Atopy is defined as the genetic propensity to develop immunoglobulin E antibodies in response to exposure to allergens and assessed by skin prick test (SPT) responses to common allergens, which may contribute to the development of the clinical disorders (phenotype). Although it is generally agreed that atopy is an important risk factor for allergic diseases such as asthma, rhinitis, and eczema, the extent to which atopy accounts for these diseases is controversial. One hundred forty one children (up to 12 years) were skin prick tested to evaluate 16 foods common to the Malaysian diet and 4 common aeroallergens. Eighty-five percent of patients had positive SPT reactivity. The most commonly implicated aeroallergen and food allergen was house dust mite (HDM) and Prawn. Seventy percent had positive SPT reactivity results to HDM and 24.8% to prawns. Fifty five percent were positive to more than one allergen and 17.7% positive to single aeroallergen. The prevalence of atopy in children with history of eczema was 90%. The incidence of HDM and food allergy especially crabs and prawns, is significantly greater in Malaysian Children with rhinitis symptoms.
The specific serum IgE levels to 20 allergens were determined by enzyme immunoassay in 90 Malaysian patients with allergic rhinitis. Ninety-two percent of patients had elevated IgE to at least 1 of the allergens. The housedust mites D. pteronyssinus and D. farinae were the major allergens, elevated IgE to either allergen being present in 86% of the patients. Prick skin tests were carried out in some of the patients, housedust mites, cat fur, dog hair and shrimp were the allergens used. Close correspondence was found between IgE and prick skin tests to the mites.
Atopy is a syndrome characterized by immediate hypersensitivity reactions to common environmental antigens. The "hygiene hypothesis" stipulates that childhood infections are associated with a lower risk of allergies. Not much has been published about the effects that the treatment of pulmonary tuberculosis (TB) has on allergies, specifically allergic rhinitis. We conducted a study to investigate the prevalence of allergic rhinitis in patients with pulmonary TB before and after treatment of their TB. Our initial study group was made up of 121 patients with confirmed pulmonary TB who were followed up by questionnaire. In addition to demographic data, they provided information about their personal and family history of atopy and their current status with regard to allergic rhinitis. After providing informed consent, all patients underwent skin-prick testing with Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis allergens before and after TB treatment. Stool samples were obtained to identify patients with worm infestation, and they were excluded from the study. In all, 94 patients completed treatment and follow-up, and their data were included in the final analysis. Of this group, 31 patients (33.0%) exhibited symptoms of allergic rhinitis prior to TB treatment, and 26 (27.7%) had a positive skin-prick test. Following treatment, only 12 patients (12.8%) reported allergic rhinitis symptoms (p = 0.004), but there was no significant reduction in the number of patients with a positive skin-prick test (n = 20 [21.3%]; p = 0.555). We conclude that the treatment of pulmonary TB results in significant relief of atopy, particularly allergic rhinitis symptoms.
The significance of food specific serum IgG4 antibody in food allergy is unclear and this led us to investigate the relevance of specific IgG4, along with IgG and IgE antibodies to two common food allergens in Malaysia. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum antibodies in 143 allergic rhinitis patients' sera, of which 47 were from patients with clinical indication of shrimp allergy, 46 with clinical indication of crab allergy and 50 without indication to either allergy. Clinical indication of allergy was based on answers to a questionnaire or results of the skin prick test. We found that the elevation of specific IgE or IgG4 is associated with shrimp and crab allergies but elevation of specific IgG is not associated with either allergy. However, the clinical utility of elevated specific IgG and IgG4 levels is pending further investigation.
Study site: Allergic rhinitis clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
The purpose of this study is to determine the relevance of the hygiene hypothesis; that is to determine if worm infestation has a protective role against the development of allergic rhinitis. A prospective case controlled study was conducted. Specific IgG levels to Toxocara were studied in 85 patients confirmed to have allergic rhinitis and were compared to levels in another 85 controls, with no form of allergy. The IgG assay was done using ELISA technique. There was a higher incidence of positive specific IgG to Toxocara in the controls as compared to allergic patients. The values were statistically significant [Chi square test (p=0.002)]. This negative association between worm infestation and allergic rhinitis suggests that a previous worm infestation could protect against the development of allergic rhinitis.