Summary of incidence and epidemiology of
Foodborne pathogens are evaluated as an important risk factor in terms of public health in developed and developing countries due to their extensiveness all around the world. Escherichia coli and other coliform bacteria are important foodborne pathogens. Some of the most important sources of contamination for these groups of microorganisms are reported as: areas with unfavorable hygiene, contaminated waste water, meat products, cereal products and vegetables. Total coliform bacteria and E. coli count is known to be the indicator of unfavorable hygienic conditions and fecal contamination in foods. Foodborne diseases, however, are a global issue. A joint approach by all countries and related international organizations is a prerequisite for detection and control of foodborne problems that pose a threat to human health and international trade. Despite their complicated biology, epidemiology and analyses, most foodborne diseases are preventable. It is of vital importance for public health that consumers and food producers act in accordance with the principles regarding internationally accepted safety methods.
- Escherichia coli
- food safety
- foodborne diseases
Microorganism of varying types and numbers can be found on food of animal and plant origin. The types and number of microorganism on food can be changed due to food processing, inappropriate purchasing, storing, preparing, cooking or serving. Increase in the number of these microorganisms due to the abovementioned changes may lead to spoiling of the food, causing a pathogenic effect on humans. The most important of foodborne pathogenic bacteria is
Escherichia coliand food poisoning
Being the prominent bacterium in the facultative anaerobic microbiota of the intestines,
People living in developing countries have often been reported to have this pathotype in their feces and shown to have developed immunity against this microorganism. Being a cause of mortality in children under 5, the most frequently observed microorganism in childhood diarrhea is ETEC and it is also responsible for 30–60% of travelers’ diarrhea. Infection is characterized by watery diarrhea and, depending on the person, its course may range from a normal course to cholera-like defecation with the addition of symptoms such as vomiting and high fever [2, 4, 7]. Diarrhea is the most common causes of mortality in society and among young children, especially those living in Asia and sub-Saharan Africa with inadequate healthcare systems and limited access to clean drinking water. Recent systematic studies have reported that each year an estimated 600,000 children under the age of 5 lose their lives. Diarrhea occurs due to the consumption of food or water contaminated with viral, bacterial or parasitic pathogens. Among these potential pathogens, the most common cause of diarrhea in children under five is the ETEC (heat-stable – ST and/or heat-labile – LT type toxin) producing
It is known to be the oldest
The ability to produce attaching and effacing (A/E) lesions is a distinctive phenotype for EPEC. Bacteria cause extensive deterioration on microvilli by strongly adhering to the host cell membrane. This adherence to the cell is mediated by an outer membrane protein called intimin. Moreover, depending on the presence of
This pathotype is a foodborne enteropathogen observed in acute and persistent diarrhea cases in children, patients with suppressed immune systems in developing countries and people traveling to endemic regions. Growth disorders and cognitive disorders in children living in developing countries, stem from EAEC infections. In the pathogenesis of EAEC, the first step is the strong adherence to the intestinal mucosa. The second step is leading to the development of enterotoxins and cytotoxins and the third step is known to be characterized with the ability to induce mucosal inflammation. Many different virulence factors regarding these three steps have been defined, however; none of them are present in all strains. Three adherence models related to EAEC have been defined. In addition to the localized adherence (LA) model that was defined first, there is also a diffuse adherence (DA) model and aggregative adherence (AA) model. The strains corresponding to the AA pattern were later defined as “Enteroadherent-aggregative
It is commonly found in foods in Mexico, including desserts and salsa sauces, and the visitors of the country are known to be more sensitive to EAEC infections during their stay rather than ETEC, which they are the most susceptible to. The reason behind this is the EAEC’s ability to suppress the immune system and cause chronic infection. EAEC is also more resistant to antibiotics compared to the other diarrheagenic pathogens. Persistent infection and chronic disruption in intestinal functions cause malnutrition and decline in physical and mental development, especially in children. Malnutrition, which is observed due to micronutrient deficiency, induces infection. Development of infection induces malnutrition. This whole cycle increases the burden of acute diarrhea .
Hep-2 or HeLa cell cultures are called DAEC due to their diffuse adherence characteristics. DAEC serotypes are known to cause chronic diarrhea in children between the ages of 1 and 5. They cause degradation in the intestinal epithelium by binding to proteins that accelerate degradation. Mild diarrhea void of fecal leukocytes is the indication of infection. In France, DAEC strains were found out to be widespread in diarrhea cases observed in inpatients from a hospital with no other enteropathogen. This situation indicates that DAEC strains may be an important diarrheagenic pathogen in developed countries. Recent studies show that some DAEC strains contain virulence factors present in uropathogenic
EIEC strains causing inflammatory damage in intestinal mucosa and submucosa are very similar to those produced by
EHEC are also named Shiga toxin producing
EHEC has a wide spectrum including watery or bloody diarrhea and hemolytic uremic syndrome (HUS), which is an important factor in acute renal failure in children. The biggest EHEC O104:H4 outbreak was in Germany in 2011 with 855 HUS cases in 3842 people and 53 mortalities. This incidence, which raised concern all around the world, shows the importance of EHEC in terms of human health. Bovines are the main reservoir for these microorganisms to live on asymptomatically for years. Other smaller reservoirs for these microorganisms include sheep, goats, dogs, pigs and poultry. Other places where EHEC could stay alive for months include; bovine feces, soil and water. Butchering or processing of animals or contamination of plants through contaminated water or manure are the main routes for EHEC to spread to the food chain . Following 3–12 days of incubation period after infection with
The incidence and epidemiology of the important serotypes of
|Pathogenic ||Site of infection||Associated disease||Incidence||Target population||Significant transmission route|
|ETEC||Small intestine||Traveler’s diarrhea, chronic childhood diarrhea (in developing countries)||16 U.S. outbreaks (1996–2003); prevalence 1.4% in patients with diarrhea; 79,420 cases of travelers’ diarrhea each year (in the USA)||International travelers and children in developing countries||Food (raw produce, street vendors) and water|
|EPEC||Small intestine||Infant diarrhea||Hundreds of thousands of deaths world wide||Children in developing countries||Water, infant formula|
|EHEC||Large intestine||Hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS)||110,000 cases and 61 deaths annually in the USA||All ages||Food (beef produce), person-to-person, water, animals|
|EIEC||Large intestine||Dysentery||Low in developed countries||Children in developing countries||Water (rare), person-to-person|
|EAEC||Intestine||Watery diarrhea with or without blood in the stool, acute and chronic||Developed and developing countries||Children and adults, travelers||Food, water, person-to-person|
3. Food safety and high-risk foods
Food safety means ensuring consumer safety and protecting products from biological, physical and chemical hazards throughout the whole process starting from the field to processing, storing, distributing, preparing and cooking . In many countries around the world, people started to have a more conscious perspective on food and environment. Consumers tend to prefer food that is more natural, less processed, environment-friendly, healthy and produced safely. This tendency makes up the basis of the “preventive/protective” (pro-active) approach for measurements to be taken towards food safety both nationally and globally. This approach based on risk analysis is the most appropriate and effective method for controlling foodborne hazards. It also necessitates the application of proper control systems in the production chain . Foodborne diseases are a global subject. A common approach by all countries and related international organizations is a prerequisite for the detection and control of foodborne problems threatening human health and international trade. Despite their complicated biology, epidemiology and analyses, most foodborne diseases are preventable. Public health institutions, food industry and consumers must be devoted to prevent foods from getting contaminated at farms, restaurants and homes. In outbreaks of foodborne diseases, continuous monitoring is vital for revealing the disease tendencies in foods, regions and associated pathogens. Genotype and subtype information obtained from contaminated strains are required for tracing the source of contamination, characterizing and comparing the strains .
The food safety management systems with a classical basis that were once accepted for safe production and consumption of foods has proven to be inefficient and researchers/organizations proposed the “risk-based food safety” approach. Risk-based food safety approach is significantly different than the classical hazard-based approach. In this regard, a food safety management system aims at estimating the risks to human health as well as defining, choosing and implementing strategies to control and decrease these risks. According to Codex Alimentarius, risk analysis is a process consisting of three components: risk assessment, risk management and risk communication. Today, the new approach is considered as an approach enabling food safety issues to be diagnosed more accurately and define strategies required to decrease these issues more effectively [23, 24, 25]. The principles of risk-based food safety are defined with a four-step framework. The first step includes a series of initial risk managements such as defining the food safety issues, developing a risk profile, setting risk management goals, deciding on the need for a risk assessment, forming a risk assessment policy, creating a risk assessment and/or risk ranking commission and analysis of the results following the assessment. In the second step, different risk management options are defined and the options are chosen after the assessment. The third step includes the implementation of risk management precautions. Lastly, in the last step, observations are carried out in appropriate areas within the food chain and this step is utilized in reviewing the effectiveness of the risk management precautions. This step usually includes public health monitoring in order to collect data on changes. In summary, this approach aims at improving the food safety in high-risk food/hazard combinations, decrease the burden of foodborne diseases and increase the consumer safety .
Billions of people in the world are under unsafe food risk. Each year, hundreds of thousands of people become sick or lose their lives due to consumption of unhygienic, high-risk foods. This is why safe food saves lives. In addition to improving the health of individuals and the public, safe food also boosts the economic growth in the regions where it is improved. Food safety covers four main areas, as shown in Table 2 microbiological safety, chemical safety, personal hygiene and environmental hygiene .
4. Storage conditions and hygiene in foods
Controlling the entry of contaminants into the food chain can be difficult. In addition to poor hygiene, unfavorable transfer and storage conditions for foods or contaminated raw material usage also play a part in contamination. Low quality or contaminated foods may cause shipments to be canceled on an international level. This poses an obstacle for the trade between countries . Food safety objectives are based on preventive actions such as safe raw material usage, good production practices and procedures with critical control points for hazard analysis. It is possible for the success of these preventive actions to reflect on the incidence of foodborne diseases. WHO and Center for Control of Foodborne Infections and Intoxications in Europe stated that one of the most important factors contributing to foodborne outbreaks were markers required for improving general hygiene and most of these were under the control of producers/consumers and listed these markers as following:
Poor general hygiene
Consuming raw products
Using contaminated materials
Contamination through infected people
Using contaminated tools
Mistakes in processing
Too early preparation
Too long storage time
Contamination during the last preparation phase
Inadequate heating before reusing .
Attention should be paid to purchasing, preservation, preparation, cooking and serving processes for ensuring food hygiene and safety. While purchasing foodstuffs, attention should be paid to the shipment conditions, packaging and keeping the cold chain in potentially high-risk foods such as fish, meat, chicken and milk. Storage rules should be followed during storing. First in first out (FIFO) rule should be followed in storages. Temperature in storage units should be checked regularly and cooked meals should be left to cool down in room temperature before being stored in fridges. Shelves should be made of rustproof material and foods should be kept at least 15 cm away from the floor and walls. There should be different sections for each food group (meat group, dairy group, fruit and vegetable group) so that cross-contamination is prevented. There is a risk of microorganism contamination from personnel, tools, environment or foods (cross-contamination) during the preparation phase. Color code system could be implemented in cutting areas to be able to prevent this from happening. Potentially high-risk foods should be processed without waiting. Cooked meals should be served in maximum 2 hours. Frozen foods should be thawed in 4–7°C. Internal temperature of poultry should be at least 75°C while cooking. Temperature of foods such as meat, fish and eggs should be increased to at least 63°C and they should be processed at this temperature for at least 2 minutes. Internal temperature of hot meals should be kept at 65°C in bain-marie with a closed lid. While serving food, clean containers should be used to transfer or hold the food. Cold foods should be kept under 4.5°C in a closed container. Preservation time is as important as preserving conditions when it comes to development, growing and spreading of microorganisms. Preservation times for some foods are listed in Table 3 [22, 29].
|Food||Preservation time (day)|
|Big piece of meat||3–5|
|Milk and cream||3–4|
5. Different pathotypes of
E. coliand outbreaks
If we take a general look at the incidence and epidemiology of disease-causing
In meat products, non-O157 STEC prevalence varies between 2.4 and 30.0% for minced meat, 17.0 and 49.2% for sausage and 8.6 and 49.6 in meat put up for sale. When STEC contamination reports verifying that the STEC O157 prevalence had ranged between 0.2 and 27.8% for the last 30 years were assessed in terms of STEC O157 and non-O157 presence in bovine meat, non-O157 STEC rates were observed to be ranging between 2.1 and 70.1% . Besides, EHEC serotypes were reported to stay alive for 9 months in −80°C and that they were not affected by the storage conditions of pieces of meat frozen in −20°C.
In a study conducted on children’s nursery in Japan between 2010 and 2013, it was detected that 68 of 1035 outbreaks were of EHEC origin. It is known that 30 of the 68 outbreaks (46%) were foodborne . It is also known that there were two EIEC outbreaks reported in England in June of 2014. These cases are rare in England. However, it is emphasized that EIEC has a capacity to cause large and potentially serious gastrointestinal outbreaks in Europe and that it should be considered as a potential pathogen in foodborne outbreaks . In 2011 (between May 1st and July 4th) 2971 STEC related gastroenteritis cases including 18 deaths and 845 HUS cases including 36 deaths were reported along with laboratory approval, among 3816 cases reported to the public health officials in Germany. Moreover, the number of HUS cases during outbreaks was reported to be approximately 70 times the figures that corresponds to the same period of previous years . In another report from Germany, a case-control study was conducted with 26 patients with HUS and 81 control cases. The incidence of the disease was associated with kale consumption in the univariate analysis and with kale and cucumber consumption in the multivariate analysis. Twenty-five percent of the cases reported eating kale and 88% reported eating a salad . In another case in Scotland in 1994, 71 cases were reported including 1 death and 11 HUS cases due to non-pasteurization of milk. In an
Along the food chain, controllability and traceability are of great importance for ensuring the consumer safety and for foods to be protected from biological, physical and chemical hazards starting from the field to the moment of consumption. Consumers constitute the last ring of the food safety. The purchasing power and consciousness of consumers help ensure food safety and are the most important factors for protection and prevention against risks. Prevention of
Biological protection precautions are also very important. It is claimed that 8.0 log10 cfu/g lactic acid bacteria causes a 1.6 log10 cfu/g decrease in
Under the HACCP, the term hazard refers to any substance or condition that has the potential to cause adverse health effects and that is unacceptable. These hazards can be caused by the biological, chemical or physical contamination in the raw material, semi-processed or finished food product. Hazard analysis is defined as the assessment of the severity of the hazard and the likelihood of it happening. HACCP is a system managed based on seven principles to identify, assess and control possible hazards for food [17, 44];
Conduct hazard analysis
Identify critical control points (CCP)
Establish critical limits
Establish monitoring procedures
Establish corrective actions
Establish verification procedures
Establish documentation and record procedures .
These principles are accepted by state institutions, trade associations and the food industry. Today, food safety systems based on HACCP principles are successfully implemented in food processing facilities, retail food stores and global food service operations. Following HACCP rules in production facilities is vital. In a slaughterhouse in Mexico it was emphasized that HACCP should be applied in addition to antimicrobial treatment to reduce the presence of potential pathogens such as
Comprehensible written instructions and procedures
Records of actions, mistakes and reviews
Records of production and distribution
Proper storage and distribution
Complaint and recall systems .
In conclusion; it should not be forgotten that as a foodborne pathogen