Avian infectious bronchitis and deep pectoral myopathy - a case control study

Area of Science:

• Veterinary Virology
• Poultry Pathology
• Molecular Diagnostics

Background:

• Infectious bronchitis virus (IBV) causes significant economic losses in poultry.
• Deep pectoral myopathy (DPM) in broilers is a lesion associated with IBV variants, leading to meat condemnation.
• Understanding the relationship between IBV and DPM is crucial for disease management.

Purpose of the Study:

• To investigate the association between IBV infection and deep pectoral myopathy in broilers.
• To compare the frequency of IBV detection in different tissues (trachea, muscle, cecal tonsils) of broilers with and without DPM.
• To describe tracheal and muscle histopathological findings in relation to DPM.

Main Methods:

• A case-control study involving 40 broiler flocks, with 23 flocks exhibiting DPM (cases) and 17 without (controls).
• Samples of trachea, cecal tonsil, and supracoracoid muscle were collected for reverse-transcription (RT-PCR) analysis to detect IBV.
• Histopathological examination of muscle and tracheal tissues was performed.

Main Results:

• Histopathology confirmed myopathy in case group muscles, characterized by necrosis and inflammation, while control muscles were normal.
• Tracheal samples showed mononuclear inflammatory cell infiltration and nodule formation in some cases.
• IBV was detected by RT-PCR in 25 out of 40 flocks; IBV was detected directly in muscle samples. No statistically significant association was found between IBV and DPM.
• Higher IBV detection rates were observed in cecal tonsil samples, highlighting organ-specific diagnostic importance.

Conclusions:

• The direct causal relationship between IBV and deep pectoral myopathy in this study was not established.
• IBV can be detected in muscle tissue, but cecal tonsils may offer higher diagnostic sensitivity for IBV detection.
• The findings underscore the importance of selecting appropriate tissues for accurate IBV diagnostics in broiler flocks.