Application of environmental sampling to investigate a case of avian chlamydiosis in a pet store and breeding facility leading to mass bird exposures

Chlamydia psittaci is a bacterium that causes chlamydiosis in birds and can cause zoonotic psittacosis in people. In November 2017, we received notification of a suspected case of avian chlamydiosis in a captive cockatiel (Nymphicus hollandicus) that was sold by an online pet bird retail and breeding facility in Washington State. We describe the investigation with emphasis on how environmental sampling was used to guide veterinary and public health interventions. Bird samples were collected either from pooled droppings, pooled plumage or individual nasal and choanal swabs. Environmental samples were obtained by swabbing cleaning mops, tables and cage structures. All samples were tested by polymerase chain reaction and positive samples underwent genotyping. Approximately 1000 birds representing four taxonomic orders were kept within an open‐space warehouse. Eight of 14 environmental samples and one of two pooled faecal samples were positive for Chlamydia spp. The contaminating strain of Chlamydia spp. was identified as genotype A. The facility was closed for environmental disinfection, and all psittacines were treated with oral doxycycline for 45 days. Ten of 10 environmental and two of two pooled faecal samples were negative for C. psittaci 11 months after the completion of environmental disinfection and antimicrobial treatment. This investigation highlights the importance of preventing and mitigating pathogen incursion in an online pet retail and breeding facility. Environmental sampling is valuable to guide animal and public health interventions for control of C. psittaci, particularly when large numbers of birds are exposed to the pathogen.