2nd August 2023

Evaluation of the Unwell Returning Traveller

Introduction

The increase in international travel over recent decades has led to higher numbers of travellers developing a febrile illness during or soon upon returning to the UK. There is an extensive list of differential diagnoses to consider, and therefore a systematic approach to patient management will enable timely and suitable treatment.

As discussed earlier, most patients with febrile illnesses presenting to a UK hospital with a travel history do not end up with a clear-cut pathogenic diagnosis. Of those that do, malaria is the most common and prudent to consider, given the possibility of severe disease progression. All patients with a travel history in countries with known malaria transmission should have multiple sets of blood cultures & malaria screens. Other diagnoses, inclusive of dengue, enteric fever (typhoid & paratyphoid), HIV seroconversion and rickettsia infections, are also important considerations due to their common importation into the UK. The more esoteric pathogens may require serological or molecular testing at specialist reference laboratories.

In all cases of a returned febrile traveller, a detailed and structured history should include the following:

• Geographical locations visited
• Dates of travel and onset of illness
• Pre-travel preparation (including malaria prophylaxis)
• Activities during travel/type of travel
• Risk assessment of viral haemorrhagic fever (due to the very serious nature of these infections)
• Patient immune status
• Bites and wounds

Disease Presentations

A ‘Fever Plus’ approach, whereby recognising a fever in addition to an acute key symptom such as diarrhoea or rash, can be extremely useful in narrowing down differentials to inform further investigation and management.

Table 4: A ‘Fever Plus’ approach by key symptom(s)

Diagnostics

Not all disease presentations follow a predetermined diagnostic sieve, so additional investigations are needed. A thick and thin blood film for malarial parasites from at least two separately timed samples is required to exclude malaria.

Serology tests are available to identify the viral antigen when suspecting ‘FAR Syndrome’ viral infections – presenting with Fever, Arthralgia and Rash – such as Dengue and Zika Virus. Molecular testing, such as PCR, may be available and is ultimately more specific to rule out certain viral pathogens.

Remember that Tuberculosis (TB) is particularly unreliable to culture. If suspecting TB, a ‘GeneXpert’ test is often available and more reliable for diagnosis; this uses PCR to identify conserved regions of the mycobacterial genome alongside genes encoding resistance to anti-TB regimen drugs.