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travel medicine

travel and immunisations / prophylactic medicines

  • travellers to parts of Asia are often recommended to have:
    • all routine vaccinations up to date, in particular, polio, measles, mumps, tetanus, meningococcal
    • hepatitis A and hepatitis B virus vaccination as both a very common and preventable by vaccination
    • rabies vaccination
      • if you do not have this vaccination, you MUST keep away from cats, dogs, monkeys, bats, etc and you MUST immediately cleanse wound AND have a 4-5 course vaccination starting immediately after ANY bite from a mammal, otherwise there is a risk of contracting rabies which is an incurable lethal infection which will kill you - no one survives!
      • pre-travel vaccination also avoids the need for immunoglobulin vaccine after a bite.
    • malaria prophylaxis - this does NOT guarantee you won't get malaria!
    • take specific anti-mosquito measures to reduce risk of dengue fever, Japanese encephalitis and malaria
    • Japanese encephalitis virus vaccination recommended if:
      • spending a month or more in rural areas of high risk in endemic regions,
      • spending 1 year or more in Asia even if primarily staying in urban areas,
      • and should be considered for shorter-term travellers, particularly if travel is during the wet season or anticipated to be repeated, and/or there is considerable outdoor activity and/or accommodation is inadequately screened against mosquitoes.
  • avoid hospitalisation in countries with high rates of multi-resistant organisms (ie. most Asian countries) as 25% of travellers will become colonised with these and bring them home and run the risk of developing very difficult to treat urinary tract infections (UTIs) / cystitis, bone and wound infections, etc
  • there are high rates of hepatitis C virus and HIV / AIDS in many countries, but no vaccinations available to prevent these - avoid iv drug use, needlestick injuries and practice safe sex
  • cholera vaccination is rarely indicated for most travellers, as the risk of acquiring cholera for travellers in general is very low, provided that general precautions to avoid contaminated food and water are taken.
    • it is only indicated for those travellers at considerable risk:
      • those working in humanitarian disaster situations
      • those with achlorhydria and those at increased risk of severe or complicated diarrhoeal disease, as the vaccination will reduce risk of E.coli traveller's diarrhoea by 15% for 3 months, as well as risk of cholera.
  • yellow fever vaccination may be recommended for those travelling to Africa, Central or Southern America

flying and thromboembolism

  • risk of deep venous thrombosis (DVT) and pulmonary embolism (PE) increases during, and for several weeks after, flights of four or more hours.
  • incidence increases with flight duration, oestrogen use, PH DVT/PE, and co-existing predisposing conditions.
  • clinically evident episodes occur at an incidence of 1 per 4500 long-haul flights.
  • there is no evidence that risk is reduced by aspirin.
  • risk may be reduced by:
    • regular walks around the cabin - but not possible when sleeping and thus there is still risk
    • vigorous ankle flexion against resistance
    • lower leg compressive stockings
    • avoiding oestrogen Rx including OCP 2-3 months prior to travel
    • adequate fluid intake (avoid diuretics including alcohol and caffeine)
    • LMW heparin given immediately before the flight at the usual prophylactic dose1), or warfarin but given the risk of bleeding, these are only recommended for those at high risk of DVT/PE.

moderate DVT risk

  • combined oral contraceptive pill (OCP) use - especially 3rd generation OCP's which have a 4-6x risk compared with non-users
  • inherited thrombotoic states
  • varicose veins
  • short stature (as increased popliteal compression from the seat)

relatively high risk

  • PH DVT/PE
  • recent surgery
  • active cancer
  • combination of moderate risk factors
  • very long haul flights (>10,000 km)
  • prolonged immobility

travel and pregnancy

  • more details at Better Health Channel
  • travel is unlikely to be a problem for a healthy pregnant traveler in the second trimester, however, there are a few risks that need to be considered:
    • DVT risk from prolonged flights or car/bus trips
    • avoid air travel after about 35 weeks and prepare for a possible delivery from 20 weeks
      • almost all airlines decline to fly women beyond 36 weeks of gestation and for some it is 34 weeks. In the phase between 28 and 36 weeks, most airlines will demand that the passenger bring her doctor’s letter stating that she is fit to fly and that she is unlikely to go into labour within 36 hours.
      • the cutoff should be earlier for twin pregnancies as risk or premature labour is higher.
    • avoid live viral vaccines, such as Yellow Fever
    • avoid regions with endemic infections which are particularly problematic in pregnancy such as
      • malaria
      • influenza epidemics
      • developing nations
    • cosmic radiation risk from flights is particularly a risk for frequent flyers in the 1st trimester:
      • the mother’s body provides no significant shielding for a conceptus from galactic radiation received during air travel.
      • when cruising at 33,000 feet (10,000 metres), the level of radiation exposure is 35 times that at sea-level.
      • it is 64 times when the jet reaches 39,000 feet (13,000 metre), cruising altitudes seen in transcontinental flights.
      • long haul aircraft flights radiation exposure is ~5 microSv per hour
      • radiation from a chest Xray is about 100 microSv or equivalent to a 20 hour flight or 10 days of background radiation.
      • a 9.4hr flight from Greece to New York at max. 41,000 feet gives exposure of 67 microSv - well under the maximum accepted exposure to a foetus throughout the pregnancy of 1000 microSv or 500 microSv for a given month 2).
      • for an occasional flier, this level of exposure is still safe.
      • there is no real scientific evidence that their babies are adversely affected even in the at risk stage of early pregnancy, nevertheless, air crew in some airlines are monitored for radiation exposure.
      • pregnant crew members can minimize occupational exposure to galactic radiation by working on short, low-altitude, low-latitude flights.
travel_med.txt · Last modified: 2015/03/07 09:16 by wh