Concurrent tropical pulmonary eosinophilia and allergic bronchopulmonary aspergillosis in asthma: a prospective observational study from a filariasis-endemic region

Tropical pulmonary eosinophilia (TPE) and allergic bronchopulmonary aspergillosis (ABPA) share cough, wheeze, eosinophilia, and marked immunoglobulin (Ig) E elevation and may coexist in patients with asthma in filariasis-endemic settings. We prospectively characterized this overlap phenotype at a tertiary respiratory center in eastern India. Eligible patients older than 10 years had a documented prior physician diagnosis of asthma and, at presentation, an absolute eosinophil count (AEC) >1000 cells/µL and total IgE >1000 IU/mL; all underwent evaluation for both TPE and ABPA. These laboratory thresholds were study-entry criteria and were not substituted for disease-specific diagnostic definitions. TPE attribution required a compatible clinic-serological profile and a study-defined post-diethylcarbamazine (DEC) haematological response of at least 50% reduction in AEC. For the present analysis, ABPA was classified according to the revised 2024 International Society for Human and Animal Mycology criteria using prospectively collected clinical, immunological, and imaging variables. In TPE-compatible patients, DEC was given before ABPA-directed therapy to preserve interpretation of the eosinophilic response. Among 312 prospectively evaluated patients, 132 met the study definitions for TPE-ABPA overlap, 77 for TPE alone, and 103 for ABPA alone. In the overlap cohort, mean age was 36.2±15.9 years; median baseline AEC was 6071 cells/µL [interquartile range (IQR) 3793-11,000] and median total IgE was 7641 IU/mL (IQR 4525-13,621). Aspergillus fumigatus-specific IgE and IgG were positive in all 132; the filarial antigen was positive in 128 (97.0%), and there was qualitative filarial IgG in all 132. The dominant recorded high-resolution computed tomography pattern was normal in 73 (55.3%), while bronchiectasis was recorded in 42 (31.8%). All overlap patients received DEC and fulfilled the study-defined ≥50% AEC response criterion. ABPA-directed treatment comprised systemic corticosteroids alone in 71 (53.8%), itraconazole alone in 41 (31.1%), and both in 20 (15.2%). Concurrent TPE and ABPA should be considered in endemic regions when asthma is accompanied by disproportionate eosinophilia and IgE elevation; recognition of one eosinophilic disorder should not prematurely terminate evaluation for the other.