What Is Yellow Fever?

Yellow fever is a virus that is transmitted to humans through mosquito bites.

Jungle yellow fever is transmitted to humans through mosquitoes that have been infected by monkeys carrying the virus.

Urban yellow fever is passed to mosquitoes from infected humans, and the mosquitoes continue to infect other humans by biting them. Yellow fever cannot be passed from human to human.

The yellow fever virus is found only in South America and sub-Saharan Africa. Jungle yellow fever is typically only passed to humans who work or travel in the rain forest. Yellow fever can only be contracted through a bite from a female mosquito.

Risk factors for getting yellow fever include traveling to an area where humans are already infected by the yellow fever virus or where there are contaminated monkeys or mosquitoes that can transmit the virus.

Symptoms for yellow fever include:

    
  • High fever
  • Chills and muscle aches
  • Vomiting, sometimes vomiting blood
  • Headache
  • Backache

    • More serious complications include:

        
  • Shock
  • Bleeding
  • Liver failure
  • Kidney failure
  • Jaundice (resulting from liver failure)

    • Symptoms typically begin 3-6 days after infection. Yellow fever is diagnosed with a blood test, but there is no course of treatment for the virus. Doctors usually recommend a long period of bed rest, along with plenty of fluids. Patients should also avoid places where mosquitoes are present to avoid spreading the disease to others.

    Illness from yellow fever varies from a self-limited illness to hemorrhagic fever, which can be very severe and lead to death.

    What Is the Yellow Fever Vaccine?

    The vaccine is a weakened, live form of the yellow fever virus. The vaccine is created by growing the live virus in a lab. The preferred storage method is frozen vials. The vaccine is administered subcutaneously (beneath the skin).

    The yellow fever vaccine is not usually given with other vaccines, but it may be given with the hepatitis B vaccine .

    Who Should Get Vaccinated and When?

    The following individuals should get vaccinated:

        
  • All individuals aged 9 months to 59 years who are traveling to or living in a place where yellow fever is present such as certain parts of South America and Africa
  • People who work in labs and may be exposed to yellow fever

    • Travelers should be vaccinated at least 10 days before departure.

    The vaccine lasts for 10 years. Every 10 years, a booster is required if you are at risk for contracting yellow fever.

    What Are the Risks Associated With Yellow Fever Vaccine?

    Common minor side effects include:

        
  • Fever
  • Soreness, swelling, or redness at the injection site
  • Muscle aches

    • Rare, serious side effects include:

        
  • Nervous system reaction
  • Severe allergic reaction
  • Organ failure

    • Who Should Not Get Vaccinated?

    The vaccine should not be given to:

        
  • Infants aged six months or younger—In rare cases when your 6-8 month-old baby must travel to high-risk areas, talk to the doctor about the vaccine.
  • People over the age of 60 are at higher risk for serious complications. If you are traveling to an area of yellow fever risk, consult an infectious disease specialist to find out if vaccination is a good choice for you.
  • People who:     
  • Are severely allergic to eggs, chicken, or gelatin
  • Have a disease that weakens the immune system, such as HIV —If you are traveling to high-risk areas, talk to your doctor about the vaccine.
  • Are receiving treatments that weaken the immune system, such as cancer treatment
  • Have cancer
  • Have problems with the thymus or have had their thymus removed
  • Are pregnant (theoretical risk to the developing fetus)—Talk to your doctor about the risks and benefits of the vaccine if you are traveling to a high-risk area. If you are vaccinated, your doctor may use a blood test to confirm immunity.
  • Are breastfeeding—If you are traveling to high-risk areas, talk to your doctor about the vaccine.

    • What Other Ways Can Yellow Fever Be Prevented Besides Vaccination?

    To decrease your chance of getting yellow fever, do the following:

        
  • Use insect repellent.
  • Wear long-sleeved shirts and long pants.
  • Stay in screened areas.

    • What Happens in the Event of an Outbreak?

    An outbreak of yellow fever in the United States is unlikely since the virus is not geographically present in this country. But in the event of an outbreak, uninfected people would be vaccinated and precautions would be taken to reduce transmission.