BARCELONA, Spain - Investigators were scouring ventilation and water systems for the source of bacteria that has infected at least 33 people with Legionnaires' disease, health officials said Thursday.
At least four of the victims, who had already suffered from other health problems, are in serious condition, said Joan Guix, director of Barcelona's Health Department.
The other 29 have been in the hospital under observation since the infections were discovered over the past three days.
All of the victims, whose ages range between 49 and 92, live in the 19th century fishing neighborhood of Barceloneta, an area predominantly inhabited by elderly people on Barcelona's Mediterranean waterfront.
Apart from living in the same area of Spain's second largest city, the infected have no lifestyle habits in common to help fin the source of the disease, city health officials said.
Chemical analyses of several air-conditioning water towers in the neighborhood were being carried out Thursday and water samples from cooling systems on top of hotels, office and residential buildings being checked.
Rose Garriga, spokeswoman of Barcelona City Hall, said results won't be release for several days.
"What we know right now is that there hasn't been a reported case since Wednesday night," Garriga said.
Legionnaires is an acute respiratory infection caused by bacteria that may contaminate water or soil. It is named for an outbreak of the illness during an American Legion convention in Philadelphia in 1976 in which 34 died.
The disease is not contagious. Symptoms include high fever, cough and shortness of breath and both elderly and people with weak health conditions are most at risk for suffering the consequences of this disease.
Disinfecting with chlorine or heat usually kills the bacteria.