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Unlabelled: Chronic rhinosinusitis (CRS) is a chronic inflammatory disorder of mucosa of the nose and the paranasal sinuses. Two major forms of CRS can be differentiated; CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). The pathophysiology and etiology of nasal polyps (NPs) are partly understood. IgG subclass deficiency was shown to be associated with an increased susceptibility to infections. However the association between NPs and IgG subclass deficiency has never been reported., Objectives: To report two cases of recalcitrant CRS and recurrent NPs with IgG subclass deficiency., Case Report: Two children (6 and 8 year-old boys) were referred to the Pediatric Allergy/Immunology Clinic, Siriraj Hospital due to a prolonged history of CRS and recurrent NPs. Both of them were treated with aggressive medical (topical and systemic corticosteroids, antibiotics, leukotriene antagonist, nasal irrigation) as well as surgical therapy, without significant improvement. Immunologic investigation in both patients showed that IgG, IgA, and IgM level were normal. IgG subclasses level in patient No. 1 were IgG1 1,235 (280-1120) mg/dl (79%), IgG2 235 (30-630) mg/dl (23.5%), IgG3 27.3 (40-250) mg/dl (1.74%), and IgG4 92.4 (11-620) mg/dl (5.9%). IgG subclasses level in patient No. 2 were IgG1 1,139 (280-1120) mg/dl (82.5%), IgG2 170 (30-630) mg/dl (12.3%), IgG3 5.6 (40-250) mg/dl (0.4%), IgG4 65.7 (11-620) mg/dl (4.8%). The diagnosis of CRS and recurrent NPs with IgG3 subclass deficiency in the first patient and IgG2/IgG3 subclass deficiency in the second patient were made. Patient No. 1 was given monthly IVIG therapy for the total of 7 courses and medications were gradually tapered. Currently, the patient is doing well after the cessation of IVIG therapy for 3 months. Patient No. 2 denied the IVIG treatment and was lost to follow up., Conclusion: We reported two cases of recalcitrant CRS and recurrent NPs in children. Immunologic work up revealed IgG subclass deficiency. The treatment with monthly IVIG improved CRS and NPs in treated patient which brought up the possibility of association between NPs and IgG subclass deficiency. Further study on the direct role of IVIG in NPs will be needed in the future.

Introduction: Adverse food reactions are not uncommon among children. Several of these reactions are IgE-mediated. Prevalence of adverse food reactions among Thai children has not been fully explored., Objectives: The objectives of the study are (1) to determine prevalence of adverse food reactions and food allergy among Thai children, (2) to determine types of foods producing such reactions, (3) to study clinical manifestations of these reactions, and (4) to study various risk factors relating to food adverse reactions among these children., Material and Method: A total of 656 Thai children were surveyed (188 subjects between 6 months to 3 years of age and 468 subjects between 3 to 6 years of age). The study was a cross-sectional study. Parents answered food allergy questionnaire. Families with children reporting adverse food reactions were invited to participate in further investigation for food allergy with skin prick testings and food challenges., Results: Forty-one of 656 children (6.25%) were reported to experience prior food reactions by questionnaire survey. Common foods reported to be the cause of reactions among younger children were cow's milk and eggs whereas seafood, particularly shrimp, was the most commonly reported food for older children. Three of 21 children underwent food challenge had positive challenges. Skin prick tests to incriminated food were all positive in these three children. Significant risk factors for developing adverse food reactions among these children were personal allergic history (OR = 4.89, CI 2.2-10.75) and family history of allergy (OR = 2.87, CI 1.42-5.89)., Conclusion: Prevalence of adverse food reactions using food allergy questionnaire was 6.25%. From a limited number of those with positive food challenges, prevalence of IgE-mediated food allergy among this group of Thai children is estimated to be 0.45% (CI 0.01-0.8%).

Like other parts of the world, prevalence of childhood allergic diseases in Thailand, particularly of asthma and allergic rhinitis, has risen sharply over the past decade. Epidemiologic studies in this country indicated that allergic sensitization (mainly to house dust mites, cockroaches and cat dander) is the major important risk factor for the development of asthma. House dust mites are the most important source of allergens causing sensitization among allergic Thai children. A nationwide survey indicated that house dust mites are ubiquitous in Thai homes. Despite the authors' earlier finding that mite allergen levels in Thailand (mean group-I allergen level of 11 mcg/g dust), exceeded the recommended international threshold level to induce asthmatic symptoms (10 mcg/g dust), mite allergen levels in homes within the Bangkok area are in the modest range (5 mcg/g dust). With mattresses in Thailand being commonly laid on hardwood surfaces, the authors demonstrated that only top-covering of these mattresses with locally produced mite-impermeable membrane, mite allergens could be substantially reduced. Other active research in pediatric allergy in Thailand include complete surveys of outdoor aeroallergens and research in pharmacologic managements of allergic diseases. The Thailand Registry of Primary Immune Deficiency has recently been established to collect data on patients with these disorders and to improve means for diagnosis and treatment for these unfortunate patients. Finally, with a recent approval for board certification in pediatric allergy and immunology, it is expected that the number of specialists in this field will increase to a sufficient level to provide adequate care for allergic/immunologic children in Thailand.

Background: Approximately seventy per cent of asthmatic children from temperate climates, with normal lung function, have exercise-induced asthma (EIA). There is certain evidence to suggest that EIA may be less frequently encountered among children who live in tropical climates. Prevalence of EIA in Asian asthmatic children has never been thoroughly studied., Objective: To study the prevalence of EIA among Thai asthmatic children., Method: A prospective study was performed to determine the prevalence of EIA in 44 Thai asthmatic children who were able to perform the spirometric maneuver. Subjects were randomly selected asthmatic children from the Pediatric Allergy Clinic, Department of Pediatrics, Siriraj Hospital. They were subjected to exercise testing on a steady state, motor-driven treadmill for 6 minutes (mean speed +/- SD = 3.7 +/- 0.4 km/h, mean level of inclination + SD = 15.0 +/- 5.2 degrees). The testing was conducted in a temperature-controlled (mean temperature +/- SD = 24.4 +/- 0.8 degrees C) and humidity-controlled environment (mean relative humidity +/- SD = 41.7 +/- 2.1%). Lung function tests were performed before exercise, immediately after and at 3, 5, 10, 15, 20 and 30 minutes after exercise. Results of the lung function test were calculated as per cent falls of forced expiratory volume in 1 sec (FEV1), peak expiratory flow rate (PEFR), and forced expiratory flow at 25 per cent-75 per cent (FEF50) from baselines. EIAs were diagnosed when drops of FEV1, PEFR and FEF50 were greater than 20 per cent, 25 per cent and 25 per cent from baseline values, respectively., Results: Of the 44 patients studied (31 boys and 13 girls; mean age 11.9 years), 34 per cent had mild asthma. Fifty-nine per cent had moderate asthma and 7 per cent had severe asthma. Eleven patients (25%) had EIA diagnosed by significant falls of FEV1's (26 +/- 12.6%), whereas, 13 patients (30%) and 20 patients (45%) had EIA defined by significant drops of PEFR's and FEF50's, respectively. A total of 23 patients (52%) had EIA by one or more diagnostic criteria. Peak times for EIA as diagnosed by FEV1, PEFR and FEF50 occurred at 3, 10, and 10 minutes respectively, after exercise. Most EIA episodes observed were of mild degree., Conclusions: The prevalence of EIA in Thai children is much lower than figures reported in studies from Western countries. By using a significant fall of FEV1's as the diagnostic criteria, only 25 per cent were diagnosed as having EIA. By PEFR and FEF50 criteria, percentages of EIA increased to 30 per cent and 45 per cent respectively. Screening for EIA, therefore, may not be an appropriate diagnostic tool for the diagnosis of childhood asthma in tropical climates.

Introduction: Conflicting results exist with regard to the efficacy of vacuum cleaners on the removal of mite allergens from bedding., Objectives: The authors prospectively compared a short term efficacy of two types of regular vacuum cleaners (National-N and Hoover-H) with a specialized cleaner (Vorwerk-V) in the removal of mite allergens from mattresses., Material and Method: Thirty-five dormitory beds with high mite allergen concentrations at the baseline period (month 0) were selected. They were matched into three groups according to group I mite allergen concentrations (N 11 beds, H 12 beds, V 12 beds). Vacuuming was performed on months 1 and 4 by the assigned vacuum cleaner in each group. Immediately after, mattresses were vacuumed by a reference cleaner (another National vacuum cleaner) at both months. Vacuuming was performed over the entire bed for 2 minutes/square meter. Group I mite allergens (sums of Der p 1 and Der f 1) were measured; concentrations and total mite allergens removed by the tested cleaners as well as by the reference cleaner, at various time points, were compared., Results: Ability to remove mite allergens by vacuum cleaners depends on weight of dust removed and also on mite concentrations in the dust samples. Despite the fact that H and V appeared to remove higher mite allergens than N, such differences were not statistically significant (p > 0.05), both at month 1, and 4. Surprisingly, mattress mite concentrations removed by both high capacity cleaner groups (V & H) increased at month 4, whereas, it remained unchanged in the third group (N). This increase led to a concomitant increase in total allergen removed by V and H. Nevertheless, remaining total allergens in the mattresses in V and H, as judged from the amount of allergens obtained by the reference cleaner, increased at month 1 and 4 compared to baseline values (p < 0.05), whereas, no change was observed in N., Conclusion: Although high capacity vacuum cleaners removed a large amount of mite allergens from mattresses, they did not sufficiently reduce mattress mite allergen burden as determined by the reference cleaner during this short term study.

Background: Seafood is a common cause of food allergy in Thai adults and children. Skin prick test is a safe and convenient way to screen seafood allergy. To date, the Allergy Unit, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University uses imported extracts for seafood skin prick test. The extracts are expensive and may not be the same species as seafood in Thailand., Objectives: To compare the consistency between local seafood allergen extracts prepared by the Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University and imported seafood allergen extracts., Methods: The study was a prospective comparative trial performed in children who attended the Pediatric Allergy Clinic, Siriraj Hospital from March 1999 to October 2000. The skin prick test was performed with the local seafood allergen extracts prepared by a pharmacist from the Department of Pharmacology and the imported seafood allergen extracts included shrimp, fish and crab. Histamine and normal saline were used as positive and negative control respectively. The positive result was recorded when wheal reaction was > or = 3 mm larger than negative control., Results: Eighty eight patients (57 boys and 31 girls) were included in this study. The average age was 7.7 years (1-15 years). Half of the patients had a history of seafood allergy. The study showed probable consistency between imported and local skin prick test of shrimp and crab extracts (kappa = 5-7) but no consistency between imported and local skin prick test of fish extracts (kappa < 5). The study also showed no consistency between history of seafood and skin prick test result., Conclusion: Local seafood allergen extracts from the Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University are safe but they cannot replace the imported seafood allergen extracts. Further investigations about sensitivity and specificity of both kinds of allergen extracts are necessary.