Avoiding Yellow Fever When Traveling Abroad

Yellow fever is a viral infection of the genus Flavivirus transmitted by the Aedes or Haemagogus mosquito. Scientists believe it originated in the African continent and emerged as a threat in the United States during the slave trade in the 1600s.

Mosquitoes transmit the yellow fever virus by feeding on the blood of an infected primate (human or otherwise), then feeding on another primate. A vaccine is available for yellow fever. The vaccine can prevent infection, but it cannot treat or cure the disease once you have it.

This article explains yellow fever mosquitoes, yellow fever history in the United States, symptoms, vaccine, and treatment.

Close up of a mosquito on a person's arm

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Where Did Yellow Fever Originate?

Yellow fever mosquitoes include the Aedes or Haemagogus species. These mosquitoes are primarily found in Africa (Aedes) and South America (Haemagogus).

Yellow fever likely originated in Africa and then spread throughout the Western hemisphere during the slave trade. It came to the United States in the 1600s, but it wasn't until 1793 that a yellow fever outbreak killed 10% of the Philadelphia population. The last major yellow fever outbreak in the United States was in 1905 in New Orleans.

How Common Is Yellow Fever?

In 2013, African data sources reveal that up to 170,000 severe cases of yellow fever were reported, with as many as 60,000 deaths.

The mosquitoes live in tropical and subtropical areas of Africa and South America. Yellow fever rarely affects U.S. travelers to these continents.

There are many African countries affected by yellow fever, including:

  • Angola
  • Cameroon
  • Chad
  • Ethiopia
  • Ghana
  • Guinea
  • Kenya
  • Liberia
  • Mali
  • Niger
  • Nigeria
  • Republic of the Congo
  • Senegal
  • Sierra Leone
  • Sudan
  • Togo
  • Uganda

Some affected South American countries include:

  • Argentina
  • Bolivia
  • Brazil
  • Colombia
  • Ecuador
  • French Guiana
  • Guyana
  • Panama
  • Paraguay
  • Peru
  • Trinidad and Tobago
  • Venezuela

Yellow fever is a serious illness with a threat of global spread. If you catch it abroad, you could theoretically spread the disease in your home country. However, certain factors would need to exist to make it possible, including mosquito species able to transmit the disease and the right tropical climate conditions.

Profile of Yellow Fever Symptoms

Once you contract yellow fever from a mosquito, the virus incubates in the body for three to six days. After that, you may begin experiencing symptoms, although many people don't have any symptoms at all.

Yellow fever is not contagious, meaning it causes illness but is not spread from person to person. Instead, it transmits via mosquitoes, disease vectors that spread the virus after biting an infected person and then biting an uninfected person.

Yellow fever symptoms include:

Symptoms typically resolve within a few days. In severe cases, a second phase of the illness begins 24 hours after initial symptoms resolve. In this phase, body systems like the liver and kidneys are affected.

Severe yellow fever symptoms in this phase include:

  • Jaundice (yellowing of the skin and eyes)
  • Dark urine
  • Abdominal pain with vomiting
  • Bleeding from the mouth, nose, eyes, or stomach

Unfortunately, severe yellow fever can be fatal.

Yellow Fever Vaccine: What It Does and Doesn't Do

The yellow fever vaccine provides lifelong protection from yellow fever. There are no booster doses; one shot prevents the disease. The vaccine is 80% to 100% effective by 10 days after vaccination and is 99% effective 30 days post-vaccine.

Health officials recommend the vaccine for people 9 months and older traveling to or living in places with a yellow fever risk.

While the yellow fever vaccine prevents it, it does not treat or cure an active infection.

Yellow Fever: Treatment and Self-Management

There is no medicine or cure for yellow fever. However, for mild cases, at-home comfort measures can help. These include:

Most people survive yellow fever. Severe yellow fever occurs in about 15% of infected people. Of them, it is fatal 30% to 60% of the time.

If you start experiencing another round of symptoms after your initial symptoms have resolved, you should seek medical attention in a hospital. This indicates a severe infection.

What Not to Do for Yellow Fever

When you have yellow fever, it is important to avoid certain things. Some medications can increase your risk of bleeding. Specifically, avoid nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, ibuprofen (Advil, Motrin), or naproxen (Aleve) when you have yellow fever.

In addition, it is critical to avoid mosquitos while you are ill. That's because you could transmit your illness via mosquitos. So, stay inside, use mosquito netting, wear long sleeves and long pants, and wear bug spray if you go outdoors for at least five days after your symptoms begin.

Travel Tips to Avoid Yellow Fever

If you are traveling to a place where yellow fever is a risk, there are some precautions you should take. These include:

  • Getting vaccinated if you plan to travel to or live in a high-risk area
  • Using insect repellent that contains DEET
  • Covering up with long sleeves and long pants when possible
  • Avoiding the outdoors during peak mosquito hours (usually dusk to dawn, although the Aedes aegypti species is most active during the daytime)
  • Staying in screened-in areas or using mosquito nets


The mosquitoes that spread yellow fever primarily live in Africa and South America. They transmit the yellow fever virus by biting human and nonhuman primates. While the United States has had yellow fever outbreaks, it is no longer a concern. Rarely will people contract the illness when they travel to places at risk for yellow fever.

Vaccination can prevent yellow fever. Yellow fever is usually mild, but it can be fatal. Severe cases occur about 15% of the time. Of those, it is fatal in 30% to 60% of cases.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Society for Microbiology. History of yellow fever in the US.

  2. Centers for Disease Control and Prevention. Transmission of yellow fever virus.

  3. World Health Organization. Yellow fever.

  4. Centers for Disease Control and Prevention. Areas with yellow fever virus transmission in Africa.

  5. Centers for Disease Control and Prevention. Areas with risk of yellow fever virus transmission in South America.

  6. World Health Organization. Yellow fever: Symptoms.

  7. Centers for Disease Control and Prevention. Yellow fever vaccine.

  8. Centers for Disease Control and Prevention. Yellow fever: Symptoms, diagnosis, and treatment.

  9. Centers for Disease Control and Prevention. Yellow fever virus: Frequently asked questions.

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By Kathi Valeii
Valeii is a Michigan-based freelance writer with a bachelor's degree in communication from Purdue Global.