Laboratory Tests Revealed High Contamination of Raw Milk Sampled from Selected Nodes of the Dairy Value Chain in Mbulu District, Tanzania

Abstract

This study was carried to investigate the levels and types of microbial contamination in raw milk from selected nodes of the dairy value chain in Mbulu District, northeastern, Tanzania. A total of 185 raw milk samples were collected from dairy farmers, vendors, and restaurants across four wards namely Endagikot, Imboru, Hydom, and Dongobesh. The target bacteria were <i>Escherichia</i> (<I>E</I>.)<i> coli</i>, <i>Staphylococcus spp</i>., <i>Klebsiella </i>(<I>K</I>.) <i>pneumoniae</i>, and <i>Enterococcus </i>(<I>E</I>.) <i>faecalis</i>. A total of 185 milk samples were collected from dairy farms, vendors and restaurants across four wards. Total viable bacteria count and bacterial isolates were analysed using culture, biochemical test and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS. Contamination increased up the chain with the lowest mean bacterial load (7.78 × 10³cfu/ml) in milk samples collected directly from udder and the highest (2.09 × 10⁴cfu/ml) in farmers bulking containers. <I>E</I>. <i>coli</i> and <i>Staphylococcus spp</i>. were the most prevalent bacteria detected at rates of 32.1 and 17 percent respectively of total samples from the vendors as well as 18.9 and 17 percent of total samples collected directly from udder. The <I>E</I>. <i>faecalis</i> and K. <i>pneumoniae</i> were detected at much lower rates (3.77 and 1.89 percent respectively). The bacteria levels determined in the present study are sufficiently high to contribute to milk-borne illnesses among consumers. The findings highlight public health risks associated with poor hygiene practices, inadequate milk handling, and environmental contamination. Enhanced training for milk handlers, improved hygiene protocols and regular surveillance are recommended to ensure milk quality and safety.