An overview of health control in Croatian aquaculture.

Aquaculture is an important segment of Croatian fishing industry with long tradition of carp and rainbow trout farming as well as marine aquaculture represented by shellfish (flat oyster and mussels), sea bass and sea bream cultivation and Atlantic bluefin tuna fattening. The fish and shellfish diseases survey is regulated by "Decree on the measures of animal health protection against infectious and parasite diseases" issued yearly by Ministry of Agriculture. This report derives from systematic clinical, parasitological, pathoanatomical, histopathological, bacteriological and virological monitoring of cultivated fish and shellfish on larger part of production during last several years. Among pathological conditions recognised on our farms, some specific viruses, bacteria and parasites represent frequently established causative nosologic agents. The overview of the main diseases with economic impact to the cultivation will be discussed in this paper.

Postweaning multisystemic wasting syndrome (PMWS) in pigs in Croatia: detection and characterisation of porcine circovirus type 2 (PCV2).

The objective of this study was to characterise porcine circovirus type 2 (PCV2) from pigs with naturally occurring postweaning multisystemic wasting syndrome (PMWS) in Croatia, and to determine the epizootiological, clinical and pathomorphological features of the disease. During a systematic health monitoring programme conducted in the period from January 2002 to June 2003, PMWS was suspected on eight different pig-producing farms in Croatia. The diagnosis of PMWS met all three key criteria: the presence of compatible clinical signs, the presence of the characteristic microscopic lymphoid lesions, and the detection of PCV2 within the lesions by polymerase chain reaction (PCR) and by in situ hybridisation (ISH). Moreover, PCV2 DNA from swine tissues was extracted and sequenced. The phylogenetic analysis of 4 Croatian PCV2 strains showed close relationship to PCV2 strains isolated in Slovenia, France, the Netherlands, the United Kingdom, China and Hungary. PCV2 was also demonstrated by electron microscopy in the lymph node of an affected animal. This is the first demonstration of PMWS in Croatia based on all scientifically accepted diagnostic criteria.

Occurrence of enteric redmouth disease in rainbow trout (Oncorhynchus mykiss) on farms in Croatia.

During the spring of 1996 and autumn of 1997 unusual mortality outbreaks among rainbow trout fry and yearlings occurred at two different trout farms, resulting in mortality of 20 and 10 per cent, respectively. Generally, the affected fish, swimming at the water surface, were reluctant to eat and were dark pigmented with visible haemorrhages around and within the oral cavity. Bacterial isolates from moribund fish from both cases were identified as Yersinia ruckeri by standard biochemical tests and API 20E. The isolated strains were found to be sensitive to tetracycline, chloramphenicol, co-trimoxazole, nalidixic acid, flumequine, enrofloxacin, carbenicillin and gentamicin. Microplate agglutination assay confirmed that both isolates belonged to serotype O1. The pathogenicity of the isolated bacteria was confirmed by challenge experiment. Titres of specific antibodies were determined in the sera of survivors. The titre was highest on the 21st day postchallenge and was detectable until the 81st day.

Determination of hexachlorobenzene (HCB) in the perirenal and dorsal fatty tissues of pigs.

The aim of this study was to assess the suitability of the perirenal fatty tissue for the determination of an organochlorine pesticide. Fatty tissue samples were prepared by the matrix solid phase dispersion (MSPD) method, and pesticide levels were determined by gas chromatography on capillary column using an electron capture detector. Results were confirmed by gas chromatography/mass spectrometry (GC/MS) system. The results showed that the perirenal fatty tissue contained significantly higher levels of hexachlorobenzene (HCB) than the dorsal fatty tissue (P < 0.01). All the levels were below the criteria for maximum residue limits established by Croatia and the EU.

First record of Marteilia sp. in mussels Mytilus galloprovincialis in Croatia.

Marteiliosis is a disease of molluscs caused by Marteilia refringens in Europe and M. sydneyi in Australia. During routine examination of cultured mussels Mytilus galloprovinciallis in the northern Adriatic, the occurrence of Marteilia sp. was recorded with a prevalence of 5%. This parasite was not detected in flat oysters reared in the same area. The affiliation of the detected parasite in M. galloprovinciallis was confirmed by in situ hybridization using a M. refringens probe, specific at the genus level. DNA of these infected mussels originating from the same area will be used to clarify the taxonomic position of this species within the genus Marteilia using a molecular approach.