Czechia is facing a sharp rise in Legionnaires’ disease, with health officials warning that this year’s infection count will likely surpass last year’s record-breaking numbers.

In just the first quarter of 2025, over 200 cases of legionellosis—an illness caused by the Legionella bacteria—have already been confirmed. That’s twice as many as in the same period last year.

According to Novinky.cz, the country recorded 620 cases in 2024, the highest annual total to date. A year earlier, there were 342. The longer-term trend is clear: in 2019, there were 280 recorded cases; a decade ago, just 25.

Legionnaires’ disease can be fatal. Last year, at least 50 people died from the illness, which mainly threatens seniors and individuals with weakened immune systems.

“And their numbers are growing,” said epidemiologist Roman Chlíbek. “Consider how many patients now suffer from immune deficiencies or cancer.”

The illness is caused by inhaling water droplets contaminated with Legionella bacteria. Symptoms often resemble the flu at first—fever, headache, muscle pain, and fatigue, followed by a worsening cough. If untreated, the bacteria can spread in the lungs and lead to severe pneumonia. Early antibiotic treatment is crucial.

A Plumbing Problem—and More

Experts believe poor maintenance of water systems is largely behind the surge. This includes old or neglected pipes, unmaintained faucets or shower hoses, and heat exchangers. Air conditioning systems and improperly heated water in boilers also contribute—especially as many households reduce water heating to cut energy bills.

“Legionella is highly adaptable and survives well in warm water,” Chlíbek explained. Hot water should reach at least 50°C, while cold water must stay under 20°C to limit bacterial growth.

“Water temperatures below 50°C allow Legionella to thrive,” confirmed Hana Bendíková, head of the anti-epidemic department at the South Bohemian Hygiene Station. “In many homes, the hot water only reaches 30 to 40°C.” Her region has reported 29 cases this year.

The Czech Republic isn’t alone. Australia, the United States, and Spain also reported elevated case numbers last year, highlighting that this is not just a Czech plumbing issue.

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