Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Font Size

Yellow Fever

Yellow fever is a viral infection transmitted by a bite from infected mosquitoes most commonly found in parts of South America and Africa. When transmitted to humans, the yellow fever virus can damage the liver and other internal organs and be potentially fatal.

The World Health Organization estimates there are 200,000 cases of yellow fever worldwide each year, resulting in 30,000 deaths. Yellow fever appears to be on the rise internationally, due to a decreased immunity to infection among local populations, deforestation, climate change, and high-density urbanization.

Recommended Related to Brain & Nervous System

Brain-Eating Amoeba

It doesn't happen often. But most summers, several Americans -- usually healthy, young people -- suffer sudden, tragic deaths from a brain-eating amoeba. What is this scary bug? How does it get to the brain? Where is it and how can I avoid it? WebMD answers these and other questions.

Read the Brain-Eating Amoeba article > >

How High Is the Risk of Yellow Fever?

The CDC has identified 44 counties with a risk of yellow fever transmission, many of them with tropical climates. While the actual number of yellow fever cases among U.S. and European travelers to these at-risk countries is low, vaccination is advised for most international travelers to these countries, because yellow fever has no cure and can be deadly.

How Does Yellow Fever Spread?

Yellow fever is typically spread to humans from bites by infected mosquitoes. People cannot spread yellow fever among themselves through casual contact, although the infection can be transmitted directly into the blood through contaminated needles.

A few different species of mosquitoes transmit the yellow fever virus; some breed in urban areas, others in jungles. Mosquitoes that breed in the jungle also transmit yelllow fever to monkeys, who, in addition to humans, are a host for the disease.

Yellow Fever Symptoms

Yellow fever gets its name from two of its most obvious symptoms: fever and yellowing of the skin. The yellowing occurs because the disease causes liver damage, hepatitis. For some people, yellow fever has no initial symptoms, while for others, the first symptoms appear from three to six days after exposure to the virus from a mosquito bite.

An infection with yellow fever typically has three phases. The first phase of symptoms can last for three to four days and then, for most people, disappears. The first phase is generally non-specific and cannot be distinguished from other viral infections.

The initial symptoms of yellow fever are:

1 | 2 | 3

Hot Topics

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

disciplining a boy
Types, symptoms, causes.
Remember your finger
Are You Getting More Forgetful?
fruit drinks
Eat these to think better.
No gym workout
Moves to help control blood sugar.
acupuncture needle on shoulder
10 tips to look and feel good.
Close up of eye
12 reasons you're distracted.
birth control pills
Which kind is right for you?
embarrassed woman
Do you feel guilty after eating?
Epinephrine Injection using Auto-Injector Syringe
Life-threatening triggers.
woman biting a big ice cube
Habits that wreck your teeth.
pacemaker next to xray
Treatment options.
caregiver with parent
10 tips for daily life.

Pollen counts, treatment tips, and more.

It's nothing to sneeze at.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.


Now check your email account on your mobile phone to download your new app.

Women's Health Newsletter

Find out what women really need.