Étude lésionnelle et bactériologique des infections du sac vitellin (omphalites) chez les poussins chair, Nord-Est de la Tunisie

The present study was carried out for three objectives: firstly, to investigate the prevalence of the yolk sac infections in broilers in the northeast of Tunisia. The second goal was to know the main germs responsible for this problem. Finally, we aimed to study the sensitivity of isolated bacteria to the main antibiotics used in the field. A total of 170 chicks (3 to 8 days) were necropsied. Suspected yolk sacs were collected using sterile swabs and sent to the laboratory for bacteriological analysis and antibiogram. Overall prevalence of 55.3% (94 chicks) was assessed. Statistically significant difference was noted among the different age groups, with highly prevalence observed in 5 days old animals (76%). Bacteriological analysis revealed that 71.3% (67 chicks) showed single bacterial infection. E. coli was the most important isolated bacteria (74.5%), followed by Klebsiella spp. (31.9%), Salmonella spp. (10.6%), Proteus spp. (9.6%) and Staphylococcus aureus (2.1%). A high correlation was noted between the chick mortality and infection by E. coli, Klebsiella and Proteus. Tested bacteria isolates (109 isolates) to twelve antibiotic agents showed high sensitivity to streptomycin, colistin, amoxicillin and amoxicillin-clavulanic-acid. A higher resistance was noted to enrofloxacin. Multidrug resistant isolates were detected in 38 (34.9%) bacteria isolates. Keywords: Yolk sac infection, Bacteriology, Multidrug resistance, Broiler, TunisiaLa présente étude a un triple objectif: d’abord pour estimer la prévalence de l’infection du sac vitellin chez le poulet de chair dans les élevages du Nord-Est de la Tunisie. Le second objectif est d’identifier les principales bactéries responsables de ce problème. Enfin, nous visons l’étude de la sensibilité des souches isolées vis-à-vis des principales molécules d’antibiotiques utilisées sur le terrain.  Un total de 170 poussins (3-8 jours d’âge) est autopsié. Les sacs vitellins suspects sont prélevés moyennant des écouvillons stériles envoyés au laboratoire en vue des analyses bactériologiques et des antibiogrammes. La prévalence globale des omphalites est de 55,3% (94 poussins). Une différence statistiquement significative est notée selon les tranches d’âge, avec une plus grande prévalence observée chez les oiseaux âgés de 5 jours (76%). Les analyses bactériologiques ont révélé que 71,3% (67 poussins) des animaux montraient une infection bactérienne unique. E. coli est la bactérie la plus isolées (74,5%), suivie de Klebsiella spp. (31,9%), Salmonella spp. (10,6%), Proteus spp. (9,6%) et Staphylococcus aureus (2,1%). Une corrélation élevée est notée entre la mortalité des poussins et l’infection par E. coli, Klebsiella et Proteus. Les isolats testés (109 isolats) vis-à-vis de 12 antibiotiques montrent une sensibilité importante à la streptomycine, la colistine, l’amoxicilline et l’amoxicilline-acide clavulanique. Une résistance élevée est notée vis-à-vis de l’enrofloxacine. Une multi-résistance est détectée chez 38 souches (34,9%) isolées. Mots clefs: Infection du sac vitellin, Bactériologie, Multi-résistance aux antibiotiques, poulet de chair, Tunisi

Virus-induced immunosuppression in turkeys (Meleagris gallopavo): A review

Immunosuppression is characterized by a dysfunction of humoral and/or cellular immune response leading to increase of susceptibility to secondary infections, increase of mortality and morbidity, poor productivity and welfare and vaccination failures. Humoral immune response depression is due to perturbation of soluble factors, as complement and chemokines in innate immunity and antibodies or cytokines in adaptive immunity. At the cellular immune response, immunosuppression is the consequence of the dysfunction of T-cells, B-cells, heterophils, monocytes, macrophages and natural Killer cells. Immunosuppression in turkeys can be caused by numerous, non-infectious and infectious agents, having variable pathological and molecular mechanisms. Interactions between them are very complex. This paper reviews the common viruses inducing clinical and sub-clinical immunosuppression in turkeys, and enteric and neoplastic viruses in particular, as well as the interactions among them. Evaluation of immunosuppression is currently based on classical approach, however new technique such as the microarray technology is being developed to investigate immunological mediator’s genes detection. Controlling of immunosuppression include, in general, biosecurity practices, maintaining appropriate breeding conditions and vaccination of breeders and their progeny. Nevertheless, few vaccines are available against immunosuppressive viruses in turkey’s industry. The development of new control strategies is reviewed

Prevalence of Coccidiosis in Free-Range Chicken in Sidi Thabet, Tunisia

Background. Enteric diseases are an important concern to the poultry industry and coccidiosis is imposing a significant economic burden worldwide. Objectives. The main goal of the present study was to investigate the prevalence of coccidiosis in free-range chicken in Sidi Thabet, northeast Tunisia. Methods. Six hundred and thirty free-range chickens along with fecal samples were collected from 15 flocks in this region and two hundred chickens were found positive for oocysts of Eimeria spp. Intestines were dissected and examined for macroscopic lesions. The mucosa of small intestine and the caeca were examined for the presence and identification of parasitic forms using parasitology methods. The mean lesion scores were usually low (2+) were attributed mainly to the caeca. Results. The overall rate of coccidiosis was 31.8%: E. tenella (61.5%), E. maxima (12%), and E. acervulina (1.5%). Mixed Eimeria species infection was observed with overall prevalence 26.5%. There was a statistically significant difference (P<0.05) among infection rates, age groups, season, diarrhea, and type of chicken. Conclusion. This is the first report of coccidiosis rate in free-range chicken in this region. Further additional studies are needed to develop better preventive measures against coccidiosis in the country

Occurrence of Chicken Infectious Anemia Virus in Industrial and Backyard Tunisian Broilers: Preliminary Results

Chicken infectious anemia virus (CIAV) is an economically important and widely distributed immunosuppressive agent in chickens. This study performed an epidemiological investigation on CIAV circulation in 195 Tunisian broilers, belonging to 13 lots from five industrial farms and in one rural farm. Fifteen animals were detected positive by a VP1 nested PCR. The amplicons were molecularly characterised by complete genome sequencing. All positive samples obtained in this study were from the rural farm, whereas the industrial farms sampled were negative. Nucleotide and amino acid sequence analyses showed a high degree of similarity among the sequences obtained, suggesting the circulation of a single CIAV strain in the positive lot. Phylogenetic analysis based on the CIAV VP1 nucleotide sequence and/or the complete genome showed that the sequences obtained in this study clustered with CIAV strains previously detected in Tunisia, Italy and Egypt, belonging to genogroup II. Our results highlight the need for constant CIAV surveillance in backyard chicken production