Abstract
Despite a high burden of chronic pulmonary aspergillosis (CPA) in Pakistan, Aspergillus-specific IgG testing is currently not available. Establishing cut-offs for Aspergillus-specific IgG for CPA diagnosis is crucial due to geographical variation. In settings such as Pakistan, where non-Aspergillus fumigatus (mainly A. flavus) Aspergillus species account for the majority of CPA cases, there is a need to explore additional benefit of Aspergillus flavus-specific IgG detection along with A. fumigatus-specific IgG detection. This study was conducted at the Aga Khan University, Karachi, Pakistan after ethical approval. Serum for IgG detection were collected after informed consent from healthy controls (n = 21), diseased controls (patients with lung diseases, n = 18), and CPA patients (n = 21). A. fumigatus and A. flavus IgG were detected using Siemens immulite assay. The sensitivity and specificity of A. fumigatus-specific IgG were 80.95% and 82.05%, respectively at a cut-off of 20 mg/L. The sensitivity and specificity of A. flavus-specific IgG were 80.95% and 79.49% at a cut-off of 30 mg/L. We report, for the first time, performance of A. flavus-specific IgG for CPA diagnosis. Although there was no statistically significant difference between the performance of both antigens, it seems contextually relevant to include A. flavus IgG in the CPA diagnostic algorithm in regions with higher non-A. fumigatus CPA infections.
Highlights
Chronic pulmonary aspergillosis (CPA) is the most common pulmonary manifestation of aspergillosis in Pakistan [1]
CPA patients and patients with other lung diseases such as chronic obstructive pulmonary disease (COPD), asthma, interstitial lung disease (ILD), and lung cancer were recruited from pulmonology service, both outpatient and inpatient
Healthy blood donors; diseased controls—diagnosed patients with COPD, asthma, ILD, lung cancer, community acquired pneumonia; patients with Allergic bronchopulmonary aspergillosis (ABPA); patients diagnosed with CPA
Summary
Chronic pulmonary aspergillosis (CPA) is the most common pulmonary manifestation of aspergillosis in Pakistan [1]. Significant burden of CPA as a post tuberculosis (TB) sequel has been estimated in the country [2]. A recent report from Pakistan reported TB and bronchiectasis as major underlying causes of CPA [3]. A recent CPA guideline for use in low- and middle-income countries highlighted the use of Aspergillus-specific IgG as the most useful test [5]. Several tests for detection of Aspergillus-specific IgG are commercially available, studies from Uganda and Europe report significant variations in cut-offs for positivity, suggesting geographical and genetic differences [6,7,8]. Aspergillus-specific IgG testing in Pakistan is not available, highlighting a strong need to evaluate this test in the country. Establishing cut-offs for positivity of Aspergillus-specific IgG for CPA diagnosis in our population is crucial to differentiate
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