Table 1 Univariable logistic regression of farm-based factors associated with serological Q fever infection on farm level

Herd size

(number of goats according to UBN registry)

≥ 800

47 (49.0)

59.6

3.7

1.6-8.6

0.0020

< 800

49 (51.0)

28.6

Ref

Mandatory vaccination area 2009

Inside

53 (55.2)

58.5

4.1

1.7-9.9

0.0010

Outside

43 (44.8)

25.6

Ref

Goat density per km²

within 5 km radius from farm

≥ 25

48 (50.0)

56.3

2.8

1.2-6.5

0.0130

< 25

48 (50.0)

31.3

Ref

Cattle density per km²

in farm municipality (excl. meat calves)

≥ 100

67 (69.8)

50.8

2.7

1.1-7.0

0.0329

< 100

29 (30.2)

27.6

Ref

Distance to nearest bulk milk PCR-positive farm

(km)

0- < 4

29 (30.2)

72.4

10.0

3.4-29.1

< .0001

4- < 8

19 (19.8)

57.9

5.2

1.7-16.5

≥ 8

48 (50.0)

20.8

Ref

Number of stables

1-2 stables

40 (41.7)

35.0

Ref

0.1424

≥ 3 stables

56 (58.3)

50.0

1.9

0.8-4.3

Use of artificial insemination

Yes

26 (27.1)

61.5

2.7

1.1-6.7

0.0370

No

70 (72.9)

37.7

Ref

Having at least one dog at the farm

Yes

84 (87.5)

47.6

4.6

0.9-22.0

0.0337

No

12 (12.5)

16.7

Ref

Having at least one rabbit at the farm

Yes

26 (27.1)

30.8

0.5

0.2-1.2

0.1138

No

70 (72.9)

48.6

Ref

Having at least one pet bird at the farm

Yes

25 (25.0)

28.0

0.4

0.2-1.1

0.0606

No

71 (75.0)

49.3

Ref

Dog(s) in goat stable

Yes

60 (62.5)

51.7

2.4

1.0-5.8

0.0415

No/unknown

36 (37.5)

30.6

Ref

Cat(s) in goat stable

Yes

34 (35.4)

58.8

2.6

1.1-6.1

0.0275

No/unknown

62 (64.6)

35.5

Ref

Signs of vermin (mice, rats, birds)

in roughage or litter during past 12 months

Unknown

14 (14.6)

64.3

2.7

0.8-8.7

0.0944

Known (yes or no)

82 (85.4)

40.2

Ref

Feeding silage

Yes

64 (66.7)

51.6

2.7

1.1-6.8

0.0269

No

32 (33.3)

28.1

Ref

Feeding maize

Yes

40 (41.7)

55.0

2.2

1.0-5.0

0.0602

No

56 (58.3)

35.7

Ref

Use of lucerne, pulp feed

or other roughage/litter

Yes

24 (25.0)

58.3

2.2

0.9-5.6

0.0972

No

72 (75.0)

38.9

Ref

Origin of straw

Abroad/unknown

59 (61.5)

49.2

1.8

0.8-4.2

0.1757

No straw or domestic straw

37 (38.5)

35.1

Ref

Feeding method

Hand/wheelbarrow

31 (32.3)

22.6

Ref

0.0202

Fodder mixer

56 (58.3)

57.1

4.6

1.7-12.4

Automatic

9 (9.4)

33.3

1.7

0.3-8.7

Sidewall ventilation

Yes

38 (39.6)

34.2

0.5

0.2-1.2

0.1252

No

58 (60.4)

50.0

Ref

Control nuisance animals

(e.g. wild birds) in 2008

Yes, by covering air spaces

15 (15.6)

73.3

2.1

1.3-15.4

0.0409

Yes, only via another ways

(a.o. capture cage)

13 (13.5)

38.5

1.0

0.3-3.4

Not applicable

68 (70.8)

38.2

Ref

Percentage of aborting goats or goats with stillbirth

in 2007-2009 or known history of abortion wave

due to Q fever since 2005

< 4%

82 (85.4)

39.0

Ref

0.0234

≥ 4% and/or abortion wave

14 (14.6)

71.4

3.9

1.1-13.5

Spread of manure

On or near own farmland

79 (82.3)

39.2

Ref

0.0497

To other places

15 (15.6)

66.7

3.1

1.0-9.9

Lambing periods in 2009

≤ 1

57 (59.4)

31.6

Ref

0.0035

≥ 2

39 (40.6)

61.5

3.5

1.5-8.1

Type of tenure

Completely closed

27 (28.1)

55.6

2.4

0.9-6.1

0.1158

Closed for female goats only

52 (54.2)

34.6

Ref

No, not closed

16 (16.7)

56.3

2.4

0.8-7.6

Goat supply from the province of Friesland

Yes

19 (19.6)

26.3

0.4

0.1-1.2

0.0806

No

77 (80.2)

48.1

Ref

Goat supply from the province of Overijssel

Yes

10 (10.4)

20.0

0.3

0.1-1.4

0.0961

No

86 (89.6)

46.5

Ref