Evaluation of the indirect hemagglutination assay for antibodies detection in aspergillosis diagnosis

Introduction. Aspergillus infection may lead to various clinical patterns according to the immune status of the patients. The diagnosis of aspergillosis may be difficult to achieve in some situations, particularly in immunosuppressed patients, and usually results from the association of clinical, radiological and biological features. Detection of specific antibodies remains of great value in diagnosing aspergilloma or allergic bronchopulmonary aspergillosis in immunocompetent patients. Objectives. To evaluate the performances of indirect hemagglutination for Aspergillus antibody detection and to determine the place of this method in the serologic diagnosis of aspergillosis. Methods. We compared three commercially available assays for the detection of Aspergillus antibodies: hemagglutination, electrosyneresis and immunoelectrophoresis which was the reference test. The evaluation of the assays comprised sensitivity, specificity, cost and feasibility. Results. One hundred and seventy six sera were analyzed with the three assays: 39 were collected from patients with aspergillosis (different patterns), 137 from controls. Sensitivity was 32 % with the hemagglutination assay (threshold 1/640), 64% with the electrosyneresis assay and 92 % with the immunoelectrophoresis assay. Specificity was 93 % with the hemagglutination assay, 100 % with the electrosyneresis and the immunoelectrophoresis assays. When the threshold of the hemagglutination assay was lowered at 1/160 the sensitivity and specificity became 76 % and 88 % respectively. The feasibility was better with the hemagglutination assay and it was less time-consuming than the other methods. Conclusion. These results suggest that the hemagglutination assay could be performed for the detection of Aspergillus antibodies if the threshold is lowered at 1/160 and the positive results are confirmed with the immunoelectrophoresis assay.