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Fever in a returning traveller

Introduction

Fever in returning travellers is common; around 8% of travellers to developing countries seek healthcare whilst abroad or after returning home, and over a quarter of such consultations are for fever with or without other symptoms. Far more travellers suffer health problems whilst abroad, but do not seek medical attention. Fever may be a manifestation of a minor, self limiting process, or a life threatening infection. The evaluation of fever requires knowledge of the geographical distribution of disease, risk factors for acquisition, incubation and specific investigations.

 

Key questions in the evaluation of such patients

Where has the patient travelled to? This will determine the risk of exposure to specific infections. The geographical region of travel and whether rural or urban environments, activities, diet, sources of water and type of accommodation will determine the pathogens the patient has potentially been exposed to. It is important to ask which parts of the country the patient visited, and about soil and water contact whilst there. The dates of travel and duration of stay will determine the timing of potential exposure and incubation period. Modes of transport, layovers and intermediate stops should also be asked about. The history should mainly focus on the preceding year, as infections acquired before this are unlikely to cause an acute febrile illness (although there are exceptions).

What pre-travel measures were taken? Vaccines received prior to travel and any chemoprophylaxis taken will influence the likelihood of some infections. A list of recommended vaccinations by country can be found on the CDC website. Enquire about childhood vaccinations also; some may not have received a full course. Vaccines vary in their efficacy, so vaccination against a particular infectious agent does not necessarily exclude this from the differential diagnosis. Details of malaria chemoprophylaxis should include drug, regimen, adherence and any gastrointestinal illness that may have reduced the efficacy. Enquire about the duration of therapy prior to and on returning from the endemic area.

Sexual history? Sexual contact with new partners is common during travel, and sexual tourism is increasing. 19% of travellers have a new partner whilst away, and around 6% of these acquire a sexually transmitted infection. History should include; number of new partners, use of barrier contraception and type of sexual activity. Enquire about other potential exposures to blood or body fluids including tattoos, piercings, dental or medical procedures and use of drugs.

 Host factors? A general history should be taken alongside travel-specific questions, such as finding out age and gender.  Immunocompromised patients are susceptible to a broader range of pathogens; risk of HIV exposure, current medications and any relevant past medical history should be included.

Timing of exposure and presentation? By determining when exposure to the pathogen occurred, it is possible to determine an incubation period, so if greater than a month, many infections can be excluded and others can be ruled in, as some infections (loa loa) require long term exposure. Different infections have varying lengths of time till presentation is common, and this can help predict ailments.

 

Examination and Investigation

Examination: Thorough examination looking for a source of infection and any localising signs indicating possible aetiology. In particular, skin lesions, lymphadenopathy, retinal or conjunctival changes, hepatomegaly, splenomegaly, signs of anaemia, genital lesions and neurological examination.

Investigations: Investigations for specific infections are given in the table.

 



Differential diagnosis

The most common infections causing systemic febrile illness in travellers are;

  • Malaria- this is covered in depth in a separate article. Any patient who has visited an endemic area and gives a history of fever should be tested for malaria. Falciparum malaria predominates in sub-saharan Africa and SE Asia, and can be fatal. Chemoprophylaxis decreases the risk, but increasing resistance and poor adherence lower efficacy. The Plasmodium malariae strain may present months or years after exposure, so may confuse a diagnosis. Malaria can act as a great imitator and patients can present with unusual symptoms, so country of visit is used to make the diagnosis, and infact malaria is assumed in a returning traveller until proven otherwise due to its frequency and deadliness.
  • Dengue fever- found in many tropical and sub-tropical regions and has a very rapid onset. No prevention is available, and treatment is supportive. Dengue haemorrhagic fever is caused by the same virus.
  • Glandular fever- caused by EBV or CMV is commonly seen in returning travellers, and may be acquired in the UK, and is very common in young travellers.
  • Enteric fevers- typhoid and paratyphi. From ingestion of contaminated food or water in many regions.
  • Viral hepatitis- many are vaccinated against hepatitis A, however hepatitis E can also cause an acute hepatitis and is also transmitted through contaminated food and water.

 

Undifferentiated fever: malaria, amoebic liver abscess, chikungunya, dengue, enteric fever, leptospirosis, schistosomiasis

Fever with rash: Dengue, VHF, schistosomiasis

Fever with jaundice: leptospirosis, viral hepatitis, VHF, yellow fever

Fever with hepato/splenomegaly: malaria, amoebic liver abscess, brucellosis, leptospirosis, trypanosomiasis, leishmaniasis

Fever with gastrointestinal symptoms: E. coli, Campylobacter, Salmonella, Shigella

Fever with respiratory symptoms: influenza, Streptococci, H. influenzae, TB

Fever with CNS symptoms: malaria, meningococcal, Japanese encephalitis, rabies, African trypanosomiasis.

 

Less common causes of fever in travellers include schistosomiasis, onchocerciasis, African and South American (Chagas) trypanosomiasis, Leishmaniasis, Japanese encephalitis and rabies. These are outlined in the table below, and further details can be found in the ‘Important tropical diseases’ article. TB is more commonly seen in those living or visiting family in endemic areas. Viral haemorrhagic fevers are rare, but occur in outbreaks and require rapid identification and management. Information on current local disease patterns can be found on the WHO and CDC websites.

 



Alongside tropical infections, other causes of febrile illness should be considered. However antibiotic resistance patterns may be different to those in the UK for organisms causing UTI, URTI etc. The range of infections that may be acquired in developing countries is wide, but can be narrowed through travel history and examination findings. 2% will have a non-infective cause of fever; a thorough history and examination are necessary

Management

This depends entirely on the underlying condition, however the initial aims usually are

1)    To exclude malaria as it is both one of the commonest and by far the most deadly, so the patient is managed assuming they have malaria until proven otherwise

2)    It needs to be established if the patient is infectious to others, especially if they have TB, haemorrhagic fever or norovirus.

3)    Sometimes due to the length of time for serology to return, a patient may begin treatment on clinical grounds alone.

4)    When prescribing antibiotics, in the absence of lab culture results to confirm resistance, it is essential to consider patterns of antibiotic resistance from the visited country. This is very important for TB and typhoid.

 

There are a few red flag symptoms that require urgent care if noticed in the febrile patient, these are:

1)    Haemmorhagic manifestations

2)    Respiratory distress

3)    Hypotension/ hemodynamic instability

4)    Confusion, lethargy, stiff neck or focal neurological signs

 

References and Further Reading

Oxford Handbook of Tropical Medicine (Oxford Medical Handbooks) OUP Oxford, 2008.

Mim's Medical Microbiology. Saunders, 2012.

Fever in returned travellers presenting in the United Kingdom: recommendations for investigation and initial management. Johnston et. al. Jounrnal of infection 2009 Jul;59(1):1-18

Evaluation of fever in the returning traveller. Up to Date. http://www.uptodate.com/contents/evaluation-of-fever-in-the-returning-traveler

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