The disease typically affects those 65 and older and those with underlying health conditions. Symptoms usually surface in two to 10 days, and the disease is spread when contaminated water droplets from faucets, humidifiers, air-conditioning systems or other sources are inhaled, health officials said. It is not spread from person to person.
Interim Baltimore Health Commissioner Olivia Farrow said officials might never learn the source of the bacteria. She said officials are conducting interviews to determine the links among the victims - four residents and a visitor. She said they were spread among two buildings in the four-building complex but did not identify them.
The state also will likely soon begin testing water sources for high levels of Legionella. The bacteria is ubiquitous, she said, and some probably would be found in many samples.
She was not advising residents to move out or change any habits. Neither was she advising the neighboring YMCA, a popular gathering spot, to make any changes.
"We find Legionella in water generally, and most people don't become ill from it," she said. "We'll try and find a common source where levels are high."
In the meantime, officials are advising residents who have symptoms to seek medical attention because the disease is highly treatable with antibiotics. Symptoms include high fever, chills, dry cough, shortness of breath, muscle aches, diarrhea, fatigue, headache and abdominal pain.
The federal Centers for Disease Control and Prevention reports that 8,000 to 18,000 people are hospitalized with Legionnaires' each year, though many infections are not diagnosed so the number might be higher. The disease is typically more common in summer and early fall. Between 5 percent and 30 percent of those who fall ill die of the disease, according to the CDC.
Thirty-one cases were reported to the Baltimore Health Department in 2008 and 25 so far this year.
Stadium Place, on 33rd Street, was built in 1999 by the Govans Ecumenical Development Corp. It provides rental housing for low- and moderate-income seniors.
Mitchell Posner, executive director of the nonprofit developer, said managers have been following all directives from the city and state since the first resident fell ill. The other cases were confirmed Wednesday, he said.
