Search

In a closed farrow-to-finish piglet producing farm 80% of 7-week-old piglets displayed respiratory disease with a 5% mortality rate. In addition to purulent bronchopneumonia in combination with interstitial pneumonia predominantly in the apical and middle lobes, fibrinous serositis was present in the thoracic and abdominal cavities. Further investigations succeeded in confirming the non-pandemic strain of porcine influenza A virus (FLUAVsw) subtype H1avN1. The molecular genetic studies on Mycoplasma (M.) hyopneumoniae and porcine reproductive and respiratory syndrome virus were negative, whereas M. hyorhinis and Haemophilus parasuis were isolated from serous membranes. The possible importance of the underrated M. hyorhinis as a cofactor for viral infections should be emphasized and we demonstrated that the cause of apical lobe pneumonia is not restricted to M. hyopneumoniae. Mother pigs had been vaccinated with an influenza vaccine covering the subtype H1avN1. Only 33% of the examined piglets had maternal antibodies in the 7th week of life. The difficulty of prophylaxis of infections by FLUAVsw in weaners due to lack of vaccine authorization for piglets before their 56th day is reflected by this observation.

The goal of this study was to examine the use of an early vaccine for Haemophilus parasuis in three and five week old piglets. In the first field trial, 144 female piglets were divided into four groups. The groups consisted of animals showing no clinical signs of the disease (clinically normal) and a second group displaying clinical signs of the disease (clinically suspect). Half of the animals belonging to both clinical groups were vaccinated. In a second field trial, 240 female piglets, which were clinically normal at the time of housing and originating from the same farm were divided into two groups. Swine from one group were vaccinated, and both groups were regularly weighed and clinically examined until the end of the growing-finishing phase. Vaccinated animals from the first field trial which were clinically weighed on average 0.353 kg more than animals from the nonvaccinated control group at 11th weeks of age. Piglets of the vaccinated clinically suspected group which were 13 weeks of age weighed on average 1.41 kg more than the piglets from the nonvaccinated group. The average clinical scores for both vaccinated groups were lower than those from the nonvaccinated groups. The results from the second field trial showed that the average weight of the vaccinated group was higher by 3.1 kg than those of the control group.Also, a significant difference in weight gain was found beginning in the thirteenth week of age. The percentage of altered animals or animals unfit for growing-finishing was 8.3% in the nonvaccinated group at the end of the rearing phase. In comparison, this percentage was 3.8% in the vaccinated group.

In routine diagnostic it is difficult to detect a Haemophilus parasuis infection causing a polyserositis. In the presented study, a detection method by means of PCR, from collective swabs of the serosal surfaces from animals, with and without fibrinous serositis, was investigated. A significant association was detected between post mortal findings of fibrinous serositis and molecular biological detection of Haemophilus parasuis and Mycoplasma hyorhinis. However, no significant association existed between cultural detection of Haemophilus parasuis in bronchoalveolar lavage fluid and pathological-anatomical ascertainable fibrinous serositis. A significant association between Haemophilus parasuis and Mycoplasma hyorhinis could be determined in the animals that were included in this study.