0
Since the variability in virulence is supported by serotyping and genotyping (particularly, multilocus sequence typing [MLST]), researchers of the CReSA examined the relationship between the classification of 8 field strains by these methods and their capacity to cause disease in snatch-farrowed, colostrum-deprived piglets.
The experiments confirmed that snatch-farrowed colostrum-deprived piglets can be used for the reproduction of Glasser's disease by intranasal inoculation of field strains of H. parasuis.
Reproduction of disease was strain-dependent and severity of clinical signs and lesions correlated with the quantity of H. parasuis recovered from the lesions of sick animals. However, the virulence of the strains in the animal model did not show a total correlation with their serovar or their classification by MLST. Thus, further studies will be needed to find a clear virulence marker, which will eliminate the need of the animal model for testing the virulence of H. parasuis strains.
Daily weight gain (g/day; mean ± SD) after inoculation of different strains of Haemophilus parasuis.
Finally, Glässer's disease has never been described in wild boar, but a strain isolated from the nose of wild boars was able to reproduce characteristic lesions in one domestic pig. This result indicates the existence of virulent strains in wild boar, which could produce disease under the appropriate conditions (such as intensive farming and early weaning). The possibility of transmission of H. parasuis from wild boar to domestic pigs must be, therefore, taken into account.
Aragon V, Cerdà-Cuéllar M, Fraile L, Mombarg M, Nofrarías M, Olvera A, Sibila M, Solanes D, Segalés J. Correlation between clinico-pathological outcome and typing of Haemophilus parasuis field strains. Vet Microbiol. 2009 Nov 6.
