Prevalence of Listeria monocytogenes and other Listeria spp. in gulls feeding at a landfill in Zagreb, Croatia

Andrea HUMSKI, DVM, PhD, Scientific Advisor, Assistant Professor, Mario MITAK, DVM, PhD, Tenured Scientific Advisor, Marina MIKULIĆ, DVM, PhD, Research Associate, Dora STOJEVIĆ, DVM, PhD, postdoctoral student, Croatian Veterinary Institute, Zagreb, Croatia; Borka ŠIMPRAGA, DVM, PhD, Senior Research Associate, Fani KRSTULOVIĆ, DVM, Mr. Spec. Expert Advisor, Biljana JEČMENICA, Mag. Oecol. et Prot. Nat., Tajana Amšel ZELENIKA, DVM, PhD, Research Associate, Luka JURINOVIĆ*, MSc Biol., PhD, (Corresponding author, e-mail: jurinovic@veinst.hr), Croatian Veterinary Institute Branch Poultry Center, Zagreb, Croatia Abstract Gulls, as migratory wild birds are known to spread different pathogens over long distances. The aim of this study was to access the prevalence of different Listeria species in a gull population feeding at a landfill in Zagreb. In total, 390 gulls of three species were sampled: Yellow-legged Gull, Larus michahellis; Black-headed Gull, L. ridibundus and Common Gull, L. canus. The most prevalent species was Listeria innocua (14.4%), while L. monocytogenes was found in 11.3% of tested samples. Other species were present in a smaller percentage; L. welshimeri (1.3%), L. ivanovii (0.5%) and L. seeligeri (0.3%). Serotyping of L. monocytogenes isolates was performed using molecular and conventional methods, and most isolates belonged to the 1/2a and 1/2b serotypes. To the best of our knowledge, this is the first report of the presence of L. monocytogenes and other Listeria spp. in wild birds in Croatia.