We studied zoonotic transmission of Chlamydophila psittaci in 39 breeding facilities for Psittaciformes (cockatoos, parrots, parakeets, lories) that frequently used antimicrobial drugs. Genotypes A or E/B were detected in 14.9% of humans at these facilities. Information on antimicrobial drug use in Psittaciformes and a C. psittaci vaccine are urgently required.

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Chlamydophila psittaci infections in humans are underestimated. We investigated the occurrence of C. psittaci in a Belgian population of 540 individuals. Data were from a population survey (n52524) of apparently healthy community-dwelling subjects aged 35-55 years. Pharyngeal swabs and blood were taken. Individuals completed a questionnaire on professional and nonprofessional activities, smoking habits, medical history and contact frequency with different bird species. Swabs were analysed by a C. psittaci-specific and a Chlamydophila pneumoniaespecific PCR. Sera were tested by a recombinant C. psittaci major outer-membrane proteinbased ELISA, a C. psittaci whole organism-based ELISA (Serion) and a microimmunofluorescence test (Focus Diagnostics). Results confirmed our suspicion about the underestimation of psittacosis in Belgium. Psittaciformes and racing pigeons were the main infection source. Women with excessive alcohol intake defined as a mean intake of .2 units daily were more frequently infected than men. We analysed the effect of seropositivity and/or PCR positivity on inflammation (white blood cell count, high-sensitivity C-reactive protein, fibrinogen). In general, seropositivity showed a trend to slightly higher levels of inflammatory variables (all nonsignificant), whilst PCR positivity showed a trend to no effect or even lower inflammatory levels.

Background: Laboratory diagnosis of Chlamydophila psittaci, an important turkey respiratory pathogen, is difficult. To facilitate the diagnosis, a nested PCR-enzyme immunoassay (PCR-EIA) was developed to detect the Cp. psittaci outer membrane protein A (ompA) gene in pharyngeal swabs.

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.