What to do with a returning traveller who develops fever
Tropical medicine specialist Dr Tom Doherty explains when to reassure, when to test, when to treat and when to refer
A 32-year-old Caucasian woman spent four weeks on holiday in Tanzania, two weeks on the coast and two weeks on safari. She took weekly chloroquine and daily proguanil as antimalarial prophylaxis. She was well while she was away and had no other significant medical illness. Eleven days after returning to London she developed a fever associated with headache and generalised myalgia but without any other localising symptoms. She took some paracetamol and went to bed but her symptoms persisted. Two days later she became sufficiently worried to go to her GP.
What would you ask the patient?
You need to cover the following points.
· Did she travel to a malaria-endemic area?
· Did she take the prophylaxis as directed?
· Did she use mosquito repellents and wear long trousers or skirts and long-sleeved shirts after dusk?
· Did she spray her accommodation before going to bed?
· Did she sleep under a mosquito net?
· Was the net treated with insecticide?
· Had she noticed any darkening of the urine? Many patients with malaria have sufficient haemolysis to cause darkening of the urine without becoming jaundiced.
· Had she noticed any tick bites or an eschar to suggest tick typhus?
· Had she put herself at any risk of acquiring HIV?
What is the likely diagnosis and what
else could it be?
Any patient who comes back from Africa and develops a febrile illness should be assumed to have falciparum malaria which is potentially fatal. But other diagnoses need to be considered.
· Tick typhus is common in East Africa.
· Many patients with a febrile illness returning from the tropics do not have an exotic condition at all consider urinary tract infection, sinusitis, skin sepsis, chest infections and the like.
· Typhoid is surprisingly rare in travellers from Africa but needs to be excluded.
· Non-specific viral illnesses that remit spontaneously are very common among travellers.
What investigations would you initiate and why?
Anyone suspected of having malaria in whom there is no firm evidence of an alternative cause of fever should be referred urgently to hospital. A thick and thin film for malaria parasites needs to be done as a matter of urgency, and, if negative, repeated every six to 12 hours for up to two days (the film should be made and examined the same day). If microscopists are not available, a malaria antigen dipstick test could be performed but these are not 100 per cent specific or sensitive, nor are they able to quantify the parasitaemia which influences patient management.
Other investigations should include:
· A full blood count, looking particularly at the white cell and platelets. A neutrophilia may suggest bacterial sepsis, while thrombocytopenia is very common in patients with malaria.
· Cultures of blood, urine and a throat swab often provide useful information.
· A CXR is probably indicated in any patient with an unexplained fever and an abdominal ultrasound may be helpful if the fever persists.
· U&Es and LFTs are less helpful in making a specific diagnosis but it's reassuring to know they are normal.
· Serological tests have little to offer in the acute phase with the exception of amoebic serology if an amoebic liver abscess is considered.
What treatment would you offer?
Anyone suspected to have malaria should be referred urgently to hospital and everyone with falciparum malaria should be admitted, irrespective of how well they may appear. Late complications of malaria do occur. In 2000, the mortality rate for all cases reported to the Malaria Reference Laboratory at the London School of Hygiene and Tropical Medicine was 1 per cent. Quinine remains the drug of choice with the standard dose of 10mg/kg body weight given three times a day. We give quinine until all the asexual parasites have cleared from the peripheral blood and then to give a second agent such as sulfadoxine-pyrimethamine, doxycycline or mefloquine.
What preventive advice would you
offer for the future?
Chloroquine and proguanil no longer offer adequate protection. The recommended alternatives are mefloquine once weekly, doxycycline daily or Malarone daily for those who can afford it. And prevention is better than cure particularly avoiding mosquito bites.
The Hospital for Tropical Diseases
The following require admission:
· Adult patients with proven or suspected tropical disease
· Adult patients with proven or suspected infectious diseases, whether or not they have travelled to the tropics
· Adult patients for investigation of pyrexia of unknown origin whether or not they have travelled to the tropics
09061 33 77 33
Information from the Hospital for Tropical Disease, the only NHS hospital dedicated to the prevention, diagnosis and treatment of tropical disease
Pollard AJ, Murdoch DR. Travel Medicine. Health Press: Oxford, 2001
Molyneux ME, Fox R. Diagnosis and treatment of malaria in Britain.
White NJ. The treatment of malaria.
N Eng J Med 1996;335:800-6
Whitty CJM et al. Science, medicine and the future: malaria. BMJ 2002;325:1221-4
Malaria Reference Laboratory helpline: 0207 636 3924