Yes, traveling can increase your susceptibility to illness, often due to a combination of factors that challenge the body’s defenses and increase exposure to unfamiliar pathogens. Rapid changes in environment, diet, and time zones place a significant strain on the body’s systems, potentially leading to a temporary reduction in immune function. When people gather in high-density settings like airports and public transport, the likelihood of encountering and transmitting infectious agents rises considerably. These risks are broadly separated into those caused by infection and those caused by the physical stresses of the journey itself.
Infectious Risks from Contaminated Food and Water
The most common affliction a traveler may face is gastrointestinal illness, primarily acquired through ingesting contaminated food or water. Traveler’s diarrhea, affecting between 30% and 70% of travelers, is typically caused by bacteria, with Enterotoxigenic Escherichia coli (ETEC) being the most frequent culprit. These pathogens are transmitted via the fecal-oral route, usually through food or drink handled with poor sanitation. More serious infections like Hepatitis A and Typhoid Fever also spread this way. Contamination sources include ice cubes, unpasteurized dairy, raw produce, and even tap water used for brushing teeth in high-risk areas. Foods that are not freshly prepared and served steaming hot present a higher risk.
Infectious Risks from Crowded Environments
Confined spaces common in travel, such as airplane cabins, buses, and cruise ships, accelerate the transmission of respiratory and contact-based infections. Respiratory viruses like the common cold, influenza, and COVID-19 are spread primarily through droplets expelled by an infected person.
Modern aircraft ventilation systems use High-Efficiency Particulate Air (HEPA) filters, removing 99.97% of airborne particles. However, surface contamination and close-range droplet spread remain significant threats. High-touch areas like tray tables, armrests, and lavatory handles can harbor viruses for hours.
Gastrointestinal infections like Norovirus also thrive in these close quarters, particularly on cruise ships, where outbreaks are frequently reported. Norovirus is notoriously contagious and can be transmitted person-to-person, via contaminated surfaces, or through aerosolized vomit. The virus can remain infective on surfaces for days or weeks, challenging environmental hygiene in shared transport.
Physical Ailments Caused by Travel Conditions
Beyond infectious diseases, the act of traveling itself can cause non-infectious physical ailments. Jet lag, a temporary circadian rhythm sleep disorder, occurs when rapid travel across multiple time zones causes a misalignment between the body’s internal clock and the local light-dark cycle. This leads to symptoms like daytime fatigue, insomnia, and gastrointestinal distress.
Travel to high elevations introduces the risk of altitude sickness. At altitudes generally above 2,500 meters, the barometric pressure drops, reducing the partial pressure of oxygen and causing an insufficient oxygen supply to the body’s tissues. If acclimatization is inadequate, the lack of oxygen can lead to fluid accumulation in the brain or lungs.
Motion sickness arises from a sensory conflict within the brain, particularly in the vestibular system of the inner ear. The brain receives contradictory signals: the inner ear senses motion (like the rocking of a ship or car), but the eyes register a stable scene inside the cabin. This mismatch is interpreted by the brain as a possible toxic ingestion, triggering nausea and vomiting.
Preparation and Prevention Strategies
Mitigating travel-related illness begins well before departure, starting with a consultation with a travel medicine provider six to eight weeks in advance. This allows sufficient time for necessary non-routine vaccines (Typhoid Fever, Yellow Fever, or Hepatitis A) to become fully effective. Routine vaccinations like the flu shot and tetanus booster should also be current.
For preventing food and waterborne infections, travelers should adhere to the adage, “boil it, cook it, peel it, or forget it.” Rely only on factory-sealed bottled water, including for brushing teeth. Avoiding raw or undercooked meat, unpeeled fruits, and salads minimizes exposure to pathogens.
Reducing exposure to respiratory viruses requires diligent hygiene in crowded settings. Frequent handwashing with soap and water for at least 20 seconds is the most effective defense against respiratory and contact-transmitted gastrointestinal viruses. When soap is unavailable, use an alcohol-based hand sanitizer and disinfectant wipes to clean high-touch surfaces like tray tables and armrests upon boarding.
To minimize the impact of physical ailments, manage light exposure to ease jet lag symptoms, as light is the strongest external cue for the circadian clock. Traveling eastward requires maximizing light exposure in the morning, while westward travel benefits from minimizing morning light. Altitude sickness is best prevented through staged acclimatization, meaning a gradual ascent to allow the body to adjust to the lower oxygen levels.