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What are travelers' diseases?

"Travelers' diseases" is a broad term for infections that may be acquired when traveling away from home, especially from a developed or industrialized area to a less developed area. Every travel destination and each geographical location has its health risks. If you are planning a trip abroad or to another part of the country, you should educate yourself about your destinations and discuss with your healthcare practitioner:

  • Any diseases known to be prevalent in the areas you will be visiting
  • How long you plan to stay in any particular location
  • What activities you plan to do during your visit

With the proper care, many travelers’ diseases can be prevented by:

  • Avoiding or taking special precautions in environments where disease-carrying insects or animals are present
  • Avoiding risky behaviors that could result in the spread of disease
  • Taking care with food and water
  • Getting recommended vaccines and/or completing a course of preventive medications

Some diseases are found throughout the world and, unless prevented through vaccination, frequently cause childhood illnesses. In some cases, these illnesses can lead to lifelong complications. Many nations have vaccination programs to decrease the number of people who contract conditions such as measles, rubella (German measles), mumps, and polio. In areas that are unable to uniformly vaccinate their populations, these conditions can be endemic and/or there may be epidemics of the disease. Travelers who are not protected through previous vaccinations, young children who have not been fully immunized, and people with weakened immune systems may be at an increased risk of contracting one of these infections.

What are some common causes of travelers' diseases and how are they acquired?

Travelers' diseases caused by microbes such as bacteria, viruses, and parasites can be acquired in a variety of ways, such as through contaminated food or water, from animal droppings or animal bites, and from soil. Physical contact with infected animals or animal hides can also put a person at risk. Some diseases are carried by insects, such as mosquitoes, flies, fleas, and ticks. Some can be acquired while swimming in freshwater or walking with bare feet. Others are passed from person to person through contact with blood or other body fluids.

For a more complete list of diseases related to travel, including information on the way they are transmitted, visit the CDC's web page on Travelers' Health: Diseases

Accordion Title
Common Examples
  • Food and waterborne illnesses

    Some examples of important diseases that may be acquired through eating contaminated food or drinking contaminated water include:

    • Travelers' diarrhea can be caused by a variety of bacteria, viruses, and parasites found throughout the world. These microbes can be found in water and food wherever sanitation and food handling practices are poor or inconsistent. Some diarrhea caused by viruses or bacteria may develop within a few hours of infection and may go away on their own without treatment. Other illnesses caused by certain bacteria, such as salmonella and shigella, have a 48-72 hour incubation period (the time from exposure to the development of signs and symptoms). Diarrhea caused by parasites, such as giardia, tends to have a longer incubation time and, without treatment, may become chronic illnesses in some individuals.
    • Hepatitis A virus (HAV) can cause liver inflammation and jaundice,. A vaccine that protects against hepatitis A is available. It is given in 2 doses. The first shot provides protection after 4 weeks. The second shot, given about 6 months after the first, provides lasting protection.
    • Cholera is extremely rare in the U.S., but can be found in other parts of the world, such as Haiti and the Dominican Republic, as well as in areas of Africa (e.g., Burundi, Cameroon) and Asia (e.g., Afghanistan, India). People who travel to areas where cholera is a risk very rarely become infected because they typically have better access to safe food and water and do not visit areas where outbreaks are occurring. A vaccine is available and is recommended for travelers who will be going to areas where cholera is active.
    • Typhoid fever is an illness caused by the bacterium Salmonella typhi that can be life-threatening. It can cause prolonged high fever, stomach pains, weakness, loss of appetite and headache. Though rare in the U.S., it is still common in developing nations, especially south Asia. Most cases (up to 75%) that occur in the U.S. are in people who have recently traveled internationally. A vaccine is available for those traveling to areas at risk.
  • Infections from insect bites
    • Malaria is an infectious disease caused by Plasmodium parasites that are primarily spread by the bite of infected female Anopheles mosquitos. Cases of malaria in the United States are rare; they mostly occur among those who have travelled to parts of the world where malaria infections are common (endemic). Most infections occur in Africa, but malaria also exists in regions in Central and South America, parts of the Caribbean, Asia (including South Asia, Southeast Asia, and the Middle East), Eastern Europe and the South Pacific. Preventive medications are available for malaria. They need to be taken daily during your travels and for a specified time after you return.
    • Other travelers’ infections associated with bites from insects include viruses such as, dengue fever, chikungunya, West Nile virus and yellow fever. A vaccine is available for yellow fever, and proof of vaccination may be required for entry into some countries. Dengue fever is becoming more common and causing progressively larger epidemics. Zika virus has gained attention recently because it can cause severe birth defects and other health problems in babies whose mothers become infected during pregnancy. Pregnant women should avoid travel to areas where there is a risk of Zika. If they must travel to such areas, they should take precautions against mosquito bites.
  • Illnesses spread through coughing or sneezing (respiratory fluids)

    Some illnesses spread through coughing and sneezing (respiratory secretions) are less common in the U.S. but may be encountered while traveling abroad. Examples include:

    • Tuberculosis (TB)—TB is an infectious disease caused by Mycobacterium tuberculosis that primarily affects the lungs (pulmonary TB). TB is spread when a person with active, infectious TB disease coughs, sneezes, or spits, releasing droplets containing TB bacteria into the air, which are then inhaled by someone else. Although the number of cases have decreased dramatically in the U.S., international travelers are at increased risk for TB.
    • Measles, mumps, rubella—these viral infections are less common in the U.S. due to vaccination programs. They are more common in other parts of the world and you may become infected if you have not been vaccinated or if you have but your immunity has waned.
    • Influenza (flu)— The CDC recommends that everyone 6 months old and older get a flu shot each season. In particular, people who are at high risk of complications from the flu should receive the vaccine. These include young children, the elderly, residents of nursing homes and other long-term care facilities, pregnant women, and people with pre-existing conditions such as asthma, COPD, heart disease, and liver or kidney disorders.
Signs and Symptoms

While signs and symptoms of some travelers' diseases are mild and go away without any specific treatment, a few may cause a serious medical emergency. There are some illnesses that may not emerge until a traveler has returned home, with signs and symptoms that may resolve, cycle, grow progressively worse, or linger. Left untreated, a few of the serious diseases can lead to severe complications, such as blindness, organ failure, coma, and death. During and after your travel, you should pay attention to any signs and symptoms that develop. Contact your healthcare practitioner if you experience:

  • A fever or flu-like symptoms while traveling, or if you were healthy while traveling but develop a fever or flu-like symptoms within 6 months of returning home, especially from a country with malaria
  • Persistent diarrhea lasting 2 or more weeks or recurring diarrhea
  • Yellowing of the skin and or the whites of the eyes (jaundice)
  • Ongoing fatigue
  • Unexplained weight loss
  • Shortness of breath
  • Skin rash or sores

The World Health Organization (WHO) recommends that travelers have a medical exam upon their return if they experience symptoms in the weeks following their travel, or if they have a visited a country where malaria is present and returned with a fever. Those who have chronic diseases, such as cardiovascular disease or diabetes, or who may have been exposed to a serious infectious disease or spent an extended time traveling (more than 3 months) should also consult their healthcare practitioner upon their return, even if they aren't having any symptoms.

Accordion Title
Testing for Travelers' Diseases
  • Laboratory tests overview

    Sometimes it is important to identify the cause of disease in travelers, not only to treat the individual but also to prevent transmission and to document the prevalence of the specific disease, both in returning travelers and in the countries they visited.

    Tests performed will depend on signs and symptoms and the disease suspected. People who return from travel with an acute or chronic condition should consult with their healthcare provider, who may suggest a consultation with an infectious disease and/or tropical medicine specialist.

  • Tests used to diagnose cause of digestive tract symptoms

    Below are some examples of tests for infections associated with digestive tract signs and symptoms. Including traveler’s diarrhea.

    • Molecular tests may be used to detect the genetic material (DNA, RNA) of microbes infecting the digestive tract. These types of tests are gaining in use, but may not be available everywhere. A GI pathogens panel simultaneously tests for the presence of multiple disease-causing (pathogenic) microbes in a stool sample. The panel of tests detects the genetic material (RNA or DNA) of some of the more common pathogens. It can identify co-infections (more than one microbe causing infection) and identify microbes that might be missed with traditional testing.
    • Though used less commonly now, a stool culture may be used to identify causes of bacterial diarrhea.
    • Parasitic causes of diarrhea can be identified through the O&P (ova and parasite) stool test. This test is used to identify parasites and their eggs in a fresh or specially preserved stool sample. For some parasites, such as Giardia intestinalis (lamblia), Entamoeba histolytica, and Cryptosporidia antigen tests, which identify proteins associated with the parasite, have been developed.
    • Because identifying the cause of viral diarrhea is complex, viral causes of diarrhea may not be tested unless the virus causes a large number of people to become ill, such as an outbreak of norovirus on a cruise ship.
  • Tests for infections caused by insect bites

    The following are some examples of tests for infections associated with bites from insects, such as mosquitoes.

    • The parasite that causes malaria (Plasmodium species) infects red blood cells. It can be identified by collecting a blood sample and examining specially stained "thick and thin" blood smears on slides under the microscope. A rapid antigen assay also has been developed to detect the malaria parasite from a blood sample without a microscopic examination.
    • Depending on an individual’s travel history, one or more viruses may be tested such as
  • Tests for respiratory illnesses

    Depending on travel history, vaccination history and signs and symptoms, tests for infections spread through respiratory secretions may be done. Examples include:

    • Tests for tuberculosis (TB)—a TB screening test may be done to determine whether you have been exposed. If an active infection is suspected, then AFB testing may be done
    • Several infections are prevented through vaccination but testing may be done if it is suspected you are not immune and have signs and symptoms. Examples include:
  • Non-laboratory tests

    Sometimes X-rays or CT scans may be used to evaluate specific organs, such as the lungs or liver, for evidence of infection or damage.

Accordion Title
Prevention
  • Vaccinations

    Advance planning can help prevent many travelers' diseases. Prior to a trip, you should consult with a healthcare provider to discuss your travel plans, verify that you have been vaccinated as needed, and determine whether you require any booster vaccines to maintain your level of protection. Since many vaccines take time to become effective or may require more than one dose, it is advised that you consult with a healthcare provider 4 to 6 weeks before you leave on your trip. Many medical centers affiliated with academic universities have a travelers' clinic where those preparing to go abroad can obtain expert advice. The CDC website has a page that will help you Find A Clinic

    Vaccines that may be needed include:

    • Hepatitis A
    • Hepatitis B
    • Influenza (flu)
    • Japanese encephalitis
    • Measles, mumps, and rubella
    • Meningococcal meningitis
    • Pneumococcal
    • Polio
    • Rabies
    • Tetanus and diphtheria
    • Typhoid fever
    • Varicella (chickenpox)
    • Yellow fever
    • Cholera

    Read more at the Centers for Disease Control and Prevention (CDC) Travelers' Health interactive web page.

  • Insect-borne diseases

    When it comes to diseases spread by mosquitoes, ticks, flies, and other biting insects, your first line of defense is to protect yourself against insect bites. To avoid insect bites:

    • Wear long-sleeved shirts and long, loose-fitting pants. Both should be light in color. Tuck pant legs into socks.
    • Use EPA-registered insect repellents containing DEET, picaridin, oil of lemon eucalyptus (OLE), or IR3535m. Use these products only as directed, and pay close attention to their instructions for use by pregnant women and children.
    • Treat shoes, socks, pants, bedding, and tents with the repellant permethrin.
    • Sleep in rooms that are screened against insects, or sleep under a mosquito net.
    • Avoid or empty water from sites where mosquitoes breed, such as buckets, pots, or old tires.
    • Carefully inspect your hair, skin, and clothing for ticks after outdoor activities.

    If you are traveling to areas where malaria is prevalent, your healthcare provider may recommend preventive medications, such as mefloquine or chloroquine, to begin taking prior to departure. These medications need to be taken regularly during travel and for a specified time period after you return home.

  • Food and waterborne diseases

    There are several steps you can take to prevent food- and water-borne illnesses during travel. Precautions to take in developing countries include:

    • Avoid tap water. This includes refusing ice in drinks, because the water used to make the ice might be contaminated. Allow drinking glasses to air dry before putting beverages into them. Do not brush your teeth with tap water. Do not swallow water while showering or bathing.
    • Drink beverages made with water that has been boiled for a minimum of 1 minute, but preferably 3 minutes.
    • Drink water that you treat yourself with iodine or chlorine tablets used according to directions.
    • Drink canned and bottled beverages. Be sure the caps on bottled beverages are still sealed before you drink them. Wipe the rims of cans and bottles before drinking/pouring if they are wet when you receive them.
    • Don’t swim in potentially contaminated fresh water, such as ponds or rivers. Even swimming pools with inadequate chlorination pose a risk. Talk to your healthcare practitioner if your trip will include water-based activities.
    • Avoid raw fruits and vegetables. Eat only food that has been cooked and is still hot or fruit that you know has been washed in safe/treated water and you have peeled yourself.
    • Other foods to avoid include:
      • Raw or undercooked meat, poultry, seafood, and eggs
      • Unpasteurized milk and milk products, especially soft cheeses
      • Prepared food that has been left unrefrigerated for several hours, especially food containing meat, poultry, eggs, and dairy products
      • Food prepared by street vendors
Treatment

In spite of taking every precaution, travelers may still become ill, either during their trip or several months after they have returned home. In general, the earlier travelers' diseases are detected and diagnosed, the easier they are to treat. Treatment will depend on the particular disease. You should know which symptoms signal the need to seek prompt medical care in the country you are visiting and which may be safely self-medicated.

If you become seriously ill while traveling, your home country's embassy or consulate can help you find medical care. For a complete list of embassies and consulates, see the U.S. Department of State website. If you become ill with a fever, a flu-like illness, or bloody diarrhea while traveling, seek immediate medical attention.

Self-care tips for travelers’ diarrhea include:

  • Drink plenty of fluids to avoid dehydration. Be sure you are drinking bottled water or water that has been boiled or treated with iodine or a commercial chlorine product. If possible, drink rehydration drinks to replace lost electrolytes.
  • The most common cause of travelers’ diarrhea can often be treated with over-the-counter products that control the frequency of diarrhea.
  • Your healthcare provider might prescribe an antibiotic for you to carry with you during your travels. These can be taken to treat diarrhea; however, they should be avoided if the diarrhea is bloody.
  • Seek immediate medical care if you have severe abdominal cramps, high fever, blood or mucus in your stool, and/or severe dehydration
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