YOU MAY NOT THINK ABOUT diseases as you prepare for your next trip, but your health is at risk in many destinations. To stay safe, make sure you and your family are current on vaccinations. Each year, unvaccinated travelers become infected while in other countries, bringing the disease into the United States and spreading it to others.

Six to eight weeks before any international trip, check the Travelers’ Health section of the Centers for Disease Control and Prevention website for your destination, related health notices and vaccine recommendations or requirements. The CDC’s TravWell mobile app (free from Google Play and the App Store) also provides destination-specific vaccine recommendations, a travel preparation checklist and a customizable healthy travel packing list. See your health care provider or a travel doctor four to six weeks before travel to discuss where you will travel abroad.

The TravWell app allows you to store travel documents, keep a record of medications and immunizations and set a reminder to get vaccine booster doses or take medications. Other key features include emergency service numbers for every destination and during-travel features accessible offline.

The CDC divide travel vaccinations into three categories: routine, recommended and required. The only vaccine classified as required is the yellow fever vaccination for travel to certain countries in sub-Saharan Africa and tropical South America. Routine vaccinations are those normally administered during childhood in the United States and include diphtheria, tetanus, pertussis, measles, mumps, rubella, varicella, poliomyelitis, hepatitis B, hepatitis A, haemophilus influenzae type b, rotavirus, meningococcus, pneumococcus and human papillomavirus. Make sure you are up to date on these vaccinations and do not require a booster.

Recommended vaccinations protect travelers from illnesses seen in other parts of the world. Your health care provider or travel doctor can determine which vaccines are recommended based on your destination, where you will spend your time (rural versus urban), the season you are traveling, your age, your overall health status and your vaccination history.

Travelers not vaccinated are at risk of contracting measles or pertussis (whooping cough). Outbreaks of these two diseases still occur in countries in Europe, Asia, Africa and the Pacific. Worldwide, about 20 million people get measles a year and about 146,000 people die from the disease. The majority of measles cases enter our country via unvaccinated U.S. residents. Last year’s large multistate outbreak of measles was likely caused by a traveler who got measles while abroad and then visited a California amusement park while infectious.

Measles is highly contagious and spreads to others through coughing and sneezing. It is so contagious, 90 percent of people close to an infected person and not immune become infected. An infected person can also spread measles to others four days before the rash develops. The best way to protect yourself is vaccination.

Pertussis is a contagious disease spread when infected people cough and sneeze near others. Early symptoms are similar to a cold and include runny nose, low fever, mild cough and a pause in breathing for babies. Later symptoms include fits of many rapid coughs followed by a high-pitched “whoop,” vomiting and exhaustion. Pertussis is serious for babies. Among babies younger than 1 year who get pertussis, more than half will be hospitalized and one in 100 will die.

Pertussis occurs in all countries, so all travelers are at risk. Pertussis rates are the highest in developing countries where few people are vaccinated. Babies too young to receive their first three pertussis shots are most at risk. Adults, even those who received pertussis vaccines as children, should be revaccinated with a one-time dose of Tdap vaccine. It is estimated 30–50 million people get pertussis and 300,000 people die from it each year worldwide.

Influenza spreads rapidly throughout the world. The risk for exposure during travel depends on the time of year and destination. In the Northern Hemisphere, flu season begins as early as October and lasts until April or May. In the temperate regions of the Southern Hemisphere, influenza typically occurs April–September. In the tropics, influenza occurs throughout the year.

In the Northern and Southern hemispheres, especially when traveling as part of large groups, such as on cruise ships, you can be exposed to influenza during months that fall outside those listed. Large groups can include people from areas of the world where influenza viruses are circulating. Everyone 6 months and older should get a flu vaccine yearly, preferably in the fall before the U.S. flu season begins. The flu vaccine given in the Northern Hemisphere usually protects against the main viruses that may circulate in other parts of the world.

Check the CDC travel health notices for current health issues related to specific destinations so you can learn of disease outbreaks that may affect your health. Travel medicine clinics in the United Sates include the International Society of Travel Medicine and the American Society of Tropical Medicine and Hygiene, staffed with infectious disease specialists who may or may not practice travel medicine.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition.