Q Fever and Pneumonia in an Area with a High Livestock Density: A Large Population-Based Study

Lidwien A M Smit,Johan Beekhuizen,Annemieke W J Opstal-Van Winden,Dick Heederik,Mariëtte Hooiveld,Femke Van Der Sman-De Beer,Inge M Wouters,Joris Yzermans,Joan A Caylà

doi:10.1371/journal.pone.0038843

Lidwien A M Smit, Johan Beekhuizen + Show 7 more

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https://doi.org/10.1371/journal.pone.0038843

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Abstract

Concerns about public health risks of intensive animal production in the Netherlands continue to rise, in particular related to outbreaks of infectious diseases. The aim was to investigate associations between the presence of farm animals around the home address and Q fever and pneumonia.Electronic medical record data for the year 2009 of all patients of 27 general practitioners (GPs) in a region with a high density of animal farms were used. Density of farm animals around the home address was calculated using a Geographic Information System. During the study period, a large Q fever outbreak occurred in this region. Associations between farm exposure variables and pneumonia or ‘other infectious disease’, the diagnosis code used by GPs for registration of Q fever, were analyzed in 22,406 children (0–17 y) and 70,142 adults (18–70 y), and adjusted for age and sex. In adults, clear exposure-response relationships between the number of goats within 5 km of the home address and pneumonia and ‘other infectious disease’ were observed. The association with ‘other infectious disease’ was particularly strong, with an OR [95%CI] of 12.03 [8.79–16.46] for the fourth quartile (>17,190 goats) compared with the first quartile (<2,251 goats). The presence of poultry within 1 km was associated with an increased incidence of pneumonia among adults (OR [95%CI] 1.25 [1.06–1.47]).A high density of goats in a densely populated region was associated with human Q fever. The use of GP records combined with individual exposure estimates using a Geographic Information System is a powerful approach to assess environmental health risks.

Highlights

The number of farms in the Netherlands has been declining for decades, the total number of farm animals is still increasing
Univariate tests of association showed that adult patients with pneumonia were older than subjects who were not diagnosed with pneumonia or ‘other infectious disease’ in 2009
The presence of goats around the home address was associated with a diagnosis of ‘other infectious disease’, whereas goat or other farm animal exposures were not associated with pneumonia in children

Summary

Introduction

The number of farms in the Netherlands has been declining for decades, the total number of farm animals is still increasing. Concerns about public health risks of increasingly intensive animal production continue to rise, in particular related to emerging zoonotic infectious diseases such as avian and swine influenza, and Q fever [1]. Infection may lead to asymptomatic seroconversion in 60% of patients, while a variety of acute clinical manifestations such as flulike symptoms, hepatitis, and atypical pneumonia may occur in others. Most acute Q fever patients present with a mild, self-limited febrile illness, some patients have to be hospitalized with a severe pneumonia [3]. Chronic Q fever may develop in less than 5% of acute cases, manifesting most commonly as endocarditis with a considerable mortality [3]. Protracted fatigue and impaired quality of life are other common sequels in acute Q fever patients [4,5]

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