Yellow fever

Yellow fever is a viral infectious disease transmitted by mosquitoes found in tropical Africa and Central and South America.


Yellow fever is a viral infectious disease transmitted by mosquitoes found in tropical Africa and Central and South America. An asymptomatic or mild progression with flu-like symptoms is normal. However, a second disease phase with a high mortality rate can occur, during which patients suffer from severe bleeding. Vaccination is recommended and is sometimes compulsory for travellers to the tropics.


  • Incubation period: 3-6 days
Mild progression

Asymptomatic or mild progression is normal

Severe progression

Second, toxic phase after a short period of recovery (approx. 15% of infections)

  • Fever rises again and organ damage occurs
  • So-called haemorrhagic fever: coagulation disorders
    • Severe internal bleeding
    • Nosebleeds
    • Vomiting of blood (sometimes black)
    • Blood in stools
    • Bleeding from skin and mucous membranes
  • Liver damage: yellow skin
  • Death is caused by multiple organ failure (in approx. 20% of cases)

Causes and treatment


  • Pathogen:
    • Yellow fever virus (family of flaviviruses: Zika, dengue fever, TBE virus)
    • Where found: tropics, so-called “yellow fever belt” (Africa, Central and South America)
  • Transmission
    • Bite by infected tiger mosquito (yellow fever mosquito)

Further treatment by your doctor / in hospital

Possible tests
  • Blood test (search for pathogen)
Possible therapies
  • No way to treat the causes
  • Treatment of symptoms
    • Painkillers and fever-reducing medication
  • Hospitalisation in intensive care unit may be needed

What can I do myself?

  • Travel preparations
  • Yellow fever vaccination
    • Approved vaccination centres according to FOPH list
    • At least 10 days before departure
    • Vaccination is compulsory for entry to some countries
    • Vaccine provides lifelong protection
  • Mosquito protection
    • Light-coloured, long-sleeved clothing
    • Mosquito net
    • Suitable and tested insect repellent
    • Don't go outside at dusk or at night

When to see a doctor?

Further information

Federal Office of Public Health, FOPH (Bundesamt für Gesundheit, BAG)

Ostschweizer Infostelle für Reisemedizin (Eastern Switzerland Information Centre for Travel Medicine)

Swiss Tropical and Public Health Institute (Schweizerisches Tropen- und Public Health-Institut)

FDFA (travel links)


yellow fever, YF, yellow plague, yellow jack, bronze john, Siamese illness

Exclusion of liability

CSS offers no guarantee for the accuracy and completeness of the information. The information published is no substitute for professional advice from a doctor or pharmacist.