Abstract: Indirect hemagglutination assay (IHA) was developped by sensitizing glutaraldehyde-tannin fixed sheep red blood cells with sonicated product of Haemophilus parasuis (Hps) serovar 4,5 and 13 isolated strains. All 15 standard sera of Hps were positive. Antibody titers were 1∶2⁵ to 1∶2¹⁰,and sensitivity significantly higher than gar gel precipitation test(AGPT). the positive sera of other 16 viruses and bacterium were negative excluded Actinobacillus pleuropneumoniae(APP). 620 clinical serum were detected and the positive ratio was 67.58%. The results showed that this IHA was sensitive,specific and could be used for antibodies detection and epidemiological investigation of Hps.

Key words: Haemophilus parasuis; indirect hemagglutination assay; antibodies detection