الفهرس 
History, incidence and distribution of the diseaseOnly 14 pages are availabe for public view
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Abstract
Infectious bursal disease(IBD), (Infectious bursitis - Gumboro disease) is an acute highly contagious viral infection of young chickens described first by
Cosgrove (1962) in the Delmarva area .The disease leading to direct and indirect
significant economic losses to the worldwide poultry industry (Chettle et al., 1989;
Van Den Berg et al., 1991 and Rautenschlein et al., 2005).The direct economic
losses of IBD is due to morbidity and mortality rate while the indirect impact is due
to immunosuppression of infected birds (Allan et al., 1972; Ivanyi and Morris,
1976; McNulty et al., 1979; McIlory et al., 1993; Kumar et al., 2002 ; Kataria
et al., 2004 ; Jackwood et al., 2006; Rautenschlein et al., 2007, and Williams and
Sellers 2012).
Cosgrove (1962)) described IBD disease for the first time as a specific new
one of chickens. He referred to as (avian nephrosis) because of the occurrence of
severe and extensive kidney damage caused by this disease, he also added that there
is abnormal swelling of the BF or the cloacal bursa, an organ responsible for the
humoral immune response in birds. The disease received the common name of
Gumboro from the area known as Gumboro in Delaware; U.S.A., where the
condition was discovered for the first time.
Winterfield et al. (1962) isolated the causative agent and proposed the name
infectious bursal agent (IBA). On the other hand, Hitchner (1970 a and b )
proposed the term infectious bursal disease (IBD) to refer to the disease causing
specific lesions in the Bursa of Fabricus.
The etiological virus of the disease belongs to the recently described
Birnaviridae (Brown, 1986, VandenBerg, 2000; Rautenschleins, 2003, and
Sareyyupoglu and Akan, 2006).
Viruses belonging to this family possess genomes consisting of two segments
(bi-segmented) of double-stranded RNA (Van den Berg, 2000 and 2002). Tow
distinct serotypes I and II have been identified (Mcferran et al., 1980 and
Jackwood and Saif, 1983). Serotype I produces clinical disease and distinct
lesions in BF with muscular hemorrhage and serotype-2, which infected both
chickens and turkeys and was recorded as non-pathogenic for both species.