Detection of CHLAMYDIA PSITTACI in feral pigeons (COLUMBA LIVIA DOMESTICA) in Slovakia and their characterisation

Chlamydia psittaci, an obligate intracellular bacterium, which is the etiologic agent of avian chlamydiosis in birds and ornithosis/psittacosis in humans, has been reported to be one of the most common pathogens found in feral pigeons worldwide, and thus constitutes a zoonotic risk. The aim of the study was to investigate pigeons in Slovakia living in areas in close proximity to humans for the presence of C. psittaci, using pharyngeal and cloacal swabs. 122 clinically healthy pigeons from different geographical regions of Slovakia were examined for the presence of C. psittaci. The adult pigeons of both genders were captured during the summer period in the urban centres of Slovakian towns. Each sample was examined by molecular method PCR, and in the case of positive result the identity of the obtained sequence was examined by a BLAST search. Of the total number of 244 examined samples, 14 (5.7%) showed positivity for C. psittaci infection, 5 of which were from pharyngeal swabs (4.1%) and 9 from cloacal swabs (7.4%). A positive result was detected in 13 pigeons (10.7%). Phylogenetic analysis showed that all the positive samples are genetically very close to genotypes B and genotype E. Phylogenetic examination of the 14 isolates of C. psittaci identified in the presented study, based on 23S rRNA gene sequence, revealed their close relationship with C. psittaci genotypes B and E. Both genotypes are predominantly prevalent in pigeons and both can be transmitted to humans. Therefore, it is necessary to perform screening examinations of animals and analyse the epidemiological factors affecting the way of transmission and circulation of pathogen.