Inspections during Foodborne Illness Outbreaks
When a public health agency becomes aware of an outbreak of foodborne illness, they put into place interventions to stop the transmission. Central to that effort is an environmental assessment referred to as an inspection. Companies may also employ third party inspectors during outbreaks to determine the strength of prevention efforts. Legal firms and private investigators interested in understanding how these outbreaks occur, and why, increasingly conduct inspections during or after foodborne illness outbreaks (See WALB Article on PCA).
The Causes of Foodborne Illness
The key principle guiding the inspector is the understanding of the causes of outbreaks. Pathogens cause disease when they are present in sufficient numbers in food to produce an infection or intoxication. How they get into food and survive to the consumer depends on a series of related factors that the inspector must develop as the basis for his inspection techniques.
The Agent, the Host and the Environment
It is fundamental to understand the relationships between the host, the environment and the agent. The characteristics of the host or victim such as age and health status play a role in disease transmission. In addition to the vulnerability of the host, the victim must consume the food so there are logistic considerations about the host and his exposures. The location of the victim, the amount or form of the food consumed, and other facts about consumption and handling relate to whether the person will come in contact with the pathogen. Onset of illnesses and types of symptoms are particular to pathogens and help to provide confirmation of the agent at work.
The Environmental Route of Exposure
The environment plays an essential role in supporting the disease transmission pathway. Disease transmission through the environment occurs when a reservoir of the agent is present and exploits a means of spread. Since the organism in most cases is not motile, it needs a vehicle to get from its reservoir to the food. There it must survive and/or proliferate in the food product. Environmental conditions significantly affect contamination, growth of bacteria, and survival of any pathogen in the food.
Contamination, Growth and Survival
The act of contamination can occur through people, water, vectors such as pests, surfaces, and potentially through the air. Growth of the pathogen occurs when sufficient moisture and temperature are available to the organism for a sufficient time. Facts about the food itself and its ability to support microbial growth include its nutrient content, water content and level of acidity, as well as any processing aids used that influence growth. Survival of the organisms in the food or environment is dependent upon the surface available for colonization, cleaning and sanitary practices, and treatments used on the product such as cooking or pasteurization.
Foodborne agents include over 200 known pathogens; bacterial pathogens that exist in a spore or vegetative cell, viruses, parasites, and toxins. The ability of the organism to survive environmental conditions depends on a number of factors, but Salmonella, Listeria, E coli O157:H7and several other pathogens appear to be hardy enough to survive for long periods, possibly months in ideal conditions. Some spore forming organisms such as Clostridium botulinum need anaerobic conditions to grow, and anaerobic conditions in product and packaging favor other pathogens as well. The reservoir of the pathogen is often difficult to discern. The value of environmental-microbial testing to inspection is that it can identify locations where the organisms have been harboring. Suspicious areas always include moist areas as well as surfaces receiving repeated exposure to dirt and environmental contamination such as floors and drains. There is always a possibility that incoming raw products continually seed the production environment with contamination. It is also possible that multiple reservoirs of the organism in the environment or in people lead to cross contamination throughout the production system.
The Inspection and Analysis
With the understanding of the pathway of infection and the complex relationships between the agent, host and environment, investigators apply an analysis of the food production process. Inspection is a process of observation and the inspector analyzes his observations to determine the likely exposures of the final product to contamination and to identify the process steps that allow proliferation and survival.
Analysis of Production
Food production processes start with the receipt of raw materials but the process at any one step in the food supply are interconnected with all other points right up to consumption. The inspector conducts a visual inspection of the structure, environment, equipment, layout and other factors while focusing on the production process.
Raw materials can contain the pathogen, and include packaging as well as the other ingredients ultimately used in the finished product. While visual observations may reveal potential problems, microbiological and other analysis may be necessary to determine the safety of incoming materials. It is safe to say the opportunity for contamination is significant in raw agricultural commodities grown in the soil and raw meat and other raw, animal foods.
Receiving is usually followed by storage although there may be some immediate use of products as they arrive Stored products may be subjected to hazardous environmental conditions such as pests, dirt, chemicals and foreign of objects Any moisture or signs of vermin where food or packaging is stored increases the risk for contamination.
Foods may be staged into production and be in various forms during processing. Since handling of products occur during production (or preparation), the human element becomes important as does machinery and equipment used, utensils, and the flow of foods through the process itself. Any point can lead to contamination or growth of bacteria if the process is not controlled. Cross contamination can occur when there is poor maintenance of food contact surfaces or under poor storage conditions.
Packaging occurs in food processing while service occurs at the retail level as the final step in the production process. Transportation is an intermediate step in the supply chain and can lead to contamination of finished products. Servers in food service environments can also contaminate foods that were otherwise safe to consume. The key is to analyze the entire food production process and avoid missing hazardous steps.
Photographs, samples and other techniques such as interviewing provide additional evidence in the development of theories of causation and bolster the data obtained through the inspection process. The inspection findings may also benefit from a statistical approach and ranking of factors in terms of their significance and severity. A final report captures the data from all findings and often leads to a conclusion about how foods became contaminated.
Inspection during Foodborne Illness Outbreaks is an Essential Tool
Inspection as a tool in foodborne disease investigation is a critical part of preventing the further spread of pathogens. Inspections also lead to an understanding of the complex associations that influence the probability that a foodborne agent reached a product by a specific pathway. Inspections form a central piece in determining what went wrong and how to prevent similar outbreaks it in the future.
Inspectors should make it clear to operators that they must apply the outbreak inspection findings to the process under study as a matter of urgency and take corrective actions to improve it and other similar processes.
Whether or not an inspection is routine or occurs during or after an outbreak, the ultimate value of inspection in general is to improve the food supply. When applied in a very systematic fashion, inspections during foodborne illness outbreaks can move food safety efforts forward very effectively and dramatically protect the public in the future.