Hyera, EmilMsalya, GeorgeKarimuribo, Esron D.Kurwijila, Lusato R.Alonso, SilviaRoesel, KristinaGrace, Delia2026-09-292026-09-292016https://www.suaire.sua.ac.tz/handle/20.500.14820/7957Isolation and Identification of Listeria Species along the Milk Value Chain in one region of TanzaniaIntroduction The genus Listeria contains gram positive, non-spore forming, catalase-positive, oxidase-negative and facultative anaerobic bacteria. Two species are pathogenic of which L. monocytogenes represents the only pathogen of public and veterinary health significance and L. ivanovii is usually restricted to causing disease in ruminants. L. monocytogenes causes large outbreaks of Listeriosis in humans, with a mortality rate of 9 – 44%. Most cases are foodborne related and consumption of unpasteurised milk and dairy products is the major means of zoonotic transmission. Currently, there is no information in available literature on the presence of Listeria along the milk value chain in Tanzania. In this study, the awareness of milk contamination was evaluated, total plate count (TPC) was quantified and isolation of Listeria species was attempted along the milk value chain in two districts of Tanga region in Tanzania. Methods Study sites included five villages in Handeni district and five villages in Lushoto district. In total, 114 respondents were interviewed on awareness and strategies for solving the problem of milk contamination. Then, raw milk samples were aseptically collected from each of the 114 respondents for laboratory analyses using the standard ISO procedures for food microbial analyses — Horizontal methods. Four tests i.e. haemolysis on a sheep blood agar, CAMP, oxidase and Listeria test kit were carried out to confirm the presence of L. monocytogenes and other Listeria spp. in test samples against control cultures. Data were analysed for descriptive statistics and Chi-square using the Statistical Package for Social Sciences (SPSS) version 17.0. TPC values were analysed against independent variables using the General Linear Models (GLM) procedures of the Statistical Analysis System (SAS) version 9.1 for Windows. Survey showed poor hygienic practices by the majority of actors. Most of the farmers were skipping most of the important safe hand milking steps. Few (11.8%) households were keeping cattle in well-designed and clean shelters. Only, 12.9% of households and 11.1% of restaurateurs were using Aluminium vessels/stainless steel containers for milk handling. Furthermore, very few cooling facilities were observed along the milk value chain as presented in Table 2. Results About 90 percent of all raw milk samples processed showed TPC above standard acceptable in the Eastern Africa countries (EAC) of 2.0x10 5 CFU/ml (Grade 2). Also, there was more contamination in milk samples obtained from the household farms than those which were collected from the milk suppliers and in the extensive farming system than in the intensive system (P < 0.05). Three Listeria species namely L. innocua (11.4%), L. ivanovii (1.7%) and L. monocytogenes (42.1%) were identified. L. monocytogenes were isolated and identified as the common contaminants in milk along the value chain in the study region (Table 1). Conclusion Poor bacteriological quality of milk indicates poor animal husbandry practices and poor milk handling practices. Presence of L. monocytogenes in milk provides evidence on the microbial status of milk in the Tanzanian milk value chain and insights into the magnitude and public awareness on the health risks associated with consumption of raw milk. To ensure milk safety, the awareness of actors must be improved through training on animal husbandry practices and public education on general hygienic practices in milk. Also, Sector policies, organizational structures and support services must be well concentrated to stimulate dairy development.enListeria speciesMilk value chainL. monocytogenesL. ivanoviiDairy productsArticle