A recombinase polymerase amplification-based assay for rapid detection of Chlamydia psittaci.

Chlamydia psittaci is a zoonotic agent of systemic wasting disease in birds and atypical pneumonia in mammalians including humans, constituting a public health risk. A rapid diagnostic assay would be beneficial in screening C. psittaci in the field. In this study, we developed a probe-based recombinase polymerase amplification (RPA) assay for the rapid detection of C. psittaci. The specific primer pairs and probe targeting the conserved region of the outer membrane protein A gene were designed and applied to the real-time real-time RPA assay. The test can be performed at 39°C for 20 min using a portable device, with sensitivities approaching 100 copies of DNA molecules per reaction, with no cross-reaction with other pathogens. The clinical performance of the RPA assay was evaluated in an outbreak of C. psittaci and has high accuracy levels in field applications. The epidemic C. psittaci strains were classed into 2 genotypes: A and C. Collectively, this study offers a promising approach in screening for C. psittaci both in a laboratory setting and in field settings, and RPA can be used as an effective clinical test to monitor outbreaks in domestic fowl populations.

Chlamydophila psittaci infections in turkeys: overview of economic and zoonotic importance and vaccine development.

We provide evidence on the multifactorial infectious etiology of respiratory disease in turkeys. Although Chlamydophila psittaci is difficult to diagnose, this entity should not be neglected in veterinary diagnostic laboratories. The present results suggest a pathogenic interplay between chlamydophila, avian metapneumovirus and Ornithobacterium rhinotracheale. Additionally, we demonstrate zoonotic transmission from turkeys to humans. Psittacosis due to contact with poultry probably occurs more often than is thought and the infection can be asymptomatic or symptomatic. There is no commercial C. psittaci vaccine available and currently the best option is an experimental major outer membrane protein-based DNA vaccine.

Psittacosis outbreak in employees of a turkey-processing plant.

In June 1976, 28 employees of a Nebraska poultry processing plant had clinical onset of an illness compatible with psittacosis. The diagnosis was serologically confirmed in 22 patients by fourfold or greater changes in their complement fixation antibody titers, using a Chlamydia group antigen. Lack of serologic response in the remaining patients could not be readily explained by therapy differences, timing of serologic evaluation, or severity of clinical illness. The comparable attack rates in the various processing departments were consistent with an airborne infection. However, results of the investigation also suggested that workers having both frequent contact with turkey tissues and skin injuries were more likely to be infected than other processing workers. The cost of the outbreak for reimbursed medical costs, workmen's compensation, and lost wages was $19,000. A single turkey flock was implicated as the source of infection. This flock had been screened on a voluntary basis for evidence of infection prior to slaughter, using criteria developed by the United States Department of Agriculture. Although the preslaughter screening failed to detect psittacosis infection, two turkeys from the same flock which inadvertently had not been sent to slaught were subsequently found to be infected.