Serological and immunological studies of pleuropneumonia of swine caused by Haemophilus parahaemolyticus
Nielsen, R.
Acta Veterinaria Scandinavica 15(1): 80-89
1974
ISSN/ISBN: 0044-605X PMID: 4857335 Document Number: 81033
The development of circulating antibodies for H. parahaemolyticus was studied in experimentally infected SPF pigs and in-contact SPF pigs. Blood serum titres were determined by a modified CF test with normal SPF swine serum as a source of supplementary complement factor, and by an indirect haemagglutination test. CF and IHA titres became positive within the first 2 weeks after exposure to H. parahaemolyticus, and reached peak values after 2-7 weeks. The exposed pigs showed no clinical symptoms when challenged after 6, 9 or 11 weeks. While distinct titres were thus obtained with both tests in SPF swine experimentally exposed to H. parahaemolyticus, the CF test proved more specific than the IHA test when the two were compared in a field outbreak of polyserositis (Glassers disease) caused by H. parasuis. The CF test would therefore seem to be preferable to the IHA test in field diagnostic work. A noticeable finding was that challenge did not elicit an anamnestic antibody response in any of the immune pigs; this fact, together with the negative bacteriological findings, seems to suggest that the challenge dose was unable to establish a permanent infection in the respiratory tract of the immune pigs.