Four men have died and 150 people hospitalized in the central Sverdlovsk region in an outbreak of Legionnaires' disease spread by tap water, television reported.
An elderly man died early Wednesday in the town of Upper Pyshma, becoming the fourth victim of pneumonia caused by the legionella bacteria, Russian NTV channel said.
Since July 20 at least 131 people have been diagnosed with the disease in the Ural mountain region, about 1,500 kilometers (900 miles) east of Moscow. Dozens of other people have been hospitalized in the area with less dangerous forms of pneumonia as a precaution, NTV said.
Legionnaires' disease is a form of pneumonia named after a deadly outbreak of the disease at an American Legion convention in Philadelphia in 1976. Most people infected with the bacteria never get sick, but elderly people and those with weak immune systems can be susceptible. The disease is treatable with antibiotics.
The bacteria that causes the disease was found in warm tap water, Russia's chief epidemiologist Gennady Onishchenko said, speaking on Russia's Vesti television.
Onishchenko said authorities have started to heat municipal tap water to 70 degrees Celsius (158 degrees Fahrenheit) to kill the bacteria. He added that no cases have been reported in other Russian cities.
Russia's utilities infrastructure, built in the Soviet era, needs major renovation and sometimes poses threats to public health and safety.
The legionella bacteria can spread through air from a soil or water source. The elderly, smokers and people with lung disease are at higher risk of suffering the disease.