Unpasteurized milk, dairy products, mayonnaise, and pastry icing are associated with increased risk for TD, as are foods and beverages purchased from street vendors and other establishments where unhygienic conditions may be present. Water
Although safe bottled water is now widely available in most remote destinations, travelers can treat their own water if necessary, or as an extra precaution. Techniques include boiling, filtering, chemical treatment, and ultraviolet light; boiling is by far the most effective of these methods. Boiling rapidly kills all active bacteria, viruses, and protozoa. Prolonged boiling is usually unnecessary; most microorganisms are killed within seconds at water temperature above 55–70 °C (130–160 °F). The second-most effective method is to combine filtration and chemical disinfection. Filters eliminate most bacteria and protozoa, but not viruses. Chemical treatment with halogens—chlorine bleach, tincture of iodine, or commercial tablets—have low-to-moderate effectiveness against protozoa such as Giardia, but work well against bacteria and viruses. UV light is effective against both viruses and cellular organisms, but only works in clear water, and it is ineffective unless manufacturers instructions are carefully followed for maximum water depth/distance from UV source, and for dose/exposure time. Other claimed advantages include short treatment time, elimination of the need for boiling, no taste alteration, and decreased long-term cost compared with bottled water. The effectiveness of UV devices is reduced when water is muddy or turbid; as UV is a type of light, any suspended particles create shadows that hide microorganisms from UV exposure. Medications
Bismuth subsalicylate four times daily reduces rates of travelers diarrhea.
Antibiotics
If diarrhea becomes severe (typically defined as three or more loose stools in an eight-hour period), especially if associated with nausea, vomiting, abdominal cramps, fever, or blood in stools, medical treatment should be sought. Such patients may benefit from antimicrobial therapy. A 2000 literature review found that antibiotic treatment shortens the duration and severity of TD; most reported side effects were minor, or resolved on stopping the antibiotic.The antibiotic recommended varies based upon the destination of travel. Trimethoprim–sulfamethoxazole and doxycycline are no longer recommended because of high levels of resistance to these agents. Antibiotics are typically given for three to five days, but single doses of azithromycin or levofloxacin have been used. Rifaximin and rifamycin are approved in the U.S. for treatment of TD caused by ETEC. If diarrhea persists despite therapy, travelers should be evaluated for bacterial strains resistant to the prescribed antibiotic, possible viral or parasitic infections, bacterial or amoebic dysentery, Giardia, helminths, or cholera. Antimotility agents
Antimotility drugs such as loperamide and diphenoxylate reduce the symptoms of diarrhea by slowing transit time in the gut. They may be taken to slow the frequency of stools, but not enough to stop bowel movements completely, which delays expulsion of the causative organisms from the intestines. They should be avoided in patients with fever, bloody diarrhea, and possible inflammatory diarrhea. Adverse reactions may include nausea, vomiting, abdominal pain, hives or rash, and loss of appetite. Antimotility agents should not, as a rule, be taken by children under age two.