Understanding Food Poisoning Causes

  • 14 Pages
  • Published On: 09-12-2023


Food poisoning is a food borne illness that results from consuming food items that are contaminated or toxic. The condition is associated with symptoms such as nausea, vomiting and diarrhea. It is a quite uncomfortable condition and it is unusual as the symptoms vary with individuals and there are those that may take long before they exhibit the symptoms. The symptoms vary depending on the source of infection and can range for as little as one hour to four weeks before they appear. The condition is life threatening and when not treated on time could lead to death. The most prevalent cause food poisoning is the bacterial component, such as E. coli, Listeria and salmonella. Salmonella is the major cause of bacterial infection. according to the communicable disease center (CDC), united states of America is the most hit with estimated 1,000,00 cases of food poisoning with more than 20,000people hospitalized each year which are all associated with salmonella bacteria. Parasites and viruses are not common causes of food poisoning in the world.


This report focuses on two case studies of food poisoning , the organisms responsible for causing food poisoning, the incubation period required before the symptoms appear, what symptoms have been displayed, the food stuffs involve, the group of people affected and what other pathogens can cause food poisoning (Dewberry, 1980) . Pathogens are found in almost all the food components consumed by human beings. Heat from cooking usually kills these pathogens causing the infection; undercooking food is unsafe for human consumptions. Raw foods such as fruits and vegetables are the common sources of food poisoning when consumed. When food comes into contact with the fecal matter, during preparation or processing the food stuffs become contaminated and causes food poisoning when consumed. It is recommended for one to wash their hands before preparing meals. According to statistics every individual is likely to be infected with the food poisoning once in a while (Fretz et al., 2007)Depending of the surrounding environmental conditions, some populations are likely to be at more risk as compared to others. Pregnant women are at more risk of contracting the diseases as their bodies are constantly changing and in the process the immune system becomes weak. Children are also at risk of infection especially those below 10 years as their immune system is still weak and not as much developed as that of adults. Hence food poisoning is caused by a bacterium commonly known as salmonella.


Case 1

In this case, a study was conducted in July 2006, on an outbreak of food poisoning at village in Cambridgeshire, United Kingdom. The study lasted for one week which was after a special festival event that was held by the locals to sell their farm produce to the tourist visiting the area. They are characterized by flooded gravel pits that had been converted by the local’s water sports zones. Since the number tourist had risen up, a natural reserve was constructed to suit the tourists’ needs. Trails of horse riding and bike riding were seen which were headed to the woods. The area has an average population of 5,000 people whose practice commercial agriculture of fruits and vegetables which they sell to local villagers and the visitors. It is a popular destination for visitors and after the festival an epidemic curve was constructed and it was established that the number of infection rose above normal. It was deduced that 45 people were infected with an age range of 7-71 years.

Case 2

In a traditional Christmas even that was held on 18th December in the year 1998, food was prepared in different dimensions and channel before and on the due date and stored through different refrigerators both commercial and domestic presuppose. 113 people attended the event and 76% of the people were reported to exhibit symptoms that were associated with food poisoning. One person was hospitalized as a result of infection. The turkey that was supplied to the venue was commercially prepared and stored in commercial freezers. From the four batches three were kept in a home fridge and one was directly taken to the venue. it was then sliced and placed under heat for 90 minutes . Vegetables and peeled potatoes were shortly prepared before the meal. Ice was bought 5 days before the event and stored in a domestic fridge.

Causal organism

The main causal agent in food poisoning case study 1 and 2 is the bacteria known as salmonella. It is present in food or water. In the united stated it has been identified as both are food borne diseases or waterborne diseases (Showkwae and Dillon, 1998). This parasites range in sizes from the tiny single-celled organisms to worm visible to naked eyes, which have varied life cycles with a series of development phases that use either an animal or a human being as a host. In this study, results from the table show that people were infected with the parasite as a result of consuming undercooked meat of chicken. This shows that the parasite used the animal as a host and later transmitted the infection to human beings. These parasites are transmitted from human to human, human to animal or animal to human. The CDC has estimated that the salmonella parasite has caused more than one million infections for the past one year in the united stated (Blaser and Newman, 1982). It is common in countries that experience summer weather with unrefrigerated foods which create a very ideal environment for the bacteria to develop. Salmonella infections normally occur due to poorly or undercooked foods, poor handling of chicken and eggs. In the second case study, bacterial infection may have arisen from the turkey which was stored in a domestic fridge along with other home foods. The bacteria might also have infiltrated the ice that was stored in a domestic freezer and hence causing food poisoning. Bacteria are found in almost every part of the biosphere. The human body is full of bacteria and these bacteria are harmless and instead play a vital role in maintaining balance with the human body. A good example is the human digestive system there is bacteria along the tract that help in the breaking down of food particles into smaller substances that can be absorbed by the human body. Salmonella is normally located in animal and human tracts; it is recommended that meat and chicken be boiled properly to ovoid infection (Foster and mead, 1976). Cooking with temperature above 150 destroys the bacteria. Listeria is also likely to be the causal organism of infection in the second case study. Most foods in the second case were preserved by refrigeration. The bacter is known to survive under lower temperature and may even double in numbers . these bacteria type is considered a special case it can adverse conditions and can rapidly multiply in higher temperature since the enzymes inside are and rapid growth. The bacteria can still multiple in low temperature but at a slower rate. The ability of the bacteria to survive long periods of severe conditions and its ability to still grow under refrigeration conditions has made the virus to be more recognized as an important food bome-pathogen.

Incubation period

Victims in case 1 study took an average of 2-114 days to exhibit the symptoms of the infection (Blaser and Newman, 1982). These symptoms typically vary from one person to another depending of the source of infection. Infections arising from direct sources such as consuming water that is infected are severe and take less than one day to exhibit the symptoms. Large and small intestines have an incubation period of about 1-3 days (Hauge, 1995). On averagely, the incubation period of food poisoning is 8 days by then the symptoms would be fully exposed. In case 2, the incubation period was shorter compared to case 1, with victims exhibiting symptoms in a 4.5 days and an average mean time of 1.8 days. It is rare infection with mild cases that do not require medical attention.


In case one, the symptoms observed include, watery diarrhea which was the most prevalent symptom in all the 45 people that were found infected with the parasite. About 88% of the population had abdominal cramps, 68% with nausea, 54% had fever with vomiting and bloody diarrhea exhibited in low percentages of 24% and 20% respectively. The large and small intestines can cause bloody, mucous diarrhea that is associated with abdominal cramps (Hauge, 1995). Aching muscles, fever and loss of appetite are other symptoms of diarrhea that manifest in infected patients. In most cases, these symptoms are likely to pass and one makes a full recovery. Most people with food poison take home made remedies and make full recovery. Conditions with severe cases require one top seek immediate medical care (Ray and specks, 1988). In case 2, of the infected 86 people, 98% of them were reported to have severe diarrhea case, 71% presented abdominal pains and only 5% of the infected people were vomiting. These symptoms are mild are can be treated with home remedies. And only one person from the infected people was hospitalized. The rest recovered without requiring medical attention. These symptoms begin shortly after one consumes the food that has been contaminated by the bacteria (Le Loir, Baron and Gauteir, 2003). If the condition further advances to the nervous system, one may develop symptoms such as headache, stiffness, loss of balance and confusion. In pregnant women, Listeria infection can cause mild symptoms, although the symptoms could be fatal to the baby as it may die in the womb. In new born the symptoms can include, little interest in feeding, irritability, fever and vomiting.

Foods involved

Food items that were involved in this case study were mainly fruits and vegetables namely; lettuce, spinach, tomatoes cucumbers , celery, radish, onions, carrots, broccoli, sprouts and others like the raw and undercooked eggs, strawberry ice cream, hamburger, rare or undercooked chicken and rare or undercooked beef. These foods were consumed during the outbreak and from the numbers displayed on the table, it is evident most of the farm produce contributed to the spread of the parasite (Harries et al., 2017). In case study 2, turkey was the main food source available, with some partially cooked vegetables and peeled potatoes, pudding and ice was also available. With the mode of preservation of these foods, Listeria is likely to develop as most of them were preserved by refrigeration, which preferred a condition for the replication of the virus. The virus multiplied even more when the turkey was placed under a heat, this is because the bacteria was exposed suitable temperature condition for growth.

Groups of people infected

Salmonella is very common in pregnant women and children bellow 10 years. This is because during pregnancy, the immune system of pregnant women is weak as it is still undergoing changes so as to accommodate the embryo growing in the uterus hence making the susceptible to the infection. (North, 1994) In children bellow 10 years, the condition is prevalent as their immune system is still weak and cannot fight the parasite. Anyone can get salmonella infection but some people are more likely to contract the disease than others. Adults aged 65 years are above have weak immune systems from have been weakened from medical conditions such as diabetes or heart diseases (Miliciu et al., 2016). Similar to case, case 2 is more susceptible to children bellow 10 years, pregnant women and adults older than 65 years. This is because of the weak nature of their immunity.

Some organisms have been ruled out as a probable cause of infection due to their rarity of occurrence. Bacteria such as E. coli and Listeria rarely infect people. These bacteria is present in fruits, vegetables an untreated milk and meat (Calosari, 1988). Most types of the E. coli are harmless and even have helped in keeping the human digestive system very healthy. E.coli can only make a person sick if they ingest toxin which damage the lining of the small and large intestines. These parasites are considered less effective as they normally reside in the bowel.

Which food is likely to be the probable cause

Data from the table in case study one, shows that vegetables were the most common cause of food poisoning. During the outbreak, lettuce tomatoes and carrots as these foods are consumed raw and probably the reason why the consumers were infected as 80% of the infections arise from uncooked and improperly cooked food substances (Acher, 2004). Hamburgers also constituted a major part of the infections observed, this is because in preparing a hamburger require ingredients that constitute a greater percentage of the foods consumed during festival. Raw and under cooked eggs together with improperly cooked beef and chicken contain the salmonella bacteria. Consuming such food make one sick, these food is contaminated at any stage of production, processing and cooking (Freitz et al., 2007). The partially cooked meat and chicken during the festival infected those who consumed it. In case study 2, turkey was the likely to be probable cause of infection as the three batches that were preserved in a domestic fridge might have come into contact with other foods such as vegetables and fruits stored at home. Another type of food that might have caused food poisoning is the ice that was stored in the domestic freezer.


It is estimated the every year that 1 in 6 Americans get sick of food poisoning with more than 100,00 people hospitalized of which 3,00 die of food borne diseases (Dewberry, 1950). To prevent this outbreak, food handlers should observe the following measure; Washing of hands and food surfacesbefor and after preparing them. This prevents contact with germs during preparation of food. Germs servive in many places in the kitchen area. Hands, utensils and countertops should be thoroulghly washed to reduce contamination (Merry, 1997). Separating raw food such as meat, poultry and eggs from ready to eat food. Use separate chopping boards and keep raw meat way from other foods in the refrigerator. Properly cooking food and boiling water at the right temperature kills the micro-organism present and hence reducing the risk of contracting the disese.


according to research conducted by WHO, 90% of the people infected with food poisoning get better on their own without requiring medical attention (Lawrence et al., 2007). Treating food poisoning requires supplementing the fluids lost through vomiting and diarrhea. To prevent trading the mild cases patients are adviced to replace these lost fluids by drinking enough water. Eating the saltrine crackers elps to replace the lost electrolytes. Drinking of oral de hydration such as pedialyte, infantlye is advisable to children and infants suffering from food poisoning.

Over the counter drugs can be used to reduce the impact one ones symptoms. Adults can take over the counter medicines such as loperamide and bismuth subsalicylate which can be used to treat food poisoning. Infants and children are not permitted to buy over the counter drugs unless prescribed by a doctor (Furukwa et al., 2009).Doctors normally prescribe the anti-biotic that target parasites as well as rehydration solutions. Some cases these doctors may recommend pribiotics which help reduce diarrhea and reduces the impacts of food poising. However there are still studies being conducted on the effectiveness of this medicine in treating food poisoning.

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From the above two case studies, it can be deduced that food poisoning was caused by two type of bacteria; salmonella and the Listeria. Salmonella is commonly found in fruits and vegetables while Listeria is common in refrigerated foods as is known to survive under harsh conditions. The bacteria multiply in twofold while under high temperatures as compared to when refrigerated. In case study 2, the frozen turkeys kept in the domestic fridge were the main food source that caused food poisoning. During refrigeration the turkey might have come into contact with other fruits and vegetables, however the bacteria did not die but instead was able to survive under lower temperatures and later multiplied when the turkey was put under intense heat for 90 minutes. In case study 1, fruits and vegetables such as onions, carrots and lettuce were suspected to be the main probable cause of infection. This is because there was rise in the infected number of individual who consumed these foods. The bacteria in this case study can be killed by de-freezing and boiling at temperature that are above 150 degrees. Patients in case study one exhibited symptoms like, watery diarrhea 100%, abdominal cramps 88%, 68% with nausea, 54% had fever with vomiting and bloody diarrhea exhibited in low percentages of 24% and 20% respectively while in case study 2 patients exhibits mild cases with symptoms such as, of the infected 86 people, 98% of them were reported to have severe diarrhea case, 71% presented abdominal pains and only 5% of the infected people were vomiting. Food poisoning is most prevalent in older people who are 65 years and above and in young children as their immune system is weak. Pregnant women are at risk of contracting the disease as their immune system becomes weak as the body tries to adjust to changes.

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To avoid contracting food poisoning I recommend the following guidelines.

Keep hands really clean during preparation and after preparation of every meal. This helps in keeping away bacterial infections that might have been picked on other surfaces while performing the daily house chores.

Avoid preparing meals if you feel like you have stomach flu. Instead get extra help from someone else and opt for foods that require little attention to prepare and thoroughly wash your hands.

Place food in the refrigerator without delay, don’t keep food on kitchen surfaces or in carrier bags for more than 2 hrs after it has been prepared. This avoids contamination of these foods from other surfaces.

Keep your fridge clean, regularly clean your fridge if foods are spilled, do it immediately to avoid food contact that may lead to contamination. Always keep food in the fridge wrapped to prevent further contamination.

Maintain the right temperature for these food substances, ensure the door seals are properly fitted and keep the coldest part of the fridge between 0and +4 degrees Celsius.

Maintain different chopping boards for each food you prepare. Raw meat and fish should have a separate board from the clean produce and cooked produce. Always use clean utensils and dishes.


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