There is a general misconception that the term ‘food poisoning’ implies intentional poisoning of foodstuffs with toxic chemicals. Barring crime stories which you are likely to encounter in Page 3 of your daily newspaper, this is not so. The term implies infection by certain common bacterial, viral and parasitic contaminants of foodstuffs, the subsequent release of toxins within the gastrointestinal tract, and the clinical signs and symptoms that result from this infection.
There are a host of microorganisms that can cause food poisoning. The most common culprits are Entamoeba (a common parasite that can cause dysentery), Giardia (another parasite that causes diarrhea), Campylobacter, Shigella, Salmonella (bacteria that causes typhoid), E coli, Listeria and Norovirus.
Most of the above mentioned causative agents are found in foodstuffs. Eating or drinking contaminated foods is an easy way of contracting any of them. The foodstuffs that are often the source of infection are, green leafy vegetables, any raw vegetable, raw eggs, raw fruit juices, milk and dairy products, sprouts, tuna and other seafood. Recently, in a study published in the journal, Applied and Environmental Microbiology, researchers from Shanghai Ocean University concluded that oysters are an important source of Norovirus infections. Apart from food, animal feces, diapers, agricultural products and swimming pools can also be a source of infection.
Signs and symptoms
Whatever the source of infection, food poisoning is characterised by abdominal pain, nausea and vomiting, diarrhea, fever and body ache. Dysentery is characterised by loose stools with blood and mucous. Even though most cases of food poisoning settle in a period of 5-7 days, they can persist and worsen with potentially life-threatening consequences in those who are young, elderly, or with a low immune status (such as pregnant women and those with HIV infection).
Barring bacterial and parasitic infections, for which antibiotics and anti-parasitic medications can be prescribed, the mainstay of treatment of food poisoning is supportive in nature. Fluid replacement is vital as dehydration can set in very quickly in the presence of vomiting and diarrhea. Increasing oral intake of mineral rich fluids such as coconut water, and safe fruit juices is necessary, and in severe cases, hospitalization with intravenous fluid replacement would be necessary. In children, Oral Rehydration Solution (ORS), which is available in most pharmacies and Primary Health Care Centers, is a very important step in the treatment. In the absence of ORS, 6 teaspoons of sugar and half teaspoon of salt can be mixed in a liter of boiled and cooled water, and used to rehydrate both children and adults.
Most of these infections can be easily prevented by following a few precautions. The most basic and important requirement is hand washing. Washing hands with soap solutions and disinfectants before and after eating food is a simple way of preventing contamination. While eating raw vegetables is advocated for its potential health benefits, one has to strike the balance between this and running the risk of infection with causative organisms. Keeping all vegetables in the refrigerator and rinsing them in vinegar or salt water may reduce the chance of infections. Animal products and meat should be cooked thoroughly. Only pasteurized milk and juice should be consumed. All forms of roadside eateries should be avoided. Infants should be breastfed in the initial stages until weaning is advised by the child specialist.