Yellow fever is a serious viral infection that's spread by certain types of mosquito. It’s mainly found in sub-Saharan Africa, South America and parts of the Caribbean.
The condition can be prevented with a vaccination and is a very rare cause of illness in travellers.
Six travellers from Europe and North America have died from yellow fever since 1996. None of them were vaccinated.
If you're planning to visit places where yellow fever infection is found, you should seek travel health advice about the vaccination available. A map and list of countries where yellow fever is found is available Fit for Travel website.
How yellow fever is spread
The virus that causes yellow fever is passed to humans through the bites of infected mosquitoes. The mosquitoes that spread the infection are usually active and bite during daylight hours, from dusk until dawn, and are found in both urban and rural areas.
Yellow fever can’t be passed directly from person to person through close contact.
Yellow fever symptoms
The symptoms of yellow fever occur in two stages. The initial symptoms develop three to six days after infection, and can include:
a high temperature (fever)
nausea or vomiting
muscle pain, including backache
loss of appetite
This stage will usually pass after three to four days and most people will make a full recovery.
However, around 15% of people go on to develop more serious problems, including jaundice (yellowing of the skin and whites of the eyes), kidney failure and bleeding from the mouth, nose, eyes or stomach (causing blood in your vomit and stools).
Up to half of those who experience these symptoms will die.
When to seek medical advice
You should see a doctor as soon as possible if you develop symptoms of yellow fever and are currently travelling in an area where the virus is found, or have recently returned from one of these areas.
To help determine whether you have yellow fever, the doctor will want to know exactly where you have been travelling and what symptoms you have. A blood test will be needed to confirm the diagnosis.
Treating yellow fever
There is no specific treatment for yellow fever, but the symptoms can be treated while your body fights off the virus.
Headache, high temperature and muscle pain can be treated using painkillers such as paracetamol or ibuprofen. You should also drink plenty of fluids to avoid dehydration.
If your symptoms are particularly severe, you may be admitted to hospital so that your condition can be monitored and you can receive supportive care.
Yellow fever vaccination
The vaccination against yellow fever should be given at least 10 days before travelling to an area where the infection is found, to allow your body to develop protection against the virus that causes the infection.
Some countries require a proof of vaccination certificate before they will let you enter the country. This will only become valid 10 days after you are vaccinated.
The yellow fever vaccination is given as a single injection and it offers protection to over 95% of those who have it.
The protection offered by the vaccine may be life-long, but vaccination certificates are currently only valid for 10 years, and a booster dose may sometimes be needed after this time if you are planning another visit to an area where yellow fever is found.
Even if you have been vaccinated, it’s still a good idea to take steps to prevent mosquito bites while you’re travelling – for example, by using mosquito nets, wearing loose, long-sleeved clothing, and applying insect repellent containing 50% DEET to exposed skin.
Yellow fever vaccination
If you are planning to travel to an area where you may be at risk of yellow fever, make sure you are vaccinated before making your trip.
About the yellow fever vaccine
The yellow fever vaccine is given as a single injection.
You should be vaccinated at least 10 days before you travel, as this will allow enough time for your body to develop protection against the yellow fever infection. Your proof of vaccination certificate (see below) will only become valid after this time.
The vaccination provides protection for 95-100% of those who have it. This protection lasts at least 10 years and may even be life-long.
Booster doses of the yellow fever vaccine used to be recommended every 10 years for everyone planning another visit to an area where the infection is found.
However, experts working for the World Health Organization (WHO) have recently suggested that booster does may not be necessary, and from June 2016 vaccination certificates will be valid for life (they currently expire after 10 years).
For the time being, booster doses are only recommended if you are travelling to an at-risk area, you were last vaccinated more than 10 years ago, and:
you need a valid certificate of vaccination, or
you were originally vaccinated when you were pregnant, were less than two years old, or had a weakened immune system (for example, due to an HIV infection or preparation for a bone marrow transplant)
Your local designated yellow fever vaccination centre (see below) should be able to advise you if you’re not sure whether you need to have a booster vaccination before travelling.
Where can I be vaccinated?
Yellow fever vaccinations can only be given at designated centres. For a centre to become a designated yellow fever vaccination centre, it must register with the appropriate authority. In the UK, this is either:
the National Travel Health Network and Centre (NaTHNaC)
Health Protection Scotland (HPS)
Find your nearest yellow fever vaccination centre.
The vaccination is not usually available for free so you will normally have to pay for it. On average, a single vaccination costs around £60.
Certificate of vaccination
Under regulations set out by the WHO, anyone travelling to a country or area where there is a risk of picking up or spreading the virus that causes yellow fever must have an International Certificate of Vaccination or Prophylaxis (ICVP).
You can find a list of all the countries that require you to have an ICVP (PDF, 436kb) on the WHO website. You can also search the destination information Fit for Travel website to find out whether the places you are visiting require an ICVP. An ICVP is not required for entry into the UK.
If you lose your certificate, you may be able to get another one reissued as long as you have details of the vaccination batch number and the date you had the vaccination.
Exemption from vaccination
Some people may be advised not to have the yellow fever vaccine because of the risk of potential side effects or complications.
babies under nine months of age – babies who are six to nine months old may sometimes be vaccinated, but only if the risk of getting yellow fever during travel is unavoidable
pregnant and breastfeeding women
people over 60 years of age
people with weakened immune systems – such as people with HIV and those receiving radiotherapy
people who are severely allergic to any of the ingredients in the vaccine – including people with allergies to eggs, as the vaccine contains small amounts of egg
If the yellow fever vaccination is not advised, you may be issued with an exemption letter, which may be accepted by immigration authorities.
If you have not been vaccinated, you will need to take particular care to prevent mosquito bites while travelling – for example, by using insect repellent and mosquito nets.
Side effects of the vaccine
Up to one in every three people experience mild side effects after having the yellow fever vaccine, such as:
a mild fever
soreness at the injection site
Reactions at the injection site usually occur one to five days after being vaccinated. The other side effects may last for up to two weeks.
Rare side effects
There are also some very rare, but potentially serious, side effects that can occur, including:
an allergic reaction to the vaccine; this occurs around once for every 130,000 doses given
yellow fever vaccine-associated neurological disease (YEL-AND) – a condition affecting the brain and nervous system, causing symptoms such as confusion and problems with movement and co-ordination; this occurs around once for every 250,000 doses given
yellow fever vaccine-associated viscerotropic disease (YEL-AVD) – a condition affecting your internal organs, which can lead to organ failure in some cases; this occurs around once for every 330,000 doses given
The risk of YEL-AND and YEL-AVD is higher in young babies and elderly people, which is why vaccination is not always recommended for these groups.