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 the Dominican Republic: prophylaxis is recommended for rural areas throughout the country. Prophylaxis has also been recommended for the Punta Cana resort area because of a recent outbreak there, but it appears the outbreak may be over (see "Recent outbreaks" below). For many years, the drug of choice has been chloroquine, which is inexpensive and generally well-tolerated. The recommended dosage is 500 mg weekly, starting one-to-two weeks before arrival and continuing through the trip and for four weeks after departure. Chloroquine may cause mild adverse reactions, including gastrointestinal disturbance, headache, dizziness, blurred vision, and itching, but severe reactions are uncommon. Other choices include mefloquine (Lariam), atovaquone/proguanil (Malarone)(PDF), doxycycline, and primaquine. Mefloquine is taken 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, insomnia, and nightmares. Rarely, severe reactions occur, including depression, anxiety, psychosis, hallucinations, and seizures. Mefloquine should not be given to anyone with a history of seizures, psychiatric illness, cardiac conduction disorders, or allergy to quinine or quinidine. Those taking mefloquine 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. Primaquine may cause hemolytic anemia in those with G6PD deficiency, so a blood test documenting normal G6PD levels must be obtained before starting primaquine. In those with normal G6PD levels, the main side-effect of primaquine is gastrointestinal disturbance, which can be minimized by taking the medication with food. Insect protection measures are also advised for these areas.

The following are the recommended vaccinations for Dominican Republic resorts.

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 travelers who may eat or drink away from the usual tourist destinations. 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.

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.

Polio vaccine is not recommended for any adult traveler who completed the recommended childhood immunizations. Polio has been eradicated from the Americas, except for a small outbreak of vaccine-related poliomyelitis in the Dominican Republic and Haiti in late 2000 (see "Recent outbreaks" below).

A malaria outbreak was reported in November 2004 among visitors to the Punta Cana resort area in La Altagracia Province, at the eastern end of the island. A total of 20 cases were identified in foreign travelers (four from the United States, six from Canada, and ten from European countries). The outbreak appears to have been terminated by an intensive program of mosquito control. No cases have been reported since early January. Malaria prophylaxis is no longer recommended for travelers to Punta Cana. For further information, go to MMWR, Eurosurveillance, the Centers for Disease Control, and Health Canada. In January 2000, a malaria outbreak occurred in the Bavaro Beach area and was promptly ended by mosquito control measures.

A small outbreak of poliomyelitis occurred between July 2000 and January 2001, resulting in a total of 13 cases before the outbreak was brought under control by a mass vaccination campaign. All cases occurred in people who were either unvaccinated or incompletely vaccinated. For further information, go to MMWR and the World Health Organization (PDF).

Dengue fever, a flu-like illness sometimes complicated by hemorrhage or shock, occurs in the Dominican Republic. Almost 2000 cases were reported during the first half of 2003, but the risk is generally low in beach areas. Dengue fever is transmitted by Aedes mosquitoes, which bite primarily in the daytime and favor densely populated areas. No vaccine is available at this time. Insect protection measures are recommended when dengue outbreaks occur.

Schistosomiasis is endemic. Swimming and bathing precautions are advised, as 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.

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, including ceviche. 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). 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.

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 online list of physicians and clinics in the Dominican Republic, go to the U.S. Embassy website.

Medical care is limited, especially outside Santo Domingo, and the quality of care varies widely among facilities. There is an emergency 911 service within Santo Domingo, but its reliability is questionable. Outside the capital, emergency services range from extremely limited to nonexistent. Blood supplies at both public and private hospitals are often limited and not all facilities have blood on hand even for emergencies. Many medical facilities throughout the country do not have staff members who speak or understand English. A private nationwide ambulance service, "Movi-med," operates in Santo Domingo, Santiago, Puerto Plata and La Romana; its telephone number is 532-0000 in Santo Domingo and 1-200-0911 outside Santo Domingo. "Movi-med" expects full payment at the time of transport.

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 (see the U.S. Embassy website).

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 the dosage of chloroquine is lower. 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 (see the U.S. Embassy website). 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.

As a rule, pregnant women should avoid visiting areas where malaria occurs. Malaria may cause life-threatening illness in both the mother and the unborn child. None of the currently available prophylactic medications is 100% effective. If travel to malarious areas is unavoidable, chloroquine must be taken once a week and 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.

Americans living in or visiting the Dominican Republic are encouraged to register at the Consular Section of the U.S. Embassy in Santo Domingo and obtain updated information on travel and security within the Dominican Republic. The U.S. Embassy is located at the corner of Calle Cesar Nicolas Penson and Calle Leopoldo Navarro in Santo Domingo; telephone (809) 221-2171; after hours (809) 221-8100. The Consular Section is a half-mile away at the corner of Calle Cesar Nicolas Penson and Avenida Maximo Gomez. The American Citizens Services Unit can be reached by telephone at (809) 731-4294, or via the Internet at http://www.usemb.gov.do/acs.htm. Consular office hours are 7:30 a.m. to 12:00 p.m. and 1:00 p.m. to 2:00 p.m., Monday through Friday, except U.S. and Dominican holidays.

There is a Consular Agency in the north coast city of Puerto Plata at Calle Beller 51, 2nd floor, office 6, telephone (809) 586-4204; office hours are 9:00 a.m. to 12:00 p.m., and 2:30 p.m. to 5:00 p.m., Monday through Friday, except holidays. The consular agency has a secondary office in Sosua, also on the north coast. That office may be reached at: "Sea Horse Ranch Project" Administrative Office, Carretera Sosua - Cabarete, Sosua, D.R., telephone (809) 571-3880, fax (809) 571-2374.