Table 4 Univariate and multivariable analyses of demographic, clinical, parasitological, haematological, and other risk factors for gametocyte carriage

Gender (n = 1962)

–

 Male

1061 (67.9)

501 (32.1)

1

 Female

269 (67.3)

131 (32.8)

1.03 (0.82−1.30)

Age, years (n = 1962)

p value = 0.008

 15–24

630 (62.6)

377 (37.4)

2.39 (1.57−3.64)

1.96 (1.18−3.26)

 25–34

399 (71.4)

160 (28.6)

1.60 (1.03−2.49)

1.47 (0.87−2.50)

 35–44

181 (73.6)

65 (26.4)

1.44 (0.88−2.35)

1.24 (0.69−2.21)

 ≥ 45

120 (80.0)

30 (20.0)

1

1

Occupation (n = 1955)

p value = 0.624

 Employees

108 (73.0)

40 (27.0)

1

1

 Unemployed

197 (58.3)

141 (41.7)

1.93 (1.27−2.95)

0.99 (0.62−1.60)

 Manual labourers

777 (67.6)

373 (32.4)

1.30 (0.88−1.90)

0.86 (0.48−1.52)

 Merchants

37 (74.0)

13 (26.0)

0.95 (0.46−1.97)

1.47 (0.59−3.62)

 Farmers

163 (75.5)

53 (24.5)

0.88 (0.55−1.42)

1.11 (0.67−1.84)

 Others

43 (81.1)

10 (18.9)

0.63 (0.29−1.37)

0.61 (0.26−1.47)

Ethnicity (n = 1962)

p value = 0.005

 Thai

191 (82.7)

40 (17.3)

1

1

 Burmese

577 (68.5)

265 (31.5)

2.19 (1.51−3.18)

2.25 (1.37−3.69)

 Karen

287 (62.4)

173 (37.6)

2.88 (1.95−4.25)

2.59 (1.56−4.29)

 Mon

228 (62.5)

137 (37.5)

2.87 (1.92−4.29)

2.51 (1.49−4.21)

 African

19 (95.0)

1 (5.0)

0.25 (0.03−1.93)

0.19 (0.16−2.17)

 Others

28 (63.6)

16 (36.4)

2.73 (1.35−5.51)

2.73 (1.17−6.40)

BMI, kg/m² (n = 1943)

p value = 0.605

 Normal \(\ge\) 18.5–25

953(68.9)

430 (31.1)

1

1

 Underweight < 18.5

296 (64.2)

165 (35.8)

1.24 (0.99−1.54)

0.96 (0.73−1.25)

 Overweight > 25

74 (74.7)

25 (25.3)

0.75 (0.47−1.10)

1.30 (0.74−1.94)

Population group (n = 1962)^a

–

 Thai

191 (82.7)

40 (17.3)

1

 Immigrant

1116 (65.5)

589 (34.5)

2.52 (1.77−3.56)

 Travellers

23 (88.5)

3 (11.5)

0.62 (0.18−2.18)

History of malaria (n = 1825)

p value = 0.746

 None

635 (64.8)

345 (35.3)

1

1

 1 time

322 (69.8)

139 (30.2)

0.79 (0.62−1.01)

1.08 (0.81−1.43)

 ≥ 2 times

279 (72.8)

346 (35.3)

0.68 (0.53−0.89)

0.96 (0.73−1.25)

Duration of fever, days (n = 1961)

p value < 0.001

 ≤ 3

702 (80.6)

169 (19.4)

1

1

 > 3–7

487 (63.7)

277 (36.3)

2.36 (1.89−2.95)

2.47 (1.91−3.19)

 > 7

141 (43.3)

185 (56.7)

5.45 (4.14−7.12)

5.40 (3.92−7.41)

Fever on admission (> 37.5 °C) (n = 1962)

p value < 0.001

 No

376 (61.6)

234 (38.4)

1

1

 Yes

954 (70.6)

398 (29.4)

0.67 (0.55−0.82)

0.61 (0.48−0.77)

Asexual parasite density, /µL (n = 1962)

p value = 0.002

 ≤ 5000

290 (62.2)

176 (37.8)

1

1

 > 5000–25,000

334 (67.5)

161 (32.5)

0.79 (0.61−1.04)

0.71 (0.52−0.98)

 > 25,000–100,000

346 (69.9)

149 (30.1)

0.71 (0.54−0.93)

0.74 (0.53−1.03)

 > 100,000

360 (71.1)

146 (32.2)

0.67 (0.51−0.87)

0.51 (0.36−0.72)

Haemoglobin (≤ 8 g/dL) (n = 1961)

p value < 0.001

 No

1298 (70.9)

532 (29.1)

1

1

 Yes

31 (23.7)

100 (76.3)

7.87 (5.20−11.92)

3.32 (2.06−5.33)

Thrombocytopenia,

(≤ 100,000/µL) (n = 1962)

p value = 0.002

 No

435 (63.9)

246 (36.1)

1

1

 Yes

894 (69.8)

386 (30.2)

0.76 (0.63−0.93)

0.65 (0.50−0.85)

Severe malaria

p value < 0.001

 No

1051 (73.3)

383 (26.7)

1

1

 Yes

279 (52.8)

249 (47.2)

2.45 (1.99–3.01)

2.33 (1.76−3.10)

Seasonality^b

p value = 0.006

 Rainy

925 (69.3)

409 (30.7)

1

1

 Dry

405 (64.5)

223 (35.5)

1.25 (1.02–1.52)

1.41 (1.10−1.79)

Import malaria (n = 1934)

p value = 0.128

 Indigenous

673 (71.5)

268 (28.5)

1

1

 Border

595 (62.6)

356 (37.4)

1.50 (1.24−1.82)

1.28 (1.01−1.62)

 Transnational

37 (88.1)

5 (11.9)

0.34 (0.13−0.87)

1.07 (0.28−4.07)