Table 2. Univariate analysis of selected variables for BU in the district of Tiassalé, south Côte d'Ivoire (case-control study, August-September 2012).

	No. (%) of cases	No. (%) of controls	Univariate OR	EFe or PFe
Characteristics	Subject (n = 51)	Subject (n = 102)	(95% CI)	(95% CI
Socio-demographic factors
Education status: no education/primary and secondary	29 (56.9)	40 (39.2)	2.0 (1.0–4,0)	51.1 (3.2–75.3)
Knowledge about the risk which may result in BU: little/good	34 (66.7)	41 (40.2)	3.0 (1.5–6.0)*	66.4 (32.1–83.4)
Perception about BU: mystical disease/natural disease	38 (74.5)	53 (52.0)	2.7 (1.3–5.7)*	63.0 (22.4–82.3)
Environmental factors and water contact activities
Regular contact with a surface water source (river/creek/dam/lake): yes/no	36 (70.6)	21 (20.6)	9.3 (4.3–20.0)*	89.2 (76.7–95.0)
Distance between a surface water point and place of residence: ˂500 m/˃500 m	30 (58.8)	39 (38.2)	2.3 (1.2–4.6)*	56.7 (14.0–78.2)
Regular agricultural activities (irrigated rice): yes/no	40 (78.4)	40 (39.2)	5.6 (2.6–12.3)*	82.3 (61.4–91.8)
Regular washing/bathing/swimming in surface water: yes/no	41 (80.4)	63 (61.8)	2.5 (1.1–5.6)*	60.6 (12.5–82.3)
Regular water supply at a surface water point (river/creek/dam): yes/no	34 (66.7)	39 (38.2)	3.2 (1.6–6.6)*	69.0 (37.3–84.7)
Wearing protective equipment (boots/gloves/long pants and clothes) during agricultural activities: no/yes	22 (43.1)	74 (72.5)	0.3 (0.1–0.6)*	71.3 (41.9–85.8)
Insect bites
Insect bites during water contact activities: yes/no	32 (62.7)	40 (39.2)	2.6 (1.3–5.2)	61.7 (23.4–80.8)
Health-related factors
Presence of local trauma on the skin during water contact activities: yes/no	27 (52.9)	47 (46.1)	1.3 (0.7–2.6)	24.0 (1.0 61.3)
BCG vaccination status: unvaccinated/vaccinated	18 (35.3)	62 (60.8)	0.4 (0.2–0.7)*	64.8 (29.2–82.5)

* Significant association between variable and BU

CI, confidence interval; EFe, etiologic fraction among the exposed; PFe, preventive fraction among the exposed; OR, odds ratio