Abstract
BackgroundThe knowledge about allergic sensitization and its relationship with clinical symptoms and diseases among adults in South-East Asia is poor. The aim of this study was to investigate the prevalence and pattern of allergic sensitization and the association with asthma and allergic rhinitis in adults in urban and rural Vietnam.MethodsAmong 5,782 responders to a questionnaire survey in northern Vietnam, a random sample was invited to a clinical follow-up and 684 (46%) participated. The methods included a structured interview using a modified GA2LEN study questionnaire on symptoms and possible determinants for diseases. Skin prick test (SPT) with ten common airborne indoor and outdoor allergens, lung function test, and methacholine test was performed among subjects ≤60 years of age.ResultsIn total, one third of subjects had a positive SPT reaction to at least one allergen, 36.9% of men and 31.0% of women (n.s.). The most common sensitizer was the storage mite B. tropicalis (men 27.7%; women 18.7%) followed by house dust mite D. pteronyssinus (men 16.5%; women 10.6%), and D. farinae (men 15.3%; women 6.3%), and cockroach (men 16.5%; women 10.2%). Sensitization to all major allergens were significantly more common among men and among subjects ≤45 years compared with women and subjects >45 years, respectively. The prevalence of sensitization to animals, pollen and molds were low. The majority of cockroach-sensitized subjects were also sensitized to mites. Sensitization to any allergen and all major allergens were significantly associated with rhinitis, but not with asthma. However, bronchial hyper-reactivity was significantly associated with increasing number of positive SPTs (p = 0.047).ConclusionsAmong adults in northern Vietnam sensitization to mite and cockroach most common in both rural and urban areas. The dominant sensitizer was the storage mite B. tropicalis, which should be included in future studies and also in clinical practice, owing to its association with clinical symptoms. As in the Western world allergic sensitization was associated with rhinitis and bronchial hyper-reactivity. The lack of association with asthma in South-East Asia needs to be studied further.
Highlights
In Vietnam, contrast to the westernized world, the prevalence of allergic sensitization and the patterns of sensitization to different allergens have been less investigated
The prevalence of respiratory symptoms, reported asthma and allergic rhinitis were similar among all responders at the initial questionnaire and the subsample who participated in the clinical examinations (Table 1)
The most common sensitizer among both men and women was the storage mite B. tropicalis, followed by the house dust mites D. pteronyssinus and D. farinae, and cockroach (Table 2)
Summary
In Vietnam, contrast to the westernized world, the prevalence of allergic sensitization and the patterns of sensitization to different allergens have been less investigated. In adult asthmatics in these areas, house dust mite and cockroach were the main allergens [4,5]. In southern Vietnam, population based studies in children and adolescents found a high prevalence of sensitization to house dust mite and cockroach, while sensitization to moulds and pollens was significantly less common [9,10]. This pattern was seen in the first population based study of sensitization in adults in Northern Vietnam, and we recently presented the crude prevalence measures in a short report [11].
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