What is diseases of travelers?
Removing the human body from an environment to which it is acclimated poses risks:
- Exposure to endemic illnesses in a new environment
- Illness during travel
- Illness from the rigors of travel
Exposure to Illnesses Endemic in Travel Destinations
In areas to which one is not accustomed immunologically, there is risk from both pathogenic infectious agents and the non-pathogenic infectious agents. The typical microbiome of a travel destination can exchange normal bacteria (e.g., E. coli) with portions of the traveler’s microbiome, causing gastrointestinal illness.
The pathogenic infectious organisms there can afflict newcomers vehemently. This can occur even with infections that affect the native population only minimally. Other bacteria, viruses, and parasites pose a threat to the unprepared traveler.
Travelers diarrhea, the most common illness, affecting almost 40% of those traveling from a resource-rich to a resource-poor region, is usually self-limited requiring only support. There are numerous bacterial, viral, and parasitic organisms that can cause this. E.coli. generally causes malaise, anorexia, abdominal cramps, and watery diarrhea. Other causes include Salmonella, Shigella, and Vibrio bacteria; norovirus; and Giardia, Cyclospora, and Entamoeba parasites.
Malaria, dengue fever, Chikungunya fever, typhus, leishmaniasis, and yellow fever are vector caused, e.g., mosquito bites. Travelers’ diarrhea, typhoid, brucellosis, hepatitis A, leptospirosis, cholera, and polio are risks of improperly prepared food or tainted water. Snake bites, parasitic entry, and marine hazards (jelly fish, bites, etc.) add to the usual increase in accidents abroad, especially automobile accidents when unaccustomed to strange rules, road signs and signals, and distractions, such as map reading.
Illness During Travel
Many travelers, especially elderly travelers, travel with on-going illnesses or conditions that are chronically treated, such as heart and other cardiovascular disease, diabetes, renal or liver disease, etc. Altitude reduces barometric and oxygen pressure which can challenge one’s cardiovascular system and may affect pacemaker thresholds. Crossing several time zones can interfere with a diabetic patient’s insulin schedule; sporadic eating necessitated by the rigors of travel can alter insulin needs creating the risk or hyperglycemia or insulin shock.
Travel to other areas or exotic destinations will deprive those with chronic conditions the care needed should they suffer complications; at the very least, immersion in a foreign healthcare system will make timely treatment more difficult.
Persons at risk for deep vein thrombosis may put themselves at risk with lengthy transportation, such as prolonged air, train, or bus travel. Motion sickness is always possible in moving vehicles of any kind, especially boats. Cruise ships in particular offer a new type of “institutionalized” setting in which outbreaks of gastrointestinal disease are characterized by resistances seen in hospitals and other institutions. Pregnant patient should respect additional precautions (e.g., Zika virus) or the risk of going into labor in a strange or undeveloped area.
The incubation periods of infectious diseases can be long enough to delay onset of symptoms until return home, confusing the diagnosis.
Illness due to the Rigors of Travel
Jet lag and other disruptions to one’s circadian rhythm can compromise the immune system, lowering the threshold for becoming ill and compromising the ability to resist or fight disease, as well as impact the travel plans due to excessive fatigue.