Management
of fever in travellers- All febrile patients should be asked if they have travelled abroad otherwise diagnoses of the tropical causes of fever are likely to be missed with potential serious consequences. If a traveller has been exposed to malaria this remains the most likely diagnosis.
- Some cases of viral haemorrhagic fever are caused by viruses (Lassa, Ebola, Marburg, Congo-Crimean Haemorrhagic Fever) which may be transmitted between humans and special consideration is needed to ensure that cross infection is avoided. These diseases are rarely imported into the UK. .
- The febrile traveller may have a non-tropical infection such as respiratory or enteric virus infection, pneumonia or urinary tract infection .
Reported causes of fever in returning travellers (Doherty et al, 1995)
| Diagnosis | % (n=195) |
| Malaria | 42 |
| Non-specific (probably viral) | 24.5 |
| Diarrhoeal illness | 6.5 |
| Dengue fever | 6 |
| Hepatitis | 3 |
| Respiratory infection | 2.5 |
| Urinary tract infection | 2.5 |
| Typhoid/paratyphoid | 2 |
| Tuberculosis | 2 |
| Meningitis | 1 |
| Acute HIV infection | 1 |
| Miscellaneous | 8 |
A knowledge of incubation periods, global distribution and mode of transmission of disease is important to consider in the differential diagnosis. There should be consideration of referral of patients to an Infectious Diseases Unit or of taking advice from a Consultant in infectious diseases.
Incubation periods for selected tropical infections
| Infection | Incubation |
| Falciparum malaria | 7-40 days |
| Vivax malaria | weeks to several years |
| Dengue fever | 3-4 days |
| Hepatitis A | 21-42days |
| Hepatitis B | 42-180 days |
| Typhoid/paratyphoid | 7-21 days |
| Viral haemorrhagic fevers | 2-21 days |
Discussion about interpretation of investigations and advice may be obtained from microbiologists (and haematologists for malaria).
History, Examination and Initial Investigations
The medical history of the illness should include
- a detailed travel history
- dates
- countries visited
- type of accommodation
- activities, exposure to water
- insect bites
- contact history
- sexual history
- pre-exposure immunisations
- malarial prophyllaxis used
Examination should take particular note of jaundice, haemorrhage, skin rashes, insect bites, localising signs of infection, shock.
Initial investigations should include
- full blood count including differential white cell count and platelet count
- blood films for malaria parasites
- blood cultures
- urea & eIectrolytes
- liver function tests
- urinalysis
- chest x-ray (if indicated)
- serology serum save for subsequent testing.
If VHF is suspected then investigations may need to be done in a high security infectious disease laboratory.
Malaria
- Falciparum malaria is a life-threatening disease in a non-immune individual.
- There are no dormant forms of falciparum malaria so it is highly unlikely to develop infection more than 12 weeks after the last potential exposure.
- It is advisable that patients with falciparum malaria are admitted to hospital for treatment and monitoring and preferably referred to an infectious diseases unit or, if this is not practical, advice on treatment from an infectious diseases unit should be sought. This is particularly important in cases with parasitaemia >2% in whom complications are more likely.
- Treatment of benign malaria (vivax, ovale) may not warrant hospital admission. The recommended treatment is described in the BNF. Primaquine should be given to prevent relapse provided the patient is not G6PD deficient.
- If the type of malaria is not clear then falciparum should be presumed and treated appropriately.
Viral haemorrhagic fever
- Febrile patients who have returned from potentially infected areas within 21 days should be considered for possible risk of VHF.
- The risk depends on the country visited and the activities undertaken there. It may be difficult to exclude early VHF (before the haemorrhagic manifestations) on clinical grounds alone but is often possible to do so with epidemiological knowledge.
- Potentially infected areas
- Lassa - West Africa especially Nigeria, Sierra Leone.
- Ebola - Republic of Congo (Zaire), West Africa, Sudan.
- Marburg - Sub-Saharan Africa.
- Congo-Crimean HF - Africa, Russia, Pakistani India, Afghanistan, Middle East, Eastern Europe.
- Most patients suspected to have VHF will have some other infection and it is particularly important to look for malaria as a matter of urgency.
- Patients suspected of having VHF should be discussed with a Consultant in Infectious Diseases and a Consultant in Communicable Disease Control (CCDC).
- In suspected cases of VHF, it is important to notify any laboratory handling specimens to discuss their appropriate handling. Further information is available (ACDP 1996).