Yellow fever is a virus spread by infected mosquitoes, and is found in most of sub-Saharan Africa, most of South America, parts of Central America and parts of the Caribbean. The mosquitoes that spread the Yellow fever infection are typically found in towns and rural areas, and mainly bite during the day. Fortunately, yellow fever can’t be transmitted between close contact with those that have already been infected. 

Yellow fever doesn’t always cause symptoms and the severity of symptoms differs significantly between people. While many people who experience symptoms find that clear within a few days, some suffer serious complications such as organ damage and organ failure. If you’re travelling to a risk area it is important that you protect yourself by getting a yellow fever vaccination.

Common symptoms of yellow fever

The first symptoms of yellow fever usually include:

  • High temperature / fever or chills
  • Headache
  • Nausea 
  • Vomiting
  • Feeling tired, dizzy, or unwell
  • Lower back pain
  • Sensitivity to light

It’s important that a doctor assesses your condition if you experience these symptoms during or after a stay in an area with a risk of yellow fever.

These first symptoms are followed by a period of remission; you may then either recover or progress to fatal illness. The return of symptoms is marked by the following:

  • Fever
  • Vomiting 
  • Abdominal pain
  • Kidney failure
  • Irregular heartbeat
  • Seizures, coma
  • Hemorrhaging/Bleeding

How soon after infection do you get symptoms?

Those infected will usually experience the first symptoms 3 - 6 days after contracting yellow fever. Within this time, the virus multiplies in your body. However, not everyone experiences symptoms. In some, the immune system effectively fights the virus so they do not get ill.

Most people who catch yellow fever only experience mild symptoms or none at all. However, those who do develop symptoms are at risk of complications.

Stages of yellow fever

The symptoms of yellow fever typically come and go as the disease progresses in stages.

Stage one - The first symptoms tend to be headache, muscle aches and stomach problems such as feeling and being sick. These symptoms are not very specific and they can be caused by many other diseases, which makes yellow fever difficult to spot. People infected with yellow fever may also experience jaundice (ie the skin and the whites of the eyes appear yellow). This stage usually lasts 3-4 days.

Stage two - After the first symptoms subside, infected people tend to feel better. This is called remission. While some fully recover at this point, others only cease to experience symptoms for 24 hours, before entering a third stage of yellow fever.

Stage three - People infected with yellow fever who experience further symptoms after the stage of remission will experience symptoms caused by the virus causing damage to the inner organs. This can cause a range of symptoms depending on the organs affected - this could be the heart, liver or kidneys. Stage three affects around 15% of those who experienced symptoms.

Fever, seizures, coma and bleeding disorders can all be signs of damage to the inner organs. Other possible symptoms at this stage can include irregular heartbeat and delirium. The symptoms from stage one may return.

Risks and complications

Although most people who catch yellow fever do not suffer life changing complications, there is a risk of organ failure, which can lead to permanent disabilities and death. This applies to the 15% of those infected with yellow fever whose symptoms do not resolve but return after the remission stage. If the disease progresses to cause damage to the organs, urgent medical help is required to prevent serious complications.

Can yellow fever kill you?

Yellow fever can be lethal if left untreated, especially if symptoms of organ failure are not recognised and treated in time.

If you are in a yellow fever risk area or have recently visited region with a risk of yellow fever and encounter yellow fever symptoms you must seek medical assistance immediately.