Food and Water Contamination

How Do You Get Food and Water Contamination?

Consuming food or water that is contaminated with infectious germs, chemicals, or toxins causes food poisoning. Bacteria cause approximately 80 percent of food poisoning cases.  Noroviruses are among the most common viruses that cause food poisoning. One of the most frequent sources of food poisoning is food purchased from street vendors.

Susceptibility and Resistance

All persons are susceptible to food or water borne contamination, although persons who are repeatedly exposed to certain germs may develop some tolerance. If the cause is an infectious germ, people may still be infectious and spread the illness to others even after their illness has subsided.

What Are The Symptoms?

Symptoms are highly variable and can range from very mild discomfort to serious life-threatening illness depending on the type of contamination in the food.  Frequent and common symptoms include the rapid onset of fatigue, nausea, vomiting, abdominal pain and diarrhoea, with or without mild to severe fever.  Symptoms may be resolved after about 24 hours, or may be longer lasting and severe. Episodes of illness may repeat over a period of time. Some food-borne toxins, e.g., botulism, result in life-threatening paralysis and require aggressive treatment.  

Sometimes the cause of the symptoms is suggested by the incubation time between consuming the contaminated food or water and the onset of symptoms. For some common causes of food poisoning, the Control of Communicable Diseases Manual, 19th edition, 2008, includes the following information on the range of incubation periods:  

• for staphylococcal bacterial infection: 30 minutes to 8 hrs (usually 2-4 hrs)
• for Bacillus cereus bacterial infection: 30 minutes to 24 hrs
• for Clostridium perfringens bacterial infection: 6-24 hrs (usually 10-12 hrs)
• for shellfish poisoning: within 12 hours for 4 types of shellfish poisoning
• for scombroid fish poisoning: - a few hours (resolving spontaneously within 12 hours)
• for ciguatera (fish) poisoning: - within 24 hrs
• for puffer fish poisoning, which has a 60 percent fatality rate: - a few hours   

Preventative Measures

Prevention of food or water contamination depends on cleanliness in food preparation, separation of raw and cooked food, thorough cooking, storage of cooked foods at appropriate temperatures and use of safe water and raw ingredients. Personal prevention measures include:

• Patronizing only reputable and licensed restaurants; avoid illegal food hawkers and street vendors
• Only consume food that has been cooked thoroughly
• Avoid eating raw seafood; be cautious when choosing cold dishes, including sashimi, sushi and raw oysters at a buffet
• Only drink boiled or bottled water unless you can be sure that  water sources are properly treated to eliminate contaminants.  If consuming bottled water, always be sure that the cap and seal are intact before consuming.
• Always wash hands before eating and after going to the toilet. 

Treatment

Treatment depends on the type of contamination and may include pain relief, antibiotics, rehydration (orally or intravenously), use of special anti-toxins, or even artificial respiration in the event of respiratory failure.  If the condition persists, identification of the causative agent may be required in order to prescribe a definitive treatment.  Serious illness or persistent, severe, or bloody diarrhoea, however, should be investigated at once to determine the cause and the specific treatment required.

Medications

• Antibiotics

Where Does It Commonly Occur?

Food or water contamination (gastroenteritis) is a common illness found anywhere in the world in both developed and developing countries. High-risk destinations include some of the developing countries of Latin America, Africa, the Middle East, and Asia.