Changing epidemiological trends of legionellosis in New Zealand, 1979–2009

Abstract

SUMMARYThis study evaluated the spatio-temporal variation of Legionella spp. in New Zealand using notification and laboratory surveillance data from 1979 to 2009 and analysed the epidemiological trends. To achieve this we focused on changing incidence rates and occurrence of different species over this time. We also examined whether demographic characteristics such as ethnicity may be related to incidence. The annual incidence rate for laboratory-proven cases was 2 . 5/100 000 and 1 . 4/100 000 for notified cases. Incidence was highest in the European population and showed large geographical variations between 21 District Health Boards. An important finding of this study is that the predominant Legionella species causing disease in New Zealand differs from that found in other developed countries, with about 30-50% of cases due to L. longbeachae and a similar percentage due to L. pneumophila for any given year. The environmental risk exposure was identified in 420 (52 %) cases, of which 58 % were attributed to contact with compost ; travel was much less significant as a risk factor (6 . 5 %). This suggests that legionellosis has a distinctive epidemiological pattern in New Zealand.

Soil as a source of Legionella pneumophila sequence type 47

“…8,9 The transmission of L. pneumophila from soil to humans has also been described. 10 Natural soil as a source of pathogenic Legionella bacteria causing human infections warrants further investigation.…”

Knowledge to Predict Pathogens: Legionella pneumophila Lifecycle Critical Review Part I Uptake into Host Cells

“…L. longbeachae has been shown to have enzyme systems that may assist in the degradation of plant material, possibly explaining its soil harbor [55]. Epidemiological patterns of legionellosis differ in these regions too; studies have shown that more than 50% of confirmed cases in New Zealand and Australia were a result of contact with compost [56,57].…”

Atypical Pneumonia

“…Rainfall, high humidity, and work in gardens with compost are risk factors for acquiring Legionella disease. 5–7 Most of the cases of legionnaires’ disease are associated with Legionella pneumophila , but many other bacterial species have been found to cause Legionella lung infections. 7,8 …”