Prevalence of Haemophilus parasuis serovars isolated in Spain from 1993 to 1997

From 1993 to 1997, 327 strains of Haemophilus parasuis were isolated from spanish swine in our Diagnostic Laboratory and 174 strains (53.2%) were serotyped. Four serotypes, sv. 5 (18.4%), sv 4 (16%), sv. 2 (9.2%) and sv. 13 (8%) were the most frequently isolated and 29.3% of the studied strains were classified as non typable. The results obtained indicate that the distribution of the serotypes in Spain is very similar to that found by other researchers in Germany, Australia, Canada and alike to that found in the United States.     

BSE in the Netherlands: an update

Up to 2006, there have been 82 cases of BSE in cattle born in the Netherlands. This article reviews the current situation regarding BSE in the Netherlands and summarizes the clinical symptoms of the disease. Data from the Netherlands show that a passive surveillance system, by which farmers and veterinarians have to report suspect clinical cases, has a low sensitivity. The epidemiology of, and risk factors for, BSE are discussed. All the Dutch cases of BSE can be attributed to cross-contamination of feed with meat-and-bone meal. On the basis of information about the epidemic and the cases reported to date, it is anticipated that the number of cases of BSE will continue to decline in the Netherlands and Europe. The European Commission has presented a road map that describes how the European BSE policy can be changed in the short and long term if the current favourable trend in BSE cases continues. It is time for a new phase in the management of BSE but with continued protection of the public's health and eradication of BSE.     

In vitro markers for virulence in Yersinia ruckeri

In this study, different traits that have been associated with bacterial virulence were studied in Yersinia ruckeri. Two isolates that had been shown to cause disease and mortality in experimentally infected rainbow trout were compared with five avirulent isolates. Both virulent isolates showed high adhesion to gill and intestinal mucus of rainbow trout, whereas the majority of non‐virulent strains demonstrated significantly lower adhesion. A decrease in adherence capability following bacterial treatment with sodium metaperiodate and proteolytic enzymes suggested the involvement of carbohydrates and proteins. All strains were able to adhere to and invade chinook salmon embryo cell line (CHSE‐214), fathead minnow epithelial cell line (FHM) and rainbow trout liver cell line (R1). One non‐virulent strain was highly adhesive and invasive in the three cell lines, whereas the virulent strains showed moderate adhesive and invasive capacity. The internalization of several isolates was inhibited by colchicine and cytochalasin‐D, suggesting that microtubules and microfilaments play a role. For all strains, intracellular survival assays showed a decrease of viable bacteria in the cells 6 h after inoculation, suggesting that Y. ruckeri is not able to multiply or survive inside cultured cells. Analysis of the susceptibility to the bactericidal effect of rainbow trout serum demonstrated that virulent Y. ruckeri strains were serum resistant, whereas non‐virulent strains were generally serum sensitive.