engleski

Diagnosis of Chlamydia infections in poultry in Croatia

In poultry, chlamydial infections are often misdiagnosed due to symptoms similar to those caused by other respiratory pathogens (Harkinezhad et al., 2009 ; Dickx et al., 2010). Since avian chlamydiosis is a dangerous zoonosis, it is recommended that birds, especially the ones in close contact with humans, as well as poultry kept in backyard flocks or in controlled enclosure, should always be examined for the presence of chlamydial agents when clinical signs related to the respiratory, nervous or gastrointestinal systems are present. Even if the aetiological agent is already detected, it could be reasonable to test also for Chlamydia spp., as it was described that chlamydial infections can appear as mixed infections, especially as pathogenic interplay between some viruses and other bacteria (Malkinson et al., 1987 ; Van Loock et al., 2006 a, b). In the last few years, several studies provided evidence that C. psittaci is not the only chlamydial agent occurring in birds, but also C. abortus (Pantchev et al., 2009), C. suis and C. muridarum (Lemus et al., 2010), C. pecorum and C. trachomatis can appear (Sachse et al., 2012), as well as novel, so-called atypical chlamydiae (Laroucau et al., 2009). From that point of view, if specific diagnostic tools are negative for the presence of C. psittaci, it is recommended to test for the presence of bacteria of the family Chlamydiaceae and then, if this appears positive, to identify the chlamydial species. In the last decade, molecular methods were considered as highly appropriate diagnostic tools for Chlamydia spp., and specific conventional or real-time PCR assays are often used for the detection of this difficult-to-grow intracellular microorganism. In Croatia, since 2008, the diagnosis of Chlamydiaceae is conducted by using real-time PCR, and in 2010, the Laboratory for Chlamydia at the Department of Poultry Diseases, Faculty of Veterinary Medicine University of Zagreb, became accredited according to ISO 17025 and has been serving as National Reference Laboratory. Annually, 750-900 samples are being examined for the presence of Chlamydiaceae, and in 2012 a total of 8.5% of examined samples were found positive. The majority of positive samples belonged to C. psittaci, but occasionally other chlamydiae were also present. Three cases of occurrence of C. psittaci and atypical Chlamydia spp. in different poultry species, detected together with some other microorganisms, which probably enhanced the severity of clinical signs, but also masked the presence of chlamydial infection and the resulting zoonotic risk, will be described in detail. Results of these investigations were or will be reported individually in international journals or at other conferences (Prukner-Radovčić et al., 2012 ; Zocevic et al., 2012 ; Prukner-Radovčić et al., 2013).

Chlamydia; poultry; PCR

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