Medical Health Encyclopedia

Infectious Causes

A number of infectious organisms, including bacteria, parasites, and viruses, can cause diarrhea in the traveler. These organisms are most often transmitted through contaminated food and water. Bacteria and viruses cause diarrhea within a few hours and up to 3 days, while diarrhea from parasites can occur 7 to 14 days after exposures. In about 10 - 50% of cases, the cause of TD is unknown.

• The most common bacterial cause of traveler's diarrhea is Escherichia coli ( E. coli). It is an enterotoxigenic organism, which means it is toxic to the intestines. E. coli accounts for between 20 - 50% of cases. It is found in soil, water, and milk and occurs in major regions in the worlds, with the highest rates in Latin American and the lowest in Asia. Diarrhea caused by E.coli is generally explosive, non-bloody, and accompanied by nausea, vomiting, cramps, and fever.
• Noroviruses, also called Norwalk-like viruses, are an increasingly common cause of traveler’s diarrhea in countries such as Mexico and Guatemala. Recent studies of travel in these destinations rank noroviruses second to E. coli for causing diarrhea.
• Shigella is the bacterial cause of dysentery, affecting 15% of travelers. It is common in countries experiencing natural disasters, socioeconomic upheaval, or during other times when sanitary food and water are difficult to procure. Shigella causes bloody and mucus-laden diarrhea along with fever, cramps, and exhaustion.
• Campylobacter is a very common bacterial cause of diarrhea in certain regions, notably Thailand and Morocco, during the winter.
• Giardia is a parasite found in contaminated water in every country in the world. It can cause chronic diarrhea lasting for several weeks, causing vague pain, weight loss, excessive burping, bloating, and fatigue.
• Entamoeba histolytica is a parasite that is prevalent Mexico, India, Africa, and Central and South America. It produces small stools that contain blood and mucus. If the condition becomes chronic, it can resemble inflammatory bowel disease (IBD). It is important to distinguish the two, since corticosteroids used to treat IBD can have dangerous effects in people carrying the parasite.
• Additional common culprits are the bacteria Salmonella, parasites (Cryptosporidiosis, Cyclospora. mocrosporidia), and rotavirus (usually in Latin America).