A diagnosis of yellow fever is usually made based on your symptoms and by carrying out a blood test.
It can sometimes be difficult to diagnose yellow fever based on the symptoms alone because the symptoms are often similar to a number of other conditions, including:
- malaria – a tropical disease that's spread by night-biting mosquitoes
- typhoid fever – a serious and potentially fatal bacterial infection
- viral hepatitis – inflammation of the liver that's caused by a virus
- leptospirosis – a bacterial infection that's spread to humans from some animals, such as rats
- Dengue fever – an infectious disease that's also transmitted by the Aedes aegypti mosquito
Blood test
If you have yellow fever, a blood test will be able to detect the presence of special proteins called antibodies, which are produced by the body to fight the virus.
The blood test may also show a reduction in the number of infection-fighting white blood cells (leukopenia). This can happen because the yellow fever virus affects your bone marrow, which is the spongy material that's found in the hollow centres of some bones and produces blood cells.
