In the last 40 years, low pathogenic avian influenza virus (LPAIV) subtype H9N2 has been endemic in most Middle Eastern countries and of course Egypt which is one of the biggest poultry producers in the middle east region. The major losses with the H9N2 virus infections come from complicated infections in commercial broiler chickens, especially E. coli infection. In this work, 2,36,345 Arbor acres broiler chickens from the same breeder flock were placed equally in four pens, where two pens were vaccinated against LPAIV of subtype H9N2 virus, and the other two pens served as non-vaccinated controls. All were placed on the same farm under the same management conditions. A total of twenty birds from each pen were moved to biosafety level−3 chicken isolators (BSL-3) on days 21 and 28 of life and challenged with LPAIV-H9N2 or E. coli. Seroconversion for H9N2 was evaluated before and after the challenge. The recorded results revealed a significant decrease in clinical manifestations and virus shedding in terms of titers of shedding virus and number of shedders in vaccinated compared to non-vaccinated chickens. In groups early infected with LPAIV-H9N2 virus either vaccinated or not vaccinated, there was no significant difference in clinical sickness or mortalities in both groups, but in late infection groups with H9N2 alone, non-vaccinated infected group showed significantly higher clinical sickness in comparison with infected vaccinated group but also without mortality. In groups co-infected with E. coli (I/M) and H9N2, it showed 100% mortalities either in vaccinated or non-vaccinated H9N2 groups and thus reflect the high pathogenicity of used E. coli isolates, whereas in groups co-infected with E. coli (per os to mimic the natural route of infection) and LPAIV-H9N2, mortality rates were significantly higher in non-vaccinated groups than those vaccinated with H9N2 vaccine (15 vs. 5%). In conclusion, the use of the LPAIV H9N2 vaccine has significantly impacted the health status, amount of virus shed, and mortality of challenged commercial broilers, as it can minimize the losses and risks after co-infection with E. coli (orally) and LPAIV-H9N2 virus under similar natural route of infection in commercial broilers.

The aim of this work was planned to study the prevalence of mycoplasma organisms in chickens from different localities of Kaluobia, Monofia and Gharbia governorates. In this study a total of 36 farms were examined for prevalence of mycoplasma organisms, these farms were : 3 layer, 20 broilers, 12 balady and one breeder, these farms were located in El Monofia, El Gharbia and El Kaluobia Governorates through application of two methods for diagnosis of Mycoplasma gallisepticum(MG) and Mycoplasma synoviae (MS). Flocks were examined for the detection of MG and MS infection by isolation and polymerase chain reaction (PCR). In layers 3 flocks were examined for presence of MG, the overall incidence were 14.66% out of the 12% from diseased birds and 2% from apparently healthy one. In broiler from 20 flocks were examined for presence of MG, the overall incidence were 30.38% out of the 33.63% from diseased birds and 12.5 % from apparently healthy. In balady from 12 flocks were examined for presence of MG, the overall incidence were 23.47% out of the 24.54% from diseased birds and 0 % from apparently healthy 4 out of 100 (4%) and 20 out 100 (20 %) for MS and MG respectively in diseased breeder in one flock. Mycoplasma gallisepticum field strain was sequenced and compared with the data base on Genbank. The Sequence analysis confirmed the presence of mgc2 virulent gene. The sequenced MG field strain was used in a laboratory experiment to confirm its pathogenicity through studying the clinical signs, body weight and histopathological lesions and minimum inhibitory concentration (MIC) for antibiotics and found that Tiamulin and Doxycycline gave lower concentration. Therefore, identification of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) using PCR is more accurate and faster than ordinary identification.

Infectious Laryngotracheitis (ILT) is an acute highly contagious respiratory disease of chickens. It has significant economic importance due to mortalities and the drop in egg production. In this study, seventy samples from different layer farms were collected from the outbreaks that occurred in Qalyubia province, Egypt, at the period from February 2018 till May 2019 to detect ILTV by molecular characterization through polymerase chain reaction assay (PCR) as well as isolation on the specific pathogen free-embryonated chicken eggs (SPF-ECEs) through chorioallantoic membrane (CAM) route. Post mortem examination of infected chickens revealed hemorrhagic tracheitis with fibrino-hemorrhagic casts and caseated materials. The PCR revealed amplification of a 688bp fragment of Infected Cell Protein 4 (ICP4) gene. Following that, seven samples were sequenced and phylogenetically analyzed. Sequence analysis of the ICP4 gene of these samples revealed complete identity with TCO (tissue culture origin) vaccines and the vaccine-related strains, which were previously isolated from Giza, Sharqia, Kafr El Sheikh, and Faiyum provinces through the years 2007 to 2018. Inoculation of ILTV PCR positive samples on SPF-ECE appeared as yellowish-white pock lesions on the inoculated CAM from the first passage. From these results, we can say that ILTV circulating in Egypt is a vaccinal strain that regains its virulence from the back passage in birds and causes outbreaks all over the country.

Ceacal coccidiosis one of Nine Eimeria species affecting chickens and results in severe economic losses. Sixty-seven GIT sample were collected from broiler flocks showing bloody diarrhea in Kalyoubia governorate. 88% of collected samples were found to be positive for cecal coccidiosis after using microscopical and molecular identification. Different control strategies as diclazuril, vaccination (coccivac B ® and isolated strain as field strain vaccine) and the aqueous extract of neem plant (Azadirachta indica) were used to control cecal coccidiosis in experimentally infected broiler chicks. The results showed that the diclazuril was the best protection method as there was a significant improvement in performance parameters, significant drop in oocyst shedding, dropping scoring, lesion scoring and cecal mucosal scraping scoring. Also, there was minimal histopathological alteration in the cecum of infected broilers in comparison with other treatments. The neem extract treated group also recorded an improvement in the aforementioned parameters in comparison with the vaccinated infected birds. The vaccination of birds using isolated strain achieved better protection against coccidia infection than the imported strain.

The ameliorative effects of some different antimycotoxicosis compounds (AMCs) against the adverse effects induced by intoxication of dietary aflatoxin (AF) and/or ochratoxin (OT) on the immune system performance in broiler chicks were investigated.AF (23 ppb), OT (17 ppb) and mixed doses were fed and in association with antimycotoxin feed additives; product A (combination of Eubacterium BBSH 797 and Trichosporon mycotoxinivoran, plant extract, algae extract) or product B (nano-clay, seaweed extract, yeast cell wall, diatomaceous earth) from 1 day old chicks to 21 day. The intoxicated chicks treated with AMCs; product C(combination of bacterial cell wall extract, oligosaccharides, L-form bacteria extract, group of mycotoxin biotransforming enzymes, organic acid and salts, hepatic and renal tonic and vitamins)or product D in drinking water (isomaltooligosaccharide, micronized-mannan oligosacharide, lactobacillus extract and cholestyramine) were used in the drinking water of 2 weeks old chicks after appearance of signs. Results revealed that chicks intoxicated with AF and/or OT showed significant (P<0.05) decrease in the relative weights of the main immune organs and the antibody titers against vaccines of Newcastle disease (ND) and Infectious bursal diseases (IBD) viruses, in addition to significant (P<0.05) increase in the cumulative histopathological lesion scores of thymus, bursa of Fabracius and spleen. The adverse effects of AF and/or OT on the relative weights and the histopathological lesion scores of the tested immune organs and the antibody titers against ND and IBD vaccination were significantly (P<0.05) improved with dietary supplementation of AMCs products A or B. While the treatment of the intoxicated chicks with AMCs products C or D in the drinking water showed partially and temporarily improvement in the relative weights and the histopathological lesion scores of the tested immune organs and did not improve the negative effects of AF and/or OT on the antibody titers against ND and IBD vaccines.