Food worker experiences with and beliefs about working while ill.

Transmission of foodborne pathogens from ill food workers to diners in restaurants is an important cause of foodborne illness outbreaks. The U.S. Food and Drug Administration recommends that food workers with vomiting or diarrhea (symptoms of foodborne illness) be excluded from work. To understand the experiences and characteristics of workers who work while ill, workplace interviews were conducted with 491 food workers from 391 randomly selected restaurants in nine states that participated in the Environmental Health Specialists Network of the Centers for Disease Control and Prevention. Almost 60% of workers recalled working while ill at some time. Twenty percent of workers said that they had worked while ill with vomiting or diarrhea for at least one shift in the previous year. Factors significantly related to workers having said that they had worked while ill with vomiting or diarrhea were worker sex, job responsibilities, years of work experience, concerns about leaving coworkers short staffed, and concerns about job loss. These findings suggest that the decision to work while ill with vomiting or diarrhea is complex and multifactorial.

Invasive listeriosis in the Foodborne Diseases Active Surveillance Network (FoodNet), 2004-2009: further targeted prevention needed for higher-risk groups.

BACKGROUND: Listeriosis can cause severe disease, especially in fetuses, neonates, older adults, and persons with certain immunocompromising and chronic conditions. We summarize US population-based surveillance data for invasive listeriosis from 2004 through 2009. METHODS: We analyzed Foodborne Diseases Active Surveillance Network (FoodNet) data for patients with Listeria monocytogenes isolated from normally sterile sites. We describe the epidemiology of listeriosis, estimate overall and specific incidence rates, and compare pregnancy-associated and nonpregnancy-associated listeriosis by age and ethnicity. RESULTS: A total of 762 listeriosis cases were identified during the 6-year reporting period, including 126 pregnancy-associated cases (17%), 234 nonpregnancy-associated cases(31%) in patients aged <65 years, and 400 nonpregnancy-associated cases (53%) in patients aged ≥ 65 years. Eighteen percent of all cases were fatal. Meningitis was diagnosed in 44% of neonates. For 2004-2009, the overall annual incidence of listeriosis varied from 0.25 to 0.32 cases per 100,000 population. Among Hispanic women, the crude incidence of pregnancy-associated listeriosis increased from 5.09 to 12.37 cases per 100,000 for the periods of 2004-2006 and 2007-2009, respectively; among non-Hispanic women, pregnancy-associated listeriosis increased from 1.74 to 2.80 cases per 100,000 for the same periods. Incidence rates of nonpregnancy-associated listeriosis in patients aged ≥ 65 years were 4-5 times greater than overall rates annually. CONCLUSIONS: Overall listeriosis incidence did not change significantly from 2004 through 2009. Further targeted prevention is needed, including food safety education and messaging (eg, avoiding Mexican-style cheese during pregnancy). Effective prevention among pregnant women, especially Hispanics, and older adults would substantially affect overall rates.

Sex-based differences in food consumption: Foodborne Diseases Active Surveillance Network (FoodNet) Population Survey, 2006-2007.

BACKGROUND: This analysis used data from the most recent Foodborne Diseases Active Surveillance Network (FoodNet) Population Survey (May 2006 through April 2007) to examine differences in the consumption of various types of foods between men and women. METHODS: Participants were surveyed by telephone and asked whether or not they had consumed certain foods in the past 7 days, including the following "high-risk" foods commonly associated with foodborne illness: pink hamburger, raw oysters, unpasteurized milk, cheese made from unpasteurized milk, runny eggs, and alfalfa sprouts. Data were weighted to adjust for survey design and to reflect the age and sex distribution of the population under FoodNet surveillance. RESULTS: A total of 14 878 persons ≥ 18 years were interviewed, of whom 5688 (38%) were men. A higher proportion of men reported eating meat and certain types of poultry than women, whereas a higher proportion of women ate fruits and vegetables. A higher proportion of men than women reported consuming runny eggs (12% versus 8%), pink hamburger (7% versus 4%), and raw oysters (2% versus 0.4%). A higher proportion of women than men ate alfalfa sprouts (3% versus 2%). No differences by sex were observed for consumption of unpasteurized milk or cheese. CONCLUSIONS: Data from the FoodNet Population Surveys can be useful in efforts to design targeted interventions regarding consumption of high-risk foods. Moreover, understanding the background rates of food consumption, stratified by sex, may help investigators identify the kinds of foods likely to be associated with outbreaks in which a preponderance of cases occur among members of one sex.

Flocculant-disinfectant point-of-use water treatment for reducing arsenic exposure in rural Bangladesh.

We introduced flocculant-disinfectant water treatment for 12 weeks in 103 households in Bangladesh to assess if drinking water would be chemically and microbiologically improved and the body burden of arsenic reduced. The median concentration of arsenic in tubewell water decreased by 88% after introduction of the flocculant-disinfectant from 136 microg/l at baseline to 16 (p < 0.001). The median concentration of total urinary arsenic decreased 42% from 385 microg/g creatinine at baseline to 225 microg/g creatinine after intervention (p < 0.001). Among 206 post-intervention drinking water samples that were reportedly treated on the date the sample was collected, 99 (48%) lacked residual free chlorine and 100 (49%) were contaminated with thermotolerant coliforms. The flocculant-disinfectant markedly reduced arsenic in drinking water, but treated drinking water was frequently contaminated with fecal organisms. The lesser reduction in urinary arsenic compared to water arsenic and the health consequences of this reduction require further research.

Listeria monocytogenes contamination patterns for the smoked fish processing environment and for raw fish.

Reliable data on the sources of Listeria monocytogenes contamination in cold-smoked fish processing are crucial in designing effective intervention strategies. Environmental samples (n = 512) and raw fish samples (n = 315) from two smoked fish processing facilities were screened for L. monocytogenes, and all isolates were subtyped by automated ribotyping to examine the relationship between L. monocytogenes contamination from raw materials and that from environmental sites. Samples were collected over two 8-week periods in early spring and summer. The five types of raw fish tested included lake whitefish, sablefish, farm-raised Norwegian salmon, farm-raised Chilean salmon, and feral (wild-caught) salmon from the U.S. West Coast. One hundred fifteen environmental samples and 46 raw fish samples tested positive for L. monocytogenes. Prevalence values for environmental samples varied significantly (P < 0.0001) between the two plants; plant A had a prevalence value of 43.8% (112 of 256 samples), and plant B had a value of 1.2% (3 of 256 samples). For plant A, 62.5% of drain samples tested positive for L. monocytogenes, compared with 32.3% of samples collected from other environmental sites and 3.1% of samples collected from food contact surfaces. Ribotyping identified 11 subtypes present in the plant environments. Multiple subtypes, including four subtypes not found on any raw fish, were found to persist in plant A throughout the study. Contamination prevalence values for raw fish varied from 3.6% (sablefish) to 29.5% (U.S. West Coast salmon), with an average overall prevalence of 14.6%. Sixteen separate L. monocytogenes subtypes were present on raw fish, including nine that were not found in the plant environment. Our results indicate a disparity between the subtypes found on raw fish and those found in the processing environment. We thus conclude that environmental contamination is largely separate from that of incoming raw materials and includes strains persisting, possibly for years, within the plant. Operational and sanitation procedures appear to have a significant impact on environmental contamination, with both plants having similar prevalence values for raw materials but disparate contamination prevalence values for the environmental sites. We also conclude that regular L. monocyrogenes testing of drains, combined with molecular subtyping of the isolates obtained, allows for efficient monitoring of persistent L. monocytogenes contamination in a processing plant.

Polymerase chain reaction-based methods for detection of Listeria monocytogenes: toward real-time screening for food and environmental samples.

A review is presented of nucleic acid amplification-based methodology, specifically polymerase chain reaction (PCR)-based assays, for the detection of Listeria monocytogenes in food and environmental samples. Until recently, developmental challenges including poor sensitivity, due in part to reaction inhibition by components of the sample matrix, and the potential for false-positive reactions have limited routine application of PCR-based screening assays. Commercial assays address these challenges while offering convenient, standardized protocols, a high level of automation, and results within 2 days after the sampling date. Although sample enrichment is necessary to achieve desired detection limits, continued efforts toward template purification will facilitate the development of assays offering real-time, quantitative results. The development of ribonucleic acid (RNA) amplification-based assays may increase in importance, particularly if end-product testing is prioritized by regulatory agencies, as messenger RNA appears to serve as an accurate indicator of cell viability. Further, the increase in target copy number may improve assay sensitivity. PCR-based screening methods offer efficient, reliable results and are ideal for monitoring the presence of L. monocytogenes in foods and in the food processing environment.

Polymerase Chain Reaction Assay Coupled with Fluorescence Detection on Microwell Plates for Listeria monocytogenes in Foods.

This study evaluates a polymerase chain-reaction assay coupled with fluorescence detection (PCR-FD) in microwell plates for Listeria monocytogenes in dairy and food samples. Guanidinium thiocyanate/silica-extracted cultures and milk and dairy-food samples were used as templates for a PCR assay in microwell plates, with a primer pair that amplifies a 221 bp segment of the internal transcribed spacer (ITS), in the presence of 0.5 µg/ml of ethidium bromide. Fluorescence of the PCR products was measured with a CytoFluor 2300 fluorescence measurement system (Millipore Corporation, Bedford, MA). The lowest level of detection of the assay was 10 to 100 CFU. A total of 326 food samples were tested, both by culture and by PCR-FD. The overall sensitivity of the PCR-FD assay was 95.2% and the specificity was 89.9%. Positive and negative predictive values were 74.8% and 99.4%, respectively. Based on the results obtained in this study it appears that the PCR-FD assay described here can be useful for screening a large number of milk and dairy-food samples for contamination by Listeria monocytogenes .