Estimation of hepatitis E virus (HEV) pig seroprevalence using ELISA and Western blot and comparison between human and pig HEV sequences in Belgium.

Zoonotic transmission of hepatitis E virus (HEV) is of special concern, particularly in high income countries were waterborne infections are less frequent than in developing countries. High HEV seroprevalences can be found in European pig populations. The aims of this study were to obtain prevalence data on HEV infection in swine in Belgium and to phylogenetically compare Belgian human HEV sequences with those obtained from swine. An ELISA screening prevalence of 73% (95% CI 68.8-77.5) was determined in Belgian pigs and a part of the results were re-evaluated by Western blot (WB). A receiver operating characteristic curve analysis was performed and scenarios varying the ELISA specificity relative to WB were analysed. The seroprevalences estimated by the different scenarios ranged between 69 and 81% and are in agreement with the high exposure of the European pig population to HEV. Pig HEV sequences were genetically compared to those detected in humans in Belgium and a predominance of genotype 3 subtype f was shown in both swine and humans. The high HEV seroprevalence in swine and the close phylogenetic relationships between pig and human HEV sequences further support the risk for zoonotic transmission of HEV between humans and pigs.

Tetracycline-resistant Chlamydia suis in cases of reproductive failure on Belgian, Cypriote and Israeli pig production farms.

Similar cases of severe reproductive failure associated with the presence of Chlamydia suis in two Belgian, one Cypriote and one Israeli pig farrowing to slaughter farms are presented. Vaginal and rectal swabs from 39 sows were examined by culture and DNA microarray. Nineteen of 23 (83 %) C. suis-positive sows were infected with tetracycline-resistant C. suis strains, as determined by MIC tests. Furthermore, boar semen from a German artificial insemination centre, intended for export, was positive for C. suis. Emergence of tetracycline-resistant C. suis strains was confirmed.

Noroviruses and sapoviruses in pigs in Belgium.

Porcine noroviruses and sapoviruses belong to the family Caliciviridae and are rarely reported in European countries. In this study, swine stools from a region representative of northern Europe were screened for these viruses by RT-PCR. Both porcine noroviruses and sapoviruses were detected, showing their circulation in this region. The porcine norovirus strains were genetically related to genotype 19 strains in the genogroup II of the genus Norovirus. The porcine sapovirus strains were genetically related to the porcine enteric calicivirus Cowden reference strain and to newly described porcine strains in the genus Sapovirus.

The possibility of positive selection for both F18(+)Escherichia coli and stress resistant pigs opens new perspectives for pig breeding.

F18(+)Escherichia coli infections causing post-weaning diarrhoea and/or oedema disease are a major cause of economic losses in pig industry. To date, no preventive strategy can protect pigs from F18(+)E. coli infections. One of the most attractive approaches to eliminate F18(+)E. coli infections is the selection for pigs that are resistant to F18(+)E. coli infections. However, this strategy was not believed to be favourable because of reports of genetic association with the stress-susceptibility gene in the Swiss Landrace. To investigate this potential association more thoroughly, 131 randomly selected Belgian hybrid pigs were genotyped for both the F18(+)E. coli resistance alleles (FUT1(A)) and the stress-susceptibility alleles (RYR1(T)) and their association was investigated by determining the linkage disequilibrium. This linkage disequilibrium (LD=-0.0149) is close to zero and does not differ significantly from 0 (likelihood ratio test chi(1)(2)=1.123, P=0.29), demonstrating no association between the FUT1(A) and RYR1(T) alleles. Furthermore, only a small fraction (4.6%) of the Belgian pigs was found to be resistant to F18(+)E. coli infections. Our results suggest that selection for F18(+)E. coli resistant pigs might be an attractive approach to prevent pigs from F18(+)E. coli infections, unlike to what has previously been postulated.