Limits...
The emergence of Leptospira borgpetersenii serovar Arborea in Queensland, Australia, 2001 to 2013.

Lau CL, Skelly C, Dohnt M, Smythe LD - BMC Infect. Dis. (2015)

Bottom Line: Differences in risk factors for the most common serovars were compared.Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year.Serovars varied significantly between ages and occupational groups, and serovar Arborea was most strongly associated with 'other agricultural/rural workers'.

View Article: PubMed Central - PubMed

Affiliation: Queensland Children's Medical Research Institute, Brisbane, Australia. colleen.lau@uq.edu.au.

ABSTRACT

Background: Leptospirosis is an emerging infectious disease, with increasing frequency and severity of outbreaks, changing epidemiology of populations at risk, and the emergence of new serovars. Environmental drivers of disease transmission include flooding, urbanisation, poor sanitation, changes in land use and agricultural practices, and socioeconomic factors. In Queensland, human infection with Leptosira borgpetersenii serovar Arborea was first reported in 2001. This study aims to report the emergence of serovar Arborea in Queensland from 2001 to 2013, and investigate potential risk factors for infection and drivers of emergence.

Methods: Data on laboratory-confirmed cases of human leptospirosis in Queensland were obtained from the enhanced surveillance system at the WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis in Brisbane, Australia. The changing epidemiology of serovar Arborea from 2001 to 2003 was described with respect to case numbers, proportion of leptospirosis cases attributed to the serovar, and geographic distribution. Differences in risk factors for the most common serovars were compared.

Results: During this period, 1289 cases of leptospirosis were reported, including 233 cases attributed to serovar Arborea. Risk factors for infection include male gender (91 % of cases), occupation, and recreational exposure. Most common occupations recorded were banana workers (28.4 %), meat workers (7.2 %), dairy farmers (5.8 %), graziers/stockmen (5.5 %), 'other agricultural/rural workers' (16.4 %), and tourists or tourism operators (4.6 %). Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year. The proportion of annual cases attributed to Arborea peaked at 49 % in 2011 after unprecedented flooding in Queensland. Mapping of cases by residential location showed expansion of the geographic range of serovar Arborea, concentrating mostly around Brisbane, Cairns and Innisfail. Serovars varied significantly between ages and occupational groups, and serovar Arborea was most strongly associated with 'other agricultural/rural workers'.

Conclusions: Leptospira borgpetersenii serovar Arborea has been emerging in Queensland since 2001, with increase in case numbers, the proportion of leptospirosis infections attributed to the serovar, as well as expansion of its geographic distribution. Reasons for this emergence are unknown, but climatic factors and environmental change are likely to have played important roles.

Show MeSH

Related in: MedlinePlus

Methods used to design a multi-region cartogram used to summarise postcode areas. a creating a simple outline of Queensland, b creating and overlaying a fishnet grid, and c manually editing postcode areas that overlapped multiple cartogram regions
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4465322&req=5

Fig1: Methods used to design a multi-region cartogram used to summarise postcode areas. a creating a simple outline of Queensland, b creating and overlaying a fishnet grid, and c manually editing postcode areas that overlapped multiple cartogram regions

Mentions: There are over 450 postcodes in Queensland that vary significantly in geographic area coverage, and mapping case data by postcodes or postcode centroids could therefore produce maps that distort the true location and density of cases. For example, Fig. 1c shows a postcode that covers a very large area and is composed of multiple non-contiguous parts. In order to improve the representation of the geographic location and number of cases across the state, we designed a cartogram to summarise postcode areas into approximately 30 regions. An outline of Queensland (Fig. 1a) was overlaid with a 'fishnet' grid to provide the underlying pattern of cartogram regions (Fig. 1b). Over 90 % of postcode areas fell within one cartogram region. For the small number of postcodes areas that overlapped multiple cartogram regions, a manual editing process was used to determine the region that most accurately represents that postcode (see example in Fig. 1c). Some cartogram regions were combined because they were overlapped by very large postcode areas.Fig. 1


The emergence of Leptospira borgpetersenii serovar Arborea in Queensland, Australia, 2001 to 2013.

Lau CL, Skelly C, Dohnt M, Smythe LD - BMC Infect. Dis. (2015)

Methods used to design a multi-region cartogram used to summarise postcode areas. a creating a simple outline of Queensland, b creating and overlaying a fishnet grid, and c manually editing postcode areas that overlapped multiple cartogram regions
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4465322&req=5

Fig1: Methods used to design a multi-region cartogram used to summarise postcode areas. a creating a simple outline of Queensland, b creating and overlaying a fishnet grid, and c manually editing postcode areas that overlapped multiple cartogram regions
Mentions: There are over 450 postcodes in Queensland that vary significantly in geographic area coverage, and mapping case data by postcodes or postcode centroids could therefore produce maps that distort the true location and density of cases. For example, Fig. 1c shows a postcode that covers a very large area and is composed of multiple non-contiguous parts. In order to improve the representation of the geographic location and number of cases across the state, we designed a cartogram to summarise postcode areas into approximately 30 regions. An outline of Queensland (Fig. 1a) was overlaid with a 'fishnet' grid to provide the underlying pattern of cartogram regions (Fig. 1b). Over 90 % of postcode areas fell within one cartogram region. For the small number of postcodes areas that overlapped multiple cartogram regions, a manual editing process was used to determine the region that most accurately represents that postcode (see example in Fig. 1c). Some cartogram regions were combined because they were overlapped by very large postcode areas.Fig. 1

Bottom Line: Differences in risk factors for the most common serovars were compared.Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year.Serovars varied significantly between ages and occupational groups, and serovar Arborea was most strongly associated with 'other agricultural/rural workers'.

View Article: PubMed Central - PubMed

Affiliation: Queensland Children's Medical Research Institute, Brisbane, Australia. colleen.lau@uq.edu.au.

ABSTRACT

Background: Leptospirosis is an emerging infectious disease, with increasing frequency and severity of outbreaks, changing epidemiology of populations at risk, and the emergence of new serovars. Environmental drivers of disease transmission include flooding, urbanisation, poor sanitation, changes in land use and agricultural practices, and socioeconomic factors. In Queensland, human infection with Leptosira borgpetersenii serovar Arborea was first reported in 2001. This study aims to report the emergence of serovar Arborea in Queensland from 2001 to 2013, and investigate potential risk factors for infection and drivers of emergence.

Methods: Data on laboratory-confirmed cases of human leptospirosis in Queensland were obtained from the enhanced surveillance system at the WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis in Brisbane, Australia. The changing epidemiology of serovar Arborea from 2001 to 2003 was described with respect to case numbers, proportion of leptospirosis cases attributed to the serovar, and geographic distribution. Differences in risk factors for the most common serovars were compared.

Results: During this period, 1289 cases of leptospirosis were reported, including 233 cases attributed to serovar Arborea. Risk factors for infection include male gender (91 % of cases), occupation, and recreational exposure. Most common occupations recorded were banana workers (28.4 %), meat workers (7.2 %), dairy farmers (5.8 %), graziers/stockmen (5.5 %), 'other agricultural/rural workers' (16.4 %), and tourists or tourism operators (4.6 %). Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year. The proportion of annual cases attributed to Arborea peaked at 49 % in 2011 after unprecedented flooding in Queensland. Mapping of cases by residential location showed expansion of the geographic range of serovar Arborea, concentrating mostly around Brisbane, Cairns and Innisfail. Serovars varied significantly between ages and occupational groups, and serovar Arborea was most strongly associated with 'other agricultural/rural workers'.

Conclusions: Leptospira borgpetersenii serovar Arborea has been emerging in Queensland since 2001, with increase in case numbers, the proportion of leptospirosis infections attributed to the serovar, as well as expansion of its geographic distribution. Reasons for this emergence are unknown, but climatic factors and environmental change are likely to have played important roles.

Show MeSH
Related in: MedlinePlus