Reflections on a career in public health: evolving foodborne pathogens, environmental health, and food safety programs.

Events affecting environmental health and food safety policy, programs and organization and emerging or identified foodborne diseases are reviewed by decade. The review starts with the impact of the 1940s war years on environmental sanitation, as it was called, and disease control. It continues with the intensifying disease surveillance and improvements in sanitation of the 1950s and the improvements in foodborne-disease surveillance and the reorganization of environmental programs of the 1960s. Many previously unknown foodborne pathogens were identified, and more changes in environmental policy came about in the 1970s. Evaluation of foodborne-disease control measures were initiated. In the 1980s, evaluation of major foodborne-disease problems came to the forefront. In the 1990s, the media and consumer groups became aware of foodborne-disease problems and concerned with the environment. The first decade of the 21st century will be faced with continuing dilemmas posed by emerging diseases and will need to provide solutions through the balancing of science, education, and politics.

Where we are in retail food safety, how we got to where we are, and how do we get there?

Food safety has not yet been attained. This is evident from reported foodborne-disease outbreaks, laboratory-confirmed cases of diseases that can be foodborne, estimates of foodborne illness based on surveillance data, and out-of-compliance risk factors. Several activities have had an impact on food safety, but there are limitations in the way each of those activities has been or is being conducted. The activities include foodborne-disease surveillance; food sampling and testing; swabbing and testing of utensils; inspection and enforcement of regulations; use of the Food Code; on-site hazard analyses, on-site monitoring of critical control points and prompt corrective actions; applied research and challenge testing; training of public-health and food regulatory personnel; training of food workers, supervisors, and managers; and education of the public. To attain food safety, we must use common (microbiological) sense and understand the principles of transmission of foodborne-disease etiological agents and their control. A change of attitudes and program focus is necessary.

Hazards and Critical Control Points of Food Vending Operations in a City in Zambia.

Hazard analyses were conducted at several cooked food vending operations in a large city in Zambia, near a downtown bus park and at a large market. Samples of raw, processed, and cooked foods sold on streets or by small food shops were collected and tested for common foodborne pathogens and indicator organisms. Results showed that some raw foods (ground meat, chicken, chicken intestine) or processed foods (dried minnows; kapenta) were contaminated by salmonellae or contained high populations of Staphylococcus aureus (pasteurized milk) or Bacillus cereus (caterpillars). Cooking usually gave time-temperature exposures that would have been lethal for vegetative forms of foodborne pathogens. Holding of foods other than nshima often provided time-temperature exposures conducive to microbial growth, particularly in foods held overnight. Large populations of aerobic mesophilic organisms, thermotolerant coliform bacteria, and sometimes Escherichia coli were recovered from these foods. Ten million Clostridium peifringens per gram were isolated from a sample of leftover beef stew. Large populations (> 105) of S. aureus were recovered from a sample of leftover chicken, and large populations of B. cereus (> 107) were isolated from leftover rice. Time-temperature exposures during reheating had variable effects in terms of killing the microorganisms that germinated from surviving spores or that reached the foods after cooking, but heat-stable toxins would not have been inactivated.

Hazards and Critical Control Points of Food Preparation in Homes in Which Persons Had Diarrhea in Zambia.

Following identification of some cases of diarrhea from persons who either sought treatment at a health clinic that served two townships near a large city in Zambia or got water from a deep protected well in one of the townships, hazard analyses were done of food preparation and storage practices at 17 homes. Samples of foods at various stages of preparation, foods held overnight, and drinking water were collected from the homes of the ill persons and were tested for common foodborne pathogens and indicator organisms. Salmonella was isolated from a sample of leftover kapenta (cooked dried minnows). Thermotolerant coliforms and Escherichia coli were isolated from water from shallow wells and a treated community supply. Although thermtolerant coliforms were not recovered from the protected well site, they were isolated from a sample of water collected in a home that used this supply. Several leftover foods, however, contained much larger populations of thermotolerant coliforms and larger populations of aerobic mesophilic organisms than the water. Furthermore, leftover nshima (boiled and whipped corn meal) and porridge contained large populations (>105) of Bacillus cereus per gram. Foods during cooking attained temperatures that would have been lethal to vegetative cells of foodborne pathogens. After cooking, they were subjected to time-temperature abuse during holding until eaten or while held overnight.

Hazards Associated with Holding and Reheating Foods at Vending Sites in a Small Town in Zambia.

Hazard analyses were done at 11 cooked-food-vending sites and related food-vending operations in a small-town market along a highway in Zambia. The analyses consisted of observations and time-temperature measurements at the vending sites and interpretations of results of laboratory tests of samples of foods (including leftovers) collected after holding and reheating. Salmonellae were isolated from dried ants, a cooked meatball on display, and pumped river water used by the vendors. Ants for sale at the market contained 107 Bacillus cereus cells per g. Nshima (boiled maize meal) was held at high temperatures in pans over glowing charcoal in which steam was generated throughout the entire holding period during the day, preventing bacterial growth. Large populations of B. cereus , however, were isolated from a sample left overnight at ambient room temperature. Cooked foods other than nshima were held at room or outdoor ambient temperatures throughout the day and overnight. High aerobic mesophilic colony, thermotolerant coliform and, in a few foods, Escherichia coli counts were found in foods after several hours of holding during the day of preparation and of foods held overnight. Temperatures attained during reheating were variable and sometimes would have resulted in survival of foodborne pathogens that multiplied during holding.

Surveillance of Foodborne Disease IV. Dissemination and Uses of Surveillance Data.

Comparisons of etiologic agents, vehicles, significant ingredients, place of mishandling, and method of food processing or preparation with specific contributory factors are particularly useful in identifying specific hazards, specifying operations that are candidates for designation as critical control points, and assessing risks. After foodborne disease surveillance data have been received, tabulated, and appropriately interpreted, summary information needs to be disseminated in a timely fashion to those who can use it for preventing foodborne diseases. This action should be taken at all levels of the surveillance network. Surveillance information is used to determine the need for food safety actions, which involves planning and implementing programs and assessing the effectiveness of the actions taken. Uses of the data include (a) developing new policies and procedures and revising priorities, (b) evaluating effectiveness of programs, (c) justifying food safety program budgets based on estimated costs offoodborne illness, (d) modifying regulations so that they relate to contemporary foodborne disease issues, (e) conducting hazard analyses and risk assessments and instituting programs oriented to hazard analysis critical control points (HACCP), (f) starting or improving a public information campaign and educating the public, (g) notifying and training food industry personnel, (h) training agency staff and public health students and professionals, and (i) identifying new problems and research needs from the data. Implementing these approaches will necessitate changes in traditional food safety activities. This four-part series of articles concludes with recommendations to be considered by local, state/provincial, national, and international agencies responsible for foodborne disease surveillance.

Surveillance of Foodborne Disease III. Summary and Presentation of Data on Vehicles and Contributory Factors; Their Value and Limitations.

Foodborne disease outbreak data are collected, collated, interpreted and disseminated to improve food safety programs at all organizational levels. Part II of this series described the disease aspects of foodborne surveillance. This part (III) focuses on the food components, with collation of data to list vehicles, significant ingredients, the places where foods were mishandled, the methods of processing or preparation, and operations that contributed to outbreaks. Specific food items should be cited as vehicles, but they will have to be put into subgroups and categories for some tabular presentations. Significant ingredients are the items in combined (mixed) foods that are the likely sources of the etiologic agents. Places of mishandling include farms, dairies, aquatic and land environments where foods are harvested, processing plants, food service establishments, homes, and transportation. Multiple places may contribute to the mishandling in any outbreak. The method of processing include all sorts of processing operations. The method of preparation is classified into the following food service systems: raw unaltered foods, assembled/prepare serve, cook-serve, cook hold-hot, cook chill serve, cook chill reheat, and acidify serve. The contributory factors are situations or operations that allow contamination of foods and survival and/or proliferation of the etiologic agents in the foods. This data will provide direction for setting food safety program priorities, suggest places and operations at which regulations need to be established and enforced, and indicate educational and training needs. Definitions of the terms used in the tables are given, and the value and limitations of each set of data in the tables and in tables of related information commonly presented in foodborne disease surveillance summaries are reviewed. The data from the tables should be used to improve food safety programs, which is the subject of the next part of this series.

Surveillance of Foodborne Disease II. Summary and Presentation of Descriptive Data and Epidemiologic Patterns; Their Value and Limitations.

This second part of a four-part series on foodborne disease surveillance concentrates on tabulation of data to show the common diseases and to detect those emerging in a community, region or nation. Over several years, these data give a continued description of foodborne illnesses. The presentation starts with a summarization of the incidents, outbreaks, and cases that occur over a defined interval and continues with a breakdown of specific etiologic agents or diseases that make up the summary figures. Suggested tables showing time and place of occurrences are given. These, along with data on persons who acquire these diseases, form the epidemiologic patterns of foodborne diseases. Definitions of the terms used in the table and criteria for confirming categories of etiologic agents are given. The value and limitations of each set of data in the tables are critically reviewed. The same sort of presentation is continued for data on vehicles, method of processing and preparation, and contributory factors in the next part of this series.

Surveillance of Foodborne Disease I. Purposes and Types of Surveillance Systems and Networks.

This is the first part of a four-part series on foodborne disease surveillance. Although these articles are primarily built on expertise gained within North America, the substance is of value to any community or country wishing to initiate or improve its surveillance system. Foodborne disease surveillance is necessary for preventing further spread of foodborne disease and includes identifying and controlling outbreaks at the time they are occurring; gathering data on incidence of these diseases and prevalence of their etiologic agents, vehicles, and reservoirs; identifying factors that led to the outbreaks; providing a data bank for HACCP systems and risk assessments; estimating health and economic impacts of foodborne diseases; and providing information upon which to base rational food safety program goals and priorities. Reports of outbreaks by local health agencies to regional and, then, national agencies responsible for disease surveillance, laboratory isolations of certain foodborne pathogens from human beings, sentinel community studies, and hazard surveillance are the types of foodborne disease surveillance activities that are used to varying extents in Canada and the U.S. In recent years, some national surveillance reports have been collated internationally in Europe and Latin America. Surveillance at local, state/provincial, national, and international levels must be coordinated for effective and rapid transfer of data. Computer software can assist investigation and management of the information submitted through surveillance networks. Information summarized on individual reports usually includes (a) location of the event, (b) clinical data, (c) epidemiologic data, (d) laboratory findings, and (e) results of on-site investigations. Each outbreak report should be subjected to critical review before classifying it into the various categories of surveillance data. Such a review would also be useful when comparing surveillance data from different places and intervals. Highlights of individual reports are tabulated as line listings that are the direct sources of surveillance data, which are the subject of the second and third parts of this series.

Hazard Analysis: The Link between Epidemiology and Microbiology.

Epidemiologic inquiry, collation of data and statistical calculations are useful in identifying the place foods were mishandled or mistreated and the probable vehicle of foodborne disease. Biases during collection of information and classification of cases and control can lead to false conclusions. Laboratory analyses can confirm the etiologic agent and vehicle if an appropriate sample is collected, and sometimes trace the source of the etiologic agent. Laboratory analyses may give negative or misleading results depending on the samples collected and the quantity of samples collected. Hazard analyses are necessary to determine the mode of contamination, the means by which the pathogen survived processing, and the conditions that allowed the pathogenic bacteria to increase to populations or elaborate toxins sufficient to cause the illness. Hazard analysis is the link between epidemiology and microbiology that identifies events that contributed to the causation of outbreaks and, hence, provides information upon which to initiate control actions and to base preventive measures.

Another Decision-Tree Approach for Identification of Critical Control Points.

Decision trees have been used as an aid to selection of critical control points as part of the development of hazard analysis critical control point (HACCP) systems. The background for those in existence is described. Another decision-tree approach that follows the logic in the IAMFES manual Procedures to Implement the Hazard Analysis Critical Control Point Approach is presented. It takes into consideration impending hazards, the effect of actions exercised at the operation in question, whether control actions should be taken at this or subsequent operations and whether the CCP will be monitored and corrections made. Further, guidelines are given for selecting an operation as a critical control point. A decision tree to aid in the evaluation of risks is presented, considering whether illness will result, the severity of the illness and the likely occurrence of this outcome, based upon epidemiologic or challenge study of related events. These decision trees provide additional tools to aid in the development of HACCP systems.

Health Risks and Consequences of Salmonella and Campylobacter jejuni in Raw Poultry.

Salmonella and Campylobacter jejuni are major human pathogens and poultry and poultry products are frequent vehicles of these bacteria. Estimates place the annual incidence of human salmonellosis and campylobacteriosis between 1 and 4 million each. Hazards are associated with contamination, survival or growth during production, transportation, processing and preparation. Animals are contaminated from a variety of sources on farms and the contaminants are spread during processing. Scalding, defeathering, evisceration and giblet operations are major points of spread. Further spread can occur during handling in markets and kitchens. Insufficient thermal processing or cooking allows survival. Improper handling of cooked poultry frequently results in cross contamination from previously handled raw carcasses and parts. Improper refrigeration provides conditions for multiplication of salmonellae. Estimates of annual costs of poultry-associated cases of salmonellosis and campylobacteriosis in the United States range from $64 million to $114.5 million and $362 million to $699 million, respectively. The need for a cost-effective solution to these poultry-borne human disease problems is apparent.

L' analyse des risques - points critiques pour leur maîtrise : comment apprécier les risques liés à la préparation et à la conservation des aliments / Frank L. Bryan / Hazard analysis critical control point evaluations : a guide to identifying hazards and assessing risks associated with food preparation and storage

Cet ouvrage explique en quoi le système HACCP d'analyse des risques - points critiques pour leur maîtrise constitue une méthode rationnelle, fiable et rentable de réduction des risques susceptibles d'entraîner des maladies d'origine alimentaire ou des gaspillages d'aliments. Constatant que les mesures classiques telles que l'analyse du produit fini ou les examens médicaux systématiques des personnes employées à la manipulation des aliments sont largement insuffisantes pour garantir la salubrité des produits alimentaires, l'ouvrage se concentre sur les nombreux avantages pratiques des évaluations fondées sur l'analyse des risques, proposant des recommandations précises sur l'utilisation du système HACCP pour recenser les risques lors de la préparation et du stockage des aliments, évaluer les risques connexes et axer les procédures de contrôle sur ces "points critiques". Tout au long de l'ouvrage, de nombreux exemples sont utilisés pour montrer en quoi la méthode HACCP, qui est axée sur la détermination et la maîtrise directe des opérations à haut risque peut, mieux que tout autre, garantir la salubrité des aliments. Ce livre s'adresse aux membres des services de santé publique qui ont reçu un minimum de formation en microbiologie et en technologie alimentaire

Risks of Salmonellosis and Staphylococcal Food Poisoning From Pakistani Milk-based Confectioneries.

Hazards of milk-based products were conducted in three confectionery manufacturing shops in a city in Pakistan. The incoming khoa (a heat-concentrated milk product having a water activity of approximately 0.97) was initially contaminated with staphylococci and contained enterotoxin. The confectionery was subsequently cooked to temperatures that would be lethal to staphylococci, but staphylococci were often found in high numbers in the finished products. Recontamination occurred during handling. Khoa-filled confectionery and confectionery made from renin-processed cheese were contaminated by salmonellae. The contaminants reached the products either during cooling or handling after cooking. Multiplication occurred in the warm environment of the shop and may continue in products having high water activity during transport and within retail outlets. Critical control points are source of ingredients (particularly khoa), formulation, cooking (except for preformed enterotoxins), cooling, and cold storage. Milk-based products of the types evaluated pose a high risk of causing foodborne illness.

Hazards and Critical Control Points of Vending Operations at a Railway Station and a Bus Station in Pakistan.

Hazard analyses (which included watching operations, measuring temperatures of foods throughout preparation and display, and sampling and testing for microorganisms of concern) were conducted of vending operations at a railway and a bus station in a large city in Pakistan. Commonly prepared foods which were surveyed included: rice, pulses, chick peas, ground meat and potato mixtures, meat stew, and okra. Temperatures were measured and samples were collected from a variety of other foods. Large numbers (104-7) of Clostridium perfringens were isolated from samples of pulses, ground meat dishes, and chick peas collected during display, 8 to 10 h after cooking. Aerobic colony counts were also high in these and other foods that were held for several hours, unless hot, at temperatures >55°C throughout the holding periods or periodic reheating practiced (which was done by a few vendors). Cooking was usually thorough, but spores survived which germinated during the display period. High temperature holding or periodic reheating maintained safe foods, and hence, are critical control points for these operations. Education about these matters ought to be directed at health and transportation authorities, vendors, and the public.

Hazards and Critical Control Points of Street-Vended Chat, a Regionally Popular Food in Pakistan.

A hazard analysis (which included watching operations, measuring temperatures of foods throughout preparation and display, and sampling and testing for microorganisms of concern) was conducted of a street vendor's operation. Chat is a popular dish in certain areas of Pakistan. It consists of sliced cooked potatoes, fried graham and pulse dough, and chick peas or red beans garnished with lasi (a fermented milk) and a fruit syrup. Staphylococci reached the cooked potatoes during peeling, cutting, and other handling. These bacteria increased up to 105 while the contaminated foods were held for several hours. Counts up to 105 Bacillus cereus were isolated from the cooked doughs after a 6-h or longer holding period. Large numbers (usually >105) of coliform bacteria and aerobic mesophilic colonies (106-9) were isolated from all foods after handling and holding for several hours. Ingestion of these foods must be considered high risk unless handling of cooked items can be kept to a minimum and the time of holding reduced to less than 6 h. Critical control points are handling after cooking and holding on display. Health agency personnel in developing countries, vendors, and consumers of these foods need to be informed of the hazards and appropriate preventive measures.

Hazards and Critical Control Points of Street-Vending Operations in a Mountain Resort Town in Pakistan.

Hazard analyses (which included watching operations, measuring temperatures of foods throughout preparation and display, and sampling and testing for microorganisms of concern) were conducted of vending operations of chicken, rice, pulse patties, and ice cream in a resort town in Pakistan. Salmonellae were isolated from ground meat, chicken flesh (from all operations surveyed), cutting boards, egg shells (eggs used in pulse patties), and buffalo milk (used for milk shakes). Greater than 105 coliform bacteria were isolated from raw milk, ice-cream mixes and products, and pulse-patty mix. Time-temperature exposure during cooking was adequate to kill salmonellae, but there were potentials for recontamination from cutting boards, knives, and hands of the vendor. Buffalo milk was held in a freezer and not boiled by the vendor as is usual in Pakistani homes to retard spoilage. Hence, because pathogens were not killed, milk shakes were a health risk. Pulse patties were not always thoroughly cooked, so pathogens could have survived. Holding stacks of them on a griddle for several hours would have allowed germination and growth of bacterial spores and growth of resulting cells. Health agency personnel in developing countries, vendors, and consumers of these foods need to be informed of the hazards and appropriate preventive measures.

Hazards and Critical Control Points of Food Preparation and Storage in Homes in a Village and a Town in Pakistan.

Hazard analyses were conducted in 13 homes in each of a village and a town in Pakistan. Pulses, lentils, chick peas, potatoes, rice, and combinations of them, curd, and weaning preparations were commonly prepared in both locations, and meat dishes were prepared in the town. Cooked foods were left, usually at room ambient temperature, overnight in over 50% of the homes. Samples of foods cooked in the morning and eaten at noon usually had mesophilic aerobic colony counts less than 104 CFU/g, but those left overnight usually ranged between 106-9 CFU/g. Coliform bacteria were isolated from 77% of samples; many of the counts exceeded 105/g. Greater than 104/g Staphylococci aureus were isolated from curd and buffalo milk which had been previously heated. Clostridium perfringens were isolated from 18% of samples; once from pulses left overnight in quantities exceeding 107/g. Only three samples contained Bacillus cereus . Salmonella was not recovered from any of 28 samples. Hazards were primarily associated with holding the foods after preparation. Critical control points are cooking, manipulation of foods after cooking, holding cooked foods, and reheating.

Hazard analysis critical control point evaluations : A guide to identifying hazards and assessing risks associated with food preparation and storage

The hazard analysis critical control point (HACCP) system is a relatively new approach to the prevention and control of foodborne diseases, which seeks to identify the hazards associated with the various stages of food production and preparation, assess the related risks, and determine the operations where control procedures will be effective

This publication provides guidance on the application of the system to the preparation and storage of food in homes, food service establishments, cottage industries, and street markets. Drawing on approaches used by a number of food-processing companies, it outlines the principles that underlie the HACCP concept, as well as providing practical advice on how to conduct an analysis, and numerous examples of critical control points and monitoring procedures for commong foods and processing operations

This guide is intended for use by public health personnel with some training in food microbiology and technology, who are concerned with the prevention of foodborne disease. It will assist in the planning of foof safety and health education activities focused on the types of food commonly prepared and eaten by the local population

Evaluaciones por análisis de peligros en puntos críticos de control : Guía para identificar peligros y evaluar riesgos relacionados con la preparación y la conservación de alimentos / Hazard analysis critical control point evaluations : A guide to identifying hazards and assessing risks associated with food preparation and storage

El sistema de análisis de peligros en puntos críticos de control (APPCC) constituye un método relativamente nuevo para prevenir y combatir las enfermedades transmitidas por los aliementos. Mediante su aplicación se pretende identificar los pelibros vinculados con las diversas etapas de la producción y preparación de alimentos, evaluar los riesgos correspondientes y determinar en qué operaciones resultarán eficaces los procedimientos de control

Esta obra brinda orientación sore la manera de aplicar el APPCC en la preparación y el almacenamiento de alimentos en el hogar, los establecimientos de alimentación, las industrias artesanales y los puestos de la calle. Basándose en métodos empleados por varias empresas elaboradoras de alimentos, se describen los fundamentos del concepto del APPCC y se facilitan consejos prácticos sobre la manera de efectuar los análisis, así como abundantes ejemplos de puntos críticos de control relacionados con alimentos y procesos de elaboración alimentaria comunes

La presente guía está destinada al personal sanitario con conocimientos de microbiología y tecnología de los alimentos que interviene en la prevención de enfermedades de origen alimentario, a quienes ayudará a planificar las actividades de inocuidad de los alimentos y educación sanitaria centradas en los tipos de alimentos comúnmente preparados y consumidos por la población local