Estimation of the spread of pathogenic mycobacteria in organic broiler farms by the polymerase chain reaction.

Organic poultry breeding allows for increased exposure of birds to soil, faeces, and wildlife, which have been associated with the transmission of mycobacterial infections. Therefore the aim of this study was to investigate the spread of the major pathogenic mycobacteria in organically reared broilers in Greece using a diagnostic algorithm that relied on a combination of the polymerase chain reaction (PCR) and the restriction fragment length polymorphism analysis (RFLP). Liver, spleen and gonads from 81 to 150 days old broilers were aseptically collected post-mortem. 500 broilers from a population of 35,370, reared in the 25 registered as organic farms in Greece for the 2005 were used. DNA was isolated and incorporated to PCR targeted to 16S-rRNA gene (for Mycobacterium spp.), IS6110 (for Mycobacterium tuberculosis complex-MTBc), IS1245 (for Mycobacterium avium complex-MAC), IS901 (for M. avium subsp. avium-MAA) and hsp65 (for Mycobacterium genavense, by PCR-RFLP). The mean prevalence of mycobacteria detected by PCR with a 95% confidence interval was estimated to 4.4-8.8%. The relevant percentage with regard to the mycobacterial species that were included in this study was 0.17-2.03% for MAC, 2.11-3.39% for MTBc and 0.66-3.08% for mycobacteria not belonging to any of the above groups. None of the mycobacteria detected were identified as MAA or M. genavense. Considering that avian tuberculosis has been eradicated from conventional farms, the level and the pattern of positivity recorded here, indicates that our results may be associated with the specific conditions that apply to organic breeding.

Outbreak of avian mycobacteriosis in a flock of two-year-old domestic pigeons (Columba livia f. domestica).

This report describes an outbreak of avian mycobacteriosis in a flock of 100 two-yr-old pigeons. Over a 6-mo period, the sick pigeons showed cachexia followed by death. In Columbiformes classic tubercles rarely develop, but in these affected pigeons granulomatous nodular lesions of various sizes, containing numerous acid-fast bacilli, were found in the internal organs. The lesions were observed in the liver, spleen, intestine, bone marrow, ovary, and oviduct. Despite their breeding age, atrophy was also found in the ovary and oviduct. Microorganisms belonging to Mycobacterium avium complex were identified in the affected tissues by polymerase chain reaction.