1. Ask about reasons for travel, activities and precise dates.
Diagnosis of travel-related illnesses relies on a detailed travel history including where the patient travelled (country and region), reasons for travel (visiting relatives or business trip) what they did (such as swim in lakes, visit a game park or have local sexual contacts).
Also ask about precise dates of travel to include or exclude infections based on their incubation period and time to presentation. The dates of onset and duration of symptoms, along with details of pre-travel immunisations and compliance with prophylaxis, are valuable.
2. Be alert to illness that can rapidly be fatal or a danger to the public.
The priority is to rule out infections that can rapidly be fatal such as malaria or meningitis, or infections that are a threat to public safety such as viral haemorrhagic fevers.
Viral haemorrhagic fevers are extremely rare, but anyone who presents with an unexplained fever within three weeks of a visit to an area in sub-Saharan Africa where cases are reported (rural central and west Africa) should be isolated while under investigation – particularly if there is a history of contact with body fluids of an infected person or animal.
3. Look for patients at high risk of malaria.
Any patient presenting with unexplained fever or flu-like illness should be asked for a history of travel to avoid missing a diagnosis of malaria.
Over 95% of infections with Plasmodium falciparum occur within two months of
leaving an endemic area, but most occur within 10 days. Symptoms are usually non-specific and include malaise, fever, and occasionally rigors.
Patients who travelled to visit family and friends are at an eight-fold higher risk of having malaria than others. Deaths from malaria are predominantly in older travellers and travellers who have been on ‘winter sun' holidays, particularly in the Gambia.1
4. Don't overlook common health problems.
Health problems common in the general population occur in travellers too. Headaches, malaise, viral respiratory infections and fevers are frequent in travellers and are not always tropical infections.
5. Consider other symptoms to identify the cause of a fever.
The cause of fever in an unwell returned traveller may be difficult to identify and not always have a precise aetiology.
Consider enteric infection (typhoid and paratyphoid) if the patient presents with fever and abdominal pain, particularly after a visit to the Indian subcontinent. A history of fever, rash and recent travel to South East Asia may be due to dengue fever. Consider Rickettsial infection in a traveller who has a fever and skin rash following safari in southern or east Africa. If there is no obvious organ involvement – for example pneumonia, skin sepsis or rash – and the patient is acutely unwell, admission to hospital would be wise.
6. Consider exposure to STIs.
Sexual contact in developing countries exposes travellers to tropical infections such as chancroid, lymphogranuloma venereum, granuloma inguinale (donovanosis), and syphilis. HIV seroconversion illness may present with generalised flu-like symptoms of fever, sore throat, lymphadenopathy, generalised rash, muscle and joint pain and pneumonia, usually two to six weeks after exposure.
7. Conduct stool microscopy and culture in patients with diarrhoea.
Traveller's diarrhoea is the most frequent infection occurring during travel. Most episodes last two to three days, but 1-4% of episodes will persist for four weeks or longer. The initial investigation consists of stool microscopy and culture, but in around half of cases no pathogen will be identified. Giardia lamblia is occasionally identified as the cause of persistent diarrhoea in travellers returned from India or Pakistan. Other parasitic causes of diarrhoea include Entamoeba histolytica and Cryptosporidium parvum. Enteric infections can trigger a post-infectious irritable bowel syndrome with long-term sequelae in 1-4% of patients.
8. Identify skin infections in returned travellers.
Schistosomiasis presents with an urticarial rash, fever and eosinophilia, and a history of fresh-water exposure in Africa four to eight weeks earlier.2 Cutaneous myiasis is more frightening – the patient who has returned from sub-Saharan Africa or Latin America may describe a boil-like lesion where movement of the larva of the tumbu or bot-fly can be felt.
Vaseline under an occlusive dressing placed over the lesion asphyxiates the larva, forcing it to move on to the skin. Cutaneous larva migrans, tungiasis, scabies and other parasites are less common and require specific topical therapy.
9. Refer unexplained eosinophilia for further investigation.
Unexplained eosinophilia (greater than 0.5%) in a symptomatic returned traveller requires further investigation for a helminthic infection.
If they do not have atopy, investigation – starting with a search for ova in the stool and then serological testing for other helminths and trematodes – might help explain the raised count. This can be simply done as an outpatient in a specialist centre.
10. Seek specialist advice if unsure.
Advice can be sought from infectious and tropical diseases centres including the Liverpool School of Tropical Medicine on 0151 705 3100, The Royal Liverpool University Hospital on 0151 706 2000, and the on-call tropical medicine registrar (24-hour service) at the Hospital for Tropical Diseases London via the University College London Hospital Switchboard on 020 3456 7890 or 0845 155 5000.
Dr Ron Behrens is a consultant physician in tropical and travel medicine and Bernadette Carroll is a research fellow at the Hospital for Tropical Diseases, London
References
1 Checkley A, Smith A, Smith V et al. Risk factors for mortality from imported falciparum malaria in the UK over 20 years: an observational study. BMJ 2012;344:e2116
2 Johnston V, Stockley J, Dockrell D et al. Fever in returned travellers presenting in the UK: recommendations for investigation and initial management. J Infect 2009;59:1-18
