Assessment of exposure to staphylococcal enterotoxins genes by consumption of ready to consume milk products in milk shop outlets in Mbeya, Tanzania

This study assessed the exposure of humans to Staphylococcus species expressing the Enterotoxins genes (SEs) through consumption of boiled-milk-served-hot and fermented milk in Mbeya, Tanzania. A survey involving 120 consumers revealed that 67.5% of the respondents were buying raw milk from milk shops for home consumption. About 76% of respondents boiled milk before consumption, 14.8% ferment the milk after boiling and 5.8% consumed fermented milk without boiling. Children (30%) consumed milk more frequently than other members in the family. Among consumers who buy milk from the milk shops, 71% were daily consumers of both boiled milk served hot and fermented milk. Approximately, 1197 L (90% CI, 987-1416) of ready to consume milk was sold per day. Of which 860 L (90% CI, 645-1071) and 337 L (90% CI, 168-530) were boiled-milk-served-hot and fermented milk, respectively. Out of the ready to consume milk, 490 L (90% CI, 464-516) of boiled-milk-served-hot was contaminated with SEs gene compared to 77.5 L (90% CI, 67-88) of fermented milk. Daily 2394 people were consumers of milk and their products. Exposure assessment shows that the probability of consuming boiled-milk-served-hot and fermented milk contaminated with SEs gene at a milk shop was 0.42 (90% CI, 0.071-0.838) and 0.17 (90% CI, 0-0.62), respectively.  It was estimated that every day, 363 (90% CI, 341-385) and 58 (90% CI, 49-66) people were likely to consume boiled milk taken hot and fermented milk contaminated with SE gene, respectively. The finding shows that exposure to SEs gene was two times more likely to occur in people who consume boiled-milk-served-hot than in people who consume fermented milk (OR. 2.221 (90% CI, 0.6-6.16). Awareness creation on proper food handling among milk handlers to reduce contamination along the milk value chain is recommended.   Key words: Boiled milk served hot, foodborne disease, public health, fermented milk.