Travel Medicine

• Cabin air pressure (CAP):
• At cruising altitude, CAP is lower than pressure at sea level, leading to hypoxia and expansion of gases within the body. Many healthy passengers tolerate this well.
• Passengers with certain medical conditions, especially lung disease and blood disorders (SCDx/SCA), may not tolerate it and may need supplementary oxygen supply during the flight.
• Gas Expansion:
• As the aircraft climbs, decreasing cabin air pressure causes gases to expand.
• Similarly, as the aircraft descends, increasing pressure in the cabin causes gases to contract.
• Airplane ear/ear barotrauma/barotitis media:
• Refers to the stress exerted on the eardrum, Eustachian tube, and other ear structures when air pressure in the middle ear and environment are out of balance.
• Gas expansion during the climb causes air to escape from the middle ear and sinuses, usually without causing problems (resulting in a "popping sensation" in the ears).
• As the aircraft descends, air must flow back into the middle ear and sinuses to equalize pressure differences. If this does not happen, the ear and sinuses may feel blocked, and pain can result – known as airplane ear.
• Signs and symptoms include pain in the ear, slight hearing loss, or a stuffy feeling in both ears (eardrum bulging outward or retracting inward due to changes in pressure).

Prevention of Gas Expansion Effects

• Swallowing, chewing, or yawning (clearing the ears)
• Try Valsalva maneuver to unplug your ears
• Avoid sleeping during ascents or descents
• Take a decongestant before you get on the airplane, especially if you have a common cold (swollen sinuses)
• For infants, breastmilk feeding/suckling or giving a pacifier (dummy) to stimulate swallowing

Note: Any condition that can interfere with the normal function of the middle ear can increase the risk of airplane ear. This would include:

• Stuffy nose, an allergy, a cold, or throat infection
• Not all colds require a change in travel plans. However, a severe cold or an ear infection may be a reason to change or delay a flight.

Cabin Humidity and Dehydration

• Lower humidity can lead to skin dryness and discomfort of eyes, mouth, nose, and exposed skin.
• Prevention:
• Skin moisturizing lotion
• Nasal saline
• Spectacles rather than contact lenses

Ozone

• A form of O₂ that occurs in the upper atmosphere and may enter the aircraft cabin together with fresh air supply.
• In older aircraft, ozone can lead to irritation of the lungs, eyes, and nasal tissues.
• Ozone is broken down by heat and removed by compressors that provide pressurized air for the cabin.

Motion Sickness

• Common for road travelers, rarely for air travelers except in the case of severe turbulence.
• Prevention:
• Choose a seat in the mid-section of the cabin.
• Keep eyes fixed on the horizontal.
• Avoid rapid head movements.
• Sleep if able.
• Keep motion sickness bag accessible.
• Avoid drinking alcohol during the flight and for 24 hours before travel.
• Consult a doctor before traveling.

Immobility, Circulatory Problems, and DVT

• Prolonged immobility can lead to pooling of blood in the legs, resulting in leg swelling, stiffness, discomfort, and deep vein thrombosis (DVT).
• According to the WHO, the risk of DVT approximately doubles after a long flight (>4 hrs) and other forms of travel where travelers are exposed to prolonged seated immobility and multiple flights within a short period.

Jet Lag

• Symptoms caused by the disruption of the body’s “Internal Clock” and circadian rhythms it controls. Disruption occurs when crossing multiple time zones.
• Jet Lag may lead to:
• Indigestion and disturbance of bowel function
• General malaise
• Daytime sleepiness and difficulty in sleeping at night
• Reduced physical and mental performance
• Disturbances for travelers who take medication according to a strict timetable (e.g., insulin, oral contraceptives)
• Prevention of Jet Lag
• Prevention- cannot be prevented!
• General measures to reduce the effect of jet lag:
• Rest before departure and during the flight
• Eat light meals and limit consumption of alcohol
• Caffeine should be limited to normal amounts
• Create the right conditions for sleep
• Consider short-acting sleeping pills
• Melatonin (in some countries)

Psychological Problems of Travel

• Main problems when flying are:
• Stress
• Fear of flying
• Air rage
• Prevention: Health education, aircraft disinfection, proper counseling, and medical consultations before departure.

Contraindications to Air Travel

• Infant < 7 days old
• Women > 36th week of Pregnancy OR (>32nd week of multiple pregnancy & until 7 days after delivery)
• Medical conditions:
• Angina pectoris or chest pain at rest
• Serious or acute infectious disease
• Decompression sickness after diving
• Increased intracranial pressure due to hemorrhage, trauma, or infections
• Infection of the sinuses, ear, or nose particularly if Eustachian tube is blocked
• Recent myocardial infarction & stroke
• Psychotic illness except when fully controlled
• Recent surgery or injury
• Severe chronic respiratory diseases, and unresolved pneumothorax
• Sickle cell disease
• Note: Some of these can be relative or absolute contraindications depending on the circumstances.

• International Labour Organization (ILO) conventions require:
• Vessel carrying > 100 crew members
• International voyage of > 3 days or longer to (must) provide a physician for care of the crew
• Health Hazards for Sea Travelers:
• Physical Hazard: Noise, vibration, UV light exposure, heavy lifting, slippery surfaces, steep ladder, etc.
• Chemical Hazards: Exposure to chemical cargos, fuel, cleansers, and diesel exhaust.
• Biological Hazards: Transmission of contagious diseases.
• Psycho-social Hazards: Social isolation, language barrier, circadian rhythm disruption, substance abuse, delayed access to medical care.
• Communicable Diseases:
• Gastroenteritis
• Respiratory infections
• Non-Communicable Diseases

Factors that Have Contributed to Outbreaks in Sea Travel

• Contaminated bunkered water, inadequate disinfection of water
• Portable water contaminated by sewage on ship
• Poor design & construction of storage tanks for potable water
• Deficiencies in food handling, preparation & cooking
• Use of sea water in the galley (kitchen)

Road Traffic

• Most frequent cause of death among travelers
• Constitute typical risk in many countries particularly developing countries
• Causes
• Traffic laws - are limited / not enforced
• Roads - poorly constructed and maintained
• Road signs and lighting are inadequate
• Poor driving habits
• Lack of familiarity with the roads
• Traffic mix is more complex than in developed countries
• Different vehicles, animal-drawn vehicles, other conveyances plus pedestrians - all sharing same road space

Prevention

• Travelers - both drivers & pedestrians should be extremely attentive & careful on the roads
• Have full insurance cover for medical report of both illness & injuries
• Carry an international driving license as well as your national driving license
• Obtain information on the regulation governing traffic & vehicles maintenance, and on the state of the roads, in the countries to be visited
• Check the state of the car/its parts
• Know the informal rules of the road, be vigilant where the traffic drives on opposite side to your country
• Do not drive on unfamiliar roads
• Do not use motorcycle, bicycle or tricycle
• Do not drive after drinking alcohol
• Drive within the spread limit
• Always wear seat belt

For Yellow Fever vaccines, according to international measures, the world is divided into three zones:

• Infected (endemic) zone: The virus, vectors, and the environment favor transmission.
• Infectable (receptive) zone: There is no virus, but the environment favors transmission.
• Non-infectable zone: There is no virus, vector, and the environmental conditions are not suitable; no preventive measures are required.

Measures applied for infected zones:

1. Port and airport:
   • Should be away from the city.
   • Apply insecticides periodically.
2. The plane: Insecticides spray in planes before leaving.
3. Individuals:
   • Valid vaccination certificates.
   • Cases of yellow fever should not leave the country.

Measures applied for Infectable (Receptive) Zone (Latitude 43°N & 43°S):

• All planes and ships should be disinfected on arrival.
• Only travelers carrying valid vaccination certificates are allowed to enter. If not vaccinated or vaccinated less than 10 days ago, they should be quarantined for six days.
• Monkeys and apes should be quarantined for seven days.

Non-infectable zone (Areas North & South of Latitude 43°):

There is no virus, no vector, and the environmental conditions are not suitable.

Yellow fever vaccine:

• 1 dose is sufficient.
• Protective for 10 years.
• Age range: Minimum age is 9-12 months. Seek medical advice for infants aged 6-9 months who are traveling to high-risk areas.
• International Certificate of Vaccination or Prophylaxis (ICVP) is required for yellow fever.
• The certificate is valid 10 days after vaccination and for a subsequent period of 10 years.

• Antimalarial drugs are recommended for prophylaxis for non-immune travelers visiting malaria-endemic areas.
• In areas with chloroquine (CQ)-sensitive malaria, weekly CQ is the drug of choice.
• In areas with CQ-resistant P. falciparum, weekly mefloquine or daily doxycycline is recommended.
• Chemoprophylaxis should be started 1 week before arriving in a malaria-endemic area and continued during travel and for 4 weeks after leaving the area.

• Diarrhea is the most frequent health impairment among travelers, with a risk of 7% of travelers to developed countries and 0-90% of travelers to some parts of the developing world.
• The most common symptoms, in addition to diarrhea and fecal urgency, are abdominal cramps, nausea, vomiting, and general malaise.
• It often results in incapacitation for more than 10% of international excursions.
• The most frequent etiologic agents are:
• Enterotoxigenic Escherichia coli (ETEC) and Enteroaggregative E. coli (EAEC)
• Others include Shigella spp., Salmonella spp., Campylobacter spp., Vibrio parahaemoliticus (Asia), Rotavirus (Latin America), and protozoa (Giardia, Cryptosporidium, Cyclospora spp., and Entamoeba histolytica) – Noroviruses

• Malaria: most important for international travelers
• Others include the following:
• Dengue (in the Caribbean, Central and South America, and SE Asia)
• Tick-borne encephalitis (from the bite of an infected tick or rarely ingesting unpasteurized dairy products)
• Loiasis (prevention: 300mg Diethylcarbamazine adult dose)
• Tick- and mite-borne typhus, relapsing fever, bartonellosis, and plague (especially in some Central and West African countries) can be prevented by using 100mg of Doxycycline daily

• The risk is increased by exposure to multiple or professional partners
• HIV/AIDS
• Hepatitis B infection

Safer sexual practices, including:

• Use of condoms throughout intimacy
• Immunization against Hepatitis B is a must for those who may engage in casual sex while abroad

• Schistosomiasis from slow-moving fresh water
• Barefoot walking exposes the traveler to a variety of hazards
• Cutaneous larva migrans from dogs and cats
• Hookworm infections
• Strongyloidiasis