Prevalence of Mycoplasma Infections in Sheep and Goats in Jiangsu, China
Authors: Cheng Cheng , Qiu Tian , Tao Jianping , Cheng Darong 
Published: December 2024

Background: Mycoplasma infections are widespread globally, causing respiratory and extrapulmonary diseases in animals, particularly in sheep and goats. Symptoms include coughing, nasal discharge, respiratory distress, and pneumonia. Several Mycoplasma species like Mycoplasma ovipneumoniae (MO), Mycoplasma capricolum ssp. capripneumoniae (MCCP), Mycoplasma mycoides ssp. capri (MMC), and Mycoplasma arginini (MA) are identified as causes. MA was first identified in sheep with respiratory diseases in 1972, and its presence has been consistently reported. In China, MA isolation from respiratory samples was achieved in 1991, correlating with pulmonary lesions. Sheep and goats are economic resources in China. In recent years, China encourages the sheep and goat breeding model to convert into scale. Nevertheless, sheep and goats farming are threatened by Mycoplasma, which greatly slowed down the production. Currently, there is a scarcity of data and reports regarding Mycoplasma infection in sheep and goat farming in Jiangsu province. This study aims to determine the prevalence and species of Mycoplasma in sheep and goats in Jiangsu province. The results may contribute to the prevention and control of Mycoplasma infection in Jiangsu region, and will also expand our understanding of the distribution of these respiratory diseases in sheep and goats.
Materials, Methods & Results: The study collected 920 nasal swab samples from sheep and goats in six cities in Jiangsu province. Following sample processing, DNA extraction was carried out using the lysis boiling method for both clinical samples and reference strains. Subsequently, PCR amplification was conducted utilizing universal and specific primers to detect and identify Mycoplasma species. Finally, the positive PCR products underwent sequencing and were compared for phylogenetic analysis. The results show that through using PCR specific primers to amplify genes associated with the Mycoplasma, 109 (11.85%) were confirmed to be Mycoplasma positive out of 920 samples that were collected from clinically diseased (470) and healthy (450) sheep and goats from Jiangsu province, China. 109 positive samples were obtained and classified as MO in 78.9% and MA in 21.1%. No MCCP and MMC were detected, and there was no evidence of mixed Mycoplasma infection. The phylogenetic analysis of the partial sequences of positive samples based on the MO p113 gene and MA ADI gene showed a high degree of similarity with some sequences of Mycoplasma in GenBank.
Discussion: Among clinically healthy animals, 28 out of 450 samples (6.22%) tested positive, while among those with respiratory diseases, 81 out of 470 samples (17.23%) were positive, indicating a higher risk of respiratory disease in infected sheep and goats. Mycoplasma was found even in asymptomatic sheep and goats, suggesting it may not be the sole cause of respiratory symptoms. Immunized animals had lower infection rates, indicating some effectiveness of current vaccines, though overall efficacy remains modest. Regional variations in infection rates may stem from differences in vaccination and hygiene practices. Out of 109 positive samples, 86 were identified as MO infection and 23 as MA infection, while no infections of MCCP and MMC were detected. In this study, MO isolates lacked a central umbilicus in colonies, while MA isolates resembled "fried egg like" morphology. MO P113 gene sequencing revealed lower homology (86.0%) with certain strains compared to ATCC 29419, GZ-QX1, and NCTC 10151. This discrepancy could be ascribed to genetic mutations or disparities in pathogenic strains. MA ADI gene sequencing showed high homology (> 99.1%) with ATCC 23838, NCTC 10129, and HAZ145 strains. This indicates that prevalent Mycoplasma linked to respiratory diseases in Jiangsu province are MO and MA.
Keywords: ovine, caprine, small ruminants, Mycoplasma, epidemiology, sequencing, hylogenic analysis.