Prevalence and Genotyping of <i>Chlamydia psittaci</i> from Domestic Waterfowl, Companion Birds, and Wild Birds in Taiwan

Abstract

<i>Chlamydia psittaci</i>, the causative agent of avian chlamydiosis, an important zoonotic disease, infects a wide range of birds. Infected birds, whether symptomatic or asymptomatic, intermittently shed the agent through respiratory and intestinal routes. Therefore, it is essential to investigate the epizootiology of <i>C. psittaci</i> in poultry, pet birds, and wild birds. In this study, cloacal or fecal swabs collected from domestic waterfowl, psittacine birds, Columbidae, and wild birds were used to determine the prevalence of <i>C. psittaci</i> in Taiwan between 2014 and 2017. The <i>C. psittaci</i> infection rate was as high as 34.2% among domestic waterfowl farms. The waterfowl isolates clustered into two groups based on <i>ompA</i> phylogeny: one group (G1-like) clustered with the Polish G1 strains; the other group (waterfowl-TW) clustered near, but independently from, the classical ABE genotype cluster. Separately, 3.1% of parrot samples tested positive for <i>C. psittaci</i> belonging to genotype A. <i>C. psittaci</i> isolates of genotype B were detected in 10.1% of racing pigeons and other Columbidae. Wild bird samples from a wildlife refuge had a 2.2% prevalence rate; among these, two atypical <i>C. psittaci</i> genotypes were detected in samples from a Malayan night heron (<i>Gorsachius melanolophus</i>) and a Taiwan barbet (<i>Megalaima nuchalis</i>). Taken together, our results revealed that the risk of <i>C. psittaci</i> transmission from domestic waterfowl and Columbidae birds to humans could be underestimated, given the high prevalence rates in these birds. Furthermore, the free-range rearing system of waterfowl in Taiwan may promote <i>C. psittaci</i> transmission between poultry and wild birds. Pet birds and racing pigeons, which are in close contact with people, are also possible sources for cross-species transmission. Further studies are necessary to elucidate the virulence, biological and genetic characteristics, and modes of transmission of Taiwanese <i>C. psittaci</i> isolates to facilitate the prevention and control of <i>C. psittaci</i> infection.