Sanitation Recommendations include avoidance of questionable foods and drinks, on the assumption that TD is fundamentally a sanitation failure, leading to bacterial contamination of drinking water and food. While the effectiveness of this strategy has been questioned, given that<unk>  have little or no control over sanitation in hotels and restaurants, and little evidence supports the contention that food vigilance reduces the risk of contracting TD, guidelines continue to recommend basic, common-sense precautions when making food and beverage choices: * Maintain good hygiene and use only safe water for drinking and brushing teeth. * Safe beverages include bottled water, bottled carbonated beverages, and water boiled or appropriately treated by the<unk> (as described below). Caution should be exercised with tea, coffee, and other hot beverages that may be only heated, not boiled. * In restaurants, insist that bottled water be unsealed in your presence; reports of locals filling empty bottles with untreated tap water and reselling them as purified water have surfaced. When in doubt, a bottled carbonated beverage is the safest choice, since it is difficult to simulate carbonation when refilling a used bottle. * Avoid ice, which may not have been made with safe water. * Avoid green salads, because the lettuce and other uncooked ingredients are unlikely to have been washed with safe water. * Avoid eating raw fruits and vegetables unless cleaned and peeled personally. If handled properly, thoroughly cooked fresh and packaged foods are usually safe. Raw or undercooked meat and seafood should be avoided. 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,<unk>  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 manufacturer's 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<unk> . Though many<unk>  find a four-times-per-day regimen inconvenient, lower doses have not been shown to be effective. Potential side effects include black tongue, black stools, nausea, constipation, and ringing in the ears. Bismuth subsalicylate should not be taken by those with aspirin allergy, kidney disease, or gout, nor concurrently with certain antibiotics such as the quinolones, and should not be taken continuously for more than three weeks. Some countries do not recommend it due to the risk of rare but serious side effects. A hyperimmune bovine colostrum to be taken by mouth is marketed in Australia for prevention of ETEC-induced TD. As yet, no studies show efficacy under actual travel conditions. Though effective, antibiotics are not recommended for prevention of TD in most situations because of the risk of allergy or adverse reactions to the antibiotics, and because intake of preventive antibiotics may decrease effectiveness of such drugs should a serious infection develop subsequently. Antibiotics can also cause vaginal yeast infections, or overgrowth of the bacterium Clostridium difficile, leading to pseudomembranous colitis and its associated severe, unrelenting<unk> . Antibiotics may be warranted in special situations where benefits outweigh the above risks, such as immunocompromised<unk> , chronic intestinal disorders, prior history of repeated disabling bouts of TD, or scenarios in which the onset of<unk>  might prove particularly troublesome. Options for prophylactic treatment include the quinolone antibiotics (such as ciprofloxacin), azithromycin, and trimethoprim/sulfamethoxazole, though the latter has proved less effective in recent years. Rifaximin may also be useful. Quinolone antibiotics may bind to metallic cations such as bismuth, and should not be taken concurrently with bismuth subsalicylate. Trimethoprim/sulfamethoxazole should not be taken by anyone with a history of sulfa allergy. Vaccination The oral cholera vaccine, while effective for prevention of cholera, is of questionable use for prevention of TD. A 2008 review found tentative evidence of benefit. A 2015 review stated it may be reasonable for those at high risk of complications from TD. Several vaccine candidates targeting ETEC or Shigella are in various stages of development. Probiotics One 2007 review found that probiotics may be safe and effective for prevention of TD, while another review found no benefit. A 2009 review confirmed that more study is needed, as the evidence to date is mixed.
Travelers' diarrhea
Dysentery
Porcine epidemic diarrhoea
Bacillary dysentery
Cholera
Jamaican vomiting sickness
Riga–Fede disease
Rotaviral gastroenteritis