Americans are being warned of a rise in mosquito-borne dengue cases across the country, raising the risk of a larger nationwide outbreak.
This year, the US has recorded a ‘higher than expected’ number of infections, with 2,241 cases detected, compared to 3,036 in all of 2023.
And a record number of dengue infections have been identified in America, where 9.7 million people have the virus – double last year.
More than 4,000 people have died from the disease this year, according to the World Health Organization.
The map above shows the provinces where dengue cases were recorded between 2020 and 2023
And this shows the number of travelers who arrived in the US between 2010 and 2023 with a dengue infection. The numbers have increased in recent years
The above shows the number of patients who tested positive for dengue despite not traveling outside the United States
The CDC warned of the public health upswing 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 becoming infected within the US.
At least six locally transmitted cases have been recorded in Florida – among people who have not recently traveled – and there is an outbreak in Puerto Rico, with an emergency declared in the area in March as the area recorded 1,500 infections.
There have also been previous small-scale outbreaks in Texas, Hawaii, Arizona and California.
The CDC’s warning comes as a number of previously virtually absent tropical diseases begin to make their way back to the US, including malaria – which prompted warnings in Florida last year.
And it was issued just ahead of the upcoming hottest summer months, when warmer weather normally causes dengue cases to rise.
In the alert, CDC officials wrote: “The 2024 global incidence of dengue was the highest ever recorded for this calendar year; many countries are reporting higher than normal numbers of dengue cases.
“Summer travel in the US often overlaps with the months of increased dengue activity in many countries.
“Epidemics in the Americas region are increasing travel-related cases and limiting local transmission in the continental United States.”
Of the dengue cases recorded in the US this year, 745 were among travelers – or among those who tested positive after recently returning from abroad – which was “higher than expected” for this time of year.
The above photos show symptoms of the dengue rash. About one in four people who are infected experience symptoms of the virus, including a skin rash
The CDC did not reveal which countries people were returning from, but Brazil has had the biggest outbreak so far this year – with 6 million suspected cases of dengue – with the situation in the capital Brasilia so bad doctors said it was reminiscent of the early days of the disease. Covid.
Major outbreaks have also been recorded in Argentina – with 400,000 cases – and Paraguay – with 250,000 – while other cases have been reported in 90 countries on all six continents so far this year.
Dengue fever cannot be transmitted from person to person, but is instead spread through the bites of infected mosquitoes.
For someone to contract the disease locally, the area’s mosquito population must have picked up the virus — normally through biting an infected person who has recently returned to the U.S. from abroad.
It is also possible that infected mosquitoes have migrated to the area or arrived by boat or plane.
Dengue fever is endemic in many countries around the world, with countries in South America, Asia and Africa typically reporting a higher number of cases.
Dengue is a potentially deadly virus transmitted to humans by infected mosquitoes and was historically known as ‘breakbone fever’
It is transmitted through bites from infected mosquitoes, which transmit the virus into the bloodstream of patients.
About one in four people who are infected develop symptoms five to seven days after a bite, including high fever, rash, muscle aches, joint pain and pain behind the eyes.
This has earned dengue the nickname ‘breaking fever’, with sufferers saying their joints and muscles can be so painful that it feels like their bones are breaking.
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 drug for dengue fever – or drug to attack the virus, but the World Health Organization says quickly replacing lost fluids reduces the mortality rate to less than one percent.
A dengue vaccine is available and approved by the FDA for children aged nine to 16, but its manufacturer – French pharmaceutical giant Sanofi Pasteur – has halted production worldwide due to a lack of demand.
There are doses available in Puerto Rico, but they are expected to run out in 2026.
The number of dengue cases has increased dramatically in Latin America. This is thought to be related to the El Nino weather cycle of the time – which brings more heavy rains to parts of the continent – leading to more standing water in which mosquitoes can breed.
At the same time, rising temperatures have caused mosquitoes to be active longer each year and to advance further north.
In areas of the world where outbreaks are not as common, the increases are partly linked to travel, which means people who become infected abroad to enter the US are then bitten by a mosquito, which carries the virus passes to the insect and allows it to take root in the local mosquito population.
In Florida, where cases are recorded in people who have not traveled abroad, residents are urged to empty any barrels of standing water near their homes as they are breeding grounds for mosquitoes.
The CDC also recommended that people take action to prevent mosquito bites, including wearing insect repellent or long pants and shirts.
Emma Cox, 27, is among those suffering from dengue fever. She had traveled to Indonesia but developed symptoms ten days after returning to Britain
Ms Cox was in Indonesia for just ten days before contracting dengue
Doctors urged them that there would be a ‘heightened suspicion of dengue’ among patients who had recently returned from a country with an outbreak.
Doctors were also urged to order appropriate diagnostic tests for the disease and to promptly report new patients to state and national authorities.
Normally it is tested via a PCR test on nasal swabs or blood samples. Other methods include an antibody test.
A young British resident, Emma Cox, 27, became infected with dengue fever during a trip to Indonesia, but initially attributed her symptoms to the flu.
On the fifth day of her ‘dream trip’ to Bali, she explained that she was experiencing muscle and joint pain and headaches. The headache was so severe that she had to wear sunglasses indoors.
On day ten the pain became so bad that she booked an emergency flight home.
Shortly after landing in Britain, she developed a rash all over her body and went to the emergency room – where doctors diagnosed her with dengue fever.
‘The virus gave me a rash that spread all over my body. “I felt terrible and thought it would never go away,” she said.
Ms Cox said there was a hole in the window of her hotel room in Bali and she woke up every morning with mosquito bites covering her body.