Yellow Fever

A Traveler’s Guide to South & Central America

What is Yellow Fever?

Yellow fever is a viral disease transmitted by infected mosquitoes. It occurs mainly in tropical areas of Africa and Central and South America and can range from a mild illness to a severe, potentially life-threatening infection.

The incubation period is usually 3-6 days. Early symptoms may include fever, headache, muscle aches, back pain, nausea, vomiting, weakness, and loss of appetite. Most people recover after the initial phase, but some patients develop a severe phase that can cause jaundice, bleeding, organ failure, and shock.

Where Does Yellow Fever Occur?

In the Americas, PAHO identifies 13 countries and territories with yellow fever risk:

• 🇦🇷 Argentina

• 🇧🇴 Bolivia

• 🇧🇷 Brazil

• 🇨🇴 Colombia

• 🇪🇨 Ecuador

• 🇬🇫 French Guiana

• 🇬🇾 Guyana

• 🇵🇦 Panama

• 🇵🇾 Paraguay

• 🇵🇪 Peru

• 🇸🇷 Suriname

• 🇹🇹 Trinidad and Tobago

• 🇻🇪 Venezuela

Importantly, yellow-fever risk does not necessarily cover an entire country. In several countries, transmission occurs only in specific regions or below certain elevations.

Areas commonly associated with higher risk

Yellow fever is particularly associated with tropical and forested areas, including parts of the Amazon Basin and other areas where suitable mosquito vectors and animal reservoirs are present.

Risk areas include parts of:

• The Amazon region of Brazil

• The Amazon and jungle regions of Peru

• Parts of Bolivia

• Parts of Colombia

• Parts of Ecuador

• Venezuela

• Guyana and Suriname

• French Guiana

• Parts of Panama

• Certain areas of Paraguay and northern Argentina

The exact risk area can change as transmission patterns evolve. In 2026, PAHO reported yellow-fever transmission in areas beyond some traditional Amazon hotspots, including parts of Brazil and Colombia.

YELLOW FEVER IN PERU

For travelers, it is important to distinguish between Cusco's highland tourist areas and the lower elevation jungle regions.

The CDC currently recommends yellow-fever vaccination for travelers aged 9 months and older going to specified areas below 2,300 meters (7,550 ft) in several Peruvian regions, including Amazonas, Cusco, Huánuco, Junín, Loreto, Madre de Dios, Pasco, Puno, San Martín, and Ucayali, as well as designated areas of several other regions.

Vaccination is not generally recommended for travel limited to the city of Cusco, the Inca Trail, or Machu Picchu. Peru does not currently require yellow-fever vaccination simply to enter the country.

Travelers continuing from Cusco to jungle destinations such as Madre de Dios, Puerto Maldonado or parts of the Amazon should check the vaccination recommendation for their specific itinerary.

THE YELLOW FEVER VACCINE

Vaccination is the most effective way to prevent yellow fever.

A single dose of yellow-fever vaccine provides long-lasting, generally lifelong protection for most people, and a booster is not routinely required under current international recommendations.

The vaccine is generally recommended for travelers aged 9 months and older who are traveling to areas where yellow fever transmission occurs.

When should you get vaccinated?

Travelers should ideally receive the vaccine at least 10 days before entering a risk area. International vaccination certificates become valid 10 days after primary vaccination.

WHO SHOULD DISCUSS THE VACCINE WITH A DOCTOR?

Yellow-fever vaccination is not appropriate for everyone. Medical advice is particularly important for:

• Infants under 9 months

• Pregnant travelers

• People with severe allergies to vaccine components, including severe egg allergy

• People with certain immune-system conditions

• People with thymus disorders

• Travelers aged 60 and older, because the risk-benefit assessment may require additional consideration

A healthcare professional should evaluate the individual traveler, their destination, itinerary, age, and medical history before vaccination.

HOW CAN TRAVELERS PREVENT YELLOW FEVER?

Vaccination is the primary prevention method, but avoiding mosquito bites remains important.

🦟 Use insect repellent

Apply an effective insect repellent to exposed skin according to the product instructions.

👕 Cover exposed skin

Wear long-sleeved shirts, long trousers, socks, and other clothing that reduces exposed skin.

🛏️ Protect yourself while sleeping

Use air-conditioned or screened accommodation where possible. In areas where mosquito exposure is possible, use a mosquito net when appropriate.

🌴 Take extra care in jungle environments

Travelers spending time in tropical forests or rural areas may have greater exposure to mosquitoes that transmit yellow fever.

💉 Vaccinate when recommended

Check the vaccination recommendation for every destination on your itinerary before traveling.

IS THERE A TREATMENT FOR YELLOW FEVER?

There is currently no specific antiviral treatment for yellow fever.

Treatment focuses on supportive medical care, including hydration, monitoring, managing fever and complications, and treatment of severe liver or kidney problems when necessary. Severe cases may require hospitalization and intensive care.

Because yellow fever symptoms can resemble other tropical diseases such as dengue, malaria, leptospirosis and viral hepatitis, medical evaluation and appropriate laboratory testing are important when yellow fever is suspected.

When should a traveler seek medical attention?

Seek medical care promptly if you develop fever, severe headache, muscle or back pain, vomiting, weakness, or jaundice during or after travel to a yellow-fever risk area.

Severe symptoms such as jaundice, bleeding, confusion, difficulty breathing, persistent vomiting, or signs of organ dysfunction require urgent medical evaluation.

YELLOW FEVER VACCINATION & ENTRY REQUIREMENTS

It is important to distinguish between:

1. Vaccination recommendation - a health recommendation based on the risk of catching yellow fever at your destination.

2. Entry requirement - a legal requirement imposed by a country that may require travelers to show an International Certificate of Vaccination or Prophylaxis (ICVP), sometimes depending on where they are arriving from or where they have recently traveled.

Countries in the Americas that require proof from all arriving travelers

According to the CDC Yellow Book's current table of countries requiring proof of yellow-fever vaccination from *all arriving travelers*, the Americas entry on that list is:

• 🇧🇴 Bolivia

• 🇬🇫 French Guiana

However, this does *not* mean that these are the only places where travelers may encounter a yellow-fever vaccination requirement.

Other countries can require proof depending on the traveler's previous countries visited, transit points, length of stay, age, or itinerary.

Example: Ecuador

Ecuador currently requires yellow-fever vaccination for travelers aged 1-60 who have spent more than 10 days in certain yellow-fever-endemic South American countries, including Colombia, Peru, Brazil and Bolivia. Additional requirements apply to travelers arriving from certain African countries. The vaccine must generally have been administered at least 10 days before entry.

Because entry regulations can change, travelers should verify the requirements for their *complete itinerary*, including transit countries and long airport connections, before departure.

*INTERNATIONAL CERTIFICATE OF VACCINATION*

When vaccination is required for international travel, travelers may need an *International Certificate of Vaccination or Prophylaxis (ICVP)*, commonly known as the "Yellow Card."

The certificate should be properly completed and validated by the authorized vaccination center. For a primary yellow-fever vaccination, the certificate becomes valid *10 days after vaccination*.

A properly documented yellow-fever vaccination certificate is generally considered valid for the *lifetime of the vaccinated person* under the International Health Regulations.

*TRAVEL SMART WITH HEY DOCTOR*

Traveling through South and Central America can involve very different environments, from high-altitude cities to tropical forests and remote jungle destinations.

• Hey Doctor helps travelers understand their medical options, connect with local healthcare services, and navigate medical care when they need assistance during their journey.

  
  

• Before traveling to a yellow-fever risk area, speak with a qualified healthcare professional about vaccination and check the latest entry requirements for every country on your itinerary.

> Important: This information is for general educational purposes and does not replace professional medical advice. Yellow-fever vaccination should be based on an individual medical assessment and the specific destinations on your itinerary. Entry requirements can change, so travelers should confirm the latest requirements with the relevant health authorities, embassy or consulate before departure.