No abstract

In order to evaluate the temporal occurrence of Cryptosporidium oocysts in Ruditapes philippinarum clams bred along the northeastern Italian Adriatic coast and molecularly characterize the isolates, 2,160 specimens (180 clams per month) were collected from three clam farms from January to December 2004. Two farms (sites A and B) were located in Venice (Chioggia, Veneto region) and one (site C) in the Marano Lagoons (Friuli Venezia Giulia region). Clams from 36 pools (i.e., one pool of 60 clams per month per site) were subjected to a high-sensitivity seminested PCR assay specific for a 360-bp diagnostic region internal to the Cryptosporidium spp. outer wall protein gene. Positive amplicons were sequenced and analyzed. Cryptosporidium DNA was found in clams from seven pools (sites A and B) during 1 month of sampling at site A and 6 months of sampling at site B, with Cryptosporidium hominis and Cryptosporidium parvum being detected. The expected infection rate of the clams was 0.36%. Site B showed a significantly higher expected infection rate (1.15%) than did the other sites (A = 0.14% and C = 0%). Given its high sensitivity and specificity, this seminested PCR assay can be considered a reliable tool for detecting and distinguishing species within the Cryptosporidium genus. The seasonal pattern of contamination and the related public health risks are of particular concern.

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Vibriosis is a significant problem in rainbow trout, Salmo gairdneri Richardson, culture in fresh water in north-eastern Italy. Furunculosis is the main cause of disease in brown trout, Salmo trutta L., and brook trout, Salvelinus fontinalis (Mitchill). Spontaneous outbreaks over the period 1975-1978 are described together with relevant husbandry and environmental parameters associated with them. Biological, chemical and physiological characteristics of 40 bacterial strains isolated from outbreaks are described.

During in zritro cultivation of bacteria, the pathogenetic factors may change in amount and quality. Knowledge of this variability is important in vaccine production. The pathogenic variability of Pusteurella piscicida broth culture (BC), extracellular products (ECPs) and whole cells (WC) was investigated in sea bass (Dicentrarchus labras) 2-3 g wet weight, inoculated intraperitoneally. Ten Pasteurellapiscicirla field strains isolated from fish affected by different outbreaks which occurred in Italian fish farms were used. When BC and ECPs were intraperitoneally injected, no variability in virulence was observed between strains of different geographical origin and no attenuation was registered between strains of different in oitro passages. The electrophoretic (SDS-PAGE) analysis of ECP showed evidence of only quantitative differences inside the panel of strains and between the same strain collected at different in ~i t r o cultivation times. ECPs produced from a BC incubated for 18-60 h were highly toxic. This ability was heat labile and not active when ECPs were administered by immersion. No toxic capacity was observed with WC where infection was greater with a 18-60 h incubation broth culture. Results seems to indicate that the toxic activity of Pasteurella piscicida is mostly due to ECP and not bounded to the cell.