Severe lamb diarrhea outbreak: Clinical features, identification of the causative agent, and a prophylactic approach.

Lamb diarrhea is an important problem and has a significance impact on the ovine sector productivity. This study aimed to identify the causative agent related to a severe diarrhea outbreak in neonatal lambs in Egypt. A total number of 30 lambs representing different farms were investigated. Faecal samples were obtained for parasitological, bacteriological, and virological examination. Tissue samples were obtained for histopathology. While blood was obtained for measuring haematological parameters and humeral immune response against the used Entero-3 vaccine®, respectively. The obtained results cleared presence of significant clinical symptoms of diarrhea, dehydration and inflammation of the large intestine which was filled with watery fluid content. Parasitological causative agents were not recorded. Enterococcus sp. was successfully isolated from 30 % of the samples (seven isolates E. faecium and two E. gallinarum) with detection of the Asa and Esp virulence genes. While E. coli was detected in 26.6 % of the cases, they were identified as O124:K72, O111:K58, O78:K80, O26:K60 with successful amplification of the Sta and F5 (K99) virulence genes. The obtained isolates were susceptible to the Amikacin . Using vaccination as a prophylactic approach resulted in decreasing mortality rates with presence of a protective seroconversion rate in the vaccinated animals. The haematological parameters showed presence of neutrophilia and lymphocytosis. Histopathologically, desquamations of the villi' enterocytes were the most common lesion. In conclusion, this study highlights the roles of bacterial and viral infection in causing severe lamb enteritis and high mortalities which necessitate establishing of ewe's vaccination programs.