Tropical Diseases

Authors: Sneha Baljekar, Tommy Rampling / Editor: Charlotte Davies / Codes: / Published: 12/02/2019


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Next to be seen is a 35 year old male, returned from Ghana, presenting with muscle pain, headaches, a history of fever and diarrhoea. There’s no side rooms, or even rooms, available to see him, and you wonder what the likely cause is.

Fever is a common presenting complaint for returning travellers who attend UK Emergency departments. The first step is to consider warning signs of sepsis. The quick sequential organ function assessment (qSOFA) score provides a quick assessment of those patients with a high risk of mortality, and identifies those in whom expedited treatment and intensive care management should be considered. A secondary aim is to consider the cause of fever, how to investigate it, and whether isolation is required. It is relevant to consider infections with tropical aetiologies in travellers recently returned from the tropics presenting with a febrile illness. The UK population is increasingly globally mobile, with more than 70 million visits abroad made by UK residents in 2017, and 39 million overseas residents visiting the UK . It is also important to be aware of the fluid nature of infectious diseases epidemiology (see ProMED and Healthmap for up to date outbreak information). This is a brief overview of five tropical diseases which can be considered in the febrile returning traveller, and which benefit from timely assessment, investigation and management.

General History Overview:

– Infection Control Precautions
– Resuscitate and symptomatic treatment
– Full history
– Full travel history: where they went, what precautions (eg. antimalarials), where they stayed, what they did (including rituals), what they ate, who they had sex with.
– Treat as appropriate
– Notify PHE.
See NaTHNaC Travel Health Pro – check NaTHNaC if your patient visited somewhere hot.


Quick facts:

1. Spread by the bite of infected anopheles mosquitoes in tropical and subtropical areas
2. The five species of malaria known to infect humans are Plasmodium falciparum (P. falciparum), P. vivax, P.ovale. P.malariae and P.knowlesi.
3. P. falciparum is the most common malaria infection diagnosed in the UK and causes the most severe illness and can be life threatening.
4. Travellers, children under 5, and pregnant women are particularly susceptible to severe malaria

When should it be considered: Malaria should be considered in all travellers reporting fevers, who have been to malaria endemic areas. Specific symptoms would be a fever, or history of a fever, as well as muscle pain, fatigue, or a flu like illness. Absence of fever does not rule out malaria, and nor does adherence to anti-malarial regimes. Worryingly, cases of airport malaria have also been reported – mosquitoes travel on an airplane to the airport, where they bite you. Consider malaria even up to a year post travel, as infection with certain species have long incubation periods. It is also important to consider malaria in patients who have been previously diagnosed and have received prior treatment elsewhere as treatment failure can occur.

Incubation period: 7-30 days, usually shorter incubation periods for P.falciparum infections and longer for P.vivax and P.ovale infections (up to 1 year).


A malaria thick and thin film should be requested along with a full blood count, U&E, LFT, CRP, coagulation screen, blood cultures, +/- capillary blood glucose and venous lactate if high clinical suspicion or the patient is unwell. Malaria rapid diagnostic tests (RDTs) can be a useful additional test, but a blood film is still required for diagnosis and indication of severity. Malaria is usually ruled out by 2-3 normal blood tests. Malaria antibody testing is not useful.

Malaria films: What you need to know

1. The species of malaria is important and will be identified on the malaria film.
2. Be aware of the parasitaemia, or parasite count – this will be given to you with the malaria film result. A parasitaemia of over 2% is a medical emergency as patients with a higher parasite count can deteriorate rapidly and may require ICU management.
3. The stage of the parasite is also important. Patients with P. falciparum infections who have schizonts identified on their malaria film need close monitoring and prompt treatment, as these will rupture, causing an increase in parasitaemia and clinical deterioration.


Malaria is not directly transmissible from person to person, so there is no need to isolate unless the patient also has other symptoms which would warrant isolation.


A full systems examination is required with focus on the central nervous system (cerebral malaria may present), respiratory examination and assessment for signs of jaundice and acute kidney injury. Remember to check for hypoglycaemia.


– Treat sepsis, if present. Remember bacterial co-infection is common.
– Treat malaria: Whether malaria is uncomplicated or severe should guide whether treatment is IV or oral, along with local protocols. Full UK malaria treatment guidelines are published by the British Infection Association. Start effective anti-malarial drug therapy immediately once a diagnosis has been made. IV artesunate is the drug of choice in ALL patients with severe malaria. If IV artesunate is not immediately available, IV quinine should be used only until artesunate can be obtained. Contact the Hospital Hospital for Tropical Diseases, London (020 3456 7890) or the Tropical and Infectious Disease Unit, Royal Liverpool University Hospital (0151 706 2000) if finding it difficult to source artesunate.


Malaria in Pregnancy: Swift obstetric opinion should be sought in any pregnant person suffering from malaria. Parenteral antimalarials should be given to pregnant women with severe malaria in full doses without delay as per your trust guidelines. There is little published evidence of the use or safety of intravenous artesunate in pregnant women, particularly in the first trimester. As per UK guidelines, however, on balance of risk, artesunate is preferred to quinine on the basis of its likely higher effectiveness in reducing mortality. Intravenous quinine (with clindamycin) is an alternative. Advice can be sought from the Hospital for Tropical Diseases registrar at the number at the foot of the article for complicated cases.

Typhoid and Paratyphoid Fever (Enteric Fever)
Quick facts:

Caused by the bacteria Salmonella typhi and Salmonella paratyphi. Enteric fever is acquired through the ingestion of food and water contaminated by the faeces of an infected person. Poor hand hygiene and sanitation are risk factors.

When should it be considered: Consider as a differential for all febrile returning travellers, particularly those returning from South Asia, reporting a history of a sustained fever, stomach pain, diarrhoea and/or constipation, weakness, headaches. Presentation is mostly a non-specific febrile illness, and patients may not always present with GI symptoms.

Incubation period:

6-30 days


Diagnosis through blood and stool cultures, but also on clinical suspicion. FBC, U&E, LFT, CRP should be requested.Examination: patients may have hepatosplenomegaly, abdominal pain, red, cutaneous macules (rose spots) and occasionally delirium. A relative bradycardia may be seen, where a fever is accompanied by a comparatively low heart rate.


Isolate in a side room, and use standard precautions (gloves and apron) if high clinical suspicion of typhoid, or if presenting symptoms require isolation, eg. diarrhoea.


If high index of suspicion for enteric fever, consider empiric treatment in accordance with local antimicrobial guidelines – we would usually use azithromycin as fluoroquinolone resistance rates can be high, particularly if the patient has returned from the Indian subcontinent. Ceftriaxone can be used in severe or complicated cases. If confirmed typhoid, treat with antibiotics – typhoid is resistant to some antibiotics, so check the sensitivities.
Warning signs typhoid is a bacterial infection, and late presentation (ie. presenting after three weeks of illness) can lead to complications and poorer outcomes.

Dengue Fever

Quick facts: Viral illness spread by the bite of infected Aedes mosquitoes, which bite during the day, in tropical and sub-tropical areas.
When should it be considered: In the recently returned traveller from an at-risk country, with a history of fever, headaches, pain behind the eyes, and/or a rash. Myalgia and arthralgia are frequent and can be severe (sometimes referred to as breakbone fever).

Incubation period:

3-14 days


FBC, CRP, U&E, LFT, clotting check the platelet count and haematocrit, as the values of these will guide your decision on whether or not to admit the patient. A rising haematocrit and significant thrombocytopenia can be a feature of Severe Dengue. Dengue fever is largely diagnosed on clinical presentation and suspicion. PCR and serology can be helpful in the diagnosis of dengue.


Treatment is supportive only, with IV fluids if required, paracetamol and monitoring via regular blood tests being the key management. NSAIDs should be avoided and it is important to be vigilant of warning signs.


Dengue fever is not directly transmissible from person to person, so there is no need to isolate unless the patient also has other symptoms which would warrant isolation.

Warning signs:

Dengue fever is in most cases, a non-severe viral illness. However, on occasion, patients can develop Severe Dengue be vigilant of signs or complaints of abdominal pain or bleeding, fluid accumulation, clotting abnormalities,rising haematocrit with low platelets, vomiting, rapid breathing, lethargy, restlessness or agitation. These patients will require extremely close monitoring and may require critical care support.
WHO guidance on dengue can be found here.

Middle East Respiratory Syndrome (MERS-CoV)

See Public Health England for individual country risk and management advice.

Quick facts:

A severe respiratory viral illness caused by the Middle East Respiratory syndrome Coronavirus (MERS-CoV) that can be spread through respiratory secretions and/or camel contact. Spread within healthcare facilities can also occur. MERS-CoV has a mortality rate of approximately 35%. For diagnosis, requires transmission risk factor, fever and abnormal x-ray not explained by another presentation.

When it should be considered: In all returning travellers from at risk countries, presenting with an acute respiratory illness, fever, cough, shortness of breath, +/- camel contact, who report drinking or eating camel products, in particular unpasteurised camel milk. Consider especially in returned pilgrims from Mecca, Hajj and Umra. It is also important to consider MERS in contacts of known or suspected cases of MERS. Follow the case definition and investigation algorithm published on the PHE website above. Remember to ask about the camels!

**Discuss with local virology services at the earliest opportunity until MERS-CoV risk has been downgraded.**

Incubation period:

2-14 days


Bloods and chest x-ray.
Virology for MERS CoV- this is done at the public health laboratory, so before you send it (not in any chutes), you need to have liased with your local virology or microbiology service. If this result is negative, you can be confident the patient doesn’t have MERS.


supportive, with excellent isolation care.
Isolation: respiratory isolation with PPE, including a long sleeve gown, eye protection, gloves and an FFP3 respirator for suspected, possible, presumptive or confirmed cases.

Amoebiasis (Amoebic dysentery)
Quick facts: Caused by the amoeba Entamoeba histolytica, spread from person to person via faeco-oral routes, or via contaminated water. Found worldwide, in tropical areas and areas with poor sanitation. Infections with E. histolytica can be asymptomatic, but life-threatening dysentery and liver abscesses can also occur.

When it should be considered: Returning travellers with a history of fever, stomach cramps and bloody, diarrhoea. Often, patients may report that these symptoms have been going on for a while. Some patients may present with features of a severe, inflammatory colitis, and anaemia due to acute blood loss. Exclusion of a surgical cause such as GI perforation may be necessary.

Incubation period:

2-4 weeks

Investigations: Urgent bloods including FBC and clotting, hot stool (a stool sample which must be sent to the laboratory within an hour of production to examine for amoebic trophozoites) and stool for microscopy for ova, cysts and parasites (OCP).


Prompt treatment with Tinidazole or Metronidazole, and with Paromomycin for cyst clearance is crucial, especially if amoebic trophozoites are seen on stool microscopy (Please contact, or encourage pharmacy to contact, The Hospital for Tropical Diseases to discuss sourcing Tinidazole or Paromomycin if these medicines are difficult to obtain locally).

Isolation: Isolating the patient is also key, particularly if the cause of diarrhoea is unclear. Pop on your pinny and gloves too, and remember to wash your hands!

Key messages

This is a very brief overview of five tropical diseases, the timely management of which can improve outcomes for the patient. They are diagnoses that can be considered in returned tropical travellers, depending on examination, symptoms, exposures and country of travel. This information should not supersede clinical judgement or be used as a prescriptive tool.

Remember, recent travel can sometimes be a red herring – the reason for the fever may not be tropical or related to travel at all.

Telephone advice regarding diagnosis and management of tropical infections can be provided by the Hospital for Tropical Diseases specialty registrar on 07908 250924. The emergency walk-in centre at the Hospital for Tropical Diseases is open from Monday-Friday, 9am-4pm, for symptomatic travellers (who are not acutely unwell) who have returned from the tropics only with the travel being within the last 6 months. See or call us on 0203 44 75957 to discuss suitability. We also offer specialist pre – travel advice for complex and routine travellers please contact or 0203 44 75999.

Follow The Hospital for Tropical Diseases at @htropdis.

References and further reading

  1. NaTHNac Travel Health Pro
  2. Centre for Disease Control (CDC) Yellow Book (2018) CDC Division of Parasitic Diseases and Malaria
  3. Public Health England
  4. The Hospital for Tropical Diseases
  5. Office of National Statistics (2017)
  6. Fink, D, Wani, R, Johnston, V Fever in the returning traveller, BMJ 2018; 360. (Published 25 January 2018)


  1. Mohana Ashokkumar says:

    very useful information in a short note

  2. Mohana Ashokkumar says:

    very useful information

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