The yellow fever virus is found in tropical and subtropical areas of Africa and South America. The virus is spread to people by the bite of an infected mosquito. Yellow fever is a very rare cause of illness in U.S. travelers. Illness ranges from a fever with aches and pains to severe liver disease with bleeding and yellowing skin (jaundice). Yellow fever infection is diagnosed based on laboratory testing, a person’s symptoms, and travel history. There is no medicine to treat or cure infection. To prevent getting sick from yellow fever, use insect repellent, wear long-sleeved shirts and long pants, and get vaccinated.

What is yellow fever?

Yellow fever is a disease caused by a virus that is spread to people by the bite of an infected mosquito.

Where does yellow fever virus occur?

Yellow fever virus is found in tropical and subtropical areas in South America and Africa. Yellow fever virus is a very rare cause of illness in U.S. travelers to these areas.

How soon do people get sick after being bitten by an infected mosquito?

The incubation period (time from infection to illness) is usually 3-6 days.

What are the symptoms of yellow fever?

Initial symptoms of yellow fever include sudden onset of fever, chills, severe headache, back pain, general body aches, nausea and vomiting, fatigue, and weakness. Most people improve after these initial symptoms. However, roughly 15% of people will have a brief period of hours to a day without symptoms and will then develop a more severe form of yellow fever disease. In severe cases, a person may develop high fever, jaundice (a condition that involves yellow discoloration of the skin and the whites of the eyes), bleeding (especially from the gastrointestinal tract), and eventually shock and failure of many organs. Roughly 20-50% of people who develop severe illness may die.

How is yellow fever diagnosed?

Diagnosis is usually based on blood tests that look for virus or antibodies that a person’s immune system makes against the viral infection.

What is the treatment for yellow fever?

No specific treatments have been found to help patients with yellow fever. If possible, patients with yellow fever should be hospitalized for treatment of their symptoms and closely observed by healthcare workers. Rest, fluids, and use of pain medications and fever-reducing medications may relieve symptoms of fever and aching. Certain medications should be avoided, such as aspirin or other non-steroidal anti-inflammatory drugs (such as ibuprofen and naproxen), because these may increase the risk for bleeding.

How can people reduce the chance of getting infected with yellow fever virus?

Yellow fever can be prevented by vaccination. The vaccine is a live but attenuated (less potent) strain of the virus. Travelers should also take actions to prevent mosquito bites when in areas of Africa or South America with yellow fever virus transmission.

• Use insect repellent. When you go outdoors, use an EPA-registered insect repellent such as those containing DEET, picaridin, IR3535, or oil of lemon eucalyptus on exposed skin. Even a short time outdoors can be long enough to get a mosquito bite. For details on when and how to apply repellent, see Insect Repellent Use and Safety.
• Wear proper clothing to reduce mosquito bites. When weather permits, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or another EPA-registered repellent will give extra protection. Clothing pre-treated with permethrin is commercially available. Mosquito repellents containing permethrin are not approved for application directly to skin.
• Be aware of peak mosquito hours. The peak biting times for many mosquito species is dusk to dawn. However, Aedes aegypti, one of the mosquitoes that transmits yellow fever virus, feeds during the daytime. Take extra care to use repellent and protective clothing during daytime as well as during the evening and early morning. Staying in accommodations with screened or air-conditioned rooms, particularly during peak biting times, will also reduce risk of mosquito bites.

What should I do if I think a family member might have yellow fever?

If you or anyone in your household has symptoms that are causing you concern, consult a healthcare provider promptly for proper diagnosis.

Yellow fever virus is an RNA virus that belongs to the genus Flavivirus. It is related to West Nile, St. Louis encephalitis, and Japanese encephalitis viruses. Yellow fever virus is transmitted to people primarily through the bite of infected Aedes or Haemagogus species mosquitoes. Mosquitoes acquire the virus by feeding on infected primates (human or non-human) and then can transmit the virus to other primates (human or non-human). People infected with yellow fever virus are infectious to mosquitoes (referred to as being “viremic”) shortly before the onset of fever and up to 5 days after onset.

Yellow fever virus has three transmission cycles: jungle (sylvatic), inter­mediate (savannah), and urban.

• The jungle (sylvatic) cycle involves transmission of the virus between non-human primates (e.g., monkeys) and mosquito species found in the forest canopy. The virus is transmitted by mosquitoes from monkeys to humans when humans are visiting or working in the jungle.
• In Africa, an intermediate (savannah) cycle exists that involves transmission of virus from mosquitoes to humans living or working in jungle border areas. In this cycle, the virus can be transmitted from monkey to human or from human to human via mosquitoes.
• The urban cycle involves trans­mission of the virus between humans and urban mosquitoes, primarily Aedes aegypti. The virus is usually brought to the urban setting by a viremic human who was infected in the jungle or savannah.

The majority of people infected with yellow fever virus will either not have symptoms, or have mild symptoms and completely recover.

For people who develop symptoms, the time from infection until illness is typically 3 to 6 days.

Because there is a risk of severe disease, all people who develop symptoms of yellow fever after traveling to or living in an area at risk for the virus should see their healthcare provider. Once you have been infected, you are likely to be protected from future infections.

• Most people will not have symptoms.
• Some people will develop yellow fever illness with initial symptoms including:
  • Sudden onset of fever
  • Chills
  • Severe headache
  • Back pain
  • General body aches
  • Nausea
  • Vomiting
  • Fatigue (feeling tired)
  • Weakness
  • Most people with the initial symptoms improve within one week.
  • For some people who recover, weakness and fatigue (feeling tired) might last several months.
• A few people will develop a more severe form of the disease.
  • For 1 out of 7 people who have the initial symptoms, there will be a brief remission (a time you feel better) that may last only a few hours or for a day, followed by a more severe form of the disease.
• Severe symptoms include:
  • High fever
  • Yellow skin (jaundice)
  • Bleeding
  • Shock
  • Organ failure
• Severe yellow fever disease can be deadly. If you develop any of these symptoms, see a healthcare provider immediately.
• Among those who develop severe disease, 30-60% die.

Yellow fever infection is diagnosed based on laboratory testing, a person’s symptoms, and travel history.

• There is no medicine to treat or cure infection from yellow fever.
• Rest, drink fluids, and use pain relievers and medication to reduce fever and relieve aching.
• Avoid certain medications, such as aspirin or other nonsteroidal anti-inflammatory drugs, for example ibuprofen (Advil, Motrin), or naproxen (Aleve), which may increase the risk of bleeding.
• People with severe symptoms of yellow fever infection should be hospitalized for close observation and supportive care.
• If after returning from travel you have symptoms of yellow fever (usually about a week after being bitten by an infected mosquito), protect yourself from mosquito bites for up to 5 days after symptoms begin. This will help prevent spreading yellow fever to uninfected mosquitoes that can spread the virus to other people.

A safe and effective yellow fever vaccine has been available for more than 80 years.

• A single dose provides lifelong protection for most people.
• The vaccine is a live, weakened form of the virus given as a single shot.
• Vaccine is recommended for people aged 9 months or older and who are traveling to or living in areas at risk for yellow fever virus in Africa and South America.
• Yellow fever vaccine may be required for entry into certain countries.
• Vaccination requirements and recommendations for specific countries are available on the CDC Travelers’ Health page.

Yellow fever vaccine is recommended for people who are 9 months old or older and who are traveling to or living in areas at risk for yellow fever virus in Africa and South America.

For most people, a single dose of yellow fever vaccine provides long-lasting protection and a booster dose of the vaccine is not needed. However, travelers going to areas with ongoing outbreaks may consider getting a booster dose of yellow fever vaccine if it has been 10 years or more since they were last vaccinated. Certain countries might also require a booster dose of the vaccine; visit Travelers’ Health for information on specific country requirements.

Talk to your healthcare provider to determine if you need a yellow fever vaccination or a booster shot before your trip to an area at risk for yellow fever.

Some people may have an increased risk of developing a reaction to the vaccine, but may still benefit from being vaccinated. These people, or their guardians, should talk to a healthcare provider about getting vaccinated:

• Between 6 and 8 months old
• Over 60 years old
• Pregnant
• Breastfeeding

A few people should not get the vaccine. Vaccine is not recommended for people who are:

• Allergic to a vaccine or something in the vaccine (like eggs)
• Aged 6 months or younger
• Organ transplant recipients
• Diagnosed with a malignant tumor
• Diagnosed with thymus disorder associated with abnormal immune function
• Diagnosed with a primary immunodeficiency
• Using immunosuppressive and immunomodulatory therapies
• Showing symptoms of HIV infection or CD4+ T-lymphocytes less than 200/mm (less than 15% of total lymphocytes in children aged 6 years or younger)

It is important to remember that CDC’s vaccine recommendations are a different thing than country entry requirements. Proof of yellow fever vaccine may be required for entry into certain countries.

Yellow fever vaccine has been given to many pregnant women without any apparent adverse effects on the fetus. However, since yellow fever vaccine is a live virus vaccine, it poses a theoretical risk.

Pregnant women should avoid or postpone travel to an area where there is risk of yellow fever. If travel cannot be avoided, discuss vaccination with your doctor.

While a two week delay between yellow fever vaccination and conception is probably adequate, a one month delay has been advocated as a more conservative approach.

If, for some reason, a woman is vaccinated during pregnancy, she is unlikely to have any problems from the vaccine and her baby is very likely to be born healthy.

Reactions to yellow fever vaccine are generally mild and include headaches, muscle aches, and low-grade fevers. Rarely, people develop severe, sometimes life-threatening reactions to the yellow fever vaccine, including:

• Allergic reaction, including difficulty breathing or swallowing (anaphylaxis)
• Swelling of the brain, spinal cord, or the surrounding tissues (encephalitis or meningitis)
• Guillain-Barré syndrome, an uncommon sickness of the nervous system in which a person’s own immune system damages the nerve cells, causing muscle weakness, and sometimes, paralysis.
• Internal organ dysfunction or failure

If you recently received the yellow fever vaccination and develop fever, headache, tiredness, body aches, vomiting, or diarrhea, see your healthcare provider.

Some people may have an increased risk of developing a reaction to the vaccine, but may still benefit from being vaccinated. These people, or their guardians, should talk to a healthcare provider about getting vaccinated:

• Between 6 and 8 months old
• Over 60 years old
• Pregnant
• Breastfeeding

Yellow fever is common in parts of Africa and South America. In fact, in Africa about 170,000 people get it every year. Yellow fever is not found in the United States — and thanks to the vaccine, travelers rarely get the disease.

The yellow fever vaccine is only recommended for people living in or traveling to places where yellow fever is a risk — or for people who work in labs studying the virus.

Why is the yellow fever vaccine important?

Most people who get yellow fever will only get a mild form of the disease. But in some cases, people with yellow fever can develop serious complications — including organ failure or bleeding. Serious cases of yellow fever can be deadly.

If you’re planning to travel to parts of South America or Africa where yellow fever is common, or you work in a lab studying yellow fever, getting vaccinated can protect you.

What is yellow fever?

Yellow fever is caused by a virus. Most people who get yellow fever recover after mild symptoms, including:

• Fever and chills
• Severe headache
• Back pain
• Body aches
• Upset stomach and throwing up
• Feeling tired and weak

About 15 out of 100 people who get yellow fever go on to develop more serious symptoms:

• Jaundice (yellowing of the skin or eyes)
• Bleeding from multiple parts of the body
• Liver, kidney, lung, and other organ failures

Yellow fever does not spread from person to person, like through touching or kissing. The virus that causes yellow fever is spread by the bite of an infected mosquito. Learn more about yellow fever.

Who needs to get the yellow fever vaccine?

The yellow fever vaccine is recommended for people age 9 months and older who are living in or traveling to parts of Africa or South America where there’s a risk of yellow fever. It’s also recommended for people studying yellow fever in labs.

Travelers

Everyone ages 9 months through 59 years who plans to travel to parts of Africa or South America where yellow fever is a risk needs 1 dose of the yellow fever vaccine. If you plan to continue living in or traveling to that country, it’s possible you’ll need a booster shot every 10 years.

To find out if the yellow fever vaccine is recommended or required where you’re traveling, visit CDC’s travel website.

Lab workers

If you work directly with the yellow fever virus, you need 1 dose of the yellow fever vaccine every 10 years.

Talk with your doctor about how to protect your family from yellow fever.

Who should not get the yellow fever vaccine?

Some people should not get the yellow fever vaccine, including:

• People who have had a life-threatening allergic reaction to the yellow fever vaccine or any of the ingredients in the vaccine (like eggs, chicken proteins, or gelatin)
• Infants younger than 6 months
• People with a weakened immune system from ongoing medical conditions, like HIV (with symptoms) or a disorder of the thymus (part of your immune system)
• People who have cancerous tumors
• People who have had an organ transplant

Some people may be at increased risk for having a reaction to the yellow fever vaccine — but the benefit of the vaccine may still outweigh the risk. Talk with your doctor about the benefits and risks of getting the yellow fever vaccine if you are:

• Age 60 and older
• Infected with HIV but don’t have symptoms
• Pregnant or breastfeeding

You’ll also need to discuss the benefits and risks of vaccination for your child if they are between 6 and 8 months old.

What are the side effects of the yellow fever vaccine?

Side effects are usually mild and go away in a few days. They may include:

• Pain, swelling, or redness where the shot was given
• Low fever

Serious side effects from the yellow fever vaccine are very rare.

Like any medicine, there's a very small chance that the yellow fever vaccine could cause a serious reaction.

I just received the yellow fever vaccine. Do I need to avoid contact with my immunocompromised family member?

No. There is no evidence that people who receive yellow fever vaccine shed the vaccine virus. Therefore, there is no need to avoid people including those whose immune systems do not work well.

Who should get yellow fever vaccine?

Yellow fever vaccine is recommended for people age 9 months or older who are traveling to or living in areas at risk for yellow fever virus transmission in South America and Africa. Proof of yellow fever vaccine may be required for entry into certain countries.

Who should not get yellow fever vaccine?

Infants younger than 6 months of age should not get the vaccine. In addition, anyone with a severe allergy to any part of the vaccine, including eggs, chicken proteins, or gelatin should not get the vaccine. Anyone who has had a severe reaction to a previous dose of yellow fever vaccine should not be vaccinated again.

If you have any of the following conditions, your healthcare provider can help you decide whether you can safely receive the vaccine:

• HIV/AIDS or other disease that affects the immune system
• Weakened immune system as a result of cancer or other medical conditions, transplant, or drug treatment (such as steroids, chemotherapy, or others that affect immune function)
• Thymus disorder
• Adults 60 years of age and older
• Infants 6 – 8 months of age
• Pregnant women and nursing mothers

How long does yellow fever vaccination last?

For most people, one dose of the vaccine provides long-lasting protection. Certain people may benefit from another dose of the vaccine either because they have problems with their immune system or they are in higher-risk settings.

Will I have to go to a special clinic to get a yellow fever vaccination?

Yes. Yellow fever vaccine is regulated by International Health Regulations, so only authorized providers can administer the vaccine. Most providers of yellow fever vaccine can also give you other vaccines or medicines for travel.

Is yellow fever vaccine recommended for people 60 years and older who will be traveling to areas with risk for yellow fever?

People aged ≥60 years may be at increased risk for serious adverse events (serious disease or, very rarely, death) following vaccination, compared with younger persons. This is particularly true if they are receiving their first yellow fever vaccination. Travelers aged ≥60 years should discuss with their healthcare provider the risks and benefits of the vaccine given their travel plans. In addition to considering the vaccine, travelers to endemic areas should protect themselves from yellow fever and other vector-borne diseases. Preventive measures include wearing clothes with long sleeves and long pants and using an effective insect repellent such as those with DEET, picaridin, IR3535, or oil of lemon eucalyptus.

What are the side effects of yellow fever vaccination?

Reactions to yellow fever vaccine are generally mild. They can include mild headaches, muscle aches, and low-grade fevers. There have been reports of extremely rare but serious events following yellow fever vaccination.

I think I got sick from the vaccine, what should I do?

Consult with your healthcare provider. Ask your healthcare provider to report your case to the Vaccine Adverse Events Reporting System (VAERS) if he or she thinks the vaccine has made you sick.

Does the yellow fever vaccine contain thimerosal?

No, the FDA-approved yellow fever vaccine does not contain thimerosal.

How long should a woman wait to conceive after receiving a yellow fever vaccination?

Yellow fever vaccination has not been known to cause any birth defects when given to pregnant women. Yellow fever vaccine has been given to many pregnant women without any apparent adverse effects on the fetus. However, since yellow fever vaccine is a live virus vaccine, it poses a theoretical risk. While a two week delay between yellow fever vaccination and conception is probably adequate, a one month delay has been advocated as a more conservative approach. If a woman is inadvertently or of necessity vaccinated during pregnancy, she is unlikely to have any problems from the vaccine and her baby is very likely to be born healthy.

The most effective way to prevent infection from Yellow Fever virus is to prevent mosquito bites. Mosquitoes bite during the day and night. Use insect repellent, wear long-sleeved shirts and pants, treat clothing and gear, and get vaccinated before traveling, if vaccination is recommended for you.

Prevent Mosquito Bites

Use Insect Repellent

Use Environmental Protection Agency (EPA)-registered insect repellents with one of the active ingredients below. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.

• DEET
• Picaridin (known as KBR 3023 and icaridin outside the US)
• IR3535
• Oil of lemon eucalyptus (OLE)
• Para-menthane-diol (PMD)
• 2-undecanone

Tips for babies and children

• Dress your child in clothing that covers arms and legs.
• Cover strollers and baby carriers with mosquito netting.
• When using insect repellent on your child:
  • Always follow label instructions.
  • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
  • Do not apply insect repellent to a child’s hands, eyes, mouth, cuts, or irritated skin.
    • Adults: Spray insect repellent onto your hands and then apply to a child’s face.

Tips for Everyone

• Always follow the product label instructions.
• Reapply insect repellent as directed.
  • Do not spray repellent on the skin under clothing.
  • If you are also using sunscreen, apply sunscreen first and insect repellent second.

Natural insect repellents (repellents not registered with EPA)

• We do not know the effectiveness of non-EPA registered insect repellents, including some natural repellents.
• To protect yourself against diseases spread by mosquitoes, CDC and EPA recommend using an EPA-registered insect repellent.
• Choosing an EPA-registered repellent ensures the EPA has evaluated the product for effectiveness.

Wear long-sleeved shirts and long pants

Treat clothing and gear

• Use permethrin to treat clothing and gear (such as boots, pants, socks, and tents) or buy permethrin-treated clothing and gear.
  • Permethrin is an insecticide that kills or repels mosquitoes.
  • Permethrin-treated clothing provides protection after multiple washings.
  • Read product information to find out how long the protection will last.

  If treating items yourself, follow the product instructions.

• Do not use permethrin products directly on skin.

Take steps to control mosquitoes indoors and outdoors

• Use screens on windows and doors. Repair holes in screens to keep mosquitoes outdoors.
• Use air conditioning, if available.
• Stop mosquitoes from laying eggs in or near water.
  • Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers.
  • Check indoors and outdoors.

Prevent mosquito bites when traveling overseas

• Choose a hotel or lodging with air conditioning or screens on windows and doors.
• Sleep under a mosquito bed net if you are outside or in a room that does not have screens.
  • Buy a bed net at your local outdoor store or online before traveling overseas.
  • Choose a WHOPES-approved bed net: compact, white, rectangular, with 156 holes per square inch, and long enough to tuck under the mattress.
  • Permethrin-treated bed nets provide more protection than untreated nets.
    • Do not wash bed nets or expose them to sunlight. This will break down the insecticide more quickly.

What is yellow fever?

Yellow fever is a disease caused by a virus that is spread through mosquito bites. Symptoms take 3–6 days to develop and include fever, chills, headache, backache, and muscle aches. About 15% of people who get yellow fever develop serious illness that can lead to bleeding, shock, organ failure, and sometimes death.

Who is at risk?

Travelers to certain parts of South America and Africa are at risk for yellow fever.

What can travelers do to prevent yellow fever?

Travelers can protect themselves from yellow fever by getting yellow fever vaccine and preventing mosquito bites.

Get yellow fever vaccine if recommended or if required:

• Visit a yellow fever vaccination (travel) clinic and ask for a yellow fever vaccine.
  • You should receive this vaccine at least 10 days before your trip.
  • After receiving the vaccine, you will receive a signed and stamped International Certificate of Vaccination or Prophylaxis (ICVP, sometimes called the “yellow card”), which you must bring with you on your trip.
  • The vaccine lasts for life for most people, but a booster after 10 years is recommended for certain people.

You should receive a yellow card called the International Certificate of Vaccination or Prophylaxis (ICVP) to prove that you have had yellow fever vaccine. Some countries require all travelers to show proof of yellow fever vaccination before they can enter the country. Other countries require proof of vaccination only if travelers have been in a risk area, so if you are visiting multiple countries, the order of travel may be important. Proof of vaccination is not valid until 10 days after you get the vaccine, so plan to get the vaccine early if you need it.

Note: CDC’s recommendation is different from the country’s requirement. A vaccine recommendation is designed to keep you from getting yellow fever; a vaccine requirement is the country’s attempt to keep travelers from bringing the yellow fever virus into the country. CDC does not have any control over other countries’ vaccine requirements or how they are enforced.

In rare cases, the yellow fever vaccine can have serious and sometimes fatal side effects. People older than 60 years and people with weakened immune systems might be at higher risk of developing these side effects. Also, there are special concerns for pregnant and nursing women. Talk to your doctor about whether you should get the vaccine.

Prevent mosquito bites:

Use an EPA-registered insect repellent

• Use Environmental Protection Agency (EPA)-registered insect repellents with one of the active ingredients below. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women. If also using sunscreen, always apply insect repellent after sunscreen.
  • DEET
  • Picaridin (known as KBR 3023 and icaridin outside the US)
  • IR3535
  • Oil of lemon eucalyptus (OLE)
  • Para-menthane-diol (PMD)
  • 2-undecanone

Find the right insect repellent for you by using EPA's search tool.

• Insect Repellent Tips for Babies and Children
  • Dress your child in clothing that covers arms and legs.
  • Cover strollers and baby carriers with mosquito netting.
  • When using insect repellent on your child:
    • Always follow label instructions.
    • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
    • Do not apply insect repellent to a child’s hands, eyes, mouth, cuts, or irritated skin.
      • Adults: Spray insect repellent onto your hands and then apply to a child’s face.
    • If also using sunscreen, always apply insect repellent after sunscreen.

Wear long-sleeved shirts and long pants

Treat clothing and gear with permethrin

• Use 0.5% permethrin to treat clothing and gear (such as boots, pants, socks, and tents) or buy permethrin-treated clothing and gear.
  • Permethrin is an insecticide that kills or repels mosquitoes.
  • Permethrin-treated clothing provides protection after multiple washings.
  • Read product information to find out how long the protection will last.
• If treating items yourself, follow the product instructions.
• Do not use permethrin products directly on skin.
• Watch the CDC video How to Use Permethrin.

Keep mosquitoes out of your hotel room or lodging

• Choose a hotel or lodging with air conditioning or window and door screens.
• Use a mosquito net if you are unable to stay in a place with air conditioning or window and door screens or if you are sleeping outside.

Sleep under a mosquito net

• Sleep under a mosquito net if you are outside or when screened rooms are not available. Mosquitoes can live indoors and bite during the day and night.
• Buy a mosquito net at your local outdoor store or online before traveling overseas.
• Choose a mosquito net that is compact, white, rectangular, with 156 holes per square inch, and long enough to tuck under the mattress.
• Permethrin-treated mosquito nets provide more protection than untreated nets.
  • Permethrin is an insecticide that kills mosquitoes and other insects.
  • To determine if you can wash a treated mosquito net, follow the label instructions.

If you are bitten by mosquitoes, avoid scratching the bites and apply over-the-counter anti-itch or antihistamine cream to relieve itching. See Mosquito Bite Symptoms and Treatment.

If you are bitten by mosquitoes:

• Avoid scratching mosquito bites.
• Apply hydrocortisone cream or calamine lotion to reduce itching.

If you traveled and feel sick, particularly if you have a fever, talk to a healthcare provider, and tell them about your travel. Avoid contact with other people while you are sick.