When all or most of the digestive tract is involved, diarrhea is accompanied by nausea and vomiting . Frequently the same diseases that cause diarrhea also cause fever and muscle weakness. Causes Almost any of the major causes of disease can produce diarrhea, so it is a symptom of many diseases. The most common causes of diarrhea in adults are bacteria or parasites ingested in water or food when traveling, and reactions to foods, including allergies . Worm infestations of several kinds, including hookworm , whipworm , and tapeworm , can cause the symptom.
Children are more susceptible to viral bacteria than adults.
In some people emotional upset can lead to the condition. Rarely, cancer can produce diarrhea. Often medicines or other treatments for diseases or disorders produce some diarrhea as a side effect. Nearly everyone develops diarrhea at some time during childhood as a result of infection by one of the viruses called rotaviruses. In developing countries such rotavirus infections lead to perhaps as many as 800,000 to 1 million deaths each year, but such childhood diarrhea is rarely fatal in industrialized countries.