This article is a summary based on: Morphaki, C., Mellou, K., Tsivola, C. et al. “Associations between meteorological conditions and Legionnaires’ disease reported incidence in Greece: a 17-year time-series analysis.” BMC Infectious Diseases (2026). Published under CC BY-NC-ND 4.0. Read the original study: https://doi.org/10.1186/s12879-026-14258-7
Legionnaires’ disease has been on the rise worldwide, and researchers have long suspected weather plays a role. A new study looked at whether that link holds true in Greece, where data on the subject has been scarce until now.
Researchers examined weekly case data collected across Greece from 2008 through 2024, drawing on national disease-reporting systems and a European surveillance network for the illness. They left out cases tied to healthcare settings, infections picked up outside the country, and cases where the exposure location couldn’t be pinned to a single region. They paired this with weather records covering temperature, rainfall, humidity, and wind, along with population and tourism figures from Greece’s statistics agency. The country was split into four climate zones for comparison, and the team used statistical models built to handle irregular case counts, plus a more advanced modeling approach that could capture delayed effects on the disease’s spread.
In total, the study covered 1,180 cases. Nationally, reported cases climbed steadily year over year, with a pronounced spike each summer. Heavier weekly rainfall tracked closely with more cases, and the combination of temperature and humidity mattered too: risk climbed most when humidity sat in a moderate range and temperatures fell between about 63 and 75°F (17-24°C). The more advanced modeling revealed that heat’s effect on case numbers wasn’t immediate, it built over time and peaked roughly six weeks after a stretch of very hot weather (around 86°F/30°C), nearly doubling the odds of illness. Regionally, the temperature-humidity effect showed up most strongly in the western and southern parts of the country.
The takeaway: wet weather and certain heat-humidity combinations are tied to Legionnaires’ disease activity in Greece, and the relationship varies by region. Because hot spells appear to raise risk weeks later rather than right away, health officials may be able to use weather forecasts to anticipate and target prevention efforts during the riskiest stretches of the year, especially as the climate continues to shift.
This article is a summary based on: Morphaki, C., Mellou, K., Tsivola, C. et al. “Associations between meteorological conditions and Legionnaires’ disease reported incidence in Greece: a 17-year time-series analysis.” BMC Infectious Diseases (2026). Published under CC BY-NC-ND 4.0. Read the original study: https://doi.org/10.1186/s12879-026-14258-7
