Foodborne and waterborne diseases are illnesses caused by bacteria that are present in contaminated food and water sources. Foodborne diseases often take the form of "food poisoning," with vomiting and diarrhea. Waterborne diseases can manifest as either food poisoning or pneumonia, depending on the bacteria involved.
Some foodborne and waterborne diseases come from obvious sources, like untreated water or water contaminated with human or animal sewage. Tainted water will cause a food poisoning illness. Suspicious water should always be avoided; travelers to areas with poor water supplies should drink bottled water or boil water before drinking it.
Other foodborne diseases come from foods that were contaminated anywhere in the food preparation process. Some meats are contaminated with E. coli bacteria before they reach the grocery store; other foods may be infected with Salmonella or the bacteria that causes cholera by a food handler with unclean hands. In general, the recommendations for food handling (eg, to what temperature meats should be cooked) are listed on the food products.
The waterborne disease caused by the Legionella bacteria manifests as a pneumonia called legionellosis, commonly known as Legionnaires' disease. The Legionella bacteria are found naturally in water sources and can contaminate large, contained water supplies such as hot tubs, cooling towers, and large air-conditioning supply units. The disease has symptoms of pneumonia, such as cough, fever, and chills. It can be difficult to diagnose Legionnaires' disease, but it is treatable with common antibiotics.
Except in the very young, the very old, and the immunocompromised, most foodborne and waterborne diseases cause a vomiting and diarrhea illness that is not life-threatening. The most important thing - for healthy people and the at-risk groups listed above - is to stay well-hydrated. Everyone, especially people at higher risk, should see a doctor if food poisoning is suspected. Your doctor may recommend tests on your blood or stool or antibiotics, depending on your symptoms.