Yellow fever

About yellow fever

Yellow fever is spread by a bite from an infected mosquito. You're at risk of being infected with yellow fever if you live in, or travel to, places where there are infected mosquitoes. This includes tropical areas of Central and central West Africa, South America, Panama and Trinidad.

Every year around 200,000 people worldwide are infected with yellow fever and around one in seven people who go to hospital with yellow fever die. It's very rare for people from the UK who travel to these areas to become infected.

Symptoms of yellow fever

The symptoms of yellow fever usually appear three to six days after you have been bitten by an infected mosquito. This time is called the incubation period. The symptoms usually come on suddenly and can include:

  • fever
  • shivers
  • headache
  • feeling sick and being sick
  • loss of appetite
  • muscle pain and aches
  • backache

These symptoms usually last for three to four days. After this, you should start to recover and your symptoms should gradually disappear.

However, within a day of feeling better, some people can relapse and become more seriously ill. The symptoms of this second phase of infection can include:

  • high fever
  • yellowing of your skin and the whites of your eyes (jaundice) - this is how yellow fever gets its name
  • kidney failure - you may not be able to pass urine
  • abdominal (tummy) pain and being sick
  • blood in your vomit or faeces (stools)
  • bleeding from your mouth, nose or eyes

If you do relapse, yellow fever can be life-threatening.

Causes of yellow fever

You can become infected with the yellow fever virus if you’re bitten by an infected mosquito. Mosquitoes pick up the virus from other people and monkeys that are already infected with the virus. They then pass the virus on to the next person they bite.

Because the infection is spread by certain species of biting mosquitoes, it can only be spread in countries where these mosquitoes live. The mosquitoes live and breed around houses or in the jungle.

Diagnosis of yellow fever

If you develop the symptoms of yellow fever and you are in or have recently visited an affected area, it's important to see a doctor straightaway. If you're abroad, you should go to a local hospital or see a doctor. If you're in the UK, you should see your GP. It’s important to tell your GP that you have been abroad in a place where there is yellow fever.

Your doctor will ask about your symptoms and examine you. Your GP will also do a blood test. This blood test will confirm whether or not you have yellow fever.

Yellow fever can be difficult to recognise, especially in the first few days. It can be easily confused with other diseases such as malaria, typhoid and dengue fever. It's important to get the right diagnosis so that you can get the best care.

Yellow fever is a notifiable disease. This means that if your GP thinks you have yellow fever, by law he or she has to report it.

Treatment of yellow fever

There is no specific treatment for yellow fever. However, the symptoms of yellow fever can be treated. This will help you to feel more comfortable. If you become seriously ill with yellow fever, then you may need intensive care to help you recover.

If you need pain relief, you can take over-the-counter painkillers such as paracetamol or ibuprofen. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.

You should rest and drink enough fluids to prevent you from becoming dehydrated - usually six to eight glasses a day.

If you recover from yellow fever, you will be immune to the virus for the rest of your life.

Prevention of yellow fever

You can prevent yellow fever by being vaccinated against the disease and by protecting yourself from mosquito bites.

Vaccination

An effective vaccine is available for yellow fever. You need to have the vaccine at least 10 days before you travel to a country where there is yellow fever. This gives your body time to build up immunity to the disease. The vaccine can be given at the same time as any other vaccinations you may need. Some people have a fever after having the vaccine, which may be accompanied by some flu-like symptoms. However, these symptoms only last for a few days after the vaccination.

The vaccine is given as a single injection. Almost everyone who has the vaccine will become immune to yellow fever. The vaccine will give you protection for at least 10 years, possibly the rest of your life. However, if after 10 years you're still travelling or living in an area where there is yellow fever, you should have a booster vaccination.

You can only get vaccinated at a yellow fever vaccination centre. To find your nearest vaccination centre go to the National Travel Health Network and Centre (NaTHNaC) website (see further information).

You will be given an International Certificate of Vaccination or Prophylaxis (ICVP) which becomes valid 10 days after your injection and will need updating every 10 years. You may be asked to show your ICVP before you're allowed to enter certain countries and when you travel from a country with yellow fever to one without it. This is to prevent yellow fever from spreading.

Protection from mosquito bites

Most mosquitoes are active between dusk and dawn, but the mosquitoes that spread the yellow fever virus are active during the daytime. This means that you may get bitten during the day. There are many things that you can do to protect yourself from mosquitoes and prevent getting bitten. Some of the main ones are listed below.

  • Don't go into areas where there are a lot of mosquitoes, especially at times when they are active.
  • Use an insect repellent that contains DEET and put it on any exposed areas of skin. Reapply it every few hours, particularly in hot and humid places where you’re sweating or after you have been swimming. Make sure you use insect repellent over any sunscreen. Don't spray it directly into your face, especially your lips or eyes.
  • Wear loose fitting clothes (mosquitoes can bite through tight clothes).

Even if you have had the yellow fever vaccination, it's important to protect yourself against mosquito bites.

Are there any side-effects to the yellow fever vaccine?

Answer

The yellow fever vaccination is an effective way to protect you against the virus. However, as with all medicines, there is the possibility of side-effects. These are usually mild and last for a short time.

Explanation

Yellow fever vaccine has been in use for about 60 years and, in that time, more than 300 million people have been vaccinated.

Side-effects are the unwanted but mostly temporary effects you may get after having the vaccination. Between one and three in 10 people having the vaccination will have some side-effects. These may include:

  • headaches
  • slight fever
  • aching muscles
  • soreness in the area you had the injection

If you're affected, these side-effects will start one to five days after you have had your injection and can last for up to two weeks. It's rare to have a severe reaction to the vaccine. However, a small number of people do have more serious side-effects. The main ones are listed below.

  • Hypersensitivity reaction. If you're sensitive to ingredients in the vaccine you may develop a rash, hives (urticaria), wheezing or have difficulty breathing. This type of reaction is usually due to an egg protein in the vaccine.
  • Inflammation of the brain (encephalitis). This type of reaction is extremely rare. It usually happens in babies under six months old, which is why the vaccine isn't recommended for this age group.
  • Viscerotropic disease. This is similar to having the severe symptoms of yellow fever. It can cause a fever and affect all of the organs of your body. It can be life-threatening, but is very rare. This usually affects people who have a weakened immune system, such as those who have HIV/AIDS, or those who are taking medicines that suppress the immune system.

It's important to remember that the benefits of having the vaccine far outweigh the risk of side-effects from the vaccine. If you have any questions or concerns about yellow fever or yellow fever vaccination, talk to your GP or your local vaccination centre.

Is there anyone who shouldn't have the yellow fever vaccine?

Answer

Almost everyone is able to be vaccinated against yellow fever. However, there are some times when the vaccine shouldn't be given.

Explanation

Yellow fever vaccination is suitable for almost everyone. However, you may not be able to have the vaccination if:

  • you're pregnant
  • you have had an allergic reaction to the yellow fever vaccination or any of the ingredients in it before
  • you're allergic to eggs
  • you have a condition that affects your thymus gland (such as myasthenia gravis)
  • your immune system isn’t working properly because of a health condition (for example, advanced HIV/AIDS) or a treatment (for example, immunosuppressant medicines)

Babies under the age of six months also shouldn't have the vaccination. This is because of the risk of encephalitis.

If you can't have the vaccine, but you have to travel in areas where there is yellow fever, you should protect yourself against mosquito bites.

If you can't have the vaccine and will be travelling in areas where an International Certificate of Vaccination or Prophylaxis (ICVP) is required, you may be able to get a letter of exemption.

If you have any further questions or concerns about yellow fever or yellow fever vaccination, talk to your GP or local vaccination centre.

Could yellow fever spread to the UK?

Answer

No, it isn't possible for yellow fever to spread to the UK. This is because the mosquitoes that spread the virus don't live in the UK.

Explanation

Yellow fever is widespread in parts of Africa and South America. It's spread by certain types of mosquito. When a female mosquito bites an infected person or monkey, it takes in some of their blood. When the mosquito then bites someone else, the infection is spread to that person.

Although there are mosquitoes in the UK, they aren't the type that carry yellow fever. None of the types of mosquito in the UK spread any kind of infection. Therefore, it's not possible that yellow fever will spread to the UK.

If you have any questions or concerns about yellow fever, talk to your GP or your local vaccination centre.