Travelers can encounter the following problems when going to different countries, or remote areas of their own country:

1. Travelers’ diarrhea is usually caused by bacteria, virus, or protozoa. As many as 30% to 70% of travelers suffer from it, depending on the destination.
2. Motion sickness can occur on board ships, during air travel, even on amusement rides – whenever there is too much movement in too many directions.
3. Acute mountain sickness or high altitude sickness occurs among 25% of travelers at altitudes above 2500 m., especially when rapid ascents don’t allow sufficient acclimation.
4. Jet lag is a temporary disorder among air travelers who cross three or more time zones.
5. Malaria is a mosquito-borne disease which causes 350–500 million infections worldwide and approximately 1 million deaths each year.
6. Yellow fever is a potentially fatal viral infection resulting in 200,000 cases and 30,000 deaths each year; 90% occur in Africa.
7. Meningococcal disease is a risk for travelers who have prolonged contact with local populations in the Meningitis Belt (part of Africa). The Hajj pilgrimage to Saudi Arabia has also been associated with outbreaks of meningococcal disease.
8. Typhoid fever is caused by bacteria. An estimated 22 million cases of typhoid fever and 200,000 related deaths occur worldwide each year.