the lack of up-to-date studies failed to give a clearer picture on the current scenario of HDM allergy in Malaysia. Future studies will be beneficial to the nation in preparing a better blueprint for the management and treatment of HDM allergy.

Comparative Analysis of the Immune Response and the Clinical Allergic Reaction to Papain-like Cysteine Proteases from Fig, Kiwifruit, Papaya, Pineapple and Mites in an Italian Population

Several plant papain-like cysteine proteases are exploited by the food, cosmetic, pharmaceutical and textile industries. However, some of these enzymes can cause allergic reactions. In this context, we investigated the frequency of sensitization and allergic reactions to some fruit and/or latex cysteine proteases, which are used as additives by the food industry to improve and modify the quality of their products. The FABER test was used to analyse the patients' sensitization towards five plants and, for comparison, two homologous mite cysteine proteases. In an Italian population of 341 allergic patients, 133 (39%) had IgE specific for at least one of the seven cysteine proteases under investigation. Most of the patients were IgE positive for Der p 1 and/or Der f 1 (96.38%) reported a clinical history suggestive of respiratory allergy to mites, whereas none of the subjects sensitized to the homologs from papaya, pineapple and fig reported allergy symptoms following ingestion of these foods. Only one patient referred symptoms from ingesting kiwifruit. Therefore, the obtained results showed that sensitization to the fruit enzymes was only rarely concomitant with allergic reactions. These observations, together with the literature reports, suggest that the allergy to plant papain-like cysteine proteases might mainly be an occupational disease.

The Trend of the Burden of Allergic Rhinitis Pre- and Post-COVID-19 Pandemic in the Urban Population of Perak, Malaysia

Aims

This study aims to determine the trend of allergic rhinitis (AR) prevalence in a tertiary hospital between 2017 and 2022, and to compare its prevalence pre- and post-COVID-19 pandemic.

Methods

This was a cross-sectional study involving the extraction of all Malaysian patients' medical records who were diagnosed with AR and attended the otorhinolaryngology outpatient clinic of a government-funded tertiary hospital in Malaysia between 2017 and 2022.

Results

3,744 cases out of the 57,968 first-encounter outpatient visits to the otorhinolaryngology clinic were extracted for analysis. Overall, the prevalence of AR cases ranged from 1.83 to 9.23% between 2017 and 2022. There was a significant drop of 21.38 to 70.22% between the pre- and post-COVID-19 pandemic (p < 0.001). Males (0.34 to 1.60%) were more prevalent in the 6 to 18 year old than females (0.09 to 1.23%). The trend shifted with age, whereby females (0.50 to 2.45%) experienced a higher prevalence than males (0.21 to 1.77%) as they aged from 19 to 59. The Malay (1.01 to 4.59%) demonstrated a two-time higher prevalence than the Chinese (0.30 to 2.01%) and Indian (0.40 to 2.14%) ethnicities. After stratifying by gender and ethnicity, Indian women (0.17 to 1.09%) had a higher rate of AR than their Chinese counterparts (0.12 to 0.99%) across all years.

Conclusion

The AR prevalence consistently ranged from 8.14 to 9.23% pre-pandemic. A remarkable drop was observed post-pandemic, ranging from 1.83 to 6.40%. A gender shift from male to female predominance as age progressed. The Malay had the highest prevalence of AR.

Associations between environmental characteristics, high-resolution indoor microbiome, metabolome and allergic and non-allergic rhinitis symptoms for junior high school students

Rhinitis is one of the most prevalent chronic diseases globally. Microbiome exposure affects the occurrence of rhinitis. However, previous studies did not differentiate allergic rhinitis (AR) and non-allergic rhinitis (NAR) in the microbial association analysis. In this study, we investigate 347 students in 8 junior high schools, Terengganu, Malaysia, who were categorized as healthy (70.9%), AR (13.8%) and NAR (15.3%) based on a self-administered questionnaire and skin prick tests of pollen, pet, mould and house dust mite allergens. Classroom microbial and metabolite exposure in vacuumed dust was characterized by PacBio long-read amplicon sequencing, quantitative PCR and LC-MS-based untargeted metabolomics. Our findings indicate a similar microbial association pattern between AR and NAR. The richness in Gammaproteobacteria was negatively associated with AR and NAR symptoms, whereas total fungal richness was positively associated with AR and NAR symptoms (p < 0.05). Brasilonema bromeliae and Aeromonas enteropelogenes were negatively associated with AR and NAR, and Deinococcus was positively associated with AR and NAR (p < 0.01). Pipecolic acid was protectively associated with AR and NAR symptoms (OR = 0.06 and 0.13, p = 0.009 and 0.045). A neural network analysis showed that B. bromeliae was co-occurring with pipecolic acid, suggesting that the protective role of this species may be mediated by releasing pipecolic acid. Indoor relative humidity and the weight of vacuum dust were associated with AR and NAR, respectively (p < 0.05), but the health effects were mediated by two protective bacterial species, Aliinostoc morphoplasticum and Ilumatobacter fluminis. Overall, our study reported a similar microbial association pattern between AR and NAR and also revealed the complex interactions between microbial species, environmental characteristics, and rhinitis symptoms.

The Prevalence, Clinical Picture, and Triggers of Allergic Rhinitis in Saudi Population: A Systematic Review and Meta-Analysis

Objective

To summarize the current evidence regarding the prevalence of Allergic rhinitis (AR) and its symptoms, triggers, and impact on the quality of life of the Saudi population.

Methods

A Computerized Search in MEDLINE via PubMed, MEDLINE Core database, Scopus, and Web of Science was conducted using relevant keywords. A two-stage screening process, data extraction, and quality assessment were conducted by four independent reviewers. Comprehensive Meta-analysis was used for all statistical analyses (CMA; USA: version 3.3.070).

Results

Sixteen articles (n= 31,990 patients) were included. The overall estimated prevalence of AR was 21.2%, 95% CI (12.8-33.1%). Males had a higher prevalence of AR than females (31.7% vs 27.1%), although the difference was not significant (OR=1.24, 95% CI: 0.78-1.953; p=0.356). Children and adolescents exhibited a lower prevalence of AR than adults (13.7% vs 31.1%). Urban AR prevalence was much greater than rural (38.4% vs 13.0%). Asthma, atopic dermatitis, and eczema are all associated with AR. The most common signs and symptoms of AR were headache 33.9%, watery discharge 28.6%, sneezing 24.6%, itchy nose, runny nose 22.2%, nasal obstruction or congestion 22.0%, loss of smell 21.9%, and wheezing 17.2%. The most prevalent triggers of AR were perfume 36.8%, dust 27.3%, air conditioning 23.4%, weather or temperature changes 17.8%, air pollution 14.5%, drugs or chemicals 13.8%, tobacco 10.8%, atopy 10.3%, and insects 10.2%.

Conclusion

The overall prevalence of AR in Saudi Arabia is 21.2%. The prevalence of AR was comparable in both males and females. However, it was higher in adults than in children and adolescents, and in urban areas than rural areas. Asthma, atopic dermatitis, and eczema co-occurrence with AR are common. AR has a negative impact on the quality of life of the patients in the form of interference with daily activities, sleep problems, difficulty of breath, and school absenteeism.

Prevalence, causes and treatments of allergic rhinitis in Malaysia: a literature review

Recently, allergic rhinitis (AR) cases have been surging rapidly in many developing countries. However, the prevalence, risk factors and treatment modalities for AR within the Malaysian population have not been thoroughly evaluated. The present study aimed to provide a complete review of literature on allergic rhinitis in Malaysia. Available data indicated that the prevalence of AR varied across different age groups and regions in Malaysia, but there is an increasing trend among the younger population. The key contributing factor is exposure and sensitization towards several airborne allergens, mainly house dust mites, cat fur and fungi, with possible genetic predispositions. In addition, variations in the symptom severity may be associated with racial orientations. For management of the disease, standard prescriptions of conventional drugs (antihistamines, intranasal corticosteroids and nasal decongestants) remain as the treatment of choice. A small proportion of the native residents tend to resort to alternative approaches of self-healing through aromatherapy and natural food consumption such as tiger’s milk mushroom and Tualang honey. In conclusion, the increase in the cases of AR in Malaysia is due to environmental and genetic factors which requires proper medical intervention as treatment strategies. The utilization of holistic approaches requires further studies and clear understanding prior to their integration into the standard of care. There are still many gaps in the knowledge and management of allergic rhinitis which demands further attention from the research community.

Screening of B-cell epitopes of Der-p1 and Der-p2 major aeroallergens by computational approach for designing immunotherapeutics

Introduction and Aim: Allergic diseases are IgE-mediated hypersensitivity reactions affecting approximately 30% of the general population globally. Dermatophagoides pteronyssinus (Der-p) is the most prevalent house dust mite (HDM) species consisting of 23 mite allergen groups. Among these, group 1 and 2 are major allergenic proteins, which causes allergic asthma in 80% of sensitized individuals, with elevated IgE titres in the serum. This study involves in silico analysis of potential B-cell epitopes of group 1 and group 2 of Der-p, which can be utilized in designing immunotherapeutic vaccines.   Materials and Methods: Allergen sequences obtained from the database- International Union of Immunological Societies (IUIS), for predicting of B-cell epitopes. The physiochemical properties and secondary structures of the obtained sequence were evaluated. The sequences were further subjected to determining antigenicity, surface accessibility, and prediction of linear and discontinuous B-cell epitope by utilizing IEDB tools.   Results: The linear and discontinuous B-cell epitopes of Der-p1 and Der-p2 aeroallergen were predicted. Further, Der-p1 and Der-p2 showed 6 linear epitopes each respectively. Conformational epitopes predicted were 123 of Der-p1 and 72 of Der-p2 respectively, by the ElliPro tool. Based on the structure, antigenicity, and surface accessibility, only 10% of Der-p1 and Der-p2 which binds to B-cell epitopes are linear and the majority are discontinuous.   Conclusion: The linear and conformational epitopes of Der-p1 and Der-p2 are predicted using in silico tools. These identified epitopes might be useful for developing epitope-based immunotherapeutics for HDM allergy.

Specific aeroallergen sensitization associated with current rhinitis among adults in southwestern Saudi Arabia

Data about allergic sensitization to rhinitis among adults are limited. The objectives were to explore the prevalence of current rhinitis (CR) and associated specific allergen sensitizations in southwestern Saudi Arabia. A cross-sectional study was conducted on 969 adults in southwestern regions of Saudi Arabia, namely Aseer, Jazan, and Al Baha. From each region, 5 primary health care centers were chosen. The validated Arabic Version of the International Study of Asthma and Allergies in Childhood questionnaire was used. Total immunoglobulin E (IgE) enzyme-linked immunosorbent assay, cytokine enzyme-linked immunosorbent assay (interleukin [IL]-4, IL-10, IL-13, and interferon-γ), aeroallergen-specific IgE immunoassay (a panel of 30 common aeroallergens; 9 indoor and 21 outdoors), and eosinophilic count were assessed. A prevalence of CR of 35.8% (95% confidence interval: 32.8%-38.9%) was found. Regarding outdoor aeroallergens, Mesquite-positive IgE antibodies were higher among CR adults (odds ratio = 1.52, 95% confidence interval: 1.02-2.21) compared to those without CR. The same significant pattern was found with Chenopodium, Ragweed, Pigweed, Russian thistle, Bermuda grass, Timothy grass, and Rye. All indoor aeroallergens were not significantly associated with CR. Total IgE and eosinophil count were significantly higher among adults with CR. In conclusion, CR in southwestern regions of Saudi Arabia is common and of significant public health importance. Aeroallergens that associate with adult sensitization to CR tend to be of the outdoor variety particularly the herbaceous grass and their pollens. The magnitude of CR and its association with exposure to outdoor aeroallergens should be taken into account by health policy decision makers, clinicians, and medical practitioners when diagnosing and treating related conditions.

Shukri N, Wong KK, Mohd Ashari NS. Zonula occludens-1 expression is reduced in nasal epithelial cells of allergic rhinitis patients

Allergic rhinitis (AR) is a common allergic disease characterized by disruption of nasal epithelial barrier. In this study, we investigated the mRNA expression of zonula occludens-1 (ZO-1), ZO-2 and ZO-3 and histone deacetylase 1 (HDAC1) and HDAC2 in AR patients compared to healthy controls. RNA samples were extracted from nasal epithelial cells of house dust mites (HDMs)-sensitized AR patients and healthy controls (n = 28 in each group). The RNAs were reverse transcribed into cDNAs for measurement of ZO-1, ZO-2, ZO-3, HDAC1 and HDAC2 expression levels by quantitative PCR. The mRNA expression of ZO-1 was significantly decreased in AR patients compared to healthy controls (p = 0.010). No significant difference was observed in the expression levels of ZO-2, ZO-3, HDAC1 and HDAC2 in AR patients compared to healthy controls. We found significant associations of higher HDAC2 levels in AR patients with lower frequency of changing bedsheet (p = 0.043) and with AR patients sensitized to Dermatophagoides farinae (p = 0.041). Higher expression of ZO-2 was observed in AR patients who had pets (p = 0.007). In conclusion, our data indicated that ZO-1 expression was lower in AR patients contributing to decreased integrity of nasal epithelial barrier integrity, and HDAC2 may be involved in the pathogenesis of the disease.

Characteristics of allergen profile, sensitization patterns and Allergic Rhinitis in SouthEast Asia

PURPOSE OF REVIEW

To highlight the characteristics of allergic rhinitis, local allergic rhinitis (LAR), and importance of allergens in Southeast Asian countries.

RECENT FINDINGS

The Asia-Pacific region is very diverse with disparities in the epidemiological data between countries as well as in the unmet needs. The prevalence of allergic rhinitis has markedly increased in the past decades, with a high variation between countries, ranging from 4.5--80.3%. In terms of LAR, the reported prevalence in Southeast Asia is similar to that of other Asian countries (3.7-24.9%) but lower than that in western countries. House dust mites, cockroach, pollens, and molds are major allergens that are known triggers for of allergic rhinitis in this region, whereas the association with helminth infection requires further investigation.

SUMMARY

There are gaps and high variation between countries in Southeast Asia regarding the prevalence of allergic rhinitis and LAR. Further studies are needed to fully elucidate the association between allergens and allergic rhinitis in Southeast Asia.

Higher Wheal Sizes of Dermatophagoides farinae Sensitization Exhibit Worse Nasal Symptoms in Allergic Rhinitis Patients

Allergic rhinitis (AR) is a global health burden and it manifests in both nasal and non-nasal symptoms. Skin prick test (SPT) is a routine procedure to diagnose AR sensitized to common allergens including house dust mites (HDMs). The degree of sensitivity of a patient toward allergens is determined by the size of the wheal formed by SPT procedure. SPT wheal sizes are influenced by recent anti-histamine usage, however it remains unclear if SPT wheal sizes are also influenced by other factors. In this study, we set out to investigate the association between SPT wheal sizes with the demographical, clinical and environmental characteristics, as well as nasal and non-nasal symptoms severity scores, of AR patients (n = 30) sensitized to common HDMs (i.e., Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis). We showed that SPT wheal sizes of HDM allergens were not associated with clinical, demographical and environmental characteristics examined. Nonetheless, significant correlations were observed between SPT wheal sizes of D. farinae sensitization with worse severity scores of all five nasal symptoms examined (i.e., sneezing, runny nose, itchy nose, congestion and postnasal drip) and four of the six non-nasal symptoms examined (i.e., throat symptoms, ear symptoms, headache and mental function). Such relationships were not observed in SPT wheal sizes of D. pteronyssinus and B. tropicalis sensitization. We suggest that increased SPT wheal sizes for D. farinae sensitization may predict the likelihood of more severe nasal and, to a lesser extent, non-nasal manifestations in AR patients.

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

Background and objective

An increasing trend of asthma prevalence was observed in Asia; however, contributions of environmental and host-related risk factors to the development of this disease remain uncertain. This study aimed to perform a systematic review and meta-analysis for asthma-associated risk factors reported in Asia.

Methods

We systematically searched three public databases (Web of Science, PubMed, and Scopus) in Feb 2021. We only included articles that reported environmental and host-related risk factors associated with asthma in the Asian population. Random-effect meta-analyses were conducted for frequently reported asthma-associated risk factors to provide an overall risk estimate of asthma development.

Results

Of 4030 records obtained from public databases, 289 articles were selected for review. The most frequently reported asthma-associated risk factor was the family history of allergy-related conditions. The random-effect asthma risk estimates (pooled odds ratio, OR) were 4.66 (95% confidence interval (CI): 3.73–5.82) for the family history of asthma, 3.50 (95% CI: 2.62–4.67) for the family history of atopy, 3.57 (95% CI: 3.03–4.22) for the family history of any allergic diseases, 1.96 (95% CI: 1.47–2.61) for the family history of allergic rhinitis, and 2.75 (95% CI: 1.12–6.76) for the family history of atopic dermatitis. For housing-related factors, including the presence of mold, mold spots, mold odor, cockroach, water damage, and incense burning, the random-effect pooled OR ranged from 1.43 to 1.73. Other risk factors with significant pooled OR for asthma development included male gender (1.30, 95% CI: 1.23–1.38), cigarette smoke exposure (1.44, 95% CI: 1.30–1.60), cigarette smoking (1.66, 95% CI: 1.44–1.90), body mass index (BMI)–related parameters (pooled OR ranged from 1.06 to 2.02), various types of air pollution (NO₂, PM10, and O₃; pooled OR ranged from 1.03 to 1.22), and pre- and perinatal factors (low birth weight, preterm birth, and cesarean section; pooled OR ranged from 1.14 to 1.32).

Conclusions

The family history of asthma was the most frequently reported risk factor for asthma development in Asia with the highest risk estimate for asthma development. This suggests a major role of the genetic component in asthma pathogenesis. Further study on asthma genetics is required to improve the current understanding of asthma etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-021-00273-x.

Comparing the concentration levels of allergens and endotoxins in employees' homes and offices

Objective

The aim of the study was to find out whether allergen and endotoxin concentrations in offices differ from those measured at the homes of employees, and identify the parameters that influence exposure.

Methods

Electrostatic dust collectors (EDCs) were placed in five office buildings (68 rooms, 436 EDCs), as well as the homes of the office workers (145 rooms, 405 EDCs) for 14 days, four times a year. In addition, surface samples were collected from the offices four times a year by vacuuming the carpeted floors. Domestic mite (DM), and the major cat and dog allergens (Fel d 1 and Can f 1) were quantified in all samples using fluorescence enzyme immunoassays. Endotoxin was measured in the EDC samples, using the Limulus amoebocyte lysate assay. The allergen and endotoxin concentrations were log transformed and analysed with multilevel models.

Results

Endotoxin concentrations were significantly higher in personal homes compared to levels measured in the offices, and depended on the number of persons living in each household, as well as the presence of a dog. DM allergens were significantly higher in households than in offices, and were significantly higher in bedrooms compared to living rooms. Offices occupied by cat owners had significantly higher Fel d 1 concentrations than offices or homes without. Additionally, Can f 1 concentrations were significantly higher in offices occupied by dog owners compared to those without.

Conclusions

Pet owners appear to transfer cat and dog allergens to their offices. Therefore, in case of allergy complaints at the office, employers and physicians might consider possible contamination by cat and dog allergens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-021-01794-9.

Nasal Epithelial Barrier Integrity and Tight Junctions Disruption in Allergic Rhinitis: Overview and Pathogenic Insights

Allergic rhinitis (AR) is a common disorder affecting up to 40% of the population worldwide and it usually persists throughout life. Nasal epithelial barrier constitutes the first line of defense against invasion of harmful pathogens or aeroallergens. Cell junctions comprising of tight junctions (TJs), adherens junctions, desmosomes and hemidesmosomes form the nasal epithelial barrier. Impairment of TJ molecules plays causative roles in the pathogenesis of AR. In this review, we describe and discuss the components of TJs and their disruption leading to development of AR, as well as regulation of TJs expression by epigenetic changes, neuro-immune interaction, epithelial-derived cytokines (thymic stromal lymphopoietin, IL-25 and IL-33), T helper 2 (Th2) cytokines (IL-4, IL-5, IL-6 and IL-13) and innate lymphoid cells. These growing evidence support the development of novel therapeutic approaches to restore nasal epithelial TJs expression in AR patients.

Changes in ambient temperature increase hospital outpatient visits for allergic rhinitis in Xinxiang, China

BACKGROUND

The effect of ambient temperature on allergic rhinitis (AR) remains unclear. Accordingly, this study aimed to explore the relationship between ambient temperature and the risk of AR outpatients in Xinxiang, China.

METHOD

Daily data of outpatients for AR, meteorological conditions, and ambient air pollution in Xinxiang, China were collected from 2015 to 2018. The lag-exposure-response relationship between daily mean temperature and the number of hospital outpatient visits for AR was analyzed by distributed lag non-linear model (DLNM). Humidity, long-time trends, day of the week, public holidays, and air pollutants including sulfur dioxide (SO2), and nitrogen dioxide (NO2) were controlled as covariates simultaneously.

RESULTS

A total of 14,965 AR outpatient records were collected. The relationship between ambient temperature and AR outpatients was generally M-shaped. There was a higher risk of AR outpatient when the temperature was 1.6-9.3 °C, at a lag of 0-7 days. Additionally, the positive association became significant when the temperature rose to 23.5-28.5 °C, at lag 0-3 days. The effects were strongest at the 25th (7 °C) percentile, at lag of 0-7 days (RR: 1.32, 95% confidence intervals (CI): 1.05-1.67), and at the 75th (25 °C) percentile at a lag of 0-3 days (RR: 1.15, 95% CI: 1.02-1.29), respectively. Furthermore, men were more sensitive to temperature changes than women, and the younger groups appeared to be more influenced.

CONCLUSIONS

Both mild cold and mild hot temperatures may significantly increase the risk of AR outpatients in Xinxiang, China. These findings could have important public health implications for the occurrence and prevention of AR.

Reduced occludin and claudin-7 expression is associated with urban locations and exposure to second-hand smoke in allergic rhinitis patients

The breakdown of nasal epithelial barrier occurs in allergic rhinitis (AR) patients. Impairment of cell junction molecules including tight junctions (TJs) and desmosomes plays causative roles in the pathogenesis of AR. In this study, we investigated the transcript expression levels of TJs including occludin (OCLN), claudin-3 and -7 (CLDN3 and CLDN7), desmoglein 3 (DSG3) and thymic stromal lymphopoietin (TSLP) in AR patients (n = 30) and non-allergic controls (n = 30). Nasal epithelial cells of non-allergic controls and AR patients were collected to examine their mRNA expression levels, and to correlate with clinico-demographical and environmental parameters. We demonstrated that the expression of OCLN (p = 0.009), CLDN3 (p = 0.032) or CLDN7 (p = 0.004) transcript was significantly lower in AR patients compared with non-allergic controls. No significant difference was observed in the expression of DSG3 (p = 0.750) or TSLP (p = 0.991) transcript in AR patients compared with non-allergic controls. A significant association between urban locations and lower OCLN expression (p = 0.010), or exposure to second-hand smoke with lower CLDN7 expression (p = 0.042) was found in AR patients. Interestingly, none of the TJs expression was significantly associated with having pets, frequency of changing bedsheet and housekeeping. These results suggest that defective nasal epithelial barrier in AR patients is attributable to reduced expression of OCLN and CLDN7 associated with urban locations and exposure to second-hand smoke, supporting recent findings that air pollution represents one of the causes of AR.

[Exploration of the correlation between allergic rhinitis and weather factors in Nanning]

Objective:To investigate the characteristics of allergic rhinitis（AR） in the Nanning area and its correlation with meteorological factors. Methods:The characteristics of 16 969 cases of AR in Nanning from May 2011 to June 2018 were analyzed. Meteorological parameters were collected from the official website of the Nanning Meteorological Bureau, including weather conditions, temperature, and wind direction. The relationship between the onset characteristics of AR patients and meteorological factors were also analyzed. Results:Among the 16 969 patients with AR, the top three inhalation allergens were dust mite（56.0%）, house dust mite（50.5%）, and cockroach（37.4%）. The skin index（SI） of dust mite, house dust mite, cockroach is correlated with sex. The SI of dust mite, house dust mite, mugwort, cockroach are correlated with age, and inhaled allergens are correlated with disease course（P<0.05）. However, those relationships were not significant（r<0.2）. The proportion of AR patients visiting the clinic in summer was the highest（3.9%） in all of the four seasons. Gender was found to be related to the grade-4 positive results of dust mite（OR=0.826, 95%CI: 0.724-0.942）, the grade-4 house dust mite（OR=0.777, 95%CI: 0.677-0.891） and the grade-3 positive results of cockroach（OR=1.236, 95%CI: 1.060-1.443）, respectively. The the daytime weather conditions were related to the grade-4 positive results of dust mite（OR=0.830, 95%CI: 0.728-0.947） and the grade 1 positive results of house dust mite（OR=0.803, 95%CI: 0.694-0.929）, respectively. The highest temperature was related to the grade-4 positive result of dust mite（OR=1.032, 95%CI: 1.020-1.043）, grade-1（OR=1.028, 95%CI: 1.001-1.056） and grade-4 （OR=1.047, 95%CI: 1.021-1.075） positive result of house dust mite, grade 1（OR=1.023, 95%CI: 1.001-1.047） and grade-4（OR=1.050, 95%CI: 1.008-1.094） positive result of cockroach, respectively. The minimum temperature was related to the positive results of house dust mites at all grades and the grade-1 positive results of cockroach（OR=0.947, 95%CI: 0.924-0.971）, but not to dust mites. The daytime wind direction was related to the grade-3 positive results of cockroach（OR=1.437, 95%CI: 1.157-1.785）. Conclusion:The number of AR patients in Nanning is highest in summer. The female is more likely to suffer from dust mite and house dust mite, while the male is more likely to suffer from cockroach. Meteorological factors are correlated with the incidence of AR.The highertemperature, the rain and the southerly wind could cause the occurrence or aggravation of AR.

Gender and occupational allergy: Report from the task force of the EAACI Environmental and Occupational Allergy Interest Group

Women's work has traditionally been considered less hazardous to health in comparison with men's work. The increased women's participation in the workforce has led to an increased attention to women's working conditions. Women and men are unequally represented in individual professions or sectors (horizontal segregation), with women also under-represented in leadership positions (vertical segregation). The selection of specific occupations can result in differences between types and levels of occupational exposures among women and men and can affect prevalence of occupational allergy. Gender distribution of work-related asthma appears to vary across countries without clear global difference. Occupational rhinitis tends to be higher in women, although is not clear if this is related to a sex/gender effect or to differences in work exposure. Women are more likely to have occupational contact dermatitis, mainly due to wet work. No clear effects of gender on rates of hypersensitivity pneumonitis have been shown. Besides variation in exposures, physical and physiological characteristics, different behaviours and health consciousness have an impact on the occupational health hazards of women and men. Occupational allergy health promotion strategies need to consider approaches for women and men adjusted by gender, and legislative actions similarly could be implemented in a more gender-sensitive way.

Mite Molecular Profile in the Th2-Polarized Moderate-to-Severe Persistent Asthma Endotype Subjected to High Allergen Exposure

BACKGROUND

The association among the IgE responses to prevailing groups of house dust mite (HDM) allergens in the concurrent asthma phenotypes has not been determined.

OBJECTIVE

The aim of the present study lays on a component-resolved diagnosis (CRD) model to investigate the mite molecular signature in subjects with type-2 inflammation asthma.

METHODS

We selected patients showing a clinically relevant sensitization to HDMs with moderate-to-severe persistent asthma. Skin prick test (SPT) with standardized mite extracts, a broad customized CRD serum sIgE panel including 9 Dermatophagoides pteronyssinus allergens and the related protein allergenic characterization, was investigated in all serum samples.

RESULTS

Ninety out of 93 (96.77%) patients with a positive SPT to HDM showed a concordant sIgE (≥0.35 kUA/L) to the crude extract of D. pteronyssinus. Major allergens (Der p 2, Der p 23, and Der p 1) were present in >70% of all subjects, with mid-tier allergens (Der p 5, Der p 7, and Der p 21) reaching up to 51% in the present cohort. A complex pleomorphic repertoire of HDM molecules recognized by IgE was depicted, including 38 distinct profiles.

CONCLUSIONS AND CLINICAL RELEVANCE

The proposed CRD panel approach, containing the most prevalent HDM allergens, appeared to be sufficient to obtain a precise D. pteronyssinus molecular diagnosis in asthmatics with a climate-dependent high-mite allergen exposure and coexisting sensitization. A dominant role of both major and mid-tier allergens has been confirmed in moderate and severe persistent asthmatics with the preponderant Th2-high endotype.

Allergic Rhinitis and Its Epidemiological Distribution in Syria: A High Prevalence and Additional Risks in War Time

BACKGROUND

Allergic rhinitis (AR) is a global disease that affects a huge proportion of people around the world especially in the Middle East, where multiple allergy-promoting factors can be found. Although AR is not fatal, it severely affects the quality of life. However, it is usually overlooked in developing countries due to resource scarcity.

METHODS

An online questionnaire on social media was used which included demographics, smoking, socioeconomic-status (SES), war-related questions, and the score for allergic rhinitis (SFAR), a simple self-reporting tool with the cut-off point at 7. Findings. This study included 968 subjects with 721 (74.5%) females. The mean age was 24.69 years with AR prevalence at 47.9%. AR was associated with male gender [P = 0.001 (OR, 1.677; 95% CI 1.249-2.253)], having a job [P = 0.049 (OR, 1.309; 95% CI 1.001-1.713)], the having a chronic medical condition (P < 0.0001) mainly other allergies [P < 0.0001 (OR, 9.199; 95% CI 3.836-22.063)] and asthma [P = 0.006 (OR, 5.060; 95% CI 1.396-18.342)], using medications (P < 0.0001) and living in particular provinces (P = 0.010). However, no significant correlation was found with type of work and war factors except being distressed by war sounds [P = 0.027 (OR, 1.348; 95% CI 1.034-1.757)]. Finally, no associations were found with age, consanguinity, SES, educational level, and cigarette or/and shisha smoking (P > 0.05). Interpretation. Approximately half of the sample displayed AR symptoms, indicating a potentially high burden of AR in the community. A correlation to being distressed from war noises was found with AR which could reflect a psychological aspect. In addition, in war harmful allergens are released which can be an additional AR risk factor which adds to the environment in the Middle East that is associated with AR. However, we need further studies to discover and minimize this huge prevalence of AR.

Immunological Factors Associated with Adult Asthma in the Aseer Region, Southwestern Saudi Arabia

Background: The prevalence of asthma is on the rise in Saudi Arabia. Data regarding the immunological profile of asthma in adults in the Aseer region, in southwestern Saudi Arabia, have not been well studied. Objectives: Our aim was to study the immunological factors associated with sensitization to asthma among adults in the Aseer region. Methods: A cross-sectional study with a nested case control design in a 1:1 ratio was conducted on a sample of adults attending primary health care centers in the Aseer region. The study used a validated Arabic version of the International study of asthma and allergies in childhood (ISAAC) questionnaire. The presence of wheezing in the past 12 months was used as a proxy for bronchial asthma. Matched age and sex controls were selected. Both groups were tested for complete blood count (CBC), total and differential white blood cell (WBC) count including eosinophils, total immunoglobulin E (IgE) measurement, allergen-specific immunoglobulin E (IgE), and cytokine levels. Results: The present study included 110 cases and 157 age- and sex-matched controls. Rye wheat was found to be a significant outdoor sensitizing agent ((odds ratio) OR = 5.23, 95% CI: 1.06–25.69). Indoors, house dust mites Dermatophagoides petronyssinus (OR = 2.04, 95% CI: 1.04–3.99) and Dermatophagoides farinae (OR = 2.50, 95% CI: 1.09–5.75) were significant. Higher total IgE (OR = 1.84, 95% CI: 1.10–3.06) and eosinophil levels (OR = 2.85, 95% CI: 1.14–7.15) were significantly associated with adult bronchial asthma in Aseer. On the other hand, the role of cytokines was not significant. Conclusions: In the present study, certain environmental agents were found to be important with regards to sensitization to bronchial asthma in adults. Knowledge about these sensitization agents should be disseminated to health providers and treating physicians in order to enhance preventive environmental control measures and asthma management. Asthma-treating physicians in the region should be alerted to the use of targeted biological therapies in selected asthmatics with difficult-to-control courses.

Sensitization to Cat: When Is Nasal Challenge Needed?

INTRODUCTION

Although the skin prick test (SPT) is a reliable diagnostic tool in perennial allergic rhinitis (PER) for patients allergic to cats, the minimum necessary SPT wheal size required to distinguish cat sensitization from true allergy remains controversial. The cat nasal challenge test (cNCT) could be considered the gold standard for detecting true cat allergy.

AIMS

To assess the difference in the frequency of cNCT positivity between cat owners and non-owners and to determine an appropriate cut-off level for SPT wheal size in detecting positive cNCT in PER patients who are candidates for allergen immunotherapy (AIT) with cat allergen extracts.

SUBJECTS AND METHODS

cNCT in the form of a nasal spray was administered to 60 adult patients with PER, i.e., cat owners (n = 19) and cat non-owners (n = 41) with positive SPT to cat fur allergen (Diater, Spain). Subjective (total nasal symptom score [TNSS]) and objective measurements (peak nasal inspiratory flow [PNIF]) for assessment of nasal patency and nasal eosinophil count [NEo]) were used to assess the nasal response. Peak expiratory flow (PEF) was used as a safety parameter during cNCT.

RESULTS

No differences were obtained in SPT wheal size and cNCT positivity between cat owners and non-owners. Positive cNCT detecting true cat allergy could be predicted by a cat SPT wheal size > 6.5 mm with 71.11% sensitivity and 100% specificity.

CONCLUSIONS

In adult patients with PER, the frequency of cat allergy was similar among cat owners and non-owners. A cat SPT wheal size ≥6.5 mm could be helpful in detecting true cat allergy by avoiding the demanding, time-consuming, and often unavailable cNCT when cat AIT is needed.

Epidemiology of allergic rhinitis and associated risk factors in Asia

This review article aims to present the epidemiology and associated risk factors of allergic rhinitis (AR) in Asia. AR-related literature published on Asia was systematically reviewed and the associated risk factors were investigated.

The prevalence of AR in Asia varied considerably depending on the geographical location, study design and population involved. Several risk factors were observed to have strong association with disease presentation across multiple studies. Among these, family income, family size, daily personal computer usage time, personal and parental education attainment, and stress level have shown some level of biological gradient influence when multiple risk levels were analyzed. This suggests that AR manifestation and presentation possibly might be strongly affected by various personal and family factors. These findings are beneficial as they may provide insights into modifiable factors that may influence AR presentation. In addition, these results indicate that strategies to reduce personal and family-related risk factors have to be developed in order to alleviate the odds of AR expression.

Do Glutathione S-Transferase Genes Modify the Link between Indoor Air Pollution and Asthma, Allergies, and Lung Function? A Systematic Review

PURPOSE OF REVIEW

Glutathione S-transferase (GST) genes are involved in oxidative stress management and may modify the impact of indoor air pollution. We aimed to assess the influence of GST genes on the relationship between indoor air pollution and allergy/lung function.

RECENT FINDINGS

Our systematic review identified 22 eligible studies, with 15 supporting a gene-environment interaction. Carriers of GSTM1/T1 null and GSTP1 val genotypes were more susceptible to indoor air pollution exposures, having a higher risk of asthma and lung function deficits. However, findings differed in terms of risk alleles and specific exposures. High-exposure heterogeneity precluded meta-analysis. We found evidence that respiratory effects of indoor air pollution depend on the individual's GST profile. This may help explain the inconsistent associations found when gene-environment interactions are not considered. Future studies should aim to improve the accuracy of pollution assessment and investigate this finding in different populations.

House dust mite allergy: Its innate immune response and immunotherapy

Over the past few decades, allergic diseases have become increasingly prevalent worldwide. House dust mite (HDM) is the most important domestic source for allergic diseases such as allergic rhinitis, asthma and atopic dermatitis. Dermatophagoides pteronyssinus (Der p) is the major environmental allergen in southeast Asia because of the humid and warm environment is suitable for its growth. In the recent year, role of HDM allergen in allergic inflammation through innate immune system has been well studied. Toll-like receptors (TLRs), protease-activated receptors (PARs) and DC-SIGN could be activated by different HDM major allergens and proinflammatory cytokines also be upregulated. Treatment efficacy for HDM allergy is unsatisfied to the patients and the medication is limited. Immunotherapy provided an alternative option for treating HDM allergy through targeted to the mechanisms of allergic reaction and represented a long-term symptoms relief. Gene specific immunotherapy was currently being developed and it could decrease allergic inflammation and improve the efficacy of treatment. In this report, we reviewed recent studies about the role of HDM allergy in innate immune system and its immunotherapy. Understanding the HDM allergen induced signal transduction pathway and developed allergen specific immunotherapy could help physicians to create precise diagnosis and solve unmet need in HDM allergy.

Allergens with Protease Activity from House Dust Mites

Globally, house dust mites (HDM) are one of the main sources of allergens causing Type I allergy, which has a high risk of progressing into a severe disabling disease manifestation such as allergic asthma. The strong protease activities of a number of these allergens are thought to be involved in several steps of the pathophysiology of this allergic disease. It has been a common notion that protease activity may be one of the properties that confers allergenicity to proteins. In this review we summarize and discuss the roles of the different HDM proteases in the development of Type I allergy.

Different clinical effect of several types of airborne allergens on the severity of bronchial hyperreactivity

BACKGROUND

Atopic sensitization belongs to the most common risk factors for bronchial asthma. However, in clinical practice, it is not clear whether sensitization against pollen and perennial allergens is differently associated with the severity of bronchial hyperresponsiveness (BHR).

AIM

To find out whether patients sensitized to perennial allergens differ in severity of bronchial hyperresponsiveness from patients sensitized to pollen allergens.

METHODS

The study includes 109 patients. Based on the results of skin prick tests, patients were divided into three groups: sensitivity to pollen allergens - group A; sensitivity to perennial allergens - group B; sensitivity to both pollen and perennial allergens - group C. Based on the histamine bronchoprovocation test, we compared the values of histamine provocative concentration causing a 20% drop in FEV₁ (PC₂₀) among particular groups of patients. Mild bronchial hyperresponsiveness was determined if the value of PC₂₀ was >4 mg/ml, while if the value of PC₂₀ was <4 mg/ml, the bronchial hyperresponsiveness was considered as moderate/severe.

RESULTS

A statistically significant difference was found in the degrees of bronchial hyperresponsiveness between the three groups of patients, namely, group A with the patients sensitized only to the pollen allergens, group B comprising patients sensitized to the perennial allergens only, and group C, involving patients sensitized to the combination of both pollen and perennial allergens. The PC₂₀ values were higher among the patients from the group A (7.46 mg/ml) compared to group B (4.25 mg/ml) and C (4.52 mg/ml). The odds ratio for moderate/severe BHR was 5.21 and 5.04 in group B and group C, respectively.

CONCLUSION

Severity of bronchial hyperresponsiveness shows differences according to sensitization to particular allergens. Perennial allergens are more often associated with serious forms of bronchial hyperresponsiveness which also have an impact on the severity and prognosis of bronchial asthma.

A cross-sectional study into the correlation of common household risk factors and allergic rhinitis in Taiwan's tropical environment

OBJECTIVE

To discuss the effect of lesser-known potential risk factors, such as bedroom showers, on the prevalence of allergic rhinitis.

METHOD

A cross-sectional, population-based study was performed using both survey and fungal culturing in southern Taiwan. There were 998 participants enrolled in the survey, and 513 sets of fungal culture obtained. With score for allergic rhinitis (SFAR) more than 7, the patient was defined to have allergic rhinitis. Risks of allergic rhinitis were calculated as odds ratios for various predicted risk factors by logistic regression. Correlation between predicted risk factors and fungal level were examined with linear regression.

RESULTS

The adjusted odds ratio of frequently using bedroom shower to having allergic rhinitis was 1.572 (95% confidence interval: 1.090-2.265), and 0.962 for people with older age to have AR (95% confidence interval: 0.949-0.976). As to the 24-hour fungal level, the standardized coefficient was 0.254 for frequent use of bedroom shower, and 0.106 for window open hours.

CONCLUSIONS

Use of bedroom shower is a potential risk factor for allergic rhinitis development.

Indoor allergen exposure and asthma outcomes

PURPOSE OF REVIEW

The aim of the present review is to discuss updates on research regarding the relationship between indoor allergen exposure and childhood asthma with a focus on clinical effects, locations of exposure, and novel treatments.

RECENT FINDINGS

Recent data continue to demonstrate that early life sensitization to indoor allergens is a predictor of asthma development later in life. Furthermore, avoidance of exposure to these allergens continues to be important especially given that the vast majority of children with asthma are sensitized to at least one indoor allergen. New research suggests that mouse allergen, more so than cockroach allergen, may be the most relevant urban allergen. Recent evidence reminds us that children are exposed to clinically important levels of indoor allergens in locations away from their home, such as schools and daycare centers. Exposure to increased levels of indoor mold in childhood has been associated with asthma development and exacerbation of current asthma; however, emerging evidence suggests that early exposure to higher fungal diversity may actually be protective for asthma development. Novel treatments have been developed that target TH2 pathways thus decreasing asthmatic responses to allergens. These therapies show promise for the treatment of severe allergic asthma refractory to avoidance strategies and standard therapies.

SUMMARY

Understanding the relationship between indoor allergens and asthma outcomes is a constantly evolving study of timing, location, and amount of exposure.

Dust mite allergen, glutathione S-transferase, induces T cell immunoglobulin mucin domain-4 in dendritic cells to facilitate initiation of airway allergy

BACKGROUND

Allergens from dust mites play a critical role in the pathogenesis of airway allergy. The mechanism by which dust mite allergens induce allergic diseases is not fully understood yet.

OBJECTIVE

This study tests a hypothesis that the eighth subtypes of Dermatophagoides farina allergen (Derf8) play an important role in the induction of airway allergy.

METHODS

The protein of Derf8 was synthesized via molecular cloning approach. Dendritic cells (DC) were stimulated with Derf8 in the culture, and then, the expression of T cell immunoglobulin mucin domain 4 (TIM4) in dendritic cells (DC) was analysed. The role of Derf8 in the induction of airway allergy was evaluated with a mouse model.

RESULTS

Exposure to Derf8 markedly induced the TIM4 expression in DCs by modulating the chromatin at the TIM4 promoter locus. Derf8 played a critical role in the expansion of the T helper 2 response in the mouse airway via inducing DCs to produce TIM4. Administration with Derf8-depleted dust mite extracts (DME) inhibited the allergic inflammation and induced regulatory T cells in mice with airway allergy.

CONCLUSION

Derf8 plays an important role in the initiation of dust mite allergy. Vaccination with Derf8-deficient DME is more efficient to inhibit the dust mite allergic inflammation than using wild DME.

Fractional exhaled nitric oxide (FeNO) among office workers in an academic institution, Malaysia--associations with asthma, allergies and office environment

OBJECTIVE

There are few studies on fractional exhaled nitric oxide (FeNO) and respiratory symptoms among adults in tropical areas. The aim was to study associations between FeNO and selected personal factors, respiratory symptoms, allergies, office characteristics and indoor office exposures among office workers (n = 460) from a university in Malaysia.

METHODS

Information on health was collected by a questionnaire, skin prick test and FeNO measurement. Temperature, relative air humidity, carbon monoxide and carbon dioxide were measured in the offices. Settled dust was vacuumed in the offices and analyzed for endotoxin, (1,3)-β-glucan and house dust mites allergens, namely Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1). Two-level linear mixed models and multiple logistic regression were used to analyze the associations.

RESULTS

One-fourth (25.9%) of the office workers had elevated FeNO level (≥ 25 ppb) and 61.5% had HDM, cat, seafood or pollen allergy. Male gender (p < 0.001), current smoking (p = 0.037), height (p < 0.001) and atopy (p < 0.001) were associated with FeNO. The amount of vacuumed dust was associated with FeNO among atopic subjects (p = 0.009). Asthma and rhinitis symptoms were associated with FeNO (p < 0.05), especially among atopic subjects. In particular, a combination of atopy and elevated FeNO were associated with doctor-diagnosed asthma (p < 0.001), rhinitis (p < 0.001) and airway symptoms last 12 months (p < 0.001).

CONCLUSION

Gender, smoking, height and atopy are important risk factors for elevated FeNO levels. A combination of allergy testing and FeNO measurement could be useful in respiratory illness epidemiology studies and patient investigations in tropical areas.