Prevalence of Salmonella spp. and Escherichia coli in raw milk value chain in Arusha, Tanzania

Abstract

This study aimed to investigate the prevalence of Salmonella spp. and Escherichia coli (E. coli) in milk value chain in Arusha, Tanzania. A total of 75 raw milk samples were collected from smallholder dairy farmers, street vendors and outlet shops in Arusha and Arumeru districts. A questionnaire survey was also used to assess hygienic practices along the chain. Salmonella and E. coli were detected in 28/75 (37.33%) and 68/75 (90.67%) samples, respectively. Bangata ward in Arusha showed relatively high prevalence of Salmonella spp. (42.11%) while Akeri ward in Arumeru showed relatively low prevalence (31.58%). In milk value chain, the highest prevalence was observed in street vendors (43.75%) while the lowest prevalence was in dairy farms (33.33%). Mean count for E. coli from milk producers, vendors and shops were 3.0 x 103 , 8 x 103 and 6.6 x 103 cfu/mL, respectively, indicating a significant (p < 0.05) increase in E. coli load along the chain. Furthermore, confirmatory test showed that Salmonella isolates were predominantly identified as Salmonella enterica serovar Arizonae. Besides, Salmonella and E. coli, other enterobacteria detected were Enterobacter cloacae, Klebsiella pneumonia, and Serratia marcescens. Taken together, qualitative and quantitative findings revealed that poor animal husbandry, poor hygienic practices, lack of refrigeration and less awareness of the zoonotic pathogens had a significant impact on the prevalence of detected bacteria, posing a public health risk.