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Abstract The in-ovo experimental infection (egg shell penetration) of Aermonas hyDROPhila at 18 days old ECE was revealed the decrease hatchability to 91.7 % and 8.3 % embryonic mortalities. The dead embryos exhibited severe congestion in liver, myocardium, and yolk sac. The survivor chicks acquired omphalities, septicaemia, enteritis, and bad feed conversion rate. The viability of Aermonas hyDROPhila was investigated under controlled laboratory conditions. In tap water, and different materials; chicken crates, faeces, ration, saw dust and straw for 26 days, 11 days, 9 days, 23 days, 22 days and 17 days, respectively. The pattern of cloacal shedding of Aermonas hyDROPhila in experimentally infected parent chickens during a period of 2 weeks. The cycle of infection in parent chickens experimentally infected with Aermonas hyDROPhila. Faecal shedding of the inoculated organism revealed higher percentage in orally infected chickens than subcutaneously infected ones. However addition of probiotic to the ration of orally infected chickens resulted in lowering of this shedding. On studying shedding in fertile eggs collected from these chickens; ”egg shell contamination revealed 12 % in orally infected chickens. In the orally infected and probiotic treated birds it was decreased to 4 % , while no shedding of Aermonas hyDROPhila was determined in subcutaneously experimentally infected birds. These results draw attention to the role of oral infection as a possible route of I vertical transmission through intestinal colonization and contamination of egg shells during their passage via the cloaca and also spots light on the usefulness of probiotic usage in controlling vertical transmission via this route. All samples taken from albumin, egg yolk and internal organs of parent chickens on their sacrificing revealed negative result for re-isolation of Aeromonas hyDROPhila. It could be concluded that Aeromonas hyDROPhila is not congenitally transferred because it was not recovered from albumin and yolk. No clinical signs could be noticed in Aeromonas hyDROPhila infected parent chickens via oral or subcutaneous routes, and the organism was not recovered from their internal organs at the end of the experiment. It could be concluded Aermonas hyDROPhila assumes a persistent nature during which shedding occurs and the egg contamination takes place during the intestinal passage, therefore ovary and oviduct do not play a role in dissemination of the infection. |