Legionellosis in Poland in 2015

The aim of the study was to assess the epidemiological situation of legionellosis in Poland in 2015 in comparison to the preceding years.

We reviewed data published in the annual bulletin: “Infectious diseases and poisonings in Poland in 2015” and its prior versions along with the legionellosis case reports sent from Sanitary- Epidemiological Stations to the Department of Epidemiology of NIPH - NIH.

In Poland, both two forms of legionellosis - Legionnaires’ disease (a severe form of disease accompanied by pneumonia) and Pontiac fever (mild, influenza-like form of infection) - are notifiable. In 2015, a total of 23 cases of Legionnaires’ disease have been reported (there were no reports of Pontiac fever). The annual incidence rate 0.060 (per 100,000 population) slightly increased when compared to previous year as well as to the median (incidence) for 2009-2013. The infections were reported in 10 provinces, including five, which in previous years usually did not register any cases; however, there is a number of provinces that did not identify any LD cases in recent years. The incidence in males (0.097 per 100,000) was almost 4-times higher compared to females (0.025). Except for one cluster of two, all cases were sporadic; All patients required hospitalization. The Sanitary Inspection reported four fatal cases – all men 43- 67 years/old. Eighteen cases were likely acquired in the country, including a cluster of two cases linked with contaminated building water system. Four cases were associated with travels abroad (to Russia, Croatia, United Arab Emirates and USA) and in one case the exposure occurred during the transport of goods (lorry driver).

This study suggests, that legionellosis is likely under recognized and under diagnosed in all provinces of the country. Geographical variations in incidence may reflect local differences in availability of laboratory tests for LD. Number of detected cases - without information on the number of laboratory tests performed - do not appear to be sufficient to fully assess the epidemiological situation.