Pathological and Molecular Investigation of Pasteurella multocida Infection in Romane Lambs in an Industrial Herd Around Tehran, Iran

Background: Pasteurellosis is one of the causes of acute respiratory disease and sudden death in neonatal and young lambs. Pasteurella multocida is a Gram-negative bacillus bacterium that is a common agent of ovine pneumonia, typically dealing with stress or immunosuppressive conditions. Early diagnosis is essential for epidemic control and herd management. Methods: During one lambing season in an industrial Romane herd located around Tehran, Iran, ۴۳ of ۲۵۶ lambs (۱۶.۸%) showed respiratory signs, and ۲۶ died (۱۰.۱%). Gross lesions included purulent exudate in the lungs and hepatic discoloration of pulmonary tissue. Samples were cultured on selective media and examined by PCR. For detection of the KMT۱ gene, primers KMT۱T۷ and KMTSP۶ (۴۶۰ bp amplimer) were used, while capsular type A was identified using primers CAPA-FWD and CAPA-REW (۱۰۴۴ bp amplimer). Lung tissue samples were processed and stained with H&E for histopathological evaluation. Results: P. multocida was confirmed by both bacterial culture and PCR in several samples. Histopathological examination revealed neutrophilic infiltration into alveoli, hemorrhage, and necrosis, which aligns with gross findings and confirms pneumonic pasteurellosis. Conclusion: This study demonstrates the significant impact of P. multocida infection in Romane lambs, causing notable morbidity and mortality. The use of necropsy, histopathology, and molecular diagnostics simultaneously provides a precise framework for field identification of the disease. Early detection and management of stressful conditions play a crucial role in reducing fatality rates.

کلیدواژه ها:

Pasteurellosis ، Pasteurella multocida ، lamb ، PCR ، histopathology