Traveling to colder regions does not directly cause cold or flu but the cold weather increases the risk of getting ill. According to Dr. Walter B. Koppel, medical director of the Baltimore-based MEDEX Assistance Corp., a provider of emergency medical and security assistance for travelers, change of air temperature one breathes in is enough to trigger viral growth in lungs and sinuses. The main risk, however, is not the weather, but people the one travels with. Organized group tourism brings together people from various regions, where influenza viruses might circulate in a given season.
In tropical regions influenza occurs throughout the year. In other regions of the Southern Hemisphere it strikes mainly from April through September and in the Northern Hemisphere it occurs from November through March. We should not underestimate the danger: in the USA only the disease is responsible for approximately 36,000 deaths a year. Even a common cold could be very unpleasant while flying because pressure builds up in the ear canal and sinuses during take off and landing.
It is advisable, that travelers to potentially “dangerous” areas get immunized against influenza. In the USA the influenza vaccine is available in the beginning of September each year, but might be more difficult to find after December. Vaccinations should be received at least 2 weeks before the trip. The most endangered category is people over 50. If there is a possibility of getting infected the traveler should also try to avoid stress, caffeine and other stimulants, which increase heart rate and can heighten stressful feelings.
According to Centers for Disease Control and Prevention (part of the USA Department of Health and Human Services (HHS)), reports of influenza in a chosen travel destination shall not be seen as a reason to chancel the trip. Some cruise lines have started surveillance for respiratory illness among both passengers and crew members. Also, some cruise lines vaccinate their crew members against influenza.