Correlation between clinico-pathological outcome and typing of Haemophilus parasuis field strains

A paper published by Dr Virginia Aragón (CReSA) shows that the severity of Glässer’s disease correlates with the quantities of H. parasuis recovered from the lesions. Moreover, for the first time, disease in domestic pigs has been reproduced with a strain isolated from the nasal cavity of wild boars.

H. parasuis is the etiologic agent of Glässer's disease in pigs, which is pathologically characterized by serofibrinous polyserositis and arthritis. H. parasuis includes virulent and non-virulent strains and confirmation of virulence is still dependent on experimental reproduction of the disease.

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.

This study has been recently published as “Correlation between clinico-pathological outcome and typing of Haemophilus parasuis field strains. Aragon V, Cerdà-Cuéllar M, Fraile L, Mombarg M, Nofrarías M, Olvera A, Sibila M, Solanes D, Segalés J. Vet Microbiol. 2009 Nov 6”.

Download the full paper Correlation between clinico-pathological outcome and typing of Haemophilus parasuis field strains:

To contact the author of this paper:

Dr. Virginia Aragón Fernández
Bacterial Diseases Unit
Telephone no.: +34 93 581 44 94
Fax: +34 93 581 44 90
Edifici CReSA. Campus UAB
08193 Bellaterra (Barcelona) Spain

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