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Volume 17, Number 9—September 2011

Dispatch

Q Fever among Culling Workers, the Netherlands, 2009–2010

Jane WhelanComments to Author , Barbara Schimmer, Peter Schneeberger, Jamie Meekelenkamp, Wim van der Hoek, Mirna Robert–Du Ry van Beest Holle, and Arnold IJff
Author affiliations: Author affiliations: National Institute for Public Health and the Environment, Bilthoven, the Netherlands (J. Whelan, B. Schimmer, P. Schneeberger, W. van der Hoek, M. Robert–Du Ry van Beest Holle); European Centre for Disease Prevention and Control, Stockholm, Sweden (J. Whelan); Jeroen Bosch Hospital, ’s-Hertogenbosch, the Netherlands (P. Schneeberger, J. Meekelenkamp); ArboUnie, Utrecht, the Netherlands (A. IJff)

Main Article

Table 2

Variables associated with Q fever seroconversion among 246 workers who were seronegative before culling small ruminants, the Netherlands, 2009*

Variable No. (%) workers
Univariable analysis
Multivariable analysis†
Total Seroconversion RR (95% CI) p value‡ RR (95% CI) p value
Total
246 (100)
43 (17)






Sex
F 6 (2) 2 (33) Reference
M
240 (98)
41 (17)

0.51 (0.16–1.64)
0.301



Age, y
<45 96 (39) 14 (15) Reference
>45
150 (61)
29 (19)

1.33 (0.74–2.38)
0.339

2.0 (0.93–4.16)
0.07
Level of education
Low 39 (21) 5 (13) Reference
Medium 103 (55) 18 (17) 1.36 (0.54–3.42)
High
44 (24)
8 (18)

1.42 (0.51–3.98)
0.765



Minimum distance of residence from nearest infected farm, km
>5 174 (73) 32 (18) Reference
<5
63 (27)
9 (14)

0.78 (0.39–1.53)
0.460



Medical history§
No 128 (75) 23 (18) Reference
Yes
42 (25)
5 (12)

0.66 (0.27–1.63)
0.358



Current or past smoker
No 84 (44) 16 (19) Reference
Yes
108 (56)
16 (15)

0.78 (0.41–1.46)
0.435



Total hours worked inside farm perimeter¶
0–20 81 (33) 5 (6) Reference Reference
21–100 82 (34) 18 (22) 3.56 (1.39–9.12) 5.53 (0.71–42.77) 0.102
>100
80 (33)
20 (25)

4.05 (1.60–10.26)
0.003

7.75 (1.02–58.99)
0.048
Mean farm size >1,500 animals#
No 167 (68) 22 (13) Reference
Yes
79 (32)
21 (27)

2.02 (1.18–3.44)
0.010

1.75 (0.93–3.30)
0.081
Worked mostly inside stable
No 110 (45) 11 (10) Reference
Yes
133 (55)
31 (23)

2.33 (1.23–4.42)
0.006

2.58 (1.04–6.37)
0.040
Animal abortions on farm
No 208 (85) 33 (16) Reference
Yes
38 (15)
10 (26)

1.66 (0.89–3.07)
0.119

0.93 (0.45–1.91)
0.844
Any previous culling experience
No 85 (43) 15 (18) Reference
Yes
114 (57)
17 (15)

0.84 (0.45–1.59)
0.603



Adherence to hygiene and preventive measures**
Fully compliant 91 (50) 13 (14) Reference
Not compliant
91 (50)
17 (19)

1.31 (0.68–2.53)
0.424

0.94 (0.51–1.72)
0.829
Months spent culling
Dec 2009–Mar 2010 only
(mean temperature 3.2°C) 105 (54) 18 (17) Reference
Apr–Jun 2010 only
(mean temperature 13.9°C) 2 (1) 1 (50) 2.92 (0.69–12.41)
Dec 2009–Jun 2010 87 (45) 21 (24) 1.41 (0.80–2.47) 0.288

*Total for each category may be <246 because of missing data. RR, risk ratio; CI, confidence interval.
†All data available for n = 180 in multivariable analysis.
‡Pearson χ2.
§History of cardiorespiratory disease, liver disorders, diabetes, cancer, immunosuppression, allergies, skin conditions.
¶Data only available for n = 194, those who worked inside the farm perimeter.
#Weighted mean number of animals on farms worked by participants.
**Includes wearing mask, gloves, overalls, hairnet, showering after exposure.

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