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Prevalence data were collected from official microbiological records monitoring four selected foodborne pathogens (Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, and Campylobacter jejuni) in raw milk sold by self-service vending machines in seven Italian regions (60,907 samples from 1,239 vending machines) from 2008 to 2011. Data from samples analyzed by both culture-based and real-time PCR methods were collected in one region. One hundred raw milk consumers in four regions were interviewed while purchasing raw milk from vending machines. One hundred seventy-eight of 60,907 samples were positive for one of the four foodborne pathogens investigated: 18 samples were positive for Salmonella, 83 for L. monocytogenes, 24 for E. coli O157:H7, and 53 for C. jejuni in the seven regions investigated. No significant differences in prevalence were found among regions, but a significant increase in C. jejuni prevalence was observed over the years of the study. A comparison of the two analysis methods revealed that real-time PCR was 2.71 to 9.40 times more sensitive than the culture-based method. Data on consumer habits revealed that some behaviors may enhance the risk of infection linked to raw milk consumption: 37% of consumers did not boil milk before consumption, 93% never used an insulated bag to transport raw milk home, and raw milk was consumed by children younger than 5 years of age. These results emphasize that end-product controls alone are not sufficient to guarantee an adequate level of consumer protection. The beta distribution of positive samples in this study and the data on raw milk consumer habits will be useful for the development of a national quantitative risk assessment of Salmonella, L. monocytogenes, E. coli O157, and C. jejuni infection associated with raw milk consumption.

For more than 30 yr, a control plan for Streptococcus agalactiae and Staphylococcus aureus has been carried out in more than 1,500 dairy herds of the province of Brescia (northern Italy). From 2010 to 2011, the apparent prevalence of Strep. agalactiae has been relatively stable around 10%, but the apparent prevalence of Staph. aureus has been greater than 40% with an increasing trend. The aim of this paper was to estimate and compare the diagnostic accuracy of 3 assays for the detection of Strep. agalactiae and Staph. aureus in bulk-tank milk samples (BTMS) in field conditions. The assays were a qualitative and a quantitative bacteriological culture (BC) for each pathogen and a homemade multiplex real-time PCR (rt-PCR). Because a gold standard was not available, the sensitivities (Se) and specificities (Sp) were evaluated using a Bayesian latent class approach. In 2012 we collected one BTMS from 165 dairy herds that were found positive for Strep. agalactiae in the previous 2-yr campaigns of eradication plan. In most cases, BTMS collected in these herds were positive for Staph. aureus as well, confirming the wide spread of this pathogen. At the same time we also collected composite milk samples from all the 8,624 lactating cows to evaluate the within-herd prevalence of Strep. agalactiae. Streptococcus agalactiae samples were cultured using a selective medium Tallium Kristalviolette Tossin, whereas for Staph. aureus, we used Baird Parker modified medium with added Rabbit Plasma Fibrinogen ISO-Formulation. In parallel, BTMS were tested using the rt-PCR. Regarding Strep. agalactiae, the posterior median of Se and Sp of the 2 BC was similar [qualitative BC: Se=98%, posterior credible interval (95%PCI): 94-100%, and Sp=99%, 95%PCI: 96-100%; quantitative BC: Se=99%, 95%PCI: 96-100%, and Sp=99%, 95%PCI: 95-100%] and higher than those of the rt-PCR (at 40 cycle threshold, Se=92%, 95%PCI: 85-97%; Sp=94%, 95%PCI: 88-98%). Also in case of Staph. aureus, the posterior medians of BC were generally higher than those of rt-PCR. In fact, although the Se of BC was slightly lower (rt-PCR at 40 cycle threshold, median Se=99%, 95%PCI: 97-100%, and qualitative BC, median Se=94%, 95%PCI: 87-99%), the Sp was much higher (rt-PCR at 40 cycle threshold, median Sp=67%, 95%PCI: 38-97%; qualitative BC, median Sp=95%; 95%PCI: 76-100%). Our study confirms that BC and rt-PCR are reliable diagnostic tools to detect Strep. agalactiae and Staph. aureus, and rt-PCR results should be confirmed by BC carried out on BTMS and possibly on composite milk samples.

Two quantitative risk assessment (RA) models were developed to describe the risk of salmonellosis and listeriosis linked to consumption of raw milk sold in vending machines in Italy. Exposure assessment considered the official microbiological records monitoring raw milk samples from vending machines performed by the regional veterinary authorities from 2008 to 2011, microbial growth during storage, destruction experiments, consumption frequency of raw milk, serving size, and consumption preference. Two separate RA models were developed: one for the consumption of boiled milk and the other for the consumption of raw milk. The RA models predicted no human listeriosis cases per year either in the best or worst storage conditions and with or without boiling raw milk, whereas the annual estimated cases of salmonellosis depend on the dose-response relationships used in the model, the milk storage conditions, and consumer behavior in relation to boiling raw milk or not. For example, the estimated salmonellosis cases ranged from no expected cases, assuming that the entire population boiled milk before consumption, to a maximum of 980,128 cases, assuming that the entire population drank raw milk without boiling, in the worst milk storage conditions, and with the lowest dose-response model. The findings of this study clearly show how consumer behavior could affect the probability and number of salmonellosis cases and in general, the risk of illness. Hence, the proposed RA models emphasize yet again that boiling milk before drinking is a simple yet effective tool to protect consumers against the risk of illness inherent in the consumption of raw milk. The models may also offer risk managers a useful tool to identify or implement appropriate measures to control the risk of acquiring foodborne pathogens. Quantification of the risks associated with raw milk consumption is necessary from a public health perspective.