Girma ZewdeFanta Desissa2026-08-072026-08-072010-06-01https://etd.aau.edu.et/handle/123456789/8814A cross- sectional Study was conducted from October 2009 to March 2010 with the main objcctive to assess quantitatively the risk of consuming informally marketed milk contaminated with Staphylococcus aureus in Debre-zeit. The study employed a participatory risk assessment following the method recommended by the Codex Alimentarius Commission.Rapid rural appraisal and key informants interview with pre tested questionnaire were used to generate data on milk handling, quantity of milk produced and consumed and the habits of milk consumption.A deterministic model was developed to assess quantity of milk contaminated with S. aureus using data on prevalence of S. aureus in farm bulk milk and collection centers bulk milk, raw milk consumption habit, milk handling practices and quantity of milk at the point of exposures along the dairy value chain as risk inputs. Monte Carlo Simulation was used to simulate the quantity and proportion of milk contaminated with Staphylococcus aureus entero-toxin (SEs). Two hindered fifteen milk samples and two hundred eighteen participants were included in the study. The milk samples comprised raw farm bulk milk (170), milk collection centers bulk milk (25) and pastcurized milk (20). The participants included 170 dairy farmers, 14 milk collectors, 25 consumers, l production manager at processing plant and 8 hotel managers. The result showed 44%;72 % and 0% prevalence of S. aureus in farm bulk milk, milk. collection centers bulk tank milk.and pasteurized milk respectively. Comparison of the contamination rate of farm bulk milk with S.aureus among different collection centers showed statistically a significant differences (x2 =31.784,df=13, p=0.003). The milk produced and collected in peri-urban areas was significantly more contaminated with S. aureus (25/39, 64.1%) than milk produced and collected in urban areas (50/131, 38.2%) (x2=7.18, df= l, p=0.007). About 24,000 L of milk was estimated to be produced per day in and around DZ of which around 23% (5,500 L) milk was collected by Ada dairy cooperative society from the cooperative members. The survey result showed that 32% of the dairy producers and 36% of the consumers had the habit of consuming raw milk. The behavior of raw milk consumption was most common in illiterate group (62.9%) and the proportion was significantly higher than the other education level groups (p=0.0145). Risk factors for consumption or raw milk among dairy producers such as income, education level, location of farm and knowledge staphylococcal poisoning were considered. Among these, only residing in peri-urban areas was a risk factor for consuming raw milk (p<0.001). The study showed that 166.7 L (90%CI:125.2-213.6), which is 0.7% (90% CI: 0.5-0.8) of the lotal daily production and everyday, 333 (90% CI: 250-427) people could acquire Staphylococcal poisoning in the urban areas of Debre Zeit Despite the limitations and the data gap, we demonstrated the benefit of participatory risk assessment not only as a risk evaluation tool but also as a helping device in the decision-making and the risk managementenRiskdeterministic modelMonte CarloBulk milkDairy value chainDebre-ZebreS. AureusThesis