Making it Work: The Application of Time as a Public Health Control in the Field
* Time as a public health control (TPHC) is increasingly being recognized as a viable alternative to temperature control for potentially hazardous foods in the developed world.
* Considerable ambiguity remains, however, as to when and how TPHC should be applied at the field level.
* The author did not identify standardized methods for having health departments receive applications from food vendors, for evaluating such applications for approval or rejection once received, or for monitoring food products subsequent to such an approval.
* The author outlined a standardized approach to the application, assessment, and evaluation of potentially hazardous ready-to-eat food in initiatives for time as a public health control.
* A structured format for the application, approval, monitoring, and evaluation of potentially hazardous ready-to-eat foods by management and field personnel helps--improve consistency in the application of TPHC principles,--demonstrate due diligence (for environmental public health departments), and--relieve district environmental health officers (EHOs) from the pressures of having sole responsibility over the approval process.
* Historically, temperature control requirements (i.e., temperatures outside the 4[degrees]C-60[degrees]C[40[degrees]-140[degrees]F] bacterial growth "danger zone") have been enshrined in public health legislation to minimize the likelihood that bacteria will grow enough in potentially hazardous food to induce illness in susceptible human populations.
* Due in part to concerns voiced by the retail food industry and the public vis-a-vis such legislation, other factors are being considered in lieu of temperature as part of new food protection strategies to prevent microbial growth.
* Such determinants are based on applied science, risk assessment, and hazard analysis critical control point (HACCP) principles.
* While noted health agencies have pioneered the introduction of TPHC from the unofficial fringes of food safety into the mainstream of food protection initiatives, problems persist with the application of such initiatives at the field level.
* Many jurisdictions still lack the legislative means to recognize TPHC as a viable alternative to traditional temperature control approaches and even in areas where legislation is found, it is often inconsistently applied.
* Proprietors involved in the preparation and service of ethnic foods have often clashed with food safety regulations common to Canada, Australia, and the United Kingdom.
* The understanding and use of TPHC initiatives can allow health departments to permit a more traditional display of some food products under set conditions, whereby preserving both the quality and safety of these products.
* Where jurisdictions have allowed time rather than temperature alone as a means to help ensure food safety, conditions set by the regulatory body have included limiting the display of potentially hazardous foods at ambient room temperature to less than four hours, time labeling the product while on display, and discarding the food product at the end of that period.
* One of the greatest struggles encountered in the development of these standards was the selection of an initial inoculate for "modeling" for many of the specified pathogens.
* The inoculate of 1,000 org/g is selected for modeling purposes for two reasons.
* First, the value is consistent with related work, including the most recent version of FDAs Food Code.
* Second, common sense dictates that in cases where fewer than 1000 org/g may be considered an infectious dose, any introduction of the organism into the food product will likely be sufficient to cause illness irrespective of holding times and conditions, i.e., subsequent growth is of less importance compared to the introduction of the pathogen in the first place.
* The successful application of TPHC in commercial food establishments ultimately relies on a good working relationship between food establishment operators and local heath officials.
Cryptosporidiosis Outbreak in a Nassau County, Florida, Return Travel Group from Ireland, May 24, 2006 June 4, 2006
* The Nassau County Health Department (NCHD) in Florida investigated an outbreak of gastrointestinal (GI) illness in a returning choral group who toured Ireland from May 24 to June 4, 2006.
* A physician who traveled with the group reported gastrointestinal (GI) illness in approximately 19 of the 41 travelers with an onset period of 0-3 days after returning to Florida on June 4.
* The travel group, consisting predominantly of retirees, had performed at several churches and at a dinner theater in Ireland.
* NCHD administered a telephone questionnaire to 40 of the 41 group members to examine possible water exposures; common meals; and food, travel, and clinical histories.
* The results of the questionnaire showed that 29 people met the case definition for the outbreak.
* The mean age of the travel group members was 64.8 years (range: 23-79 years).
* All 40 were non-Hispanic Caucasians.
* Twenty-five (62.5%) were female, 15 (37.5%) were male.
* Travel group members who returned on the group flight on June 4 were classified as Group 1 (32 persons).
* Travel group members who stayed in Europe and did not return to the United States on June 4 were classified as Group 2 (9 persons).
* Twenty-four members of Group 1 and five of the eight people surveyed in Group 2 met the case definition for GI illness.
* The attack rate in Group 1 was 75% compared to 62.5% in Group 2.
* The similar attack rates in the two groups supports the hypothesis that the group exposure did not occur on the return flight on June 4.
* The mean duration of illness was 4.6 days.
* Cases reported a mean of 4.5 symptoms.
* Group members stayed at the same four hotels and had a group meal plan that included breakfast at the hotels and five group dinners.
* The group dinners were held at the four hotels and also at a dinner theater restaurant prior to their choral performance.
* NCHD was informed by the trip organizers that the travel group had exposure to water that may have come from a private well while at the dinner theater restaurant.
* This group meal occurred on May 31 at a 150-year-old establishment in rural Killarney, Ireland.
* Several of the travel group members reported that farm animals and horses were located on the premises.
* During the dinner, travelers had a choice of either water or an alcoholic beverage; soft drinks were not available.
* Many travelers chose to drink water since they were performing later that night.
* The analysis of survey data showed a strong association between the consumption of drinking water at the dinner theater restaurant and developing GI illness.
* The dinner occurred seven days before the peak of the onset dates, which is consistent with the incubation period of Cryptosporidium.
* The risk for the exposed group was 96.6% and the risk for the unexposed was 16.7%.
* The risk ratio was 5.79, suggesting that those who drank water at the dinner theater restaurant were 5.8 times more likely to develop illness than those who did not.
* The overall risk of drinking water and developing GI illness was 82.9%.
* The sanitation inspector in Ireland reported that the dinner theater had an approved public water system and that the dinner theater restaurant's proprietor had both a private well (reportedly used for personal needs only) and a publicly regulated water source (for restaurant operations).
* The inspector reported that the restaurant's proprietor stated that only the public water source was used for restaurant operations.
* The epidemiological data obtained in the investigation, laboratory analysis, incubation periods, and exposure possibilities suggest that the infection was acquired in Ireland and that the drinking water exposure is a plausible hypothesis for the source of the infection.
* However, the exact source of the infection and the transmission mechanism cannot be confirmed.
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|Publication:||Journal of Environmental Health|
|Date:||Sep 1, 2008|
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