الفهرس 
History, incidence and distribution of the disease.Only 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.
Introduction 2
In1986 very virulent (vv) strains of IBD have emerged in Europe, which can
cause up to70% flock mortality in laying pullets and 100% in SPF chicken (Chettle
et al., 1989 and Van Den Berg et al., 1991). In Egypt (in the summer of 1989),
severe outbreaks of very virulent IBD (vvIBDV), similar to those reported in
European countries in both vaccinated and non-vaccinated flocks, and were
associated with high mortalities (El-Batrawi, 1990; Ahmed, 1991 and 1993;
Khafagy et al., 1991; El-Shorpagy, 1992; Ghanem, 1994, Sultan, 1995 and
Hassan et al. 2002).
In spite of intense multiple vaccination with serotype I vaccines and restrict
sanitary and biosecurity measures the disease was continued to be a problem in
several parts of the world, including Egypt.
The complete prevention of the disease was not achieved yet probably because
the emergence of new antigenic subtypes (Eterradossi et al., 1998, and
Zierenberg et al., 2000)
IBD can be controlled both by live and inactivated vaccines. According to
virulence, there were four kind of live serotype I vaccines: intermediate plus or hot,
intermediate, mild intermediate, and attenuated mild strains. The protective
efficacy of IBDV vaccines is traditionally evaluated in SPF chickens. But under
field condition, residual maternal antibody (MA) levels may interfere with vaccines
efficacy. Under experimental condition, it was demonstrated that intermediate
IBDV vaccines may break through residual MA and induce protective immunity,
but mild vaccines not cause the disease. Over all, successful IBDV vaccination
depends on the time of vaccination, the vaccine strain, the MA status of the flock,
as well as the epidemiological field isolate. (Tuskamoto et al., 1995;
Rautenschlein et al., 2005, and Jachwood 2011). In addition control of IBDV via
adequate management and sanitation (Van Den Berg and Meulemans, 1991 and
Van Den Berg, 2000), so control policy based on vaccination is considered the
principle method used for control of IBD in chickens and was initially based on
immunization of broilers and replacement pullets with various commercial
serotype-1 live vaccines of the mild and intermediate types, and in breeder pullets
either the inactivated oil-emulsion vaccines were used to boost immunity at the
point of lay. Control of the disease via through management and sanitation are not
adequate to control IBD (Van den Berg and Meulemans, 1991 and Van den Berg,