Americans are being warned about a surge in mosquito-borne dengue cases popping up across the country, raising the risk of a larger nationwide outbreak.
A 'higher-than-expected' number of infections have been recorded in the US this year, with 2,241 cases detected compared to 3,036 over the whole of 2023.
And a record-breaking number of dengue infections have been detectedin the Americaswhere 9.7million people have the virus — double last year's tally.
The World Health Organization says more than 4,000 people have died from the disease this year.
The above map shows the counties that recorded dengue cases between 2020 and 2023
And this shows the number of travelers arriving in the US with a dengue infection from 2010 to 2023. Numbers have ticked up in recent years
The above shows the number of patients who tested positive for dengue despite not traveling outside of the United States
The CDC warned of the uptick in a public health alert released today, saying many infections were linked to travelers returning to the US from countries where the disease is spreading rapidly.
But people are also being infected within the US.
InFlorida, at least six locally transmitted cases -those in people who have not traveled recently - have been recorded and there is an outbreak in Puerto Rico, with an emergency declared in the territory in March as the territory recorded 1,500 infections.
There have also been previous small-scale outbreaks inTexas, Hawaii, Arizona and California.
The CDC's warning comes as a number of previously near-absent tropical diseases begin to make their way back into the US, including malaria — which prompted alerts in Florida last year.
And it was issued just ahead of the upcoming hottest summer months, when warmer weather normally causes dengue cases to spike.
In the alert, CDC officials wrote: 'Global incidence of dengue in 2024 has been the highest on record for this calendar year; many countries are reporting higher-than-usual dengue case numbers.
'US summer travel often overlaps with the months of increased dengue activity in many countries.
'Epidemics in the Americas region increase travel-associated cases and limited local transmission in the continental United States.'
Of dengue cases recorded in the US this year, 745 have been in travelers — or those who tested positive after recently returning from abroad — which was 'higher-than-expected' for this time of year.
The above photos shows symptoms of the dengue rash. About one in four people who are infected suffer from symptoms of the virus, including a rash
The CDC did not reveal which countries people were returning from, but so far this year Brazil has the largest outbreak — with 6million suspected dengue cases — with the situation in the capital, Brasilia, so bad doctors said it was reminiscent to the early days of Covid.
Large outbreaks have also been recorded in Argentina — with 400,000 cases — and Paraguay — with 250,000 — with other cases reported among 90 countries so far this year across all six continents.
Dengue fever cannot be passed from human-to-human, and is instead spread by the bites of infected mosquitoes.
For someone to catch the disease locally, the area's mosquito population has to have picked up the virus — normally via biting an infected person who recently returned to the US from abroad.
It could also be the case that infected mosquitoes have migrated into the area or arrived on boats or airplanes.
Dengue fever is endemic in many countries across the world, with countries in South America, Asia and Africa tending to report a higher number of cases.
Dengue is a potentially deadly virus passed to people by infected mosquitoes and was historically known as 'breakbone fever'
It is transmitted via bites from infected mosquitoes, which transfer the virus into the blood stream of patients.
About one in four people who are infected develop symptoms five to seven days after a bite, including a high fever, rash, muscle aches, joint pain and pain behind the eyes.
This has earned dengue the moniker 'break-bone fever', with sufferers saying their joints and muscles can be so painful it feels like their bones are breaking.
Out of those who develop symptoms, one in 20 suffer from a severe form of the disease, which can cause bleeding, gasping for air and shock.
Thirteen percent of patients die from the disease if they do not receive treatment.
There is no antiviral for dengue fever — or drug to attack the virus, but the World Health Organization says that by rapidly replacing lost fluids the mortality rate drops to less than one percent.
A vaccine for dengue is available and approved by the FDA for children aged nine to 16 years old, but its manufacturer — French pharma giant Sanofi Pasteur — has discontinued production globally, citing a lack of demand.
Doses are available in Puerto Rico, but these are expected to run out by 2026.
Dengue cases have surged in Latin America, thought to be linked to the El Nino weather cycle at that time — which brings more heavy rains to areas of the continent— leading to more standing water in which mosquitoes can multiply.
At the same time, rising temperatures have allowed mosquitoes to be active for longer each year and advance further north.
In areas of the world where outbreaks are not as common, upticks are being linked in part to travel, leading to people who become infected abroad to enter the US then get bitten by a mosquito, which passes the virus to the insect and allows it to take root in the local mosquito population.
In Florida, where cases are being recorded in people who have not traveled abroad, residents are being urged to empty any vessels containing standing water that they have near their home as these are breeding grounds for mosquitoes.
The CDC also recommended people take action to prevent mosquito bites, including via wearing insect repellant or long pants and shirts.
Emma Cox, 27, is one of those to report suffering from dengue fever. She had traveled to Indonesia, but 10 days after returning to the UK, she developed symptoms
Ms Cox had been in Indonesia for just 10 days before coming down with dengue
For doctors, officials urged them to have an 'increased suspicion of dengue' among patients who had recently returned from a country with an outbreak.
Physicians were also urged to order appropriate diagnostic tests for the disease and to quickly report any new patients to state and national authorities.
It is normally tested for via a PCR test done on nasal swabs or blood samples. Other methods include an antibody test.
One young UK resident, Emma Cox, 27, became infected with dengue fever while on a trip to Indonesia, but originally attributed her symptoms to the flu.
On day five of her 'dream' trip to Bali, she explained how she began to suffer from muscle and joint pain and a headache that was so severe she had to wear sunglasses while indoors.
On day ten, the pain became so bad that she booked an emergency flight back home.
Shortly after landing in the UK, she then developed a full-body rash and went to the ER — where doctors diagnosed her with dengue fever.
'The virus gave me a rash that spread right across my body — I felt horrendous, and thought it wasn’t ever going to go away,' she said.
Ms Cox said there had been a hole in her hotel room window in bali and that she would wake up with mosquito bites covering her body every morning.
