An outbreak of Legionnaires' disease has killed five people and infected more than 230 others in Portugal, the authorities there say.
Most of the cases have been in Vila Franca de Xira, a town about 25km (16 miles) north-east of Lisbon.
The World Health Organisation (WHO) says the outbreak constitutes a "major public health emergency".
Legionnaires' disease is a pneumonia-like lung infection caused by the legionella bacteria.
The source of the outbreak is yet to be found. Local media report that the bacteria has been discovered in a cooling tower in Vila Franca de Xira, but it is thought there may be other sources.'Unusual and unexpected'
Thirty-eight people are being treated in intensive care, officials say. Facilities in many of the capital's hospitals were stretched because of the outbreak, Portuguese media reported.
"This is the biggest Legionnaire's disease (outbreak) in Portugal and is considered a major public health emergency," WHO spokesman Christian Lindmeier said.
The outbreak was "unusual and unexpected", Mr Lindmeier added.
Portuguese President Anibal Cavaco Silva has expressed his condolences to the victims. He said the public should trust the health authorities to deal with the outbreak.
Legionnaires' disease is caught by inhaling infected water. The bacteria can grow in cooling towers, air conditioning and other artificial water supply systems.
It mostly affects people aged over 50, with those already in poor health most at risk.
It was first identified in the US in the 1970s following an outbreak at a hotel hosting a veteran organisation known as the American Legion.