IMMUNOLOGIC RESPONSE OF CHICKEN TO NATURAL, EXPERIMENTAL INFECTION AND VACCINATION WITH HAEMOPHILUS PARAGALLINARUM

Abstract

The prevalence rate of H. paragallinarum from diseased chicken among different farms at Port Said, lsmalia and El Giza Governorates was studied. One hundred and fifty alive diseased chickens of different ages and breeds were subjected to clinical and bacteriological examination. Infected birds showed signs of infectious coryza such as nasal discharge, swelling of infraorbital sinus (unilateral or bilateral), facial swelling, retardation of growth in growing birds, in addition to swelling of wattles and drop of egg production in laying birds. The percent of isolation of Haemophilus organisms from diseased chickens was 6%.

The isolated Haemophilus organisms were identified morphologically, biologically, biochemically and serologically as H. paragallinarum serovar A.

The results of antibiotic sensitivity test revealed that all field isolates as well as standard strain were sensitive to gentamycin, kanamycin, chloramphenicol, tetracycline and oxytetracycline but resistant to ampicillin, streptomycin and colistin.

Isolated H. paragallinarum organisms were pathogenic when inoculated into chicken embryos causing 100% death within 24-48 hours with congestion of the dead embryos. On the other hand in