The returning traveller can pose particular challenges for a GP and the patient's recent destination is important.1
For example, malaria is more likely in travellers from sub-Saharan Africa, but dengue fever is more likely in other areas.
A detailed history is essential (see box below). Preventive measures can give a false sense of reassurance; typhoid vaccination is only 70 per cent effective, and malaria can still occur despite fastidious prophylaxis.
Incubation periods can vary widely. Dengue fever usually appears in less than 10 days, while viral hepatitis may take several weeks to manifest.
Malaria usually presents within three months, but in some patients with Plasmodium falciparum it can be delayed for as long as a year. In a few cases, mefloquine as prophylaxis can delay presentation.
Diseases to consider
Febrile illness is a common presenting symptom for malaria, dengue fever, infectious mononucleosis, dysentery and typhoid.
Suspected malaria is a medical emergency and demands urgent blood films and/or specialist referral. There are between 1,500 and 2,000 cases of malaria each year in the UK, with 10-20 deaths.2
Most cases in the UK are due to P falciparum. It has the potential to cause death within 24 hours and may present with non-specific symptoms.
Dengue fever is on the increase3 and is transmitted by the Aedes aegypti mosquito. It presents as a severe flu-like illness that may develop into a haemorrhagic fever that can lead to serious illness and death.
Yellow fever is a viral illness also transmitted by Aedes aegypti, and occurs in parts of Africa and South America. Jaundice, fever and a sore throat occur. Lassa fever is similar, and immediate action is required if this is suspected.
Hepatitis can present with fever and with or without jaundice. Hepatitis A and B account for most cases, but less common causes include hepatitis C and E, coxiella, cytomegalovirus and infectious mononucleosis.
Legionnaires' disease can present with fever, generalised myalgia and cough. Men over the age of 50 are most at risk. TB should also be considered.
Diarrhoea is a common symptom, and duration of symptoms, the presence of fever, and blood or mucus in the stool may all be significant. Causes of persistent severe diarrhoea include the parasites Giardia lamblia, Entamoeba histolytica and Cyclospora. Campylobacter and shigella are also frequently encountered.
Diarrhoea with fever may be a presenting feature of malaria. Right hypochondrium pain could be due to an amoebic liver abscess.
A clinical examination will detect rashes, bites, throat symptoms and spleen, liver or lymph node enlargement. FBC (with thick and thin films for suspected malaria), LFT and urine, stool and blood cultures are mandatory. Throat swab, chest X-ray and sputum culture may be performed as appropriate.
Malaria should be the diagnosis in a returning traveller with fever until proved otherwise. Two further thick and thin films must be taken 12 to 24 hours apart if the first films are negative. For dengue fever, an enzyme-linked immunosorbent assay test can be useful.
LFTs are deranged in viral hepatitis but mildly elevated in malaria, dengue fever and typhoid. Eosinophilia may be marked in helminth infections such as filariasis, cutaneous larva migrans and hookworm infestation.
Stool samples for cysts, ova and parasites, and serological tests (your local laboratory can advise you) may give a definitive result. Mebendazole may be indicated.
Schistosomiasis (bilharzia) carries a risk of potential long-term effects such as bladder cancer. All freshwater rivers and lakes can harbour snails infected with schistosoma.
Screening tests are positive in about 11 per cent of those who have visited endemic areas regardless of symptoms.
Diarrhoea with watery stools and flatus for two weeks or more suggests giardiasis even if stool microscopy is negative. Repeat samples should be sent and blood films for parasites and tests for Clostridium difficile requested. Gastroenteritis can lead to lactose intolerance, so long-standing diarrhoea may be a feature of this development.
Genital rashes and ulcers should prompt screening for STIs including HIV, syphilis and chancroid.
Early specialist referral is necessary for many of these diseases. Suspected P falciparum malaria should be admitted to hospital. Non-P falciparum malaria can be treated as an outpatient if the patient remains well.
Quinine with doxycycline is usually given under specialist guidance. There is no specific treatment for dengue fever, but supportive therapy can greatly help in haemorrhagic fever. Typhoid is treated with fluoroquinolones, but resistance can occur. Cephalosporins may be introduced if there is a lack of response to treatment.
Mild diarrhoea should initially be treated symptomatically, while awaiting stool sample reults. Moderate and severe diarrhoea can be treated with ciprofloxacin 500mg twice a day for five days. For suspected giardiasis, metronidazole or tinidazole can be used.
The risks of infections and infestations while abroad can be reduced by good basic hygiene and avoiding undercooked food and contaminated water.
Appropriate vaccinations and antimalarial prophylaxis will reduce morbidity and mortality.
If a returning traveller is unwell, it can often be prudent to seek early expert advice from the local infectious disease unit, and always to consider malaria as a potential diagnosis. All major imported infections are notifiable diseases.4
- Dr Aziz is a GP in Bristol
|Important travel history facts to note|
1. Freedman DO, Weld LH, Kozarsky PE et al. Spectrum of disease in relation to place of exposure among ill returned travellers. N Engl J Med 2006; 354: 119-30.
2. Lalloo DG, Shingadia D, Pasvol G et al. UK malaria treatment guidelines. J Infect 2007; 54: 111-21.
3. WHO. Dengue and dengue haemorrhagic fever. Factsheet No.117. March 2009. Available at: www.who.int/mediacentre/factsheets/fs117/en/ (accessed 16 February 2010).
4. Health Protection Agency. Notifications of infectious diseases (NOIDs). Available at: www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1191942172947 (accessed 16 February 2010).