Raw milk consumption behaviour and assessment of its risk factors among dairy producers in urban and peri-urban areas of Debre-Zeit, Ethiopia: Implication for public health

A cross-sectional study was conducted from October 2009 to March 2010 in order to assess the risk to public health associated with raw milk consumption. The study investigated raw milk consumption behaviour, factors associated with the consumption of raw milk and milk handling practices among dairy farming communities in urban and peri urban areas of Debre-Zeit. A total of 170 dairy farmers were surveyed. Whether the levels of education, income, urbanisation and awareness of milk borne diseases could be associated with raw milk consumption was tested by statistical analyses. Of the 170 participants, 54 (31.8%) producers had a habit of consuming raw milk. The proportion of dairy farmers consuming raw milk was significantly higher in peri urban areas (94.8 %) than in urban areas of Debre-Zeit (13.0 %, 2=89.3, df=1, OR=124.1, p < 0.001). Of the factors tested, only residing in peri urban areas was significantly associated with consumption of raw milk (p < 0.001). All, 29.4% and 19.4% of the farmers included in this study used plastic containers for transporting, milking and storing milk, respectively. The proportion of farmers who stored milk at room temperature (46.5 %) was significantly higher than those who stored at refrigeration temperature (24.1 %, 2=13.9, df=2, p = 0.001). Storage of milk at room temperature for more than 24 hours for milk fermentation was a common practice among those who did not boil milk for consumption (82.0%, 41/50). The majority of the 170 dairy farmers (85.6 %) were unaware of milk borne diseases associated with consumption of raw milk. The study showed that the habit of raw milk consumption, poor milk handling practices and inadequate knowledge of milk borne diseases among dairy producers imply the risk of milk borne diseases in the study area

Contamination of informally marketed bovine milk with Staphylococcus aureus in urban and peri urban areas of Debre-Zeit, Ethiopia

A cross-sectional study was conducted from October, 2009 to March, 2010 to assess the level of contamination of informally marketed milk with Staphylococcus aureus at farms and milk collection centers in Debre-Zeit, Ethiopia. One hundred and seventy raw farm bulk milk samples, 25 mixed bulk milk samples and 20 pasteurized and packaged milk samples were collected from 14 milk collection centers and isolation and identification of S. aureus were carried out following standard method. S. aureus was isolated from 44% of farm bulk milk and 72% of milk collection centers’ bulk milk and it was not detected from pasteurized milk samples. Contamination rates of farm bulk milk with S. aureus were significantly different among the collection centers (c2 = 31.8, df = 13, p = 0.003). The milk produced and collected in peri-urban areas was significantly more contaminated with S. aureus (64%) than milk produced and collected in urban areas (38%) (c2 = 7.18, df = 1, p = 0.007). The frequency of isolation of S. aureus in milk collection centers bulk milk varied between 67 and 100% among collection centers. However, the contamination rates were not significantly different among these collection centers (c2 = 1.5, df = 4, p = 0.83). The overall contamination rate at collection centers (72%) was significantly higher than that at the farm level (33%, c2 = 10.6, df = 1, p = 0.001). Overall, the study revealed that milk produced and collected in and around Debre-Zeit was found to be contaminated with S. aureus, raising the issue of quality control and improving the safety of milk to safeguard the consumer from associated health problems and enabling the producers to earn much more from milk sale

Isolation and identification of Staphylococcus aureus from informally marketed bovine milk in urban and peri urban areas of Debre Zeit

A cross-sectional study was conducted from October 2009 to March 2010 to assess the level of contamination of informally marketed milk with Staphylococcus aureus at farms and milk collection centers in Debre Zeit, Ethiopia. One hundred seventy raw farm bulk milk, 25 mixed bulk milk samples and 20 pasteurized and packaged milk samples were collected from 14 milk collection centers and isolation and identification of S. aureus were carried out following standard method. S. aureus was isolated from 44 % of farm bulk milk and 72 % of milk collection centers’ bulk milk and it was not detected from pasteurized milk samples. Contamination rates of farm bulk milk with Staphylococcus aureus were significantly different among the collection centers where samples were collected (x squared=31.8, df=13, p=0.003).The milk produced and collected in peri-urban areas was significantly more contaminated with S. aureus (64%) than milk produced and collected in urban areas (38%) (x squared=7.18, df=1, p=0.007). The frequency of isolation of S. aureus in milk collection centers bulk milk varied between 67% and 100% among collection centers. However, the contamination rates were not significantly different among these collection centers (x squared= 1.5, df=4, p=0.83). The overall contamination rate at collection centers (72%) was significantly higher than that at the farm level (33%, x squared=10.6, df=1, p=0.001). Overall, the study revealed that milk produced and collected in and around Debre Zeit was found to be contaminated with S. aureus, raising the issue of quality control and improving the safety of milk to safeguard the consumer from associated health problems and enabling the producers to earn much more from milk sale

Risk assessment of staphylococcal poisoning due to consumption of informally-marketed milk and home-made yoghurt in Debre Zeit, Ethiopia

The objectives of the study were twofold: to prove that participatory risk assessment can be applied to informally-marketed foods, and to assess the risk of staphylococcal poisoning through consumption of raw milk and home-made yoghurt in Debre Zeit, Ethiopia. Rapid urban appraisals were combined with conventional interviews to identify and quantify formal and informal milk value chains and to collect information on consumers’ food preparation and consumption behavior. Milk was sampled in 170 dairy farms and 5 milk collection centres and microbiological tests were conducted. Published data on milk fermentation in Ethiopia was combined with a growth model of Staphylococcus aureus to develop a stochastic risk model. The annual incidence rate of staphylococcal poisoning was estimated to be 20.0 (90% CI: 13.9-26.9) per 1,000 people. When the effect of fermentation was removed from the model, the annual incidence rate increased to 315.8 (90% CI: 224.3-422.9) per 1,000 people, showing the importance of traditional food preparation methods in risk mitigation; traditional milk fermentation reduced the risk by 93.7%. Improving the safety of milk and dairy products could be achieved through supporting appropriate traditional food preparation and consumption where an industrial risk mitigation system is not feasible. Participatory risk assessment was shown to be applicable to informal food value chain

Propagation and arrest of dikes under topography: Models applied to the 2014 Bardarbunga (Iceland) rifting event

Dikes along rift zones propagate laterally downslope for tens of kilometers, often becoming arrested before topographic reliefs. We use analogue and numerical models to test the conditions controlling the lateral propagation and arrest of dikes, exploring the presence of a slope in connection with buoyancy and rigidity layering. A gentle downslope assists lateral propagation when combined with an effective barrier to magma ascent, e.g., gelatin stiffness contrasts, while antibuoyancy alone may be insufficient to prevent upward propagation. We also observe that experimental dikes become arrested when reaching a plain before opposite reliefs. Our numerical models show that below the plain the stress field induced by topography hinders further dike propagation. We suggest that lateral dike propagation requires an efficient barrier (rigidity) to upward propagation, assisting antibuoyancy, and a lateral pressure gradient perpendicular to the least compressive stress axis, while dike arrest may be induced by external reliefs