Published 28 June 2026

South America Travel Health: From Yellow Fever to Altitude — What Travellers Need to Know

South America is one of the most diverse and demanding destinations on earth from a travel health perspective. A single itinerary can take you from sea-level Amazon jungle — where yellow fever, malaria, and dengue circulate year-round — to Andean cities above 3,400 metres where altitude sickness affects the majority of first-time arrivals, and then to Patagonian wilderness where the main risks are cold exposure and remoteness from medical care. The vaccine and health preparation required for a week in Buenos Aires is almost nothing. The preparation required for a month moving between the Amazon, Cusco, and the Bolivian salt flats is substantial.

This guide covers the key health risks across South America's most visited countries — Brazil, Peru, Colombia, Argentina, Bolivia, Ecuador, and Chile — with honest, source-backed guidance on yellow fever, altitude sickness, malaria, Zika, dengue, and food and water safety. No two itineraries are the same, which is why the single most important thing in this article is the advice at the end: see a travel health professional before you go.

Yellow Fever: An Active and Expanding Risk

Yellow fever is the dominant vaccine concern for South America in 2025 and 2026, and the situation has worsened compared to previous years. In March 2026, the Pan American Health Organization issued an epidemiological alert warning of sustained yellow fever transmission across parts of South America, with cases being reported in areas that had not previously seen transmission, including outside the Amazon basin. During the first seven weeks of 2026 alone, PAHO confirmed 34 human cases and 15 deaths across Bolivia, Colombia, Peru, and Venezuela. The CDC issued a Level 2 travel notice — Practice Enhanced Precautions — for yellow fever in South America, noting that in the first three months of 2025, 131 human cases were confirmed with 53 deaths, compared to just 61 cases and 30 deaths in all of 2024.

PAHO noted that the vast majority of confirmed cases in 2025 and 2026 were in people who were not vaccinated. There is no treatment for yellow fever. A single dose of the vaccine provides lifelong protection under current WHO rules, though a booster may be recommended in certain high-risk situations or for travellers whose certificate is more than ten years old. The vaccine takes ten days to become fully effective and must be administered at a designated travel clinic — not all general practitioners carry it.

The countries and regions where the CDC recommends yellow fever vaccination for travellers are broad and cover most of the continent's interior. Vaccination is recommended for most of Brazil (including São Paulo state following recent urban-area cases), most of Colombia, Peru, Ecuador, Bolivia, Paraguay, Venezuela, Guyana, and Suriname. Chile and most of Argentina are among the very few South American countries where yellow fever vaccination is generally not recommended, due to low transmission risk. However, if you are travelling between countries in the region, carrying your yellow fever certificate protects you from border complications even where it is not strictly required for direct arrivals from North America or Europe.

The practical lesson from recent outbreak data is clear: do not skip this vaccine if your itinerary includes forested or jungle areas, the Amazon basin, or any of the affected countries listed above. Sources: PAHO — Sustained Yellow Fever Transmission in South America, March 2026 | CDC — Yellow Fever in South America, Level 2 Notice | CDC — Countries at Risk for Yellow Fever: South America

Altitude Sickness: The Risk That Catches Most Travellers Off Guard

Altitude sickness is the health risk that most visitors to the Andes either underestimate or simply do not know to prepare for. It affects people regardless of age, fitness level, or previous travel experience. Research cited by travel medicine sources suggests that approximately 40 to 50 percent of travellers who fly directly to Cusco, Peru (3,399 metres / 11,152 feet above sea level) experience some form of acute mountain sickness (AMS), with 10 to 15 percent developing moderate symptoms that significantly affect their trip. Bolivia's capital La Paz sits at approximately 3,640 metres — the highest capital city in the world — and the Uyuni Salt Flats reach over 3,650 metres.

Altitude sickness occurs when the body ascends to elevations where oxygen concentration is significantly lower than at sea level. At Cusco's elevation, the body receives approximately 35 percent less oxygen per breath than at sea level. Symptoms of mild AMS include headache, nausea, fatigue, dizziness, and difficulty sleeping — all of which typically appear within the first twelve to twenty-four hours after arrival at altitude and resolve within one to three days with acclimatisation. More serious forms — high-altitude pulmonary oedema (HAPE) and high-altitude cerebral oedema (HACE) — are less common but can be life-threatening and require immediate descent and medical attention.

There is no vaccine or medication that prevents altitude sickness entirely, but there are proven strategies for reducing risk. The most effective is gradual acclimatisation — arranging your itinerary so you ascend progressively, spending time at intermediate altitudes before reaching your highest points. A recommended sequence for a Peru-Bolivia itinerary is Lima (sea level) to Arequipa (2,300 metres) for one to two days, then Cusco (3,399 metres), then Lake Titicaca/Puno (3,812 metres). Machu Picchu itself sits at only 2,430 metres — lower than Cusco — and so travellers who have acclimatised in Cusco first typically manage the site without difficulty, even though the Inca Trail reaches a high pass of 4,215 metres.

Acetazolamide (Diamox) is the prescription medication most commonly recommended by travel health professionals for altitude sickness prevention. It works by stimulating breathing and speeding up acclimatisation. It is a sulfa drug and is not suitable for people with sulfa allergies. It should not be self-prescribed; get it from your GP or travel health clinic before departure. Coca tea and coca leaves are a traditional Andean remedy widely available in Peru and Bolivia and frequently offered in hotels; they may provide mild symptom relief and are legal in both countries, though they cannot be taken across international borders.

If you develop worsening headache not relieved by rest or paracetamol, confusion, loss of coordination, or breathlessness at rest, these are signs of serious altitude illness and require immediate descent to a lower altitude. Descent is the definitive treatment. Sources: CDC Yellow Book — Travel to High Altitudes | Machu Picchu Altitude Guide — Runway Health | Peru Altitude Sickness Guide — Bolivia Hop

Vaccines Recommended Across South America

Beyond yellow fever, the following vaccines are recommended by the CDC and WHO for most travellers to South America, particularly those visiting rural areas, the Amazon, or countries outside Chile and Argentina's main urban centres.

Hepatitis A

Hepatitis A is spread through contaminated food and water and is a risk across the continent. The CDC recommends it for all travellers to most South American countries. It is one of the most common vaccine-preventable illnesses acquired during international travel. A single dose before departure provides protection for approximately one year; two doses spaced six to twelve months apart provide long-term protection. Sources: Passport Health — Central and South America

Typhoid

Typhoid is a bacterial food and water-borne illness present throughout South America. The risk is highest in rural areas and at street food stalls. The injectable vaccine provides two years of protection; the oral capsule course provides five. Neither is 100% effective, making food and water hygiene equally important. Sources: Passport Health — Central and South America

Hepatitis B

Hepatitis B is recommended for unvaccinated travellers, particularly those who may seek medical care, undergo dental procedures, or have tattoos or piercings during their trip. The full three-dose course takes six months, though accelerated schedules exist. Sources: Passport Health — Central and South America

Rabies

Rabies is present in dogs, bats, and other animals throughout South America. Pre-exposure vaccination is recommended for travellers spending extended periods in rural areas, undertaking adventure activities, or travelling to remote regions where access to post-exposure treatment may be limited. Sources: Passport Health — Central and South America

Routine Vaccines

Ensure MMR, DTP/Tdap, and COVID-19 vaccinations are up to date before departure. The CDC issued a global measles Level 1 notice in May 2025. A measles outbreak beginning in December 2025 has confirmed more than 6,000 cases in one South American country alone according to travel health monitoring services. Sources: CDC Global Measles Notice, May 2025

Malaria: Where It Matters and Where It Doesn't

Malaria risk in South America is heavily concentrated in the Amazon basin and is not a significant concern for the main urban tourist destinations. Buenos Aires, Santiago, Lima, Bogotá, Rio de Janeiro, São Paulo, Quito's city centre, and Cusco all carry no meaningful malaria risk. The Amazon jungle regions of Brazil, Peru, Colombia, Ecuador, and Bolivia are a different matter entirely, with year-round transmission.

Malaria in South America is predominantly P. vivax, which is not typically fatal but can cause significant illness and relapsing infections. P. falciparum is also present in parts of the Amazon. Chloroquine resistance is established in most South American malaria zones, so older antimalarials are not appropriate. Atovaquone-proguanil (Malarone), doxycycline, and mefloquine are the drugs recommended, depending on the specific region and your individual circumstances. Discuss your exact itinerary with your travel health professional — the difference between a riverboat trip through the Peruvian Amazon and a week in Cusco represents a completely different risk profile, and many of the same yellow-fever and antimalarial considerations apply on an East Africa safari.

Colombia has seen an active yellow fever notice since September 2025 and carries malaria risk across its Amazon and coastal regions. The CDC Colombia page noted increased risk of multiple mosquito-borne diseases following heavy rainfall and flooding as of 2025. Sources: CDC — Colombia Travelers' Health | CDC Yellow Book — Yellow Fever and Malaria by Country

Dengue, Zika, and Oropouche: The Mosquito Diseases Without Vaccines

Dengue is endemic across most of South America and is one of the more likely illnesses a traveller will encounter in the region. Brazil has carried an outsized disease burden in recent years, with millions of dengue cases recorded annually alongside sustained chikungunya outbreaks exceeding 300,000 cases and significant Zika transmission. PAHO surveillance data from early 2026 showed chikungunya remaining highly active across the region even as overall dengue case counts fell compared to 2025 peaks. Colombia accounted for approximately 24% of regional malaria cases and saw active yellow fever transmission as of September 2025.

Oropouche fever is an emerging mosquito-borne viral illness in the Amazon basin that the CDC has flagged as a risk for travellers to parts of Brazil and other Amazonian countries. There is no vaccine and no specific treatment; prevention relies on avoiding mosquito bites.

Zika virus is present throughout South America and transmitted by the same Aedes mosquitoes that carry dengue. The CDC notes ongoing risk of Zika infection for travellers across most of the continent. Zika causes mild illness in most adults but poses serious risks to unborn babies, including microcephaly and other neurological conditions. The CDC recommends that pregnant travellers or those planning pregnancy review the latest Zika guidance before travel to any affected area in South America and consult their GP or obstetrician. There is no vaccine for Zika.

For all mosquito-borne diseases in South America, prevention relies on physical measures: use a DEET-based repellent of at least 20% concentration on all exposed skin throughout the day, wear long sleeves and trousers, sleep under mosquito nets, and stay in air-conditioned accommodation where possible. Dengue mosquitoes are active during the day, unlike malaria mosquitoes which bite primarily at dusk and dawn. Sources: PAHO and Vax-Before-Travel — Mosquito-borne Disease in the Americas, February 2026 | CDC — Zika Travel Recommendations

Country by Country: Key Differences

Brazil is the continent's highest-risk destination overall. Yellow fever vaccination is strongly recommended for travel outside major coastal cities, including for São Paulo state following recent cases near urban areas. The Amazon region carries malaria risk, and dengue, chikungunya, and Zika are present nationwide. Rio de Janeiro and São Paulo themselves carry dengue and Zika risk but generally no malaria and lower yellow fever exposure. See the full Brazil country guide.

Peru is a tale of two very different environments. Lima, the coast, and the Andean highlands including Cusco and Machu Picchu are relatively low risk for vaccine-preventable diseases, with the main concern being altitude sickness and food and water safety. The Amazon regions (Iquitos, Puerto Maldonado) require yellow fever vaccination and malaria prophylaxis. See the full Peru country guide.

Colombia has seen active yellow fever cases since late 2024 extending into 2026, including in the department of Tolima and other areas not historically considered high risk. Yellow fever vaccination is strongly recommended. Bogotá itself, at 2,600 metres, is above the yellow fever transmission zone, but most travellers visit the coast or other lower-altitude regions where risk exists. Malaria and dengue are present in coastal and Amazonian areas. See the full Colombia country guide.

Argentina and Chile are the safest South American destinations from a tropical disease standpoint. Buenos Aires and Patagonia carry no malaria, no yellow fever risk, and no significant tropical disease burden. The main health preparation is routine vaccines and travel insurance. Note that if you are travelling from Argentina or Chile to other South American countries, you may need a yellow fever certificate depending on your itinerary. See the guides for Argentina and Chile.

Bolivia combines some of the continent's highest altitudes — La Paz at 3,640 metres, the Uyuni Salt Flats above 3,650 metres — with significant yellow fever and malaria risk in its Amazonian lowland regions. It is one of South America's most medically demanding destinations for travellers covering multiple regions in one trip. See the full Bolivia country guide.

Ecuador covers enormous altitude and ecological diversity in a small area, from the Galápagos Islands (low risk, no malaria) to the Amazonian lowlands (yellow fever, malaria) and Quito at 2,800 metres (no tropical disease risk, mild altitude). Yellow fever is recommended for travel below 2,300 metres. See the full Ecuador country guide.

Food and Water Safety

Traveller's diarrhoea is the most common illness acquired in South America. Studies suggest up to 70 percent of travellers to the region experience some form of gastrointestinal illness. Drink only bottled or purified water throughout the continent, including in countries with relatively good infrastructure. Avoid ice outside major international hotels. Be cautious with raw fruit and salads washed in tap water at street stalls and small local restaurants. This applies even in Uruguay and Argentina, which are otherwise low-risk destinations.

When to Seek Medical Attention

If you develop fever during travel in South America or within a month of return, see a doctor and tell them exactly where you travelled. Fever following Amazon travel can indicate malaria, dengue, yellow fever, or typhoid, and the appropriate response differs for each. Do not wait to see if it resolves on its own.

For altitude sickness specifically: if headache worsens and is not relieved by rest or paracetamol, if you feel confused or cannot walk steadily, or if you develop breathlessness at rest, descend immediately. Do not continue ascending when symptomatic.

Use the Travel Vaccine Map interactive map to compare health profiles across South American destinations, or go directly to the country guides for Brazil, Peru, Colombia, Argentina, Bolivia, Ecuador, and Chile.

Sources

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This article is for informational purposes only and does not constitute medical advice. Always consult a qualified travel health professional or GP before travel.