hepatitis e (he) is an emerging public health problem in developed countries worldwide. Nowadays, it is known that the hepatitis e virus (heV) has zoonotic potential, whereas domestic pigs and wild boars are recognized as the true reservoirs of the disease. Therefore, the aim of our study was to define the seroprevalence and viral persistence of heV in pigs and wild boars in Croatia. In total, 1424 samples originating from domestic pigs from 14 counties, and 1000 samples of wild boar origin, collected from 16 counties, were tested during 2016 for the presence of heV antibodies using a commercially available enzyme linked immunosorbent assay (eLISa). all positive samples, as well as samples originating from in-contact domestic pigs and wild boars, were further tested for the presence of heV rNa using a real time rt-PCr protocol, followed by a nested RT-PCR protocol as a confirmatory test. In 11 of 14 counties, 469 seropositive domestic pigs were found with an overall seroprevalence of 32.94% (95% CI 30.55-35.42), ranging from 8.33% to 60.00%, depending on .04%), ranging from 7.70% to 50.60%. The highest seroprevalence was found in the Vukovar-Srijem and Osijek-Baranja Counties (North-East Croatia) where pig breeding dominates and the highest density of wild boars is recorded. While no positive heV rNa samples were detected in tested domestic pigs, seventeen serologically positive wild boars (11.33%; 95%CI 7.19-17.14) younger than one year of age were found to be heV rNa positive, indicating chronic infection and possible prolonged virus spread into the environment. the detected viral presence despite the immune response indicates that wild boars have a key role in heV epidemiology.

The annual production of European flat oysters (Ostrea edulis) in Croatia is about 50 to 65 tons, and it has a long tradition. All Croatian oyster farms are subjected to the national surveillance program aiming to detect the presence of Bonamia ostreae and Marteilia refringens according to the Council Directive 2006/88/EC. Within the surveillance program, the first findings of the parasite Bonamia spp. occurred in 2016 in two production areas in the north and south of the Eastern Adriatic coast. The repeated findings of the parasite were noted up to 2020 but also on two additional sites in the north. The parasite was detected by cytological analysis of stained heart smears, histological examination, and PCR. PCR positive samples were sequenced for SSU rDNA gene, and BLAST analysis confirmed infection with Bonamia exitiosa. Attempts to prove the Pacific oyster as a putative vector of the parasite failed. The infection prevalence from 2016 until 2020 ranged from 3.3 to 20% in different sites. No mortalities were reported from the infected sites, and it seemed that infection of flat oysters with B. exitiosa did not affect their health. The study has not shown the source and way of infection spread, which imposes the need for more comprehensive molecular and epidemiological studies.