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Influence of climate and geography on the occurrence of Legionella and amoebae in composting facilities.

Conza L, Casati Pagani S, Gaia V - BMC Res Notes (2014)

Bottom Line: A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146).A general decrease in the presence and variety of species was observed with decreasing compost storage time length.The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

View Article: PubMed Central - PubMed

Affiliation: Swiss National Reference Centre for Legionella, Bellinzona, Switzerland. lisaconza@gmail.com.

ABSTRACT

Background: The incidence of Legionnaires' disease (LD) in southern Switzerland is three times higher than in northern Switzerland. Climatic and geographic factors may be potential causes for this difference.We studied the prevalence of Legionella and free-living amoebae (FLA) in compost and bioaerosol in two Swiss regions to understand the role of climate and geography in the transmission of LD. We also tried to investigate whether or not compost storage duration would influence the composition of Legionella and FLA communities.

Results: A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146). FLA were isolated from composts in northern facilities at slightly higher rates (88.2% vs. 69.2%) and at lower rates from bioaerosols (6.3% vs. 13%) than in southern Switzerland. The diversity of FLA was higher in northern than in southern Switzerland (80% vs. 65%). A general decrease in the presence and variety of species was observed with decreasing compost storage time length. A discriminant model showed that values of vapour pressure, relative humidity and temperature distinguish the two regions, which were also characterised by different contamination rates by FLA and Legionella.

Conclusions: The duration of outdoor storage may favour contamination of the compost by Legionella, and may increase the number and isolation of Legionella naturally occurring in compost. The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

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Graphical plot of the results of discriminant analysis. The centroids of the data originating from the southern facilities (1-4) are well grouped in the central part of the graph and separated from those of the northern facilities (5-8). Total variance explained by the model: 85.1%.
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Fig3: Graphical plot of the results of discriminant analysis. The centroids of the data originating from the southern facilities (1-4) are well grouped in the central part of the graph and separated from those of the northern facilities (5-8). Total variance explained by the model: 85.1%.

Mentions: Discriminant analysis revealed that the centres investigated could be grouped according to their geographic origin. The first three canonical discriminant functions explain 85.1% of the variance of the data (Table 3). Centres CF5, CF6 and CF8 grouped together very closely, with CF7 in an isolated position, but separate from the southern alpine centres CF1-CF4 (Figure 3). The temperature of the air is responsible for a large load on the first function; relative humidity and dew point characterise the second and third functions (Table 3). The sampling days were not particularly windy and the very low wind speed could not be measured.Table 3


Influence of climate and geography on the occurrence of Legionella and amoebae in composting facilities.

Conza L, Casati Pagani S, Gaia V - BMC Res Notes (2014)

Graphical plot of the results of discriminant analysis. The centroids of the data originating from the southern facilities (1-4) are well grouped in the central part of the graph and separated from those of the northern facilities (5-8). Total variance explained by the model: 85.1%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4289342&req=5

Fig3: Graphical plot of the results of discriminant analysis. The centroids of the data originating from the southern facilities (1-4) are well grouped in the central part of the graph and separated from those of the northern facilities (5-8). Total variance explained by the model: 85.1%.
Mentions: Discriminant analysis revealed that the centres investigated could be grouped according to their geographic origin. The first three canonical discriminant functions explain 85.1% of the variance of the data (Table 3). Centres CF5, CF6 and CF8 grouped together very closely, with CF7 in an isolated position, but separate from the southern alpine centres CF1-CF4 (Figure 3). The temperature of the air is responsible for a large load on the first function; relative humidity and dew point characterise the second and third functions (Table 3). The sampling days were not particularly windy and the very low wind speed could not be measured.Table 3

Bottom Line: A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146).A general decrease in the presence and variety of species was observed with decreasing compost storage time length.The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

View Article: PubMed Central - PubMed

Affiliation: Swiss National Reference Centre for Legionella, Bellinzona, Switzerland. lisaconza@gmail.com.

ABSTRACT

Background: The incidence of Legionnaires' disease (LD) in southern Switzerland is three times higher than in northern Switzerland. Climatic and geographic factors may be potential causes for this difference.We studied the prevalence of Legionella and free-living amoebae (FLA) in compost and bioaerosol in two Swiss regions to understand the role of climate and geography in the transmission of LD. We also tried to investigate whether or not compost storage duration would influence the composition of Legionella and FLA communities.

Results: A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146). FLA were isolated from composts in northern facilities at slightly higher rates (88.2% vs. 69.2%) and at lower rates from bioaerosols (6.3% vs. 13%) than in southern Switzerland. The diversity of FLA was higher in northern than in southern Switzerland (80% vs. 65%). A general decrease in the presence and variety of species was observed with decreasing compost storage time length. A discriminant model showed that values of vapour pressure, relative humidity and temperature distinguish the two regions, which were also characterised by different contamination rates by FLA and Legionella.

Conclusions: The duration of outdoor storage may favour contamination of the compost by Legionella, and may increase the number and isolation of Legionella naturally occurring in compost. The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

Show MeSH
Related in: MedlinePlus