STUDIES ON EGG DROP SYNDROME-1976: 1- EXISTENCE OF ANTIBODIES IN EGYPTIAN COMMERCIAL CHICKEN LAYERS

The entity of egg drop syndrome (EDS) was described for the first time in Netherlands in meat type parent and brown layer fowl by Van Eck et al., (1976) in which the disease displayed a number of remark- able characteristics included a sudden and severe drop in egg production (20-50%) accompanied by the production of high percentage of soft shelled and shell-less eggs, aberrant shells had poor internal quality, short-lived slight diarrhoea and without obvious clinical signs or mortality. The condition seemed to be age related, near the onset or peak production (26 to 33 weeks of age) and egg production usually recovered completely or nearly completely within 6 to 10 weeks of disease onset, thus resulted in severe economical losses, 10-16 eggs losses per hen (McFerran, 1984). Based on the results of serological examination by Van Eck et al., (1976) associated the condition with an adenoviruses infection. Soon after the first report of the syndrome, Baxendale (1978) isolated the virus which agglutinated chicken erythrocytes from buffy coat cells (BC 14 virus), while McFerran et al. (1977) also isolated a hemagglutinating virus (virus 127) from pooled nasal and pharyngeal mucosa of affected birds. Subsequently, several EDS-76 isolates were reported in several countries as reviewed by Van Eck (1986). The disease could be reproduced with both virus isolates BC 14 and 127 (Baxendale, 1978; Lutticken and Baxendale, 1980; and McCracken and McFerran, 1978). The virus isolates were indistinguishable (Baxendale, 1978; and Baxendale et al., 1978) and proved to be members of the Adenoviridae (Kraft et al., 1979; and Todd and McNulty, 1978). The virus associated with EDS-76 is widespread in waterfowl and domestic ducks and geese. Three forms of EDS-76 have been recognized. The first, or classical, form infects breeding stock and is vertically transmitted. The virus remains latent until birds came into lay, when it is activated, causing classical EDS. The second, or endemic form arises from the classic form. Virus spreads into commercial egg layers and is often spreads by eggs through common packing stations. The third form is the sporadic form which infects flock via drinking water contaminated by wild or domestic form. This form can give rise to the classical form (if-elite or grandparents were infected) or to the endemic form (McFerran, 1989). In Egypt, virus-127 was isolated from duck farms, associated with detectable HI-antibodies (Hamouda,1988). The present work represents the first record for prevalence of HI-antibodies against EDS-76 in commercial chicken layers in Egypt associated with serious egg problems.