Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands

From 2007 through 2009, The Netherlands faced large outbreaks of human Q fever. Control measures focused primarily on dairy goat farms because these were implicated as the main source of infection for the surrounding population. However, in other countries, outbreaks have mainly been associated with...

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Main Authors: Wim van der Hoek, Jan van de Kassteele, Ben Bom, Arnout de Bruin, Frederika Dijkstra, Barbara Schimmer, Piet Vellema, Ronald ter Schegget, Peter M. Schneeberger
Format: Article
Language:English
Published: PAGEPress Publications 2012-11-01
Series:Geospatial Health
Subjects:
Online Access:http://www.geospatialhealth.net/index.php/gh/article/view/111
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author Wim van der Hoek
Jan van de Kassteele
Ben Bom
Arnout de Bruin
Frederika Dijkstra
Barbara Schimmer
Piet Vellema
Ronald ter Schegget
Peter M. Schneeberger
author_facet Wim van der Hoek
Jan van de Kassteele
Ben Bom
Arnout de Bruin
Frederika Dijkstra
Barbara Schimmer
Piet Vellema
Ronald ter Schegget
Peter M. Schneeberger
author_sort Wim van der Hoek
collection DOAJ
description From 2007 through 2009, The Netherlands faced large outbreaks of human Q fever. Control measures focused primarily on dairy goat farms because these were implicated as the main source of infection for the surrounding population. However, in other countries, outbreaks have mainly been associated with non-dairy sheep and The Netherlands has many more sheep than goats. Therefore, a public discussion arose about the possible role of non-dairy (meat) sheep in the outbreaks. To inform decision makers about the relative importance of different infection sources, we developed accurate and high-resolution incidence maps for detection of Q fever hot spots. In the high incidence area in the south of the country, full postal codes of notified Q fever patients with onset of illness in 2009, were georeferenced. Q fever cases (n = 1,740) were treated as a spatial point process. A 500 x 500 m grid was imposed over the area of interest. The number of cases and the population number were counted in each cell. The number of cases was modelled as an inhomogeneous Poisson process where the underlying incidence was estimated by 2-dimensional P-spline smoothing. Modelling of numbers of Q fever cases based on residential addresses and population size produced smooth incidence maps that clearly showed Q fever hotspots around infected dairy goat farms. No such increased incidence was noted around infected meat sheep farms. We conclude that smooth incidence maps of human notifications give valuable information about the Q fever epidemic and are a promising method to provide decision support for the control of other infectious diseases with an environmental source.
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spelling doaj.art-f14efdb943784e09abdb703e5ef9d4522022-12-22T01:32:32ZengPAGEPress PublicationsGeospatial Health1827-19871970-70962012-11-017112713410.4081/gh.2012.111111Smooth incidence maps give valuable insight into Q fever outbreaks in The NetherlandsWim van der Hoek0Jan van de Kassteele1Ben Bom2Arnout de Bruin3Frederika Dijkstra4Barbara Schimmer5Piet Vellema6Ronald ter Schegget7Peter M. Schneeberger8Centre for Infectious Disease Control, National Institute for Public Health and the Environment, BilthovenDepartment of Statistics, Mathematical Modelling and Data Logistics, National Institute for Public Health and the Environment, BilthovenDepartment of Statistics, Mathematical Modelling and Data Logistics, National Institute for Public Health and the Environment, BilthovenCentre for Infectious Disease Control, National Institute for Public Health and the Environment, BilthovenCentre for Infectious Disease Control, National Institute for Public Health and the Environment, BilthovenCentre for Infectious Disease Control, National Institute for Public Health and the Environment, BilthovenDepartment of Small Ruminant Health, Animal Health Service, DeventerMunicipal Health Service “Brabant Zuidoost”, EindhovenDepartment of Medical Microbiology and Infection Control, Jeroen Bosch Hospital, ’s HertogenboschFrom 2007 through 2009, The Netherlands faced large outbreaks of human Q fever. Control measures focused primarily on dairy goat farms because these were implicated as the main source of infection for the surrounding population. However, in other countries, outbreaks have mainly been associated with non-dairy sheep and The Netherlands has many more sheep than goats. Therefore, a public discussion arose about the possible role of non-dairy (meat) sheep in the outbreaks. To inform decision makers about the relative importance of different infection sources, we developed accurate and high-resolution incidence maps for detection of Q fever hot spots. In the high incidence area in the south of the country, full postal codes of notified Q fever patients with onset of illness in 2009, were georeferenced. Q fever cases (n = 1,740) were treated as a spatial point process. A 500 x 500 m grid was imposed over the area of interest. The number of cases and the population number were counted in each cell. The number of cases was modelled as an inhomogeneous Poisson process where the underlying incidence was estimated by 2-dimensional P-spline smoothing. Modelling of numbers of Q fever cases based on residential addresses and population size produced smooth incidence maps that clearly showed Q fever hotspots around infected dairy goat farms. No such increased incidence was noted around infected meat sheep farms. We conclude that smooth incidence maps of human notifications give valuable information about the Q fever epidemic and are a promising method to provide decision support for the control of other infectious diseases with an environmental source.http://www.geospatialhealth.net/index.php/gh/article/view/111Q fever, smooth incidence maps, dairy goats, The Netherlands.
spellingShingle Wim van der Hoek
Jan van de Kassteele
Ben Bom
Arnout de Bruin
Frederika Dijkstra
Barbara Schimmer
Piet Vellema
Ronald ter Schegget
Peter M. Schneeberger
Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
Geospatial Health
Q fever, smooth incidence maps, dairy goats, The Netherlands.
title Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
title_full Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
title_fullStr Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
title_full_unstemmed Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
title_short Smooth incidence maps give valuable insight into Q fever outbreaks in The Netherlands
title_sort smooth incidence maps give valuable insight into q fever outbreaks in the netherlands
topic Q fever, smooth incidence maps, dairy goats, The Netherlands.
url http://www.geospatialhealth.net/index.php/gh/article/view/111
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