Effect of pig age and autogenous sow vaccination on nasal mucosal colonization of pigs by Haemophilus parasuis

This report describes an attempt to evaluate the effect of piglet age (with or without weaning), sow parity, and sow vaccination, on the timing of nasal mucosal colonisation of piglets by Haemophilus parasuis. We also determined the serotypes involved and compared serotypes isolated from the nasal mucosa and the trachea. Compared to tracheal swabs, nasal mucosal swabs were more easily performed and also more consistently yielded H parasuis. Serotypes obtained from each site were the same. A lower level of colonisation was found within the litters of young sows and a low level of colonization by H parasuis at weaning likely predisposes piglets to clinical disease in the nursery, assuming the presence of a virulent serotype. We found that more than one serotype of H parasuis was present in the herd and that vaccination of sows did not influence the timing of apparent colonization or the serotypes prevalent within a litter.