British tourists have been given a fresh warning about the spread of “bone-breaking fever” in Ibiza.
Two cases of dengue fever believed to have been contracted locally have raised concerns that the virus is spreading undetected.
Experts fear dozens more could become ill, and warn that mosquitoes carrying the disease are abundant in April.
Dengue, which gets its nickname from the agonizing pain it inflicts on sufferers, is typically found in tropical parts of the world, such as parts of Africa, Asia and South America.
It is estimated to infect about 400 million people a year and kill about 40,000.
The Balearic island, famous for its raucous parties and sun-drenched beaches, attracts millions of tourists each year. Neither case was shown to be locally acquired, the researchers wrote in the journal Euro Surveillance. But evidence suggests they were both, according to the team.
The stinging insect, which feeds during the day, has already spread across much of Europe in recent years, including France, Spain and Italy, as warmer conditions have helped it travel alongside humans or via the transportation of goods.
WHO bosses say it poses a “pandemic threat”.
Virologists say citizens should be aware of the possible spread of dengue in Ibiza.
The Balearic island, famous for its raucous parties and sun-drenched beaches, attracts millions of tourists each year.
Neither case was shown to be locally acquired, the researchers wrote in the Euro surveillance diary.
But evidence suggests they both were, according to the team.
The two cases of German tourists traveling separately occurred in 2022.
Positive laboratory tests confirmed the disease in 2023, which made headlines at the time.
The researchers did not record the patient’s name or age. But local reports at the time said they were between 20 and 30 years old.
In issuing the new alert, experts noted that the first, who visited the island for a week in August, developed symptoms synonymous with the infection (fever, rash and joint pain) the day they returned to Germany.
The patient recorded a positive dengue test result eight days later.
One of his traveling companions also experienced a fever and runny nose. Another suffered a sore throat, runny nose and joint pain.
Neither of them underwent testing as they did not require healthcare.
The second case traveled from Germany to the same town in Ibiza, at the beginning of October, for just under three weeks.
They developed similar symptoms the day after returning home, and a positive test was confirmed five days later.
Two traveling companions of the family also reported signs of infection days later.
However, once again they did not undergo diagnostic testing.
But the family admitted to suffering mosquito bites in their accommodation on the island.
The second case had also spent two weeks in a “dengue endemic country” before heading to Ibiza.
In an article in the journal, experts said evidence suggests that “the most likely transmission was through mosquito bites, but other possibilities cannot be totally excluded.”
They added: ‘Although the source case claimed that they had not been bitten by mosquitoes and that they had spent the entire symptomatic period at home, it is possible that the bites went unnoticed.
«The lack of detection of additional cases among Ibiza residents, especially during the time interval between the two German cases, suggests that some cases probably related to this outbreak may have gone undetected.
“It is very important to increase awareness about the detection of dengue cases in Spain and other European countries.”
Dengue has caused disease outbreaks throughout history; the first known to have occurred in 1635 in the West Indies.
It arrived in Europe in 2010 and was first detected in Ibiza in 2014.
The latest data from the European Center for Disease Prevention and Control (ECDC) shows that 71 cases of locally acquired dengue were reported in 2022, 65 of them in France and six in Spain.
Experts fear dozens more could become ill, and warn that mosquitoes carrying the disease are abundant in April. Dengue, nicknamed “breakbone fever” because of the agonizing pain it inflicts on sufferers, is typically found in tropical parts of the world, such as parts of Africa, Asia and South America.
The figure is equivalent to the total reported in the previous decade.
Some people infected with dengue do not develop symptoms. But in those who do, they usually begin between four and ten days after being bitten by an infected mosquito.
They include fever, severe headache, pain behind the eyes, muscle and joint pain, feeling sick and unwell, and a blotchy rash made up of raised spots.
Most people recover without treatment within a few days.
However, some develop a severe form of the disease. This can cause stomach pain, repeated vomiting, rapid breathing, bleeding gums or nose, and extreme tiredness.
Although there is no treatment, the sick remain in the hospital until they recover. It is recommended to rest, drink plenty of fluids and take paracetamol.
Dengue is one of a number of diseases that experts have warned will eventually take hold in Britain thanks to climate change making the UK more hospitable to its carriers.
Transmission of the virus, as opposed to imported cases, has become a growing health problem in Europe as it moves north from the tropics.