EN
In this paper, some facts have been discussed that could be important for the understanding of how the chlamydial pathogen spreads within the bird flock and to humans. The presented report has been based on pathological findings and interpretation of the results of diagnostic tests, obtained at chlamydial infection in a flock of parrots. In a two- week period, a high mortality in one flock of budgerigars (Melopsittacus undulatus) was reported. Adults as well as young older than 14 d died. The laboratory investigation confirmed the infection with Chlamydophila psittaci. In the same period two members of the owner's family showed signs of atypical pneumonia. The owner decided to eliminate the whole flock. Samples of blood and swabs from cloaca were taken before the birds were euthanised. A post-mortem examination was performed and samples from embryos and eggs were taken. For the confirmation of chlamydia infection, several different diagnostic methods were used: direct and indirect immunofluorescence, commercial immuno-enzymatic tests, isolation on chicken embryos and laboratory mice, as well as molecular detection. Avian chlamydiosis represents an important zoonosis in Europe. This is the reason for the necessity of developing more efficient methods for chlamydial disease control, and for setting up generally accepted rules in European and non-European countries.