Chlamydia psittaci in Swedish wetland birds: a risk to zoonotic infection?

Chlamydia psittaci in birds may be transmitted to humans and cause respiratory infections, sometimes as severe disease. Our study investigated the C. psittaci prevalence in migratory birds in Sweden by real-time PCR. Fecal specimens or cloacal swabs were collected from 497 birds from 22 different species, mainly mallards (Anas platyrhynchos), at two bird observatories in Sweden. DNA from C. psittaci was found in six (1.2%) birds from three different species. Five of the positive specimens were infected with four novel strains of C. psittaci, based on sequencing of partial 16S rRNA gene and ompA gene, and the sixth was indentified as a recently described Chlamydiaceae-like bacterium. Considering exposure to humans it is concluded that the risk of zoonotic infection is low.