Table 1 Characteristics of cases and controls

Total

395

1308

Age group

<21

13

3.3

140

10.7

21 to 30

130

32.9

396

30.3

31 to 40

97

24.6

238

18.2

41 to 50

76

19.2

235

18.0

51 to 60

55

13.9

197

15.1

61 and above

24

6.1

102

7.8

Gender (Female/Male)

Female

142

35.9

503

38.5

Ethnicity

Chinese

265

67.1

781

59.7

Malay

33

8.4

240

18.3

Indian

57

14.4

193

14.8

Other

40

10.1

94

7.2

Home address region

SW

52

13.4

204

15.8

C

204

52.4

646

50.0

NW

62

15.9

264

20.4

NE

61

15.7

158

12.2

SE

10

2.6

20

1.5

Country of origin (Singapore/Others)

Singapore

248

62.8

909

69.5

Healthcare recruitment site

A

217

54.9

807

61.7

B

12

3.0

24

1.8

C

34

8.6

180

13.8

D

28

7.1

63

4.8

E

33

8.4

193

14.8

F

71

18.0

41

3.1

Medical history (Diabetes/Hypertension/IHD/Malignancy/Steroid treatment) [No/Yes]

No

338

85.6

1099

84.1

Self-reported history of past dengue infection (No/Yes)

No

378

96.7

1235

95.0

Dwelling type

Multistorey public flats

291

73.7

1082

82.8

Multistorey private flats

18

4.6

64

4.9

Landed houses

35

8.9

83

6.4

Foreign (construction) workers dormitory/hostel

51

12.9

77

5.9

Dwelling floor level

mean floor

6

4^a

7

4^a

Travel history (No/Yes)

No

342

86.6

1101

84.3

Type of employment (Indoor/Outdoor/Both) and Primary mode of transportation to work (Public-train or bus/Private-taxi or car/Walking)

Unemployed

90

22.8

269

20.7

Indoor & Public

90

22.8

410

31.6

Indoor & Private

24

6.1

84

6.5

Indoor & Walking

10

2.5

41

3.2

Outdoor & Public

37

9.4

108

8.3

Outdoor & Private

24

6.1

51

3.9

Outdoor & Walking

19

4.8

29

2.2

Both & Public

52

13.2

208

16.0

Both & Private

35

8.9

80

6.2

Both & Walking

14

3.5

19

1.5

Self-reported history of mosquito bite (No/Yes)

No

291

73.7

994

76.5

Self-reported history of household dengue (No/Yes)

No

372

94.4

1294

99.2

Self-reported history of household fever (No/Yes)

No

295

74.7

1076

82.6