Evaluation of a Chlamydophila psittaci infection diagnostic platform for zoonotic risk assessment

Reports on zoonotic transmission of Chlamydophila psittaci originating from poultry are incidentally published. During recent studies in European turkeys we isolated C psittaci genotypes A, B, D, E, F, and E/B, all considered potentially dangerous for humans. This encouraged us to analyze the zoonotic risk on a Belgian turkey farm, from production onset until slaughter, using a Chlamydophila psittaci diagnostic platform. Twenty individually marked hens, as well as the farmer and two scientists, were monitored medically. Bioaerosol monitoring, serology, isolation, and nested PCR demonstrated chlamydiosis on the farm leading to symptomatic psittacosis in all 3 persons involved. ompA sequencing confirmed the zoonotic transmission of C. psittaci genotype A. Strangely, two different antibody microimmunofluorescence (MIF) tests remained negative in all infected persons. The results demonstrate the value of the currently used diagnostic platform in demonstrating C. psittaci infections in both birds and humans but raise questions regarding use of the MIF test for diagnosing human psittacosis. In addition, our results suggest the underestimation of psittacosis in the poultry industry, stressing the need for a veterinary vaccine and recommendations for zoonotic risk reduction strategies.