Earlier this year, the CDC issued a global travel notice for multiple countries over spiraling outbreaks of a mosquito-borne disease that can cause brain bleeds.
The level 1 travel advisory was issued after detecting unusual upticks in cases of dengue fever across the world.
In particular, the CDC warned of 16 countries where travelers have an increased risk of contracting the illness, warning them to take precautions to prevent mosquito bites.
Now, a new report from the agency shows there was a 359 percent rise in average annual dengue cases in the US in 2024 compared to the 2010-2023 annual average.
In 2024, the most recent data available in the report, a record 3,798 dengue fever cases were reported, an increase from the average of 828. Among the cases, 97 percent were travel-associated and the remaining three percent – 105 cases – were locally acquired.
Among all the patients, 36 percent were hospitalized and three percent of cases were severe. There were six deaths.
Cases peaked from July to September and Americans aged 50 to 59 made up the largest share of patients – 22 percent.
Travel-associated cases primarily stemmed from the Caribbean, accounting for 34 percent of cases, including the US territories Puerto Rico and the US Virgin Islands.
The CDC report said: ‘The sharp increase in travel-associated dengue highlights an urgent need for enhanced prevention strategies, improved clinical awareness, and tailored messaging for travelers to areas with ongoing dengue transmission.’
Travel-associated cases of dengue fever primarily stemmed from the Caribbean, including the US territories Puerto Rico (pictured above) and the US Virgin Islands
Dengue fever is spread when a person is bitten by an infected Aedes aegypti mosquito (pictured above). In some patients, it can trigger life-threatening health complications
The global dengue travel advisory is continuously updated and the countries currently on the list as reporting higher than usual number of the infection are Bangladesh, Bolivia, Colombia, Cook Islands, Guyana, Maldives, Mali, New Caledonia, Samoa, Somalia, Timor-Leste and Vietnam.
Dengue is present in more than 100 countries globally and is a year-round threat to travelers and local residents in high-risk countries.
A level 1 travel advisory urges Americans to practice usual precautions because of the presence of an outbreak.
It is the lowest level travel alert out of the four levels that can be issued. Level four is advice to avoid all travel.
Dengue fever, spread when a person is bitten by an infected Aedes aegypti mosquito, often causes an asymptomatic infection, but in some patients it can trigger life-threatening internal bleeding, respiratory distress and heart failure.
It can also lead to shock and organ failure, especially of the liver, brain and heart.
Patients may also develop dengue shock syndrome, a condition where severe bleeding leads to a rapid drop in blood pressure and causes the body to go into shock.
The above shows travel-associated dengue cases by region and month of illness for 2024
Children under five, adults over 65 and pregnant women are considered to be most at risk from the virus.
Dengue was virtually eradicated from the US in the 1970s, but sporadic outbreaks have been recorded since, particularly in warmer states, including Florida and California. Most cases recorded in the US are linked to international travel.
According to the CDC report, 24 percent of cases stemmed from North America and nearly 16 percent were from travel to Central America.
The report stated: ‘These findings underscore the urgent need for enhanced prevention strategies, clinical awareness, and tailored public health messaging for travelers to areas where dengue is endemic.’
The rise in travel-associated cases, the CDC continued, could result in higher risk for local transmission in parts of the US that do not typically see dengue.
The report found that the highest number of dengue cases in 2024 occurred in Florida, which saw 1,044 cases. This was followed by California with 720 cases, New York with 338 and Texas with 241.
A dengue fever rash (pictured above) typically appears two to five days after the onset of a high fever
Locally acquired dengue fever cases were reported in Florida, California and Texas. Florida recorded 85, California had 18 and Texas had two.
Health officials say about 40 to 80 percent of people infected with dengue fever do not develop any symptoms. If symptoms do develop, they appear abruptly about five to seven days after infection.
Warning signs include a fever above 100F (38C), severe headache, pain behind the eyes, bone, joint or muscle pain, and bleeding in the gums.
Some patients also develop a rash several days after experiencing a high fever.
In severe cases, patients may also suffer from severe abdominal pain, persistent vomiting and lethargy.
There is no specific cure for dengue fever and treatment consists of supportive care and therapies to manage symptoms and complications.
Doctors recommend patients with mild symptoms drink plenty of fluids and take Tylenol to ease pain.
In severe cases, patients may be admitted to the hospital for supportive care, an IV, blood pressure monitoring and a transfusion to replace lost blood.
To protect against dengue fever, there is a three-dose vaccine available, which is recommended for children aged nine to 16 years. It slashes the risk of a symptomatic infection by about 80 percent.
