CDC Warns Travelers of Dengue Surge in 11 Nations

CDC Flags Rising Dengue Activity in 11 Countries as 2026 Cases Begin to Climb

ATLANTA, United States — The brief reprieve is over. After a dip in global dengue cases through 2025, the mosquito-borne virus is surging again across multiple continents, and U.S. travelers are already feeling the impact. On January 22, 2026, the Centers for Disease Control and Prevention updated its Global Dengue Travel Health Notice, identifying eleven countries with elevated transmission or a notable uptick in cases among Americans returning from those destinations. The list includes Afghanistan, Bangladesh, and Colombia, alongside eight additional nations spanning the Americas, Asia, Africa, and the Pacific. For travelers heading into tropical zones this winter and spring, the message is unambiguous: dengue is back, and the 2026 season is shaping up to mirror the cyclical outbreaks that hit every two to five years.

The Pattern Returns

Dengue doesn't disappear; it recedes and resurges. Transmission follows predictable cycles tied to rainfall, temperature, urbanization, and mosquito breeding patterns. The 2025 slowdown offered a false sense of security for some regions. Now, as wet seasons begin in the Southern Hemisphere and travelers flock to Caribbean, Central American, and Southeast Asian destinations, the virus is re-establishing itself in corridors that saw lower activity just months ago. The CDC's notice, posted through its Travelers' Health platform, reflects real-time surveillance data. The eleven flagged countries aren't abstract warnings; they represent places where dengue is actively circulating at levels high enough to trigger concern among public health officials tracking case importation into the United States. Early 2026 numbers underscore the shift. Three dengue cases were reported in January among individuals who had traveled internationally, according to Vax-Before-Travel News. That's a small figure, but it's a leading indicator. In 2025, 429 dengue cases were documented among U.S. travelers who had been abroad. Of those, 311 cases traced back to Cuba, and 21 originated in Puerto Rico. Cuba's dominance in that tally isn't surprising. The island has struggled with dengue for years, compounded by infrastructure decay, inconsistent vector control, and limited resources for mosquito abatement. Puerto Rico, meanwhile, remains a persistent transmission zone despite its U.S. territory status. Both destinations continue to draw American travelers, many of whom underestimate the risk or skip preventive measures entirely.

What Elevated Activity Actually Means

When the CDC flags a country for "higher-than-usual dengue activity," it's synthesizing multiple data streams: local health ministry reports, WHO surveillance, traveler case histories, and hospital admission trends. The designation signals that conditions on the ground favor transmission. That could mean an active outbreak, sustained case counts above baseline, or clusters tied to specific regions within a country. For travelers, the practical takeaway is straightforward: mosquito exposure equals risk. Dengue is transmitted by Aedes aegypti and Aedes albopictus mosquitoes, which bite primarily during daylight hours, especially early morning and late afternoon. Unlike malaria-carrying mosquitoes that emerge at dusk, dengue vectors are active when travelers are out exploring, eating at open-air cafes, or walking through urban markets. There's no vaccine widely available for first-time visitors. Dengvaxia exists but is restricted to individuals with documented prior dengue infection due to the risk of severe disease in those never exposed. That leaves prevention as the only viable strategy: DEET-based repellents, long sleeves and pants treated with permethrin, and accommodations with screened windows or air conditioning.

The Geographic Spread

The eleven countries cited span four regions, reflecting dengue's expansive footprint. Afghanistan and Bangladesh anchor the list in South Asia, where monsoon rains and dense urban populations create ideal breeding conditions. Colombia represents Latin America, a region that has battled dengue for decades and where El Niño and La Niña cycles directly influence transmission intensity. The remaining eight nations, while unnamed in this notice, likely include familiar hotspots: Mexico, Brazil, the Philippines, Thailand, and others with endemic transmission and tourism infrastructure that draws millions of travelers annually. The Pacific island nations, particularly those with limited healthcare capacity, also face recurring surges tied to seasonal weather and inter-island travel. Africa's inclusion is notable. Dengue is underreported across much of the continent due to limited diagnostic capacity and overlap with malaria symptoms, but surveillance has improved. As African destinations gain traction among adventure and safari travelers, dengue exposure is becoming a more recognized risk, particularly in East Africa and island nations like Mauritius and Seychelles.

What Travelers Should Do Now

If you're traveling to any of the eleven flagged countries or other tropical destinations in the coming months, prevention isn't optional. Pack EPA-registered insect repellent with at least 20% DEET, picaridin, or oil of lemon eucalyptus. Treat clothing and gear with permethrin before departure. Stay in accommodations with intact window screens or air conditioning, and eliminate standing water around your lodging. Dengue symptoms hit hard: high fever, severe headache, joint and muscle pain, nausea, and rash. Most cases resolve with supportive care, but severe dengue can lead to plasma leakage, internal bleeding, and shock. There's no antiviral treatment. If you develop symptoms within two weeks of returning home, seek medical attention immediately and disclose your travel history. For photographers, journalists, and expedition travelers working in remote or rural areas within these countries, the risk amplifies. Extended outdoor exposure, limited access to repellent, and proximity to standing water increase bite probability. Plan accordingly. Dengue outbreaks are cyclical, but they're not inevitable for individual travelers. The virus spreads through mosquito bites, not person-to-person contact. With consistent prevention, the risk drops sharply. The CDC's updated notice exists to give you the intelligence you need to make informed decisions. Use it.