Chlamydiosis in farmed chickens in slovakiaand zoonotic risk for humans

Abstract

Introduction. Chlamydia psittaci is an obligate intracellular Gram-negative bacterium causing respiratory disease (chlamydiosis) or asymptomatic carriage in poultry. In humans, it is a zoonotic agent of ornithosis/psittacosis. Due to low awareness of the disease and variable clinical presentation, psittacosis is often remains unrecognised as such by general practitioners. Zoonotic transfer occurs through inhalation of contaminated aerosols, and originates from feathers, faecal material and respiratory tract exudates. Objective. The aim of this study was to investigate chickens for the presence of Chlamydia sp. from pharyngeal and cloacal swabs and review the zoonotic risk for humans. Materials and method. 138 clinically healthy chickens from farms in Slovakia were examined for the presence of Chlamydia sp. The age of the chickens was 6 months. Two different samples were used – pharyngeal swabs and cloacal swabs. Each sample was examined by the molecular PCR method, and in the case of a positive result the identity of the obtained sequences was examined by a BLAST search. Results. Of the total number of 276 examined samples from 138 chickens, 19 (6.9%) showed positivity for C. psittaci infection, 12 (8.7%) which were positive from pharyngeal swabs and 7 (5.1%) from cloacal swabs. None of the chickens were positive in both samples. Phylogenetic examination of the 19 isolates identified in the study, based on the 23S rRNA gene sequence, revealed that the isolates obtained were identical with C. psittaci, and genetically very close to genotypes B and genotype E. Conclusion. C. psittaci infections are apparently emerging in chickens. Chicken-processing plant employees should be considered a risk group for human psittacosis. There is a need for higher awareness and for efficient risk assessment and management.