What are travelers' diseases?
"Travelers' diseases" is a broad term for bacterial, viral, fungal, and parasitic infections that may be acquired when someone travels away from home, especially when traveling from a developed or industrialized area to a less developed area. Every travel destination and every geographical location has its hazards.
Travelers should educate themselves and discuss with their doctors their destinations, expected lengths of stay, and planned activities. With the proper care, many traveler's diseases are preventable – through avoidance of a carrier's (vector's) environment, avoidance of risky behaviors, vigilant care with food and water, chemoprophylaxis (medicines taken before and during travel to prevent a specific illness), and vaccines.
Some diseases are global in nature - they are found throughout the world and, unless prevented through vaccination, frequently cause childhood illnesses in the particular locale. 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 who are immunocompromised may be at an increased risk of contracting one of these infections.
How are travelers' diseases acquired?
Travelers' diseases can be acquired in a variety of ways, depending on the pathogen, such as through contaminated food or water, from animal droppings, and from soil. Close exposure to infected animals and physical contact with animal hides can also put someone at risk. Some diseases are carried by vectors such as mosquitoes, flies, and ticks. Others can be acquired from swimming in freshwater or by walking on the beach with bare feet, while others are passed from person to person – through close contact, needle sharing, blood, and unprotected sex.
- Travelers' diarrhea can be caused by a variety of bacteria, viruses, and parasites throughout the world. These microorganisms are found in water and food wherever sanitation and food handling practices are poor or inconsistent. People are often acclimatized to their own local bacteria and viruses but affected by microorganisms in other places. Parasites can affect both local inhabitants and those who travel.
Some viral and bacterial diarrheas tend to occur within a few hours of infection and may be self-limiting. Some, such as Salmonella and Shigella, have a 48-72 hour incubation period. Parasitic diarrheas tend to have a longer incubation time and, without treatment, may become chronic illnesses in some individuals.
- Hepatitis A virus (HAV), which can cause liver inflammation and jaundice, can also be acquired from contaminated food and water.
- Infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) may cause symptoms similar to hepatitis A, but they are transmitted through exposure to blood and body fluids, sexual contact, or perinatally (mother to infant). Risky behaviors, such as unprotected sex, may also expose travelers to HIV and other sexually transmitted diseases.
- The most common infections associated with fever are malaria, dengue fever, and yellow fever. All of these conditions are carried by mosquitoes, and they are endemic in tropical areas of the world. A vaccine is available for yellow fever, and proof of vaccination may be required for entry into some countries. Chemoprophylaxis is available for malaria. Dengue fever is a rapidly expanding disease (found in more and more geographical areas) that is causing progressively larger epidemics. There is no preventative treatment for dengue; it can be avoided by taking measures to avoid mosquito bites.
For a list of diseases related to travel, including information on their modes of transmission, visit the CDC's web page on Travelers' Health: Diseases.