Allergic aspergillosis of the respiratory tract

Abstract

Aspergillus , a genus of spore forming fungi found worldwide, affects the respiratory tract in many ways [1, 2]. The spores of this ubiquitous mould are dispersed by wind in the atmosphere and inhalation is the primary route of access in almost all forms of aspergillosis. The spectrum of Aspergillus -associated respiratory disorders comprises three well defined clinical categories (table 1): allergic manifestations, saprophytic colonisation of the respiratory tract and invasive disseminated disease [1]. Amongst the allergic aspergillosis disorders, allergic bronchopulmonary aspergillosis (ABPA) is the most recognised form. Since it was first described in England, UK, in 1952 [3], it has been documented around the world [4]. Although ABPA and allergic Aspergillus sinusitis (AAS) are mostly encountered in atopic individuals, hypersensitivity pneumonitis can occur in the nonatopic population. View this table: Table 1. Aspergillus -associated respiratory disorders Aspergillus -induced asthma (AIA) is a classical immediate (type I) IgE-mediated hypersensitivity reaction to Aspergillus antigens that presents clinically as asthma. The frequency of Aspergillus sensitisation in asthmatic subjects varies from 16% to 38% in different geographical regions [5–8]. In a trans-Atlantic comparison study, type I skin reactivity to Aspergillus antigens was elicited in 28% of asthmatic patients from Cleveland (OH, USA) and 23% from London, UK [7]. The authors were surprised at finding a direct correlation between Aspergillus skin-test positivity and severity of airflow obstruction. In a series of 105 patients with bronchial asthma, 30 (28.5%) were sensitised to Aspergillus antigens [8]. This group of 30 patients with AIA had a more severe form of asthma when compared to those with skin test positivity to antigens other than Aspergillus . This was evidenced by a statistically significant higher mean duration of illness (p<0.001), mean eosinophil count (p<0.0001), mean total IgE (p<0.05) and more usage …