Haemophilus paragallinarum , the causative agent of infectious coryza (IC), an
acute respiratory disease in chickens and fowl, was first isolated in 1931 by
De Blieck (1932). The first serious, documented outbreak in South Africa
occurred in 1968 (Buys, 1982) on a multi-age layer-farm, soon the bacterium
spread to most large production sites and established itself as the most
common bacterial infection in layers (Bragg, 1995). The disease has a low
mortality rate but leads to a drop in egg production of up to 40 % in layer hens
and increased culling in broilers and thus poses significant financial liability to
chicken farmers (Arzay, 1987; Bragg, 1995).
One of the reasons for the success of survival for this bacterium is that after
recovering from infection, birds become carriers of the bacterium, therefore
aiding the spread of H. paragallinarum (De Blieck, 1948). Secondly, the
bacterial strain belongs to one of nine serovars, which makes combating the
spread of the disease through inactivated vaccination ineffective especially
due to low cross protection among these serovars. (Rimler et al., 1977; Kume
et al., 1980a).
Various potential factors have been identified as potential virulence factors,
e.g. the haemagglutinin protein. This protein plays a crucial role in adherence
of the bacteria to the host's cells and is considered a possible virulence factor
(Sawata et al., 1982; Yamaguchi et al., 1989). Sawata and co-workers (1982)
reported at least three different haemagglutinins from H. paragallinarum strain
221 with one, HA-L, being serovar specific with the other common types
shared by the different serovars in one serogroup.It would therefore be important to understand the working and interaction of
the various virulence factors of H. paragallinarum, especially the
haemagglutinins, in order to combat this bacterium.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-09202002-141632 |
| Date | 20 September 2002 |
| Creators | Barnard, Tobias George |
| Contributors | Dr. E van Heerden, Dr. J Albertyn, Dr. RR Bragg |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://lourie.uovs.ac.za//theses/available/etd-09202002-141632/restricted/ |
| Rights | mixed, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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