Returning from a trip feeling unwell is a common experience. Biological and environmental factors contribute to increased susceptibility to illness during and after travel. Understanding these reasons helps travelers anticipate potential health challenges and take proactive steps to maintain their well-being.
How Travel Weakens Your Defenses
Travel often introduces multiple stressors that can compromise the body’s immune response. The physical demands of long journeys, time zone shifts, and altered sleeping patterns can lead to exhaustion, which in turn strains the immune system. Navigating unfamiliar environments and adhering to strict schedules also contribute to mental and physical stress, elevating levels of the stress hormone cortisol. While acute stress can temporarily boost immunity, chronic or prolonged stress, common during travel, can suppress the immune system by reducing lymphocytes, the white blood cells that fight infection.
Sleep deprivation and disrupted circadian rhythms, often caused by jet lag, further hinder immune function. During sleep, the immune system produces proteins called cytokines, which are necessary to fight infections and inflammation. Insufficient or poor-quality sleep can lower the production of these protective cytokines, making the body more vulnerable to viruses.
Dehydration, frequently encountered during travel, especially on flights with low cabin humidity, also impacts the immune system. When the body is dehydrated, it becomes more difficult for white blood cells to travel efficiently and fight off germs. Dehydration can impair the body’s ability to flush out toxins and can dry out mucous membranes, making individuals more susceptible to respiratory infections.
Where Germs Lurk and Spread
Travel exposes individuals to a higher concentration and variety of pathogens in crowded public spaces. Airports, airplanes, trains, and buses are environments where many people from different regions converge, increasing the likelihood of encountering new viruses and bacteria. High-touch surfaces in these areas, such as tray tables, armrests, seatbelt buckles, and door handles, can harbor various microbes, including bacteria like E. coli and salmonella, for hours or even days.
While there is a common misconception that recirculated air on airplanes is a major source of illness, modern aircraft use High-Efficiency Particulate Air (HEPA) filters that cycle cabin air every few minutes, removing about 99.97% of airborne particles, including viruses and bacteria. However, the low humidity in airplane cabins can dry out mucous membranes, potentially making the respiratory tract more vulnerable to airborne pathogens that are in close proximity, such as from a coughing passenger.
Food and water safety can also become a concern, particularly when traveling to regions with different hygiene standards. Contaminated food and beverages are a common cause of traveler’s diarrhea and other illnesses. Raw or undercooked meats, unpasteurized dairy products, and unpeeled fruits and vegetables washed in unsafe water can transmit pathogens.
Strategies to Stay Healthy While Traveling
Implementing good personal hygiene practices is a primary defense against illness while traveling. Regularly washing hands with soap and water for at least 20 seconds, particularly before eating and after using public restrooms, is highly effective. When soap and water are not available, using an alcohol-based hand sanitizer with at least 60% alcohol can help reduce germ transmission. Avoiding touching the face, especially the eyes, nose, and mouth, minimizes the transfer of pathogens from hands to the body’s entry points.
Staying well-hydrated is also important to support immune function and counteract the dehydrating effects of travel. Drinking plenty of water throughout the journey, and avoiding excessive alcohol or caffeine, can help keep mucous membranes moist and the body’s systems functioning optimally. Carrying a reusable water bottle and refilling it with safe water is a practical approach.
Prioritizing sleep before, during, and after travel can significantly bolster the immune system. Aiming for 7 to 9 hours of quality sleep for adults helps the body produce essential immune-fighting proteins and recover from travel-induced stress. Managing stress through techniques like mindful breathing or planning ahead to reduce travel anxiety can also help maintain immune resilience.
Making informed choices about food and water is crucial, especially in areas where hygiene practices may differ. Opting for foods that are well-cooked and served hot, avoiding raw or undercooked items, and consuming only commercially bottled or disinfected water can reduce the risk of foodborne illnesses. Wiping down high-touch surfaces in transport and accommodations with disinfectant wipes also provides an additional layer of protection against germs.