Travelers' diarrhea is the most common travel-related ailment. The cornerstone of prevention is food and water precautions, as outlined below. All travelers should bring along an antibiotic and an antidiarrheal drug to be started promptly if significant diarrhea occurs, defined as three or more loose stools in an 8-hour period or five or more loose stools in a 24-hour period, especially if associated with nausea, vomiting, cramps, fever or blood in the stool. A quinolone antibiotic is usually prescribed: either ciprofloxacin (Cipro)(PDF) 500 mg twice daily or levofloxacin (Levaquin) (PDF) 500 mg once daily for a total of three days. Quinolones are generally well-tolerated, but occasionally cause sun sensitivity and should not be given to children, pregnant women, or anyone with a history of quinolone allergy. Alternative regimens include a three day course of rifaximin (Xifaxan) 200 mg three times daily or azithromycin (Zithromax) 500 mg once daily. Rifaximin should not be used by those with fever or bloody stools and is not approved for pregnant women or those under age 12. Azithromycin should be avoided in those allergic to erythromycin or related antibiotics. An antidiarrheal drug such as loperamide (Imodium) or diphenoxylate (Lomotil) should be taken as needed to slow the frequency of stools, but not enough to stop the bowel movements completely. Diphenoxylate (Lomotil) and loperamide (Imodium) should not be given to children under age two.

Most cases of travelers' diarrhea are mild and do not require either antibiotics or antidiarrheal drugs. Adequate fluid intake is essential.

If diarrhea is severe or bloody, or if fever occurs with shaking chills, or if abdominal pain becomes marked, or if diarrhea persists for more than 72 hours, medical attention should be sought.

Though effective, antibiotics are not recommended prophylactically (i.e. to prevent diarrhea before it occurs) because of the risk of adverse effects, though this approach may be warranted in special situations, such as immunocompromised travelers.

Malaria in Laos: prophylaxis is recommended for all areas except the city of Vientiane. Either mefloquine (Lariam), atovaquone/proguanil (Malarone)(PDF), or doxycycline may be used for prophylaxis. Mefloquine is given once weekly in a dosage of 250 mg, starting one-to-two weeks before arrival and continuing through the trip and for four weeks after departure. Mefloquine may cause mild neuropsychiatric symptoms, including nausea, vomiting, dizziness, and sleep disorders. Rarely, severe reactions occur, including depression, psychosis, hallucinations, and seizures. Mefloquine should not be given to anyone with a history of seizures, psychiatric illness, cardiac conduction disorders, or allergy to mefloquine. Those taking mefloquine (Lariam) should read the Lariam Medication Guide (PDF). Atovaquone/proguanil (Malarone) is a recently approved combination pill taken once daily with food starting two days before arrival and continuing through the trip and for seven days after departure. Side-effects, which are typically mild, may include abdominal pain, nausea, vomiting, headache, diarrhea, or dizziness. Serious adverse reactions are rare. Doxycycline is effective, but may cause an exaggerated sunburn reaction, which limits its usefulness in the tropics.

Long-term travelers who will be visiting malarious areas and may not have access to medical care should bring along medications for emergency self-treatment should they develop symptoms suggestive of malaria, such as fever, chills, headaches, and muscle aches, and cannot obtain medical care within 24 hours. See malaria for details. Symptoms of malaria sometimes do not occur for months or even years after exposure.

Insect protection measures are essential.

For further information concerning malaria in Laos, including maps showing the risk of malaria in different parts of the country, go to the World Health Organization - Western Pacific Region.

The following are the recommended vaccinations for Laos:

Hepatitis A vaccine is recommended for all travelers over one year of age. It should be given at least two weeks (preferably four weeks or more) before departure. A booster should be given 6-12 months later to confer long-term immunity. Two vaccines are currently available in the United States: VAQTA (Merck and Co., Inc.) (PDF) and Havrix (GlaxoSmithKline) (PDF). Both are well-tolerated. Side-effects, which are generally mild, may include soreness at the injection site, headache, and malaise.

Older adults, immunocompromised persons, and those with chronic liver disease or other chronic medical conditions who have less than two weeks before departure should receive a single intramuscular dose of immune globulin (0.02 mL/kg) at a separate anatomic injection site in addition to the initial dose of vaccine. Travelers who are less than one year of age or allergic to a vaccine component should receive a single intramuscular dose of immune globulin (see hepatitis A for dosage) in the place of vaccine.

Typhoid vaccine is recommended for all travelers, with the exception of short-term visitors who restrict their meals to major restaurants and hotels, such as business travelers. It is generally given in an oral form (Vivotif Berna) consisting of four capsules taken on alternate days until completed. The capsules should be kept refrigerated and taken with cool liquid. Side-effects are uncommon and may include abdominal discomfort, nausea, rash or hives. The alternative is an injectable polysaccharide vaccine (Typhim Vi; Aventis Pasteur Inc.) (PDF), given as a single dose. Adverse reactions, which are uncommon, may include discomfort at the injection site, fever and headache. The oral vaccine is approved for travelers at least six years old, whereas the injectable vaccine is approved for those over age two. There are no data concerning the safety of typhoid vaccine during pregnancy. The injectable vaccine (Typhim Vi) is probably preferable to the oral vaccine in pregnant and immunocompromised travelers.

Japanese encephalitis vaccine is recommended only for long-term (>1 month) travelers to rural areas or travelers who may engage in extensive unprotected outdoor activities in rural areas, especially in the evening, during shorter trips. Japanese encephalitis is believed to occur throughout Laos. The disease is transmitted by mosquito bites, probably from May through October. The vaccine (JE-VAX; Aventis Pasteur Inc.) (PDF) is given as a series of three injections on days 0, 7 and 30. If time is short, the third dose may be given on day 14. Mild side effects including fever, headache, muscle aches, malaise and soreness at the injection site occur in about 20% of those vaccinated. Serious allergic reactions including urticaria, angioedema, respiratory distress and anaphylaxis occur in approximately 0.6% of vaccinees and may occur as long as one week after vaccination. Any person who receives the vaccine should be observed in the doctor's office for at least 30 minutes following the injection and should complete the full series at least 10 days before departure. There are no data concerning the safety of Japanese encephalitis vaccine during pregnancy. In addition to vaccination, strict attention to insect protection measures is essential for anyone at risk.

Hepatitis B vaccine is recommended for travelers who will have intimate contact with local residents or potentially need blood transfusions or injections while abroad, especially if visiting for more than six months. It is also recommended for all health care personnel. Two vaccines are currently licensed in the United States: Recombivax HB (Merck and Co., Inc.) (PDF) and Engerix-B (GlaxoSmithKline) (PDF). A full series consists of three intramuscular doses given at 0, 1 and 6 months. Engerix-B is also approved for administration at 0, 1, 2, and 12 months, which may be appropriate for travelers departing in less than 6 months. Side-effects are generally mild and may include discomfort at the injection site and low-grade fever. Severe allergic reactions (anaphylaxis) occur rarely.

Rabies vaccine is recommended only for those at high risk for animal bites, such as veterinarians and animal handlers, and for long-term travelers who may have contact with animals and may not have access to medical care. A complete preexposure series consists of three doses of vaccine injected into the deltoid muscle on days 0, 7, and 21 or 28. Side-effects may include pain at the injection site, headache, nausea, abdominal pain, muscle aches, dizziness, or allergic reactions.

Any animal bite or scratch should be thoroughly cleaned with large amounts of soap and water and local health authorities should be contacted immediately for possible post-exposure treatment, whether or not the person has been immunized against rabies.

Tetanus-diphtheria vaccine is recommended for all travelers who have not received a tetanus-diphtheria immunization within the last 10 years.

Measles-mumps-rubella vaccine: two doses are recommended (if not previously given) for all travelers born after 1956, unless blood tests show immunity. Many adults born after 1956 and before 1970 received only one vaccination against measles, mumps, and rubella as children and should be given a second dose before travel. MMR vaccine should not be given to pregnant or severely immunocompromised individuals.

Cholera vaccine is not generally recommended, even though cholera occurs in Laos, because most travelers are at low risk for infection. Two oral vaccines have recently been developed: Orochol (Mutacol), licensed in Canada and Australia, and Dukoral, licensed in Canada, Australia, and the European Union. These vaccines, where available, are recommended only for high-risk individuals, such as relief workers, health professionals, and those traveling to remote areas where cholera epidemics are occurring and there is limited access to medical care. The only cholera vaccine approved for use in the United States is no longer manufactured or sold, due to low efficacy and frequent side-effects.

Polio vaccine is not recommended for any adult traveler who completed the recommended childhood immunizations. In October 2000, the World Health Organization certified that polio had been eradicated from the Western Pacific region.

Yellow fever vaccine is required for all travelers arriving from a yellow-fever-infected country in Africa or the Americas, but is not recommended or required otherwise. Yellow fever vaccine (YF-VAX; Aventis Pasteur Inc.) (PDF) must be administered at an approved yellow fever vaccination center, which will give each vaccinee a fully validated International Certificate of Vaccination. Yellow fever vaccine should not in general be given to those younger than nine months of age, pregnant, immunocompromised, or allergic to eggs.

A cholera outbreak was reported in January 2008 from Xekong province in the southern part of Laos, near the border with Vietnam. As of January 30, more than 360 cases and at least three deaths had been identified. The outbreak might have been related to contamination of a local river, used for drinking water. The main symptoms of cholera are profuse watery diarrhea and vomiting, which in severe cases may lead to dehydration and death. Most travelers are at extremely low risk for infection. Cholera vaccine, where available, is recommended only for certain high-risk individuals, such as relief workers, health professionals, and those traveling to remote areas where cholera epidemics are occurring and there is limited access to medical care. All travelers should carefully observe food and water precautions, as below.

Two human cases of H5N1 avian influenza ("bird flu"), both of them fatal, were reported from Vientiane in March 2007. Cases on poultry farms were reported as early as January 2004. The initial outbreaks were controlled, but new cases were reported from a chicken farm in Vientiane in July 2006 and from two duck farms in the Vientiane area in February 2007. The most recent poultry outbreaks were reported from Luang Namtha province in February and March 2008 and from northern Luang Prabang province in September 2008.

Most travelers are at extremely low risk for avian influenza, since almost all human cases in other countries have occurred in those who have had direct contact with live, infected poultry, or sustained, intimate contact with family members suffering from the disease. The Centers for Disease Control does not advise against travel to Laos, but recommends that travelers should avoid exposure to live poultry, including visits to poultry farms and open markets with live birds; should not touch any surfaces that might be contaminated with feces from poultry or other animals; and should make sure all poultry and egg products are thoroughly cooked. A vaccine for avian influenza was recently approved by the U.S. Food and Drug Administration (FDA), but produces adequate antibody levels in fewer than half of recipients and is not commercially available. The vaccines for human influenza do not protect against avian influenza. Anyone who develops fever and flu-like symptoms after travel to Laos should seek immediate medical attention, which may include testing for avian influenza. For further information, go to the World Health Organization, Health Canada, the Centers for Disease Control, and ProMED-mail.

Cases of dengue fever, a flu-like illness sometimes complicated by hemorrhage or shock, occur annually in Laos. Transmission of dengue fever usually peaks from June through November, though the disease occurs year-round. As of August 2008, there were more than 1900 cases of dengue fever for the year, including 18 fatalities: nine in Champassak province, seven in Saravan province, and one each in Khammuan and Xayaboury provinces. Dengue is transmitted by Aedes mosquitoes, which bite primarily in the daytime and favor densely populated areas, though they also inhabit rural environments. No vaccine is available at this time. The cornerstone of prevention is insect protection measures, as outlined below. is transmitted by Aedes mosquitoes, which bite primarily in the daytime and favor densely populated areas, though they also inhabit rural environments.

Major dengue outbreaks occurred in 1995, 1996 and 1998. Dengue activity in the first half of 2001, though less than that seen in 1998, was higher than for the comparable period in 1999 and 2000. As of July 28, 2001, a total of 1432 cases had been reported for the year, more than half of them from the Vientiane municipality. Other provinces reporting a large number of cases included Bolikhamsay, Champassak, Khammouane, Luang Prabang, Savannakhet and Xayaboury. See the World Health Organization for details. For further information on dengue in Laos, go to the World Health Organization - Western Pacific Region.

A small number of cases of human plague are reported from Laos. The plague is usually transmitted by the bite of rodent fleas. Less commonly, the disease is acquired by inhalation of infected droplets, which may be coughed into the air by a person with plague pneumonia, or by direct exposure to infected blood or tissues. Most travelers are at extremely low risk. Those who may have contact with rodents or their fleas should bring along a bottle of doxycycline, to be taken prophylactically if exposure occurs. Those less than eight years of age or allergic to doxycycline may take trimethoprim-sulfamethoxazole instead. To minimize risk, travelers should avoid areas containing rodent burrows or nests, never handle sick or dead animals, and follow insect protection measures, as described below.

HIV (human immunodeficiency virus) infection is reported, but travelers are not at risk unless they have unprotected sexual contacts or receive injections or blood transfusions.

Other infections include

• Scrub typhus(deforested areas) and murine typhus (see Emerging Infectious Diseases)
• Schistosomiasis (Mekong delta; swimming and bathing precautions are advised, as below)
• Leptospirosis
• Hepatitis E (transmitted by contaminated food or water)
• Chikungunya fever
• Melioidosis (caused by bacteria found in contaminated soil and water, especially in agricultural fields during the rainy season; causes wound infections or pneumonia, which may progress rapidly and be life-threatening)
• Lymphatic filariasis
• Strongyloides
• Lung fluke (paragonimiasis)
• Capillariasis
• Giant intestinal fluke (fasciolopsiasis)
• Oriental liver fluke (clonorchiasis)
• Cat liver fluke (opisthorchiasis)

For an overview of health care in Laos, go to the World Health Organization - Western Pacific Region.

Do not drink tap water unless it has been boiled, filtered, or chemically disinfected. Do not drink unbottled beverages or drinks with ice. Do not eat fruits or vegetables unless they have been peeled or cooked. Avoid cooked foods that are no longer piping hot. Cooked foods that have been left at room temperature are particularly hazardous. Avoid unpasteurized milk and any products that might have been made from unpasteurized milk, such as ice cream. Avoid food and beverages obtained from street vendors. Do not eat raw or undercooked meat or fish. Some types of fish may contain poisonous biotoxins even when cooked. Barracuda in particular should never be eaten. Other fish that may contain toxins include red snapper, grouper, amberjack, sea bass, and a large number of tropical reef fish.

All travelers should bring along an antibiotic and an antidiarrheal drug to be started promptly if significant diarrhea occurs, defined as three or more loose stools in an 8-hour period or five or more loose stools in a 24-hour period, especially if accompanied by nausea, vomiting, cramps, fever or blood in the stool. Antibiotics which have been shown to be effective include ciprofloxacin (Cipro), levofloxacin (Levaquin), rifaximin (Xifaxan), or azithromycin (Zithromax). Either loperamide (Imodium) or diphenoxylate (Lomotil) should be taken in addition to the antibiotic to reduce diarrhea and prevent dehydration.

If diarrhea is severe or bloody, or if fever occurs with shaking chills, or if abdominal pain becomes marked, or if diarrhea persists for more than 72 hours, medical attention should be sought.

Wear long sleeves, long pants, hats and shoes (rather than sandals). For rural and forested areas, boots are preferable, with pants tucked in, to prevent tick bites. Apply insect repellents containing 25-50% DEET (N,N-diethyl-3-methylbenzamide) or 20% picaridin (Bayrepel) to exposed skin (but not to the eyes, mouth, or open wounds). DEET may also be applied to clothing. Products with a lower concentration of either repellent need to be repplied more frequently. Products with a higher concentration of DEET carry an increased risk of neurologic toxicity, especially in children, without any additional benefit. Do not use either DEET or picaridin on children less than two years of age. For additional protection, apply permethrin-containing compounds to clothing, shoes, and bed nets. Permethrin-treated clothing appears to have little toxicity. Don't sleep with the window open unless there is a screen. If sleeping outdoors or in an accomodation that allows entry of mosquitoes, use a bed net, preferably impregnated with insect repellent, with edges tucked in under the mattress. The mesh size should be less than 1.5 mm. If the sleeping area is not otherwise protected, use a mosquito coil, which fills the room with insecticide through the night. In rural or forested areas, perform a thorough tick check at the end of each day with the assistance of a friend or a full-length mirror. Ticks should be removed with tweezers, grasping the tick by the head. Many tick-borne illnesses can be prevented by prompt tick removal.

Avoid swimming, wading, or rafting in bodies of fresh water, such as lakes, ponds, streams, or rivers. Do not use fresh water for bathing or showering unless it has been heated to 150 degrees F for at least five minutes or held in a storage tank for at least three days. Toweling oneself dry after unavoidable or accidental exposure to contaminated water may reduce the likelihood of schistosomiasis, but does not reliably prevent the disease and is no substitute for the precautions above. Chlorinated swimming pools are considered safe.

Bring adequate supplies of all medications in their original containers, clearly labeled. Carry a signed, dated letter from the primary physician describing all medical conditions and listing all medications, including generic names. If carrying syringes or needles, be sure to carry a physician's letter documenting their medical necessity.Pack all medications in hand luggage. Carry a duplicate supply in the checked luggage. If you wear glasses or contacts, bring an extra pair. If you have significant allergies or chronic medical problems, wear a medical alert bracelet.

Make sure your health insurance covers you for medical expenses abroad. If not, supplemental insurance for overseas coverage, including possible evacuation, should be seriously considered. If illness occurs while abroad, medical expenses including evacuation may run to tens of thousands of dollars. For a list of travel insurance and air ambulance companies, go to Medical Information for Americans Traveling Abroad on the U.S. State Department website. Bring your insurance card, claim forms, and any other relevant insurance documents. Before departure, determine whether your insurance plan will make payments directly to providers or reimburse you later for overseas health expenditures. The Medicare and Medicaid programs do not pay for medical services outside the United States.

Pack a personal medical kit, customized for your trip (see description). Take appropriate measures to prevent motion sickness and jet lag, discussed elsewhere. On long flights, be sure to walk around the cabin, contract your leg muscles periodically, and drink plenty of fluids to prevent blood clots in the legs. For those at high risk for blood clots, consider wearing compression stockings.

Avoid contact with stray dogs and other animals. If an animal bites or scratches you, clean the wound with large amounts of soap and water and contact local health authorities immediately. Wear sun block regularly when needed. Use condoms for all sexual encounters. Ride only in motor vehicles with seat belts. Do not ride on motorcycles.

For an ambulance in Vientiane, call 195. For an ambulance to Thailand, where most travelers seek medical assistance, call AEK International Hospital at 66-42-342-555, Nong Khai Wattana Hospital at 66-1-833-4262, or the Setthatirat Hospital ambulance at 021-413-720.

Medical facilities are extremely limited. Most expatriates obtain their medical care in Thailand. The Friendship Bridge connecting Vientiane, Laos, to Nong Khai, Thailand, is open from 6 AM to 10 PM. Crossing after hours is usually allowed for medical emergencies. Many travelers go to AEK International Hospital (tel. 66-42-342-555) or the North Eastern Wattana General Hospital (tel. 66-1-833-4262), both of which are in Udorn, Thailand, and both of which have English-speaking staff. For simple medical procedures, Nong Khai Wattana Hospital in Nong Khai, Thailand (tel. 66-1-833-4262) is another option.

Within Laos, a common source of medical care for travelers is the International Medical Clinic operated by Mahosot Hospital, situated at the bank of the Mekong River on the Fa Ngum Road (tel. 21-4018, 21-4022, 21-4025; open 24 hours). The Australian and Swedish embassies operate modern medical clinics, chiefly for embassy staff, but will sometimes treat individuals not associated with the embassies. The Australian Embassy Clinic is located near the Australian Embassy at Nehru Street Phonexay (tel. 41-3603, 41-3610, 41-2343). The Swedish Clinic is near the Swedish Embassy at Sok Paluang Road (ph. 31-5015). Most doctors and hospitals will expect payment in cash, regardless of whether you have travel health insurance.

Drug quality is improving, but a significant percentage of the medications sold in Laos are substandard. Counterfeit pharmaceuticals remain a problem throughout Southeast Asia. Medications should be only be purchased through a reputable pharmacy with a physician's prescription.

Before you leave, make sure you have the names and contact information for physicians, clinics, and hospitals where you can obtain emergency medical care if needed.

All children should be up-to-date on routine childhood immunizations, as recommended by the American Academy of Pediatrics. Children who are 12 months or older should receive a total of 2 doses of MMR (measles-mumps-rubella) vaccine, separated by at least 28 days, before international travel. Children between the ages of 6 and 11 months should be given a single dose of measles vaccine. MMR vaccine may be given if measles vaccine is not available, though immunization against mumps and rubella is not necessary before age one unless visiting a country where an outbreak is in progress. Children less than one year of age may also need to receive other immunizations ahead of schedule (see the accelerated immunization schedule).

The recommendations for malaria prophylaxis are the same for young children as for adults, except that (1) dosages are lower; (2) Malarone is not recommended for children weighing less than 25 pounds; and (3) doxycycline should be avoided. DEET-containing insect repellents are not advised for children under age two, so it's especially important to keep children in this age group well-covered to protect them from mosquito bites.

When traveling with young children, be particularly careful about what you allow them to eat and drink (see food and water precautions), because diarrhea can be especially dangerous in this age group and because the vaccines for hepatitis A and typhoid fever, which are transmitted by contaminated food and water, are not approved for children under age two. Baby foods and cows' milk may not be available in developing nations. Only commercially bottled milk with a printed expiration date should be used. Young children should be kept well-hydrated and protected from the sun at all times.

Be sure to pack a medical kit when traveling with children. In addition to the items listed for adults, bring along plenty of disposable diapers, cream for diaper rash, oral replacement salts, and appropriate antibiotics for common childhood infections, such as middle ear infections.

International travel should be avoided by pregnant women with underlying medical conditions, such as diabetes or high blood pressure, or a history of complications during previous pregnancies, such as miscarriage or premature labor. For pregnant women in good health, the second trimester (18–24 weeks) is probably the safest time to go abroad and the third trimester the least safe, since it's far better not to have to deliver in a foreign country.

Before departure, make sure you have the names and contact information for physicians, clinics, and hospitals where you can obtain emergency obstetric care if necessary. In general, pregnant women should avoid traveling to countries which do not have modern facilities for the management of premature labor and other complications of pregnancy.

Because of the risk of malaria, pregnant women should not travel outside the city of Vientiane. Malaria may cause life-threatening illness in both the mother and the unborn child. None of the currently available prophylactic medications is 100% effective. Mefloquine (Lariam) is the drug of choice for malaria prophylaxis during pregnancy, but should not be given if possible in the first trimester. If travel to malarious areas is unavoidable, insect protection measures must be strictly followed at all times. The recommendations for DEET-containing insect repellents are the same for pregnant women as for other adults.

Strict attention to food and water precautions is especially important for the pregnant traveler because some infections, such as listeriosis, have grave consequences for the developing fetus. Additionally, many of the medications used to treat travelers' diarrhea may not be given during pregnancy. Quinolone antibiotics, such as ciprofloxacin (Cipro) and levofloxacin (Levaquin), should not be given because of concern they might interfere with fetal joint development. Data are limited concerning trimethoprim-sulfamethoxazole, but the drug should probably be avoided during pregnancy, especially the first trimester. Options for treating travelers' diarrhea in pregnant women include azithromycin and third-generation cephalosporins. For symptomatic relief, the combination of kaolin and pectin (Kaopectate; Donnagel) appears to be safe, but loperamide (Imodium) should be used only when necessary. Adequate fluid intake is essential.

Helpful maps are available in the University of Texas Perry-Castaneda Map Collection and the United Nations map library. If you have the name of the town or city you'll be visiting and need to know which state or province it's in, you might find your answer in the Getty Thesaurus of Geographic Names.

Americans living in or visiting Laos are encouraged to register at the Consular Section of the U.S. Embassy in Vientiane and obtain updated information on travel and security within Laos. The U.S. Embassy is located at Thanon Bartholonie (near Tat Dam), in Vientiane; from the U.S., mail may be addressed to U.S. Embassy Vientiane, Box V, APO AP 96546; Telephone (856-21) 212-581, 212-582, 212-585; Duty officer emergency cellular telephone (856-20) 5502-016; Consular Section fax number (856-21) 251-624; Embassy-wide fax number (856-21) 212-584; Internet: http://usembassy.state.gov/laos, E-mail: consularvienti@state.gov.

For information on safety and security, go to the U.S. Department of State, United Kingdom Foreign and Commonwealth Office, Foreign Affairs Canada, and the Australian Department of Foreign Affairs and Trade.