Fever in a returned traveller

History

Pretravel
- Vaccinations
- Prophylaxis, e.g. malaria
- Vector protection, including bed nets and mosquito spray
Travel
- Make explicit timeline of locations visited, for how long
- Assess activities and exposures in each location
- Food and water
- Recreational water
- Animals
- Vectors
- Sex
Combine timeline of exposures with incubation periods to rule out diseases
- Dengue: 3-5 days
- Malaria: 7-21 days
- Hepatitis A: 6 days to 6 weeks
- Hepatitis B: 1-6 months
- Typhoid: 7-21 days
- Non-typhoidal Salmonella: 3-7 days

Differential Diagnosis

Most common conditions

1. Malaria (20-30%) 2. Acute diarrhea or gastroenteritis (10-20%) 3. Respiratory infections (10-15%) 4. Dengue (5%) 5. Enteric fever (2-7%) 6. Skin and soft tissue infections (2-11%) 7. Rickettsioses, including African tick bite fever and Mediterranean spotted fever (3%) 8. Urinary tract infections and sexually-transmitted infections (2-3%) 9. Viral hepatitis (3%) 10. Mononucleosis or viral syndrome (4-25%)

Most common by location of travel

Sub-Saharan Africa: malaria, respiratory infections, diarrhea, skin and soft tissue infections
Southeast Asia: dengue, respiratory infections, diarrhea, malaria
South Central Asia: enteric fever, dengue, malaria, diarrhea
South America: diarrhea, respiratory infections, dengue, malaria
Central America and Caribbean: diarrhea, respiratory infections, dengue, malaria

Life-threatening infections

Disease	Incubation	Distribution	Exposures	Diagnosis
Viruses
Avian influenza	2-8 days	East and Southeast Asia	poultry	PCR
MERS-CoV	2-14 days	Arabian peninsula	infected humans or camels	PCR
Ebola, Lassa fever, or Marburg hemorrhagic fever	up to 22 days	Africa	infected humans and animals	PCR
Crimean-Congo hemorrhagic fever	1-9 days (tick) or 3-13 days (contact)	southern Europe, Middle East, Africa, northwestern China	Ixodes ticks or infected humans or animals	PCR
Yellow fever	3-8 days	South America and Africa	Aedes mosquitoes	PCR or IgM
Japanese encephalitis	5-15 days	Asia and western Pacific	Culex mosquitoes	IgM
Rift Valley fever	2-6 days	Africa and the Arabian peninsula	mosquitoes, or blood from infected animals	PCR or IgM
Rabies	20 to 60 days (usually 4 weeks)	worldwide	animal bite	saliva PCR; serum/CSF RFFIT; skin biopsy PCR or RFFIT
Bacteria
Anthrax	1 day (cutaneous) to 1-7 days (pulmonary)	Africa and Asia	infected animals or animal products	bacterial culture or PCR
Enteric fever	6-30 days	South and Southeast Asia	fecal-oral transmission	bacterial culture
Epidemic typhus	7-14 days	Central Africa, Asia, North and South America	Human body lice, flying squirrel parasites, possibly ticks	IgM/IgG and PCR
Leptospirosis	2-29 days	worldwide but particularly South and Southeast Asia and South America	urine of infected animals	IgM/IgG and PCR
Louseborne relapsing fever	4-14 days	Ethiopia, Eritrea, and Sudan	Human body lice	blood film examination, IgM/IgG, or PCR
Melioidosis	1-21 days (but up to years)	South and Southeast Asia, northern Australia, and case reports from Africa and South America	contaminated soil or surface water	bacterial culture
Endemic typhus	7-14 days	worldwide but particularly Southeast Asia	rodent fleas	IgM/IgG or PCR
Oroya fever or Carrion disease	10 days to 7 months	South America, particularly Peru	Sandflies	bacterial culture
Scrub typhus	6-20 days	Asia and northern Australia	chiggers	IgM/IgG or PCR
Rickettsial spotted fever	2-14 days	worldwide	mostly ticks	IgM/IgG or PCR
Plague	2-6 days (bubonic) or 1-3 days (pneumonic)	remote Africa, Asia, and South America	rodent fleas	bacterial culture
Protozoa
East African sleeping sickness	7-21 days	eastern and southern Africa	tsetse flies	blood film examination, lymph aspirate exam, or chancre biopsy
Falciparum malaria	7-30 days, or longer	African, Asia, South America	Anopheles mosquitoes	thick-and-thin blood film examination or rapid antigen test
Knowlesi malaria	10-14 days	Southeast Asia, particularly Borneo	Anopheles mosquitoes	thick-and-thin blood film examination

Investigations

First-line
- CBC
- Liver enzymes and function, for viral hepatitides
- Electrolytes, urea, and creatinine
- Urinalysis, for proteinuria that would suggest Leptospirosis
- Blood cultures x2, for enteric/typhoid fever
- Thick and thin smears x3 over 3 days, for malaria
Based on history and lab results
- Urine culture
- Stool culture and O&P
- Hepatitis serologies
- Serology for zika, chikungunya, and dengue viruses, with repeat in 14 days if negative
- C. difficile toxin
- NP swab