Listeria monocytogenes and Other Listeria Species from Milk and Environmental Samples and Milk Safety Assessment in Selected Areas of Eastern Ethiopia

Introduction: Listeria monocytogenes is the most common cause of listeriosis in humans and animals, as a result of food and environmental contamination. Objectives: The objective of this study was to investigate the occurrence and associated risk factors of contamination of milk with L. monocytogenes and other Listeria species and assessing milk safety in selected areas of eastern Ethiopia Material and Methods: A cross-sectional study was conducted between November 2019 to April 2020 to isolate L. monocytogenes and other Listeria species from milk, milk products, and environmental sources and to conduct milk safety assessment. A total of 430 samples were collected from milk (n=166), milk products (n=64), and environmental sources (n=200) and examined microbiologically. Listeria species were isolated from the samples based on ISO11290 standard. Descriptive studies were also used to determine the hygienic status of the farms, safety practices of milk handlers, and milk handling and consumption habits. Results: The overall occurrence of Listeria species was 38.2% and specifically that of L. monocytogenes was 11.2% from samples of milk and environmental sources. The most frequently isolated Listeria species were L. inocua (11.6%), L. monocytogenes (11.2%), and L. grayi (4%). The results showed that cheese, vendor milk, cow milk, udder, and yogurt were significantly contaminated with L. monocytogenes with the proportion of 25%, 14%, 12.8% and 8.3%, respectively. From the 143 respondents, 87.5% dairy producers, and 82.1% milk vendors used plastic milk containers during milking and transporting the milk to market centers. In addition, 31.8% of the total respondents had a habit of consuming raw milk. The results revealed poor practices of milk hygiene and lack of formal training on milk hygiene, and low level of awareness on the contamination risk associated with the consumption of raw milk. Conclusion: Listeria monocytogenes was obtained from 11.2% of the milk and related samples assessed including environmental samples. Therefore, awareness should be created among stakeholders involved in milk production and handling practices on the method of quality milk production and marketing. Furthermore, the use of standardized procedures during milking and milk handling, provision of training on the best practices of milk and milk products handling and raising the level of awareness of people working with milk is mandatory and never to be ignored.