Feature Article: Infectious Diseases and International Travel

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If you or your family members are planning any international travel this summer, you may be at risk for infections not typically encountered in the U.S. Because one of the best ways to be prepared is by being knowledgeable, we are highlighting some infections that travelers might encounter abroad.


Cholera is caused by a bacterium that infects the intestines causing diarrhea and vomiting. Severe disease occurs in 1 of 20 infected individuals and is characterized by profuse, watery diarrhea, vomiting and leg cramps, often leading to dehydration and shock if not immediately treated. Each year, between 5,000 and 7,500 infected individuals around the world die from cholera. People can be infected by consuming food, water or shellfish contaminated with the bacteria.

Cholera most commonly occurs in Africa and Asia, but cases have been imported in the U.S. and Australia. Because cholera does not typically occur in standard tourist accommodations, the vaccine isn’t usually recommended for travelers. However, travelers who plan to wander “off the beaten path” or engage in high-risk behaviors, such as eating raw or undercooked shellfish and drinking un-bottled water, might be recommended to receive the vaccine.

Hepatitis A

Hepatitis A is caused by a virus of the same name and causes inflammation of the liver (hepatitis). Symptoms can include fever, nausea, vomiting and yellowing of the skin (jaundice); however, many people do not know they are infected until their symptoms start, usually about two weeks after exposure. Hepatitis A is transmitted through food or water contaminated with sewage.

Hepatitis A is fairly common in other parts of the world, including Asia, Central America, South America, Southern Europe, the Mediterranean Basin, the Middle East, the Caribbean and Mexico. Because hepatitis A occurs even in standard tourist accommodations, travelers are often recommended to receive this vaccine before their trip.


Typhoid occurs when people ingest food or water contaminated with the bacterium, Salmonella typhi. Once ingested, the bacteria infect the intestines, causing fever, stomach pain, low heart rate and a rash. Without treatment, severe disease, including shock and death, occurs in about 1 of 5 infected people. Travelers can protect themselves by avoiding ice, unpeeled fruits, undercooked meats, shellfish, salads or food from street vendors.

Typhoid commonly occurs in Mexico, East Asia, South Asia, South America and Africa. The typhoid vaccine is recommended for travelers going to high-risk areas who will be staying for more than six weeks as well as those who will be staying in rural areas or small towns. Travelers who plan to eat uncooked foods, unpeeled fruits and drink un-bottled water during their trip are also recommended to receive this vaccine.


Dengue is caused by a virus of the same name and is spread by mosquitos. Travelers infected with dengue often experience fever, nausea, vomiting, headache, rash, and pain in the eyes, joints and muscles. Severe infection can include stomach pains, persistent vomiting, nose or gum bleeding, and, in about 1 of 100 cases, death.

Dengue is common in tropical and subtropical regions, such as the Caribbean, Central America, South America, Western Pacific Islands, Australia, Southeast Asia and Africa. A vaccine is not available to prevent dengue. However, travelers can protect themselves by preventing mosquito bites, such as by wearing long-sleeved shirts, long pants and hats, using insect repellent, and sleeping in beds covered with mosquito netting.

Japanese encephalitis virus

Japanese encephalitis virus (JEV) is transmitted through mosquito bites. JEV causes encephalitis (inflammation of the brain). Symptoms typically include fever, stiff neck, nausea and vomiting. About 1 of 4 infected individuals experience severe infection that leads to a coma and death.

JEV occurs in many countries in the Far East, including Japan, China, India, Vietnam and Thailand, among others. The JEV vaccine is not recommended for all travelers. Instead, travelers’ destination, length of stay and planned activities determine if they should receive the Japanese encephalitis virus vaccine.


Malaria is caused by a parasite transmitted by mosquito bites. Symptoms typically appear within seven to 30 days after infection and include influenza-like illness, fever and chills. In some cases, symptoms may develop up to one year after the initial mosquito bite. In the absence of treatment, severe illness and death can occur.

Malaria is common in many parts of Africa, Central America, South America, the Caribbean, Asia, Eastern Europe and South Pacific. Unfortunately, a malaria vaccine is not available; however, preventive medicine, to be taken before, during and after the trip, may be prescribed. Travelers who think they might have malaria should seek medical attention as soon as possible to begin treatment, even if they were taking preventive medications. Travelers can also prevent malaria by protecting themselves against mosquito bites.

Yellow fever

Yellow fever is also caused by a virus transmitted by mosquitos. Yellow fever causes inflammation of the liver (hepatitis) and severe bleeding (hemorrhage). Symptoms of yellow fever can include fever, muscle pain, chills, headache and yellowing of the skin or eyes (jaundice).

Yellow fever occurs mostly in Africa and South America. Many of the countries in these parts of the world require proof of vaccination for entry. In addition to receiving the vaccine, travelers can also protect themselves from yellow fever by preventing mosquito bites. The risk of yellow fever varies depending on the travel destination. So, it’s important to consult a travel medicine specialist prior to departure.

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Materials in this section are updated as new information and vaccines become available. The Vaccine Education Center staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family's personal health. You should not use it to replace any relationship with a physician or other qualified healthcare professional. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult your physician or, in serious cases, seek immediate assistance from emergency personnel.