Need to Know - Travel Medicine
Travel medicine consultant Dr Ron Behrens answers questions from Dr Kathryn Griffith
Travel medicine consultant Dr Ron Behrens answers questions from Dr Kathryn Griffith
1. A young family are excited because they have picked up a last-minute bargain trip to Thailand; it starts in the north and they leave in two weeks. How much protection can be offered to them at this late stage?
Most of what they need can be administered in the time window. I suggest they are all up to date with DTP. Adults need hepatitis A, children under 10 years rarely develop clinical hepatitis A, so I'm happy not giving it to this age group. No other vaccines are necessary, not even typhoid.
Advice on bite prevention and diarrhoea avoidance and treatment should be given. I would also have a chat about road safety, including the wearing of seatbelts, not driving at night and avoiding the tuk-tuk taxis.
Swimming in the sea can be dangerous and I'd also advise them to use beaches that have lifeguards and ensure kids are always supervised in the water. The tropical sun can be unexpectedly severe and I would recommend a sun screen of +30 for all and T-shirts for children at all times, even in the water.
Ear and eye infections associated with swimming are common among children and I would recommend a topical ear/eye antibacterial.
2. They are also taking a two-year-old. Does the same advice apply to him?
No, omit hepatitis A but ensure he's had MMR and other routine childhood vaccines. Common problems include heat and nappy rash but the possibility of skin infections – including infected insect bites – needs to be discussed along with detailed advice on the prevention and management of diarrhoea. Encourage them to take along sterilising tablets and oral rehydration salts. A car seat is important if they plan to travel in a vehicle.
3. How do recommendations change during pregnancy?
The main issue is dealing with the complexity of defining the risk of problems associated with travelling while pregnant as well as the safety versus the benefits of vaccines and drugs.
The highest risk is a pregnancy complication during travel. Most drugs and vaccines are not licensed for use in pregnancy but there is often circumstantial evidence to support their use.
Prescribing unlicensed drugs is a balance between unknown risks to the fetus and mother against the risk from the infection they may be exposed to. I would recommend that if a mother is at risk of hepatitis A or B or typhoid she should be immunised. The DTP vaccine is safe during pregnancy and should be used if appropriate.
The risk of malaria should be considered carefully. I would advise against travel to high-risk malaria areas if possible. If travel is unavoidable the most suitable anti-malarial for the area visited should be used. However, doxycycline shouldn't be used and there is insufficient information on the use of atovaquone/proguanil in pregnancy.
Mefloquine may be used in the second and third trimesters, and may also be used in the first trimester if the risk of falciparum malaria is high.
4. Many patients are concerned about the side-effects of DEET. Are there any effective alternatives and does taking vitamin B have anything other than a placebo effect?
DEET has a very good safety record and I would strongly recommend its use. It is highly efficacious at repelling most insects and there is a large body of literature on its safety in both adults and children. B12 does not work, nor do garlic and similar products.
Natural repellents on the whole have a shorter duration of effect and their toxicity is often unknown.
5. A patient came back from Russia a month ago and has felt unwell ever since. They have lots of information about giardia which they are convinced they have caught. What is the best test to confirm or rule out this diagnosis and what is the best treatment?
Other than the outbreak from St Petersburg in the 1990s, giardia is not a particularly common intestinal infection acquired in Russia. The diagnosis is made on microscopic stool examination, which may need to be repeated.
Optimal treatment is with a single 3g dose of tinidazole, which can be repeated a week or two later if symptoms persist. Around 10% of individuals have disturbed bowel function for some months after an acute intestinal infection.
6. Is there ever any indication to treat travellers' diarrhoea with ciprofloxacin?
Travellers' diarrhoea is such a common problem – affecting up to 70% of travellers in some destinations – that I believe it should be treated, especially as it interferes with leisure activities and can lead to more serious problems in a small number of compromised patients.
There is now good evidence that either a single dose or a three-day course of ciprofloxaxin, or a single 500mg dose of azithromycin will significantly shorten the duration of symptoms and lead to a rapid recovery.
I provide the treatment for travellers to take as soon as symptoms develop – the earlier it is taken, the greater the benefit.
7. How commonly do you see joint symptoms and other features of Reiter's syndrome and does this change the treatment options?
The most usual infections we see associated with painful swollen joints are summarised in the box left.
Between 1% and 5% of campylobacter infections result in a reactive arthritis, whereas with shigella the rate is 1.3 per 100,000.
Management relies on NSAIDs, local measures such as arthrocentesis, cold pads and resting the affected joint.
If an infectious agent has been isolated from the stool, this should be treated with an appropriate anti-bacterial agent. Where chlamydia is the aetiology, therapy with either doxycycline 100mg twice daily, or a single 1g dose of azithromycin can be used.
8. What is the most important tropical disease that we are likely to see in our patients returning from holiday?
This depends on the perspective – the GP's or referral centre's.
GPs are most likely to see traveller's diarrhoea, skin sepsis and occasional fevers which often settle spontaneously.
In a specialist centre, we see a number of patients with fever where, after detailed investigations, no aetiology is identified.
Where a diagnosis is made, malaria, traveller's diarrhoea (without an infective agent) and skin infections (predominantly infected insect bites) are the most common. But we also see other parasitic skin infections including cutaneous larvae migrans.
Malaria case reports are declining across England and dengue fever is now seen just as frequently. Tuberculosis is an important diagnosis not to be missed in ethnic travellers.
9. I commonly see pyrexial patients who have missed one or two anti-malarial tablets while on holiday in an endemic area. How soon would you expect to see parasites on a thick film? Is this still the best diagnostic test and do we need to repeat it if the index of suspicion is high?
It depends which anti-malarials are used and where they have been. If they have been to Central or South America or the
Indian subcontinent, a fever, particularly if the fever occurs more than three weeks after return, could be Plasmodium vivax malaria.
Both thick films (to identify an infection) and a thin film (for the species) should be made.
Anyone with malaria and a fever will have parasites in the blood, as these are creating the fever.
If the laboratory can't find them on the first film, clinical judgment needs to prevail. If the patient has been in a falciparum endemic region and has a fever on return, and the symptoms are suggestive of malaria, just three repeated blood films over 24 to 36 hours will exclude the diagnosis.
If the patient is worsening or has severe symptoms, treatment should be implemented without lab confirmation.
Atovaquone/proguanil has yet to fail because of a missed dose. Mefloquine with doxycycline very rarely fails, even with missed doses, and chloroquine with proguanil fails frequently if doses are missed. The rapid diagnostic bedside test is not as sensitive as a microscopical examination, but if it is available it can be used in conjunction with a blood film.
10. For which exotic destinations is full vaccination not needed?
The current guidelines recommend all individuals are boosted with diphtheria tetanus and parenteral polio, so you will need that as a minimum.
If travelling to the tropics, hepatitis A is present globally and the vaccine is very safe and highly effective – although not a necessity for countries such as Australia, New Zealand, Singapore and urban South Africa. That leaves the temperate regions, the Arctic and Antarctic.
11. Do you recommend any patient-friendly websites for accurate travel advice?
The National Travel Health Network and Centre site has a lot of information, which needs some interpretation. But the risk assessment for a journey cannot be accurately made from information on any website alone. These usually provide a narrow spectrum of some of the hazards faced by travellers and many other risks are often not included, particularly crime and health facilities.
The Pulse travel vaccination and malaria charts are updated monthly.
What I Will Do Now What I Will Do Now
Dr Griffith reflects on the answers to her queries
• I'll emphasise that the cornerstone of safe travel is problem prevention: avoiding bites, road and sea safety, hygiene measures and sun protection.
• Parents of young children particularly need to be advised about prevention and management of diarrhoea.
• I can reassure patients that DEET has a good safety record in both adults and children and repels most insects.
• Traveller's diarrhoea may be significantly shortened by ciprofloxaxin or azithromycin.
• It is useful to read the most recent information on failure rates with missed doses of various malaria prophylaxis regimens.
• It's useful to know that any patient who has a fever with malaria will have parasites in the blood on thick film.