Unwanted Souvenirs: Travel Illnesses Americans Are Most Likely to Bring Home This Summer

Every summer, millions of Americans travel abroad in search of beaches, bucket-list adventures, and cultural experiences. Most return with little more than photos and jet lag. Some return with illnesses they never saw coming.

Getting sick abroad is one of the top concerns for more than half of all travelers, and according to the CDC, that concern is not unfounded [1]. Up to 79% of travelers to low- and middle-income countries experience a travel-related illness during or after their trip [2]. While people often associate travel diseases with rare threats such as Ebola or avian influenza, the illnesses Americans are far more likely to encounter are much more familiar: contaminated food and water, mosquito-borne infections, and vaccine-preventable diseases.

Recent U.S. data illustrates the trend. In 2024, the country recorded 3,798 dengue cases, with more than 97% linked to travel. Measles cases rose to 2,288 in 2025 amid outbreaks worldwide, while malaria continues to cause roughly 2,000 U.S. cases each year, nearly all acquired abroad.

To better understand which illnesses matter most for today’s travelers, medical experts at Drip Hydration analyzed CDC travel health guidance, GeoSentinel surveillance data, and U.S. public health records. GeoSentinel is a global network of travel and tropical medicine clinics that tracks diagnoses in ill returning travelers. The analysis does not estimate exact infection probabilities. Instead, it identifies illnesses that appear most frequently in travel medicine data, have the potential to cause serious disease, and are commonly encountered during international travel.

The result is a practical overview of the travel illnesses most relevant to U.S. travelers this summer, where exposure risk is highest, and which symptoms should prompt medical attention after returning home.

Dr. Neal Kumar, a board-certified dermatologist with an MBA in health management and co-founder of Drip Hydration:

“The biggest risks for Americans traveling abroad are generally much more predictable: contaminated food and water, mosquito-borne infections, and gaps in routine vaccination. The challenge is that symptoms don’t always appear during the trip itself. Travelers can return home feeling fine and only develop symptoms days or weeks later, which is why recent travel history is such an important clue when seeking medical care.”

The Health Risks U.S. Travelers Should Know About

Many travelers worry about exotic diseases, but the most common travel illnesses are often far less dramatic. Stomach infections, mosquito-borne diseases, and vaccine-preventable illnesses account for the majority of travel-related health issues seen after international trips. Here’s what the data actually shows.

1. Travelers’ diarrhea

The most common travel-related illness by a wide margin. According to GeoSentinel — a global surveillance network that tracks illnesses in returning travelers seen at travel health clinics — digestive infections account for nearly 17% of all diagnoses. Caused by bacteria, viruses, or parasites in contaminated food or water, it’s a risk at almost any destination with unreliable sanitation.

• Symptoms: Loose stools, stomach cramps, nausea, and dehydration.
• Prevention: Stick to bottled or treated water, avoid ice, eat fully cooked food, and wash hands frequently. Carry oral rehydration salts.
• When to seek help: If symptoms are severe, bloody, or don’t improve within 48–72 hours. Dehydration can escalate quickly, especially in heat.

2. Malaria

Malaria causes approximately 2,000 U.S. cases per year — almost all of them imported. Early symptoms often mimic the flu, making malaria easy to overlook. Some strains can be life-threatening within days of symptom onset if untreated.

Travelers to sub-Saharan Africa face the highest malaria risk, although the disease can also be encountered in parts of Asia and Latin America.

• Symptoms: Fever, chills, sweating, headache, and fatigue. Can appear anywhere from 1 week to several months after exposure.
• Prevention: Destination-specific prescription antimalarials, DEET-based repellents, long sleeves and pants after dusk, and bed nets.
• When to seek help: Any fever after travel to a malaria-risk region should be evaluated immediately and treated as malaria until a test rules it out.

3. Dengue fever

Dengue is a mosquito-borne viral infection and one of the fastest-growing travel-related diseases affecting Americans. In 2024, the CDC recorded 3,798 dengue cases, with more than 97% linked to travel, making it a record year. The Caribbean, Mexico, and Central America were among the most common exposure regions for U.S. travelers.

Unlike the mosquitoes that spread malaria, the mosquitoes that spread dengue are most active during the day. That means travelers can be exposed while sightseeing, relaxing at the beach, or eating outdoors. There is no specific antiviral treatment for dengue, so preventing mosquito bites remains the most effective form of protection.

• Symptoms: High fever, severe headache, pain behind the eyes, joint and muscle pain, rash, and nausea. Onset typically 4–10 days after a bite.
• Prevention: EPA-registered repellent worn throughout the day, long-sleeved clothing, and air-conditioned or well-screened accommodation.
• When to seek help: Immediately if fever is accompanied by severe abdominal pain, persistent vomiting, or any signs of bleeding.

4. Typhoid fever

Typhoid is a bacterial infection spread through contaminated food and water, with South Asia carrying the highest risk for U.S. travelers. A growing concern is the rise of extensively drug-resistant strains — particularly in Pakistan, India, and Bangladesh — which can fail to respond to standard antibiotic treatment.

Vaccination is recommended before travel to high-risk destinations, though it isn’t 100% effective. Food and water precautions still matter even for vaccinated travelers.

• Symptoms: Sustained high fever, fatigue, stomach pain, and headache, developing 1 to 3 weeks after exposure.
• Prevention: Typhoid vaccine plus strict food and water hygiene throughout your trip.
• When to seek help: If you develop a persistent fever after traveling to South Asia, Africa, or Latin America, especially if it doesn’t respond to standard fever reducers. Drug-resistant strains make prompt diagnosis and correct treatment particularly important.

5. Measles

Measles is not traditionally thought of as a travel disease, but it’s increasingly relevant — and the numbers are accelerating fast. The U.S. recorded 2,288 measles cases in 2025, the most since 1992. By early June 2026, that figure had already been matched, with 2,030 confirmed cases and the year only half over. If current trends continue, 2026 could become the worst year for measles in the United States in more than three decades — and U.S. health authorities are now warning that the country may lose its measles elimination status, a designation it has held since 2000.

International travel remains one of the primary ways measles is introduced into communities with low vaccination rates. A single imported case landing in an undervaccinated pocket of the population can ignite an outbreak — and with vaccination rates declining nationally, those pockets are growing.

Measles is extraordinarily contagious. It spreads through the air and can survive in a room for up to two hours after an infected person has left.

• Symptoms: High fever, cough, runny nose, red eyes, followed by a distinctive full-body rash.
• Prevention: Two doses of the MMR vaccine. Anyone unsure of their vaccination status should verify before traveling, especially with children.
• When to seek help: As soon as measles is suspected, both for your own care and because the virus spreads so easily that early isolation matters. Complications including pneumonia and encephalitis are rare but serious.

Mosquitoes and Contaminated Water: The Real Risks Behind Most Travel Illnesses

The majority of travel-related infections cluster around just a few transmission routes. Four of the top ten health risks for U.S. travelers are mosquito-borne — dengue, malaria, chikungunya, and Zika — and three more stem from contaminated food or water: travelers’ diarrhea, typhoid, and hepatitis A. This pattern suggests prevention is less about luck and more about consistently following a few key habits: drinking bottled or treated water and using effective mosquito repellent throughout the day in high-risk regions, not just after dark.

The mosquito-borne disease picture is also shifting closer to home. In 2023, the U.S. recorded its first locally acquired malaria cases in 20 years, across four states. A locally acquired malaria case with no travel history was reported in New Jersey as recently as August 2025. And 2024 dengue cases were 359% above the 14-year annual average — a trend researchers link in part to climate change expanding mosquito ranges northward. These diseases remain primarily travel-related risks, but the geographic boundary is shifting.

The Diseases Making Headlines Aren’t Usually the Ones Travelers Catch

Some of the most well-known infectious diseases are also among the least likely to affect typical travelers. Recent global attention on outbreaks such as Ebola, hantavirus, avian influenza, or mpox often creates the impression that these are common travel risks.

In reality, these infections require very specific exposure conditions and remain extremely rare among international tourists. For example:

• Ebola outbreaks are geographically localized and require direct exposure to infected bodily fluids
• Hantavirus infections are typically linked to specific environmental exposures rather than casual travel
• Avian influenza cases are associated with close contact with infected birds or live animal markets

While these diseases are medically serious, they are not representative of the risks most travelers face. This contrast highlights an important point: the diseases that generate the most attention are not necessarily the ones travelers are most likely to encounter.

Where Travelers Face the Greatest Health Risks

Health risks vary significantly by destination, which is why certain regions are highlighted here. Many travel-related infections are more common in tropical and subtropical areas, where climate conditions, mosquito exposure, and sanitation infrastructure differ from higher-income regions.

For that reason, this analysis focuses on the Caribbean and Latin America, sub-Saharan Africa, and South and Southeast Asia. These patterns are not exclusive to the Global South, but they are more consistently observed there compared to destinations such as most of Europe, where the risk of these types of travel-related infections is generally lower.

Sources

[1] ICI: Top Travel Trends to Watch in 2026
[2] CDC: Post-Travel Evaluation of the Ill Traveler | Yellow Book

Methodology

This analysis reviewed CDC travel medicine guidance, travel surveillance data, public health records, and disease-specific research to identify the travel-related illnesses most relevant to U.S. travelers.

Rather than measuring the exact probability of infection, the ranking evaluates which illnesses travelers are most likely to encounter in travel medicine guidance and post-travel clinical settings, while also considering disease severity, available U.S. case evidence, and opportunities for prevention.

Each illness was assessed using four main factors:

• Frequency in travel medicine guidance and returned-traveler surveillance data
• Strength of available U.S. travel-associated evidence
• Potential severity of illness
• Availability of effective prevention measures, including vaccination, medication, and behavioral precautions

The result is a preparedness-focused overview, not a statistical probability ranking. Individual risk depends on destination, activities, trip length, vaccination status, and other personal factors. An in-depth overview of the methodology, sources, and data can be found here.