The term food poisoning' means any condition in which food causes a toxic reaction. This can be a result of a natural toxin in the food, a toxin acquired by the food in the course of nature (for example, a fish eating a toxic substance), spoilage leading to bacterial contamination of the food, or contamination of the food during agricultural processing (Bender, 2005).
In this article I will cover some of the most common and some more uncommon illnesses obtained by eating contaminated foods. I will discuss the causes of the illnesses, the symptoms and, where applicable, treatment and preventative measures.
I will begin with one of the most common food borne illnesses; salmonellosis, more commonly known by the bacteria that causes the disease, salmonella (Anderson, 1998).
Salmonellosis is contracted by eating foods contaminated with the salmonella, salmonella typhi and salmonella paratyphi bacterias, specifically milk, custard, egg dishes, salad dressings, sandwich fillings and polluted shellfish (Crisp & Taylor, 2001).
The bacteria live in the intestines of humans and animals and are shed through faeces (The Mayo Clinic, 2008)
Symptoms generally appear between 6 and 48 hours after eating the contaminated product (Anderson,1998). Symptoms include sharp abdominal pain (which may resemble acute appendicitis); fever; bloody, watery diarrhoea; nausea, vomiting, cramps. Dehydration because of the diarrhoea may occur. These symptoms can persist for up to two weeks (Crisp & Taylor, 2001, Anderson,1998), but generally stop after four to seven days (The Mayo Clinic, 2008).
Adequate cooking of food, proper refrigeration and thorough hand washing may help prevent contraction of salmonellosis (Anderson, 1998).
There is no reliable treatment for salmonellosis, and generally the goal of treatment is to replace lost fluids as more severe cases can lead to dehydration and malnutrition. If the infection travels out of the intestines, antibiotics are often prescribed to help destroy or impair the growth of the Salmonella bacteria. Unfortunately, because of the large percentage of cases treated with antibiotics, there have been reports of antibiotic resistant strains of Salmonella (The Mayo Clinic, 2008).
Botulism is a very rare and severe food borne illness, being fatal in two thirds of cases (Crisp & Taylor, 2001, Anderson, 1998.). Clostridium botulinum, the causing bacteria, grows in many meats (mainly smoked and salted meats, ham, sausage and shellfish) and vegetables. The bacteria grows best in oxygen free environments, and for that reason improperly processed foods in sealed containers and cans is a prime source of the bacteria (Marieb, 2001).
Clostridium botulinum produces a toxin, which causes the symptoms of botulism. This toxin is among the most poisonous substances known to humans (The Mayo Clinic, 2008).
The symptoms of botulism can be widely varied, from mild discomfort to death within twenty four hours. Some of the symptoms include lassitude (physical or mental weariness (Soanes, 2003)), double vision, difficulty focusing sight, inability of the pupils to accommodate light, weak muscles, dysphagia (difficulty swallowing). If untreated, these symptoms will progress into descending paralysis, generally beginning with the respiratory system. (Crisp & Taylor 2001, Anderson, 1998).
Treatment is antitoxins and sedatives to relieve anxiety. Two thirds of cases are fatal mainly because of delayed diagnosis or respiratory complications. Sometimes doctors prescribe laxatives to try and flush the toxin out of the digestive system (Anderson, 1998).
Preventative measures include ensuring proper canning of goods when canning them at home, sterilizing these foods by pressure cooking them at at least 120C (250F) for 30 minutes to kill any Clostridium botulinum bacteria (The Mayo Clinic, 2008).
Listeriosis is a fairly uncommon food borne disease caused by Listeria monocytogenes. (Crisp & Taylor 2001, Anderson, 1998, The Mayo Clinic, 2008). This bacteria has the unusual ability to grow in cold environments, making cold and frozen foods a prime source (The Mayo Clinic, 2008).
Although listeriosis is rare, it is deadly. The Centre for Disease Control (CDC) estimates the disease kills 500 people annually in the US alone (The Mayo Clinic, 2008).
The bacterium mainly contaminates soft cheeses, processed meats, unpasteurised milk, poultry, and seafood (Crisp & Taylor, 2001).
Listeria infection is uncommon in humans, but frequently affects shellfish, birds, spiders and some mammals (Anderson, 1998).
Symptoms include shock, hepatosplenomegaly (enlargement of the liver and spleen), a dark red rash over the torso, pneumonia, meningitis, endocarditis (inflammation of the serous membrane that lines the heart cavities; the endocardium), and circulatory collapse (Crisp & Taylor, 2001, Anderson, 1998).
Most healthy people exposed to Listeria monocytogenes don't become ill, however, pregnant women and people with weak immune systems are susceptible. If infection is suspected in a pregnant woman, treatment is begun immediately (Anderson, 1998, The Mayo Clinic, 2008). If treated early the infection can be stopped from affecting the baby (The Mayo Clinic, 2008).
The disease is treated with a variety of drugs, including ampicillin, penicillin, tetracycline and erythromycin injected intramuscularly or intravenously (Anderson, 1998).
Preventative measures include proper washing of hands, utensils and cooking surfaces, thorough washing of raw vegetables, prompt refrigeration of perishable products and avoiding unpasteurised milk and dairy products (The Mayo Clinic, 2008).
Shigellosis is an acute bacterial infection of the bowel (Anderson, 1998), caused by the Shigella family of bacteria (The Mayo Clinic, 2008). The disease is transmitted by contact with faeces contaminated with the Shigella bacteria, or by eating contaminated foods, most typically milk and milk products, seafood and salads (Crisp & Taylor, 2001).
Children are most commonly infected, and infections must be reported (Anderson, 1998).
Symptoms vary widely from mild diarrhoea to fatal dysentery (inflammation of the intestine, leading to a very watery discharge) (Anderson, 1998).
The disease is most often found in underdeveloped countries with poor sanitation conditions (The Mayo Clinic, 2008).
Shigella infection normally clears up on its own within a few days to a week, however, if treatment if required, doctors commonly prescribe antibiotics (namely sulfamethoxazole with trimethoprim, ofloxacin or ciprofloxacin) (The Mayo Clinic, 2008).
Mainly treatment is designed to prevent dehydration. For most people, drinking plenty of water is enough, but for severe cases hospitalization and an intravenous saline drip may be required (The Mayo Clinic, 2008).
Good hygiene is the best way to prevent catching or spreading shigellosis: clean hands with warm water and liquid or clean bar soap, wash vigorously for 15-20 seconds and rinse well, then dry hands with a clean or disposable towel. Make sure to turn off the tap with a towel to prevent recontamination (The Mayo Clinic, 2008).
Most strains of the bacteria Escherichia coli are harmless, occurring naturally in the intestines of healthy people and animals. However, certain strains such as E. coli 0157:H7 can cause serious and potentially deadly illness (The Mayo Clinic, 2008).
The most common source of E. coli is undercooked meat, so to prevent infection always cook meat at at least 60-70C. Also avoid untreated water that may be contaminated with faeces, wash raw produce thoroughly and wash your hands and kitchen utensils and surfaces before and after cooking with hot soapy water (Crisp & Taylor, 2001, The Mayo Clinic, 2008).
Symptoms include nausea, severe abdominal cramps, vomiting and bloody diarrhoea. These symptoms generally appear 1-8 days after eating contaminated foods (Crisp & Taylor, 2001). For most people, the disease runs its course in one day to a week, but in severe cases, people with weakened immune systems such as the elderly or children can develop haemolytic uremic syndrome (HUS), an abnormally high nitrogen waste in the body which can cause kidney failure (The Mayo Clinic, 2008, Anderson, 1998).
Currently there is no effective treatment for E. coli. The best option is bed rest and to drink plenty of fluids to prevent dehydration. Anti-diarrhoeal medication is not recommended, as it can impair the body's ability to get rid of the toxins. Researchers are currently investigating a vaccine (The Mayo Clinic, 2008).
While you have the disease it is important to avoid drinking apple and pear juices, caffeine and alcohol. Avoid high-fibre and fatty foods, dairy products or highly seasoned foods (The Mayo Clinic, 2008).
Perfringens enteritis is a food borne illness caused the bacteria clostridium perfringens (Crisp & Taylor, 2001). The bacteria live and thrive in meats that are held at warm or room temperature, even cooked meats. Symptoms are mild diarrhoea and vomiting. Symptoms appear 8-24 days after eating, and generally clear up after 1-2 days (Crisp & Taylor, 2001). There is currently no treatment for perfringens enteritis (CBW, 2008).
Staphylococcus, a potentially deadly illness caused by the bacteria Staphylococcus aureus, is most often acquired in hospitals (The Mayo Clinic, 2008). However it can be transmitted via foods like custards, cream fillings, processed meats, ham, cheese, ice cream, mayonnaise-based salads, cream sauces or casseroles (Crisp & Taylor, 2001).
Symptoms of staphylococcus include severe abdominal cramps, pain, vomiting, diarrhea, sweating, headache, fever and prostration (a condition of extreme exhaustion and inability to exert oneself further e.g. heat prostration) (Crisp & Taylor, 2001).
Symptoms usually appear 1-6 hours after ingestion and, depending on the speed of diagnosis; treatment lasts 1-2 days (Crisp & Taylor, 2001).
The first effective treatment for staph infections was penicillin, however, today barely ten percent of all staph infections respond to penicillin treatment. Because of this, staph infections are now treated with much stronger (and more toxic) antibiotics such as vancomycin (Mayo Clinic, 2008).
Unfortunately, because of the prevalence of treating staph with vancomycin, there have been reports of vancomycin resistant strains of the disease. There other drugs on the market that can be effective against staph, but not only are these very expensive, but resistances to them have already developed (Mayo Clinic, 2008).
The best prevention against staphylococcus is proper hand washing and proper refrigeration of high risk foods. If you have doubts about the food handling procedures in a restaurant, avoid high risk foods (Mayo Clinic, 2008).
The ciguatera toxin is a toxin that can contaminate fish primarily in the Caribbean and the South Pacific, causing ciguatera poisoning. The poison most commonly affects barracuda, but more than 300 species of fish have been implicated (Anderson, 1998).
Symptoms of ciguatera poisoning are vomiting, diarrhoea, paresthesia (tingling or numbness of the extremities and around the mouth), itching, fatigue, muscle weakness, pain, respiratory paralysis and a strange condition causing cold liquids to feel hot to the mouth and throat (Anderson, 1998).
The ciguatera toxin is believed to block acetylcholinesterase (an enzyme present in voluntary nerves and pain sympathetic involuntary nerves) activity (Anderson, 1998).
There is currently no effective treatment for ciguatera poisoning. Medications such as amitriptyline can reduce some of the symptoms, such as fatigue and paresthesia. Steroids and vitamin supplements are also used to support the body's recovery. There are several Caribbean naturopathic or ritualistic treatments. The most common of these involves bed rest and a guanabana juice enema (Wikipedia, 2005).
Minamata disease is a degenerative neurological disorder, caused by mercury poisoning obtained by eating seed grain heated with alkyl compounds of mercury or by eating seafood taken from mercury contaminated waters (Anderson, 1998).
Symptoms of Minamata are paresthesia, tunnel vision, difficulties in speech, impaired hearing, impaired muscular coordination, impaired concentration, physical weakness, emotional instability and stupor. Continual ingestion of contaminated foods can cause damage to the kidney tubules and corrosion of the gastrointestinal tract. In acute cases insanity, paralysis, coma and death follow within a few weeks of the onset of symptoms (Anderson, 1998).
Minamata is treated with chelation therapy, the standard treatment for heavy metal poisoning. Chelating agents are administered to help rid the body of toxins (Wikipedia, 2005).
Mushroom poisoning is caused by ingesting certain poisonous species of mushrooms. For the purposes of this report, I will focus on two of the most deadly; Amanita muscarine and Amanita phalloides (death cap) (Anderson, 1998, Bender, 2005).
The symptoms of Amanita muscarine poisoning are lacrimation (unstoppable secretion of tears), salivation, sweating, vomiting, laboured breathing, abdominal cramps, bloody diarrhoea, in severe cases coma, convulsions, circulatory failure and death. The treatment for Amanita muscarine is atropine (Anderson, 1998).
Amanita phalloides poisoning is slower but more deadly. Symptoms are similar to Amanita muscarine with the additions of liver damage and kidney failure. Death occurs in 30-50% of cases. Treatment varies (Anderson, 1998).
Alcohol consumption can complicate poisoning, causing optic neuritis (inflammation of the optic nerve) (Anderson, 1998).
Severe symptoms of mushroom poisoning usually do not appear until the toxin reaches the kidneys, which can be from minutes to hours or, in rare cases, days later (Bender, 2005). If treated mushroom poisoning usually does not cause death, but if untreated, death can occur within a few days if the species eaten is potent (Wikipedia, 2005).
Shellfish poisoning is caused by eating clams, oysters, mussels or other shellfish that have ingested the toxin producing protozoa commonly called red tide' (Anderson, 1998, Bender, 2005).
Symptoms usually appear within a few minutes of eating and include nausea, light headedness, vomiting and paresthesia. These symptoms are followed by paralysis of the extremities and respiratory paralysis (Anderson, 1998).
The severity of the disease can be reduced if the water the shellfish was cooked in is not consumed (Anderson, 1998).
Treatment for shellfish poisoning is intravenous injection of a weak solution of neostigmine methylsulfate and artificial respiration in cases of respiratory paralysis (Anderson, 1998).
In conclusion, food borne illnesses can be transmitted through foods ranging from red meats to canned foods to fish to vegetables to dairy products, and they range in severity from mild nausea and some diarrhoea to death in just a few days. The treatments for the different diseases are just as varied, though many can be treated with antibiotics. The best prevention for food borne illnesses is always good sanitation. You should always cook food properly and wash your hands, utensils and cooking surfaces before and after. If these precautions are followed, the chance of contracting a food borne illness is relatively low.
References
Anderson, K.N. (ed) 1998. Mosby's Medical, Nursing & Allied Health Dictionary, 5th Ed. Harcourt Health Sciences, St. Louis.
Bender, D. 2005. Encarta Encyclopedia Standard Edition, Microsoft Corporation.
Crisp, J. & Taylor, C. 2001. Potter & Perry's Fundamentals Of Nursing. Harcourt Health Sciences Australia, Marrickville, NSW.
Marieb, E.N. 2001. Human Anatomy & Physiology, 5th Ed. Benjamin Cummings, San Francisco.
Soanes, C. (ed) 2003. Oxford Compact English Dictionary, 2nd Ed. Oxford University Press, Oxford, England.
Website: The Mayo Clinic: . Accessed on 17/2/2008.
Website: Wikipedia, The Free Encyclopedia: . Accessed on 17/2/2008
Website: CBW: . Accessed on 17/2/2008.