Chlamydophila psittaci in homing and feral pigeons and zoonotic transmission.

Chlamydiosis is a zoonotic disease in birds caused by Chlamydophila psittaci, an obligate intracellular bacterium. There are seven known avian outer-membrane protein A genotypes, A-F and E/B. The importance of genotyping lies in the fact that certain genotypes tend to be associated with certain hosts and a difference in virulence. Genotype B is the most prevalent in pigeons, but the more virulent genotypes A and D have also been discovered. The current study assessed the prevalence of C. psittaci in 32 Belgian homing-pigeon facilities and in 61 feral pigeons captured in the city of Ghent, Belgium. Additionally, zoonotic transmission of C. psittaci was investigated in the homing-pigeon facilities. Homing pigeons were often infected, as at least one of the lofts was positive in 13 of the 32 (40.6 %) pigeon breeding facilities. Genotypes B, C and D were detected. Zoonotic transmission was discovered in 4 of the 32 (12.5 %) pigeon fanciers, revealing genotype D in two of them, whilst genotyping was unsuccessful for the other two human pharyngeal swabs. This study clearly demonstrates the possible risk of C. psittaci zoonotic transmission from homing pigeons. Pigeon fanciers often (37.5 %) used antibiotics for prevention of respiratory disease. Because of the risk of developing drug-resistant strains, regular use of antimicrobial drugs must be avoided. This study is believed to be the first to detect C. psittaci in Belgian feral pigeons. The prevalence rate in the city of Ghent was extremely low, which is beneficial for public health.