Seventy-two isolates of Haemophilus paragallinarum were serotyped according to the Page scheme, using a new hemagglutination-inhibition (HI) test. The results were compared with the plate agglutination method conventionally used in the Page scheme. The HI test used washed cells of H. paragallinarum, glutaraldehyde-fixed chicken erythrocytes, and rabbit antisera originally produced for the agglutination method. For 49 of the isolates, there was complete correlation between the results of the HI serotyping test and the previously performed agglutination test--23 were serovar A, two were serovar B, and 24 were serovar C. The other 23 isolates were nontypable by the agglutination test, but 21 of them could be serotyped by the HI method--six as serovar A, two as serovar B, and 13 as serovar C. Nine isolates required treatment of the bacterial cells with hyaluronidase for the expression of hemagglutination (HA) activity. Two isolates did not have HA activity despite hyaluronidase treatment and so could not be serotyped by the HI test.

The pathogenicity of 2 isolates of each of serovars 7, 3, 1 and 2 of Actinobacillus pleuropneumoniae was tested by intranasal inoculation into 60, 6-week-old large white pigs. Four dose rates varying from 0.27 to 560 x 10(6) organisms per pig with 10-fold serial dilutions were used. Surviving pigs were necropsied 7 days after inoculation. The proportion of pigs dying and developing gross lesions following infection was significantly greater for pigs given serotype 1 than for each of the other 3 serotypes, which did not differ significantly from each other. Twelve of 16 pigs given either of the 2 isolates of serovar 1 died after acute illness and 1 of 44 pigs given either of the 2 isolates each of serovars 7, 3 and 2 died. Pigs given serovar 1 showed high temperatures, severe respiratory distress, frothy haemorrhagic nasal discharge and weight loss. Lung lesions were produced in all 16 pigs given serovar 1, in 7 of 14 pigs given serovar 7, 7 of 14 pigs receiving serovar 3 and in 5 of 16 pigs given serovar 2. The lethal infections were characterised by a severe acute fibrinohaemorrhagic necrotising pleuropneumonia, whereas non-lethal cases had lung lesions ranging from necrotising purulent pleuropneumonia to abscessation. Significant differences between isolates in proportions of tissues culture positive for A. pleuropneumoniae for serovars 7 and 2, but not for serovars 3 and 1 suggested that isolates may vary in virulence within serovars, but more detailed studies are needed to clarify this point.

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Two cases of lnortalities in cultured red claw Materials and methods. Since 1989, sick or dead red crayfish Cherax quadricarinatus associated with systemic Vibno mimicus infections are described. In these cases, V rnirnicus appears to have been an opportunistic pathogen following stress caused by either overcrowding or mismanagement and poor water quality. Humans consuming raw or improperly cooked infected crayfish could be at risk of contracting gastrointestinal disease.

By using the Kume hemagglutinin serotyping scheme, 13 Australian isolates of Haemophilus paragallinarum were shown to constitute a new serovar within the presently termed serogroup Il. Because of the likelihood that new serovars will continue to be established, we propose a rationalization of the nomenclature of the Kume scheme. Under this altered scheme, the three recognized serogroups T, II, and III are renamed A, C, and B, respectively. Within each of the serogroups, the serovars are numbered sequentially, allowing new serovars to be added in numerical order. Thus, the nine currently recognized Kume serovars are termed A-1, A-2, A-3, A-4, B-1, C-1, C-2, C-3, and C-4.