Abstract:
Atypical Haemophilus paragallinarum have been isolated from both laying hens and broilers suffering
from typical symptoms of infectious coryza in South Africa. Re-inoculation of these bacteria into SPF
chickens resulted in similar pathology. The bacteria could be successfully re-isolated from the experimentally
infected chickens.
Four of the isolates from layers and 3 of those from broilers were found to be closely related to H.
paragallinarum serotype A (0083 strain) when tested by the use of a panel of locally developed
monoclonal antibodies in the enzyme linked immunosorbent assay (ELISA) . A total of 15 isolates from
layers and 19 from broilers were found to be more typical of previously collected South African field
isolates of H. paragallinarum. A 3rd group, consisting of 5 isolates from layers and 15 from broilers,
showed no reaction with the panel of monoclonal antibodies.
All the isolates were regarded as atypical because they no longer required V factor (NAD) for growth,
whereas strain 0083 and previously collected field isolates M 85 and SB 86 did require it.
