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 ofEimeriaspp. 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%), andE.acervulina(1.5%). MixedEimeriaspecies 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.

Marek's disease (MD) is a contagious avian viral disease that is responsible for large economic losses to farmers. The disease is caused by Marek's disease virus (species Gallid alphaherpesvirus 2), which causes neurological lesions, immune suppression, and tumor proliferation of lymphoid cells that invade a large number of organs and tissues. Despite widespread vaccination, Marek's disease virus (MDV), has shown a continuous increase in its virulence and has acquired the ability to overcome immune responses induced by vaccines. In the present study, the oncogenic serotype MDV-1 was detected by real-time PCR in DNA samples extracted from organs developing tumor infiltrations. Identification of the pathotype based on a 132-bp tandem repeat and sequencing and phylogenetic analysis of the Meq gene and its encoded protein allowed classification of the isolated viruses as "very virulent", with two new and unique mutations in the Meq gene resulting in amino acid substitutions. Sequencing of pp38, vIl-8, UL1 and UL44 genes did not reveal any new mutations that were characteristic of the Tunisian isolates or correlated with virulence. These results raised concerns about the ability of HVT and CVI988 vaccines, which are currently used in Tunisia and other countries, to protect chickens against highly virulent virus strains.

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.

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

| The presence of ectoparasites on birds can lead to low productivity and eventually death. This study was carried out to identify and estimate the prevalence of ectoparasites of free-range poultry ( Gallus gallus ), in the Northeast of Tunisia. A total of 512 birds of both sexes and aged from 1.5 month to 24 months were examined and/or necropsied. Results showed that 19 ± 3.39% (98 birds), as overall prevalence, were infested by at least one parasite specie. Young animals were more infested (13 ± 2.91%) than adults (6 ± 2.05%). There was significant difference (P < 0.05) in prevalence found during rainy and cold seasons (winter: 24 ± 6.59%; spring: 23 ± 7.83%; autumn: 20 ± 7.87%). Six species of ectoparasite were identified in the present study. Cnemidocoptes mutans (8 ± 2.35%) was the most prevalent, followed by Menopon gallinae (6 ± 2.05%), Laminosioptes cysticola (3 ± 1.47%), tick larvae of Argas persicus (3 ± 1.47%), Echidnophaga gallinacea (3 ± 1.47%) and Menacanthus stramineus (2 ± 1.22%). Infestation by one species of ectoparasite (13 ± 2.91%) was more frequently than mixed infestation (6 ± 2.05%). On the basis of these results it could be suggested that, good management, biosecurity and the education of farmers could be a vital measures to keep free from ectoparasites and improve the productivity of the chicken.