Areas of heightened disease reporting: LO HI

Yellow Fever

Spread By Mosquitos

Data Source For Areas Affected

The maps designate countries considered to be affected by a disease. Areas within countries may or may not be affected by a specific disease. Consult with a Travel Healthcare Provider or about your specific itinerary prior to travel.

Reporting activity data are provided by Sitata and derived from numerous sources, including official surveillance data and news reports. Reporting activity does not reflect current risk of infection with a disease. Not all areas report cases of disease; therefore, the absence of activity on the map does not indicate that a disease is not present. The relationship between the intensity of reporting activity and actual disease transmission is unknown and does not indicate a difference in risk. Maps do not reflect differential distribution of diseases within a country.

What Is It?

Yellow fever is caused by a virus.

Yellow fever is present in tropical areas of the world, such as Central and South America and sub-Saharan Africa. Most people infected with yellow fever virus will have mild or no symptoms. Symptoms include sudden onset of fever, chills, headache, backache, muscle pain, feeling unable to move, nausea, and vomiting. In most cases, symptoms subside after three or four days. However, some people who present with symptoms develop a more serious form that can cause jaundice (yellowing of the skin or eyes) and uncontrolled bleeding, which can be deadly.

Some countries require yellow fever vaccination prior to entry. Check specific requirements for your destination.

How is it Acquired?

Yellow fever is spread through the bite of a mosquito carrying the virus.

Mosquitos that carry the yellow fever virus are found in multiple environments throughout the day and night.

In rural West Africa, acquiring yellow fever is more likely during the end of the rainy season and the beginning of the dry season (usually July–October). However, disease transmission can still occur during the dry season in both rural and urban areas. In South America, the likelihood is highest during the rainy season (January–May).

The location and length of travel, vaccination status, and types of occupational and recreational activities one participates in also determine a person’s likelihood for mosquito exposure and getting yellow fever.

Factors that may increase the likelihood of developing a severe form of the disease include:

  • Age >40 years
  • HIV

Signs and Symptoms

While yellow fever symptoms can be mild, some people develop severe disease.

For those who do, the signs and symptoms of yellow fever include:

  • Sudden onset of fever
  • Chills
  • Headache
  • Backache
  • Muscle pain
  • Extreme physical weakness
  • Nausea
  • Vomiting

In most cases, symptoms subside after three or four days. However, some people develop a more serious form that can cause jaundice (yellowing of the skin or eyes) and uncontrolled bleeding, which can be deadly.

Precautions to Take

Below are some tips to minimize mosquito bites, especially during the day, when the mosquitos that spread yellow fever are most active.

  • Stay in buildings that have window and door screens to help keep mosquitos out
  • Use air conditioning
  • Use mosquito repellent on bare skin
  • Treat clothes and shoes with mosquito repellent
  • Wear long pants and long-sleeved shirts, socks, and shoes
  • Use a mosquito net treated with mosquito repellent over the bed

Contact your healthcare provider to discuss yellow fever vaccines prior to travel.

Proof of vaccination is required for entry into certain countries. Check specific requirements for your destination.

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