Skip to Content

Foreign Travel


Christopher Sanford

, MD, MPH, DTM&H, University of Washington;

Alexa Lindley

, MD, MPH, Department of Family Medicine, University of Washington

Last full review/revision Jul 2020| Content last modified Jul 2020

Appropriate planning reduces the risks associated with travel, including foreign travel. Prior to travel, patients and their medical providers should review planned itineraries and relevant medical histories, required vaccinations, prophylactic measures against infections such as malaria and traveler's diarrhea, and advice about personal protection measures, including those related to noninfectious threats such as road traffic crashes. For older travelers, the most common causes of death are heart attack and stroke; for other travelers, the most common cause of death is road traffic accidents.

About 1 in 30 people traveling abroad requires emergency care. Illness in a foreign country may involve significant difficulties. Many US insurance plans, including Medicare, are not valid in foreign countries; overseas hospitals often require a substantial cash deposit for nonresidents, regardless of insurance. Travel insurance plans, including some that arrange for emergency evacuation, are available through commercial agents, travel agencies, and some major credit card companies.

Directories listing English-speaking physicians in foreign countries, US consulates who may assist in obtaining emergency medical services, and information about foreign travel risks are available (see table Useful Contact for People Traveling Abroad). Patients with serious disorders should consider pretravel contact or arrangements with an organization that offers medically supervised evacuation from foreign countries.

Certain infections are common when traveling to certain areas. Immunizations should be tailored to planned destinations, and advice regarding specific measures for preventing endemic and episodic infections should be given. Carrying medications to treat common infections (eg, upper respiratory infection, traveler's diarrhea) may be helpful.

Useful Contacts for People Traveling Abroad


Phone Numbers

Web Site

International Association for Medical Assistance to Travellers (IAMAT)

US: (716) 754-4883 (Niagara Falls, NY)

Canada: (519) 836-0102 (Toronto, Ontario); (416) 652-0137 (Toronto, Ontario)

Centers for Disease Control and Prevention (CDC)

US: Toll-free (800) CDC-INFO (800-232-4636)

TTY: (888) 232-6348 (Atlanta, GA)

CDC Malaria Hotline

US: (770) 488-7788 or (855) 856-4713; after hours, (770) 488-7100 (Atlanta, GA)

CDC Zika and Pregnancy Information

US: (770) 626-6847 (Atlanta, GA)

US Department of State, Overseas Citizens Services

From US & Canada: (888) 407-4747

From Overseas: (202) 501-4444

(Washington, DC)

World Health Organization (WHO)

International: (+41 22) 791-2111

(Geneva, Switzerland)

Americas: (202) 974-3000

(Washington, DC)


Travelers should be current on all routine immunizations. Some countries require specific vaccinations (see table Vaccines for International Travel). General travel and up-to-date immunization information is available from the Centers for Disease Control and Prevention (CDC) (Travelers’ Health: Vaccinations), and malaria chemoprophylaxis requirements are available from the CDC's malaria hotline (855-856-4713) and web site (Malaria and Travelers).

Vaccines for International Travel*, †


Regions Where the Vaccine is Recommended


Hepatitis A

All low- and middle-income countries

2 doses ≥ 6 months apart; a high level of long-term protection provided by second dose‡

See also Hepatitis A Vaccine

Hepatitis B

All low- and middle-income countries, particularly China

3-dose primary series, at 0, 1, 6 months. Recommended for extended-stay travelers and all health care workers‡

See also Hepatitis B Vaccine

Japanese encephalitis

Rural areas in most of Asia and South Asia, particularly in areas with rice and pig farming

2 doses 28 days apart

Not recommended for pregnant women

Usually not advised for those spending less than one month in endemic area

Meningococcal infections

Northern sub-Saharan Africa from Mali to Ethiopia (the meningitis belt)

Required for entry into Saudi Arabia during Hajj or Umrah

Throughout the world, especially in crowded living situations (eg, dormitories)

A single dose of quadrivalent vaccine (MenACWY-D [Menactra®] or MenACWY-CRM [Menveo®]) is effective for 5 years.

Risk higher in "meningitis belt" in Africa during the dry season (December through June), and those living in crowded living conditions.

See also Meningococcal Vaccine


All countries, including US

Recommended for travelers at risk of animal bites (eg, rural campers, veterinarians, field workers, people living in remote areas)

Does not eliminate need for additional vaccinations after animal bite for added protection

Recommended during pregnancy only if risk of infection is high

See also Rabies Prevention

Typhoid fever

All low-income countries, especially in South Asia (including India)

Two preparations are available.

Pill form: 1 pill taken every other day for a total of 4 pills; protects for 5 years

  • Not safe for pregnant women

Single injection form: Protects for 2 years and is thought to be safer for pregnant women than the pill form of the vaccine.

See also Typhoid Fever Prevention

Yellow fever

Tropical South America

Tropical Africa

Although this infection is rare in travelers, proof of vaccination required for entry into many countries§

Not safe for pregnant women

Increased risk of adverse effects in the elderly§

One dose provides protection for life in most travelers

See also Yellow Fever Prevention

* In addition to the listed vaccinations, routine vaccinations for influenza, measles, mumps, rubella, tetanus, diphtheria, polio, pneumococcal disease, and varicella should be up to date.

†All recommendations are subject to change. For the latest recommendations, see the Centers for Disease Control and Prevention ( or 800-CDC-INFO [800-232-4636]). See also Overview of Immunization.

‡ There is also a combination HepA and HepB vaccine available, which is given on either a 3-dose or 4-dose schedule. (See Hepatitis A Vaccine and Hepatitis B Vaccine.)

§ For travelers over age 60, providers should consider completing the waiver section of the Yellow Card (International Certificate of Vaccination), in lieu of administering yellow fever vaccine. Those travelers should then be particularly diligent regarding personal protection measures against insects.


The COVID-19 pandemic currently active in mid-2020 has necessitated limitation of travel to and from various countries. Patients should be advised to check the website of their nation's health agency (eg, CDC in the US) for current recommendations.


Dengue fever is a mosquito-borne viral infection endemic to the tropical regions of the world in latitudes from about 35° north to 35° south. Outbreaks are most prevalent in Southeast Asia but also occur in the Caribbean, including Puerto Rico and the US Virgin Islands, Oceania, and the Indian subcontinent; more recently, dengue incidence has increased in Central and South America.

A vaccine for dengue is approved in several countries outside the US, but efficacy is only moderate and varies by dengue immune status, serotype, and patient age; studies are ongoing.

People traveling to endemic areas should try to prevent mosquito bites. Effective personal protection measures include applying DEET or picaridin to exposed skin, applying picaridin to clothing, and sleeping under a permethrin-treated mosquito net if sleeping quarters are not air conditioned (see CDC: Prevent Mosquito Bites). These measures also offer protection from other insect-transmitted diseases including Zika and chikungunya.


Influenza is common in international travelers; hence annual influenza vaccines are indicated for all travelers.


Malaria is endemic in Africa, India and other areas of South Asia, Southeast Asia, North and South Korea, Mexico, Central America, Haiti, the Dominican Republic, South America, the Middle East (including Turkey, Syria, Iran, and Iraq), and Central Asia. The CDC provides information about specific countries where malaria is transmitted (see Yellow Fever and Malaria Information, by Country ), types of malaria, and resistance patterns.

Travelers to endemic regions should take preventive measures for malaria, including chemoprophylaxis. Malaria vaccines are under development but not commercially available.


Schistosomiasis is common and is caused by exposure to freshwater in Africa, Southeast Asia, China, and eastern South America. Risk of schistosomiasis can be reduced by avoiding freshwater activities in areas where schistosomiasis is common. Asymptomatic travelers with freshwater exposure in endemic regions should be screened by serologic testing for antibody to the adult worm at 6 to 8 weeks following their most recent exposure. Alternately, travelers may elect to treat presumptively a potential exposure with praziquantel, 20 mg/kg orally 2 doses for 1 day and again at 6 to 8 weeks following the most recent exposure.

Traveler’s diarrhea

Traveler’s diarrhea (TD) is the most common health problem among international travelers. TD is usually self-limited, typically resolving in 5 days; however, 3 to 10% of travelers with TD may have symptoms lasting > 2 weeks, and up to 3% of travelers have TD lasting > 30 days. TD lasting < 1 week requires no testing. For persistent TD, laboratory testing is done.

Self-initiated treatment is indicated for moderate to severe symptoms, especially if vomiting, fever, abdominal cramps, or blood in the stool are present. Treatment is with an appropriate antibiotic (eg, azithromycin, 500 mg or one gram once, or 500 mg once a day for 1 to 3 days). Additional measures include loperamide (except in patients with fever, bloody stools, or abdominal pain and in children < 2 years); replacement of fluids; and, in the elderly and small children, electrolytes (eg, oral rehydration solution).

Measures that may decrease the risk of TD include

  • Drinking and brushing teeth with bottled, filtered, boiled, or chlorinated water
  • Avoiding ice
  • Eating freshly prepared foods only if they have been heated to steaming temperatures
  • Eating only fruits and vegetables that travelers peel or shell themselves
  • Avoiding food from street vendors
  • Washing hands frequently
  • Avoiding all foods likely to have been exposed to flies

Prophylactic antibiotics are effective in preventing diarrhea, but because of concerns about adverse effects and development of resistance, they should probably be reserved for immunocompromised patients. One option is rifaximin, 200 mg once or twice a day.

Injury and death

Road traffic crashes are the most frequent cause of death of non-elderly international travelers. Travelers should at all times use a seat belt in vehicles and a helmet when cycling. Travelers should avoid motorcycles and mopeds and avoid riding on bus roofs or in open truck beds.

Drowning is another common cause of death while abroad. Travelers should avoid beaches with turbulent surf and avoid swimming after drinking alcoholic beverages.

Problems after returning home

The most common medical problem after travel is

  • Persistent traveler's diarrhea

The most common potentially serious diseases are

People can also acquire lice and scabies after being in crowded living conditions or places where hygienic measures are poor.

Some diseases become evident months after a traveler has returned home; a travel history with exposure risks is a useful diagnostic clue when patients present with a puzzling illness. The International Society of Travel Medicine ( and the American Society of Tropical Medicine and Hygiene ( have lists of travel clinics on their web sites. Many of these clinics specialize in assisting travelers who are ill after their return home.

More Information

  • Centers for Disease Control and Prevention: Travelers' Health

Drugs Mentioned In This Article

Drug Name Select Trade
praziquantel BILTRICIDE
azithromycin ZITHROMAX
loperamide IMODIUM
permethrin ELIMITE, NIX
rifaximin XIFAXAN

Copyright © 2022 Merck & Co., Inc., known as MSD outside of the US, Kenilworth, New Jersey, USA. All rights reserved. Merck Manual Disclaimer