The time between being infected with yellow fever and the start of symptoms is usually three to six days. This is known as the incubation period.
The symptoms of yellow fever usually happen in two stages. The initial symptoms (doctors sometimes refer to the acute first stage) can include:
- a high temperature (fever) of 38ºC (100.4ºF) or above
- headache
- chills (shivers)
- nausea and vomiting
- aching muscles
- backache
- loss of appetite
Symptoms usually improve after three or four days.
Second stage
After the initial symptoms of yellow fever, about 15% of people go on to develop more severe symptoms. This is sometimes referred to by doctors as the toxic second phase. The symptoms can include:
- a recurrent high temperature
- abdominal pain
- vomiting
- a yellow tinge to the skin and whites of the eyes that's caused by liver damage (jaundice)
- kidney failure
- bleeding from the mouth, nose, eyes or stomach – you may have blood in your vomit or in your stools (faeces)
Half of the people who have the second toxic phase of symptoms die within 10-14 days. The other half recover with no major organ damage and are immune from the disease for life.
Overall, this means that around 7 or 8 people out of every 100 who develop yellow fever will die from it.
