Table 4 Characteristics of huts and activities among index cases and neighbors sleeping in at-risk sites of malaria, Phu Yen province, Vietnam, 2016

Year huts were established

1996–2006

2007–2016

9 (8.2)

101 (91.8)

24 (12.2)

173 (87.8)

33 (10.7)

274 (89.3)

0.64 (0.29, 1.44)

Duration from home to huts by motorbike

Additional time by walking

>  30 min

30 min or less

>  15 min

15 min or less

51 (46.4)

59 (53.6)

40 (36.4)

70 (63.6)

43 (21.8)

154 (78.2)

48 (24.4)

149 (75.6)

94 (30.6)

213 (69.4)

88 (28.7)

219 (71.3)

3.10 (1.87, 5.12)

1.77 (1.07, 2.94)

Number of people usually sleep in this hut in the last 12 months

>  3 persons

3 or less

55 (50.0)

55 (50.0)

35 (17.8)

162 (82.2)

90 (29.3)

217 (70.7)

4.63 (2.74, 7.81)

Minimum number of people used to sleep (from 2 or more vs 1 person)

53 (48.2)

44 (22.4)

97 (31.7)

3.23 (1.96, 5.33)

Maximum number of people used to sleep (from > 5 vs 5 persons or less)

48 (43.6)

31 (15.8)

79 (25.8)

4.15 (2.42, 7.10)

Number of huts within 500 m radius of participants

> 3 huts

0–3 huts

23 (20.9)

87 (79.1)

19 (9.6)

178 (90.4)

42 (13.7)

269 (86.3)

2.48 (1.29, 4.76)

Number of people within 500 m radius of participants

>  6 neighbors

0–6 neighbors

22 (20.0)

88 (80.9)

22 (11.2)

175 (88.8)

44 (14.3)

263 (85.7)

1.99 (1.04, 3.79)

Duration from hut to nearest cell phone coverage by motorcycle

Network available

30 min or less

30–120 min

61 (55.5)

18 (16.4)

31 (28.2)

162 (82.2)

22 (11.2)

13 (6.6)

223 (72.6)

40 (13.0)

44 (14.3)

0.27 (0.16, 0.45)

1.56 (0.80, 3.03)

5.55 (2.79, 11.07)

Drinking water sources usually be used

Stream

Well

95 (86.4)

15 (13.6)

136 (69.0)

61 (31.0)

231 (75.2)

76 (24.8)

2.84 (1.54, 5.26)