Immunizations and Antibiotics for Overseas Travel

Immunizations are a method to stimulate the body's immune system to protect itself from diseases. Immunization is done with vaccines made from the infectious virus or bacteria. A vaccine can contain a noninfectious fragment of a virus or bacteria, a weakened live whole organism that does not cause the disease, or a harmful substance that has been modified to make it harmless (toxoid). These immunizations stimulate the immune system to make antibodies so that it can respond when challenged by the real bacteria, virus, or toxin.

When traveling, it is easiest to divide vaccinations into three groups: routine, recommended, and required. Routine vaccinations are those that are recommended by the U.S. Centers for Disease Control and Prevention (CDC) to prevent serious and sometime fatal diseases. Many of these diseases are uncommon today in the United States but can be very common in foreign countries. Although most U.S. citizens have already received these vaccinations, many may not be up-to-date and require boosters. Recommended vaccinations are those vaccinations that can help protect travelers from diseases that are found in other parts of the world, specific to the countries the traveler will visit. The only vaccinations required by the International Health Regulations are yellow fever for travel to certain countries in sub-Saharan Africa and tropical South America and meningococcal vaccination for travelers to Saudi Arabia during the Hajj (the Muslim pilgrimage to Mecca).

Routine vaccinations in the U.S. include the following:

• Diphtheria
• Pertussis
• Tetanus
• Measles
• Mumps
• Rubella
• Polio
• Hepatitis A
• Hepatitis B
• Haemophilus influenza type B
• Pneumococcus
• Meningococcus
• Varicella (chickenpox)
• Human papillomavirus

Recommended vaccinations for travel (depending on which countries are being visited)

• Japanese encephalitis
• Rabies
• Typhoid
• Meningococcus (unless already received as part of routine vaccinations)
• Hepatitis A (unless already received as part of routine vaccinations)

Required vaccinations

• Yellow fever: certain countries in sub-Saharan Africa and tropical South America
• Meningococcal vaccination for travelers to Saudi Arabia during the Hajj

All vaccination series can be started on the same day. The lead time for immunization depends on the types of vaccinations needed. Some vaccination courses can take up to six months (such as hepatitis B) to receive all of the required shots. In addition, live-attenuated (weakened) viral vaccines must be spaced a month apart and can affect skin testing for tuberculosis.

Moderate-to-severe illnesses can delay immunizations, but people with mild illnesses can still be vaccinated.

The CDC has a web site with the latest information on what immunizations are required for travel to specific countries (http://wwwnc.cdc.gov/travel/
destinations/list.htm). The site also contains information on travel notices in effect and links to the State Department web site with security information about each country. The site also contains country-specific information on malaria risk and whether or not malaria prophylaxis is recommended.

Many health departments will help travelers to get their vaccinations needed for travel, and in many larger cities, there are travel clinics that only address travel medicine.

• Most vaccine courses can be interrupted without the need for extra doses. (Typhoid is an exception.)
• Typhoid vaccination is not required for international travel but is recommended for anyone older than 2 years of age. Breastfeeding is a way to protect infants against infection from water sources. Infants who are not breastfed should have carefully prepared formula and food.
• The hepatitis A vaccination should be given to travelers older than 2 years of age. It is now part of routine vaccinations. The disease is much less severe in children younger than 5 years of age compared with adults. For children younger than 2 years of age, the hepatitis A immunoglobulin should be given to confer passive immunity and protection.
• Some African countries require proof of yellow fever vaccination prior to entering the country. Note that infants younger than 9 months of age cannot be immunized for this because of the risk of contracting encephalitis. Travelers with infants in this age group are strongly advised against traveling to areas with endemic yellow fever.

• Malaria does not have a vaccine. Medication must be taken to protect against infection. Some countries have resistance to one or more of the drugs used to prevent malaria. The CDC has a web site where travelers or their physicians can check on resistance patterns and recommended medication for prevention (http://www.cdc.gov/malaria/travelers/
  country_table/a.html). Each of the drugs also has advantages and disadvantages, and travelers may, when multiple options are available, pick an option that better fits their particular situation. The following table was adapted from the CDC web site for malaria (http://www.cdc.gov/malaria/
  travelers/drugs.html).

• Everyone in malaria-prone areas should wear DEET insect repellent (for example, Ultrathon) and should seek blood evaluation for possible treatment if symptoms develop. Another repellant is Picaridin, which does not smell as strong as the DEET but requires more frequent application. Permethrin-containing repellent (for example, Permanone) can be applied to clothing, shoes, tents, gear, and mosquito nets, but permethrin is not approved for direct application onto skin. Commercially available clothing that is impregnated with permethrin will withstand multiple washings while maintaining effectiveness. Most repellents are safe for children over 2 months of age.

• Local water and undercooked food are often the cause of traveler's diarrhea (TD).
• In general, drink and eat only packaged liquids, food that is steaming hot, or fruit that you have peeled yourself. Do not use ice in areas where water can be contaminated, and avoid salads and other fresh foods. Do not eat foods from roadside vendors or brush your teeth using tap water. Despite precautions, illness rates can be up to 50%.
• One or two Imodium tablets every four hours as needed can reduce the frequency of stools, but people with fever or bloody stools should not use this agent without a doctor's order.
• Certain antibiotics (such as trimethoprim-sulfamethoxazole or ciprofloxacin) can reduce the duration of symptoms in cases of bacterial infection; however, these agents should not be used to prevent infection. In order to control the resistance of bacteria to currently effective antibiotics used to treat traveler's diarrhea when it does occur, the CDC advises against the use of antibiotics to prevent traveler's diarrhea. However, many clinicians will prescribe ciprofloxacin 500 mg to be taken twice daily for three days if the traveler develops significant diarrhea (more than three stools in eight hours or five stools in 24 hours).
• Oral rehydration therapy (ORT): The World Health Organization recommends the following salt solution mixture: 3.5 grams of salt (for example, sodium chloride), 1.5 grams of potassium chloride, 20 grams of glucose, and 2.9 grams trisodium citrate (alternatively, 2.5 grams sodium bicarbonate). These ingredients should be mixed in 1 liter of clean water. This will improve rehydration by providing both salts and glucose, which increase transport of both substances across the intestinal wall. Premixed commercial ORT preparations (such as Pedialyte) are available for children.

It may be advisable to put together your own first-aid kit, especially if traveling to a developing country or an area with limited medical care. Packing medicines for travel is critically important in many countries. Items to consider include the following:

• An appropriate bag for all items
• Any necessary prescription medications, best left in their original containers (Make sure to pack extra in case the trip is unexpectedly extended.)
• Medications for malaria, if prescribed
• Medications for treatment of traveler's diarrhea, just in case it develops during the trip
• Topical preparations for minor skin infections and wounds
• Decongestants and antihistamines for upper respiratory tract infections
• If you have known food allergies or other serious allergies for which you've been prescribed an EpiPen, make sure to take one with you.
• Medications for pain relief and fevers (ibuprofen [Advil] and acetaminophen [Tylenol])
• Thermometer
• Flashlight
• Assorted bandages

Air evacuation can be very expensive, and health care given in some countries can be of questionable quality. There are a number of companies that offer medical evacuation insurance. The cost can be several hundred dollars, but the peace of mind might be worth the expense.

There are a number of conditions that can limit your ability to travel by air. It is important that travelers know these restrictions.

• Recent heart attack: No travel above 2,000 feet for four to six weeks
• Heart failure: No travel for two weeks after an acute decompensation. Then no travel above 10,000 feet
• COPD: No travel if vital capacity is less than 50% of predicted value
• Pneumothorax: No air travel for at least 10 days
• Pregnancy: No surface travel above 15,000 ft.
• Anemia: Oxygen required if hemoglobin below 8.5g/dl
• Sickle cell disease (SS or SC variants): Avoid travel, especially to high elevations
• Deep vein thrombosis (DVT): For patients with a history of DVT, it is important to get up and move frequently, move the feet a lot, and consider using compressive stockings.
• Recent abdominal surgery with colostomy or ileostomy: No travel for one to 14 days
• Recent eye surgery: Check with your ophthalmologist.
• Recent scuba diving: Wait at least 12 hours before flying. If decompression stops occurred, wait 24 hours.