Europe is experiencing its first sustained transmission of dengue fever that has infected more than 1,300 people, says an EU agency.
The Portuguese health ministry reported 1,357 cases as of November 11, 669 of which were laboratory confirmed and 688 were probable cases, the Stockholm-based European Centre for Disease Prevention and Control (ECDC) said in a statement issued late Tuesday.
Some 25 patients from mainland Portugal, Britain, Germany, France and Sweden have been diagnosed with dengue after returning home from visits to the Portuguese island, the ECDC added.
No deaths have been recorded, it said, but stressed that given the high number of visitors to Madeira, among other things, "the outbreak is large and constitutes a significant public health event."
Dengue is spread by one of four viruses transmitted by the Aedes aegypti mosquito. It causes high fever, headaches, itching and joint pains. At an advanced stage it can lead to haemorrhaging and death.
The Aedes aegypti mosquito which carries the disease has been present on Madeira since at least 2005, the agency said, and the first two cases of dengue fever were reported among residents on October 3.
The ECDC said the outbreak was still ongoing, and recommended residents and travellers visiting the island to take "individual protective measures", such as using mosquito repellent, to avoid mosquito bites. Dengue is transmitted by a daytime mosquito.
It also urged aircraft, airports and ports in Madeira to continue disinfection procedures.
"With tourists visiting Madeira, continued import of dengue cases from the island to other EU countries is to be expected until the mosquito population is decreased and transmission interrupted," the ECDC said.
According to the UN's World Health Organisation, between 50 and 100 million dengue infections occur each year in more than 100 countries. In 1970, the disease was endemic in just nine countries.