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Sea bream, Sparus aurata L., and sea bass, Dicentrarchus labrax L., were sampled from an off- shore cage farm in eastern Greece, an inshore cage fish farm in southern Greece, and a lagoon in northern Greece. The prevalence and intensity of Metazoan parasites and factors associated with the prevalence were investigated. In Farm 1 (eastern Greece), ectoparasite prevalence in sea bream and sea bass was 61.5% and 76.9% for Monogenea, none for Isopoda, and 0 and 23% for Copepoda. In Farm 2 the prevalence was 13.3% and 26.3% for Monogenea, 13.7% and 20% for Isopoda, and 0 and 13.6% for Copepoda. In the lagoon, the prevalence of ectoparasites was 100% and 21.9% for Monogenea and Copepoda, respectively. The lagoon had the highest prevalence of parasites among the studied ecosystems, however, the variety did not significant- ly affect the health of the infected fish. In Sparidae, gill lesions were due to monogeneans while skin and eye lesions were due to larvae of the isopod Ceratothoa oestroides that caused severe pathology. Furnestinia echeneis and Diplectanum aequans were host specific to sea bream and sea bass, respectively, and persisted in all aquaculture systems. Lernanthropus kroyeri was host specific and detected only in sea bass from the cage farms.

Our objective was to find herd factors associated with pigs testing seropositive for Salmonella. Data were collected from 359 finishing-pig herds in Germany, Denmark, Greece, The Netherlands and Sweden, between 1996 and 1998. Pigs fed non-pelleted feed (dry or wet) had 2- and 2.5-times lower odds of seropositivity, compared to pigs fed pelleted feed. The protective effect of non-pelleted feed over pelleted feed may be ascribed to the structure and composition. Also, pigs that were given whey (to drink or as the liquid part of the diet) had 2.6-times lower odds to test seropositive than pigs not getting whey. Pigs produced in batches in herds with hygienic-lock facilities had >3-times lower odds for testing seropositive compared to pigs in herds where only one or neither factor was present. In herds where the caretaker(s) washed hands consistently before tending to the animals, pigs had 1.5-times lower odds of seropositivity than pigs in herds where the caretaker did not. Pigs which were able to have snout contact with pigs in neighbouring pens (because pen separations were either open or too low) had 1.7-times higher odds to test seropositive compared to pigs for which such contact was prevented. Pigs in herds recruiting from more than three supplier herds had three-times higher odds to test seropositive than pigs in herds which breed their own replacement stock or recruit from a maximum of three supplier herds.

The aim of this study was to assess the probability of detecting Salmonella from pen faecal samples in seropositive classified finishing pig herds. The study involved 77 herds from Denmark (20), The Netherlands (20), Greece (17) and Germany (20). The serological herd status was determined by the blood-sampling of 50 finishing pigs. Bacteriological sampling was performed by 20 pen faecal samples per herd. Over-all, 47% of the blood samples had an OD% larger than 10 and 23% larger than 40. Salmonella was isolated from 135 (9.3%) pen faecal samples in 32 herds (42%). Twenty-eight of these herds (87.5%) had a within-herd seroprevalence larger than 50% at sample cut-off OD% > 10. In our study, there was an increasing probability of recovering Salmonella with increasing within-herd seroprevalence. However, this was only a moderate correlation. A correlation coefficient of 0.62 was found between the proportion of culture positive- and seropositive samples in a herd at cut-off OD% > 10 and of 0.58 at cut-off OD% > 40. Serology is a measure of historical exposure, which may or may not correlate closely to the microbiological burden at the time of sampling. Due to the low sensitivity of culture methods, apparent 'false-positive' serological results may well represent real infections not detected by bacteriological testing. For screening purposes, serological testing provides an indication of exposure to Salmonella, which forms the basis for targeted sampling, intervention and logistic slaughter procedures.