Being knowledgeable about communicable diseases is essential when traveling to any country or region in the world, including in the U.S.

The number of people striking out to more exotic locations is growing rapidly as countries in North, South and Central America, Southeast Asia and the Pacific islands are now opening and encouraging tourists to return.

During the last two years, when travel was restricted, new pathogens have cropped up or spread into new areas, and travel requirements have changed since 2019.   

This article will describe the more common communicable diseases encountered in international travel, whether there is a treatment or a vaccine available, and what that treatment is.

The selection of the types of vaccines and antibiotics available will not be discussed in great detail. This should be a discussion between you and your family physician and/or infectious disease specialist and travel service.  

Common traveler’s infectious diseases

Water or foodborne infections

Hepatitis A is a common viral infection associated with drinking contaminated water or food. There is an incubation period of 15-50 days, in which people will experience fever, fatigue, nausea and jaundice.  Often the traveler will have returned home before the onset of the illness.  Prevented by a two-part vaccination.

Typhoid fever is a disease caused by Salmonella bacteria in contaminated water. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several days. This is commonly accompanied by weakness, constipation, headaches and mild vomiting. For those at high risk or for people traveling to areas where the disease is common, vaccination is recommended.  The vaccine gives about two years of protection.

Travelers’ diarrhea is the most common travel-related infection. Diarrhea occurs within 10 days of travel to an area with poor public hygiene. It’s caused by drinking water or eating foods that have bacteria, viruses or parasites. It usually goes away without treatment in a few days. However, dehydration from diarrhea can be serious.  It can be prevented by taking daily bismuth subsalicylate tablets (Pepto-Bismol®) during your travel in a high-risk area.  Loperamide (Imodium) slows the movement of food through your intestines, which lets your body absorb more liquid. Antibiotics (e.g., azithromycin) are often prescribed for severe and persistent symptoms.

Polio, or poliomyelitis, has been eliminated from most of the world, but it is still a threat in some countries. Even if you were previously vaccinated, you may need a one-time booster shot before traveling to a country where there are reported cases. Polio can also be spread by eating raw or undercooked food or drinking water or other drinks that are contaminated with the feces of an infected person

Mosquito-borne infections

Yellow fever is a virus that can cause severe fever, chills, headaches, jaundice, bleeding, shock and liver and kidney failure. Wearing long-sleeved shirts and long pants, especially early in the morning and in the evening, helps prevent infection. The yellow fever vaccine is well tolerated and now requires only one lifetime vaccination.

Malaria symptoms include fever and flu-like illness, with shaking chills, headache, muscle aches and tiredness. Nausea, vomiting and diarrhea may also occur. Malaria may cause anemia and jaundice because of the breakdown of red blood cells. Atovaquone/proguanil (Malarone), doxycycline and mefloquine are the drugs of choice for malaria prevention in most malaria-endemic regions. Chloroquine (Aralen) may be used safely in all trimesters of pregnancy, and mefloquine may be used safely in the second and third trimesters of pregnancy. The prevention of mosquito bites is equally important.

Zika and Chikungunya are common mosquito-spread viruses in many parts of the world. They cause headaches, muscle aches, red eyes, fatigue and flu-like symptoms. They are usually mild and rarely cause serious illness. Again, the prevention of mosquito bites is important. There is no vaccine available for these infections.   

Dengue fever is a related mosquito-borne illness that occurs in tropical and subtropical areas of the world. It can cause a high fever and flu-like symptoms with bleeding and long-lasting joint pain.   

Airborne and direct exposure

Coronavirus is added to the long list of travel-related illnesses that need attention when you travel. Full vaccinations with boosters will prevent serious complications but does not prevent you from catching it and experiencing some symptoms. Masking requirements in public areas and flying are changing in all countries. It is important to check vaccination and antigen-testing requirements before and during your international travel.

Meningococcal meningitis can be contracted by airborne sources and direct contact. Some countries have peak times of the year when infections increase.  A vaccine is available. It is recommended for minors and others with risk factors.

If you are planning an international trip in the near future, it is important that you check reliable and current information sources to find out travel restrictions, required testing for COVID and required immunization. The Centers for Disease Control is a primary resource.  You should also check the state departments of the countries you will be visiting, plus the World Health Organization (WHO) at www.who.int/travel-advice.  

Part Two of this article will present prevention tips to avoid communicable diseases and what medications are helpful to bring with you.