Belyhun et al. BMC Public Health 2010, 10:21 http://www.biomedcentral.com/1471-2458/10/21 Page 4 of 7 P-value 0.190 0.052 0.442 0.224$ 0.550 0.124 0.830$ 0.700 0.143 0.184 Table 2 Univariate analysis of socio-demographic characteristics and their association with soil-transmitted helminths in the birth cohort, Butajira Ethiopia, 2007 Demographic variables N (%) Soil-transmitted helminths in the mother (N = 908) Soil-transmitted helminths in the child (N = 905) Male gender Urban residence Mother’s Age 15-24 25-34 35-44 Ethnicity Meskan Mareko Silti Others* Mother’s Education No education Read write£ Formal education Mother’s Occupation House wife Trade related Others♀ Home ownership TV/Radio ownership 460 (50.7) 118 (13.0) 351 (38.7) 424 (46.7) 133 (14.7) 429 (47.3) 118 (13.0) 211 (23.2) 150 (16.5) 639 (70.2) 86 (9.5) 183 (20.2) 762 (83.9) 104 (11.5) 42 (4.6) 822 (90.5) 466 (51.4) n (%) - 37 (31.4) 155 (44.2) 183 (43.2) 57 (42.9) 183 (42.7) 57 (48.3) 98 (46.5) 57 (38.0) 290 (45.4) 37 (43.0) 68 (37.2) 338 (44.4) 42 (40.4) 15 (35.7) 367 (44.7) 197 (42.3) Crude OR (95%CI) - 0.48 (0.32,0.73) 1 0.96 (0.72,1.28) 0.95 (0.63,1.42) 1 1.26 (0.83,1.89) 1.17 (0.84,1.62) 0.82 (0.56,1.21) 1 0.91 (0.58, 1.43) 0.71 (0.51, 1.00) 1 0.85 (0.56,1.29) 0.70 (0.36, 1.33) 1.67 (1.04, 2.68) 0.91 (0.70, 1.18) P-value - 0.001 0.949 0.759$ 0.280 0.138 0.051$ 0.428 0.033 0.467 n (%) 18 (3.9) 10 (8.6) 21 (6.0) 18 (4.3) 5 (3.8) 21 (4.9) 8 (6.8) 7 (3.3) 8 (5.4) 32 (5.0) 1 (1.2) 11 (6.0) 38(5.0) 5 (4.9) 1 (2.4) 37 (4.5) 27 (5.8) Crude OR (95%CI) 0.66 (0.36, 1.23) 2.07 (1.00, 4.32) 1 0.70 (0.37, 1.33) 0.61 (0.23, 1.66) 1 1.41 (0.61, 3.27) 0.67 (0.28, 1.60) 1.10 (0.48, 2.54) 1 0.22 (0.03, 1.65) 1.22 (0.60, 2.46) 1 0.97 (0.37,2.52) 0.46 (0.06, 3.46) 0.53 (0.23, 1.24) 1.52 (0.82, 2.84) * Sodo, Dobi, Oromo, Amhara, ♀ Farm related, profession related, trade related and daily laborer, $p for trend £ read and write but have no formal education N = total number of study participants, n = number of outcome for each exposure amongst those getting their water from a pipe inside the housing compound (18.5%), and the lowest in those using a river (3.9%) (Table 3). Being an urban resident was associated with increased risk of infection in the child (OR 2.07; 95% CI 1.00-4.32), but this was of bor- derline statistical significance (p = 0.052). Risk factors independently associated with STH in mothers The independent predictors of maternal infection identi- fied from multivariate analysis are shown in Table 4. Soap use (adjusted OR = 1.40; 95% CI 1.04-1.88 for infrequent users compared with daily users, p for trend = 0.018) and urban living (adjusted OR = 0.45; 95% CI 0.28-0.73, p = 0.001), remained significant factors. Risk factors independently associated with STH in children In multivariate analysis, after controlling for urban/rural residence and gender, the only significant predictor of infection in children was household source of water (p = 0.001) with the greatest risk of infection seen for those using piped water inside the compound (Table 4). Discussion This study is the first, to our knowledge, to explore the prevalence of and risk factors for STH infection in an infant population in Ethiopia. The study found a high prevalence of hookworm infection among mothers, which exceeded the national average. However, the pre- valence was generally low in children. The study inden- tified key environmental factors linked with STH infection which are amenable for intervention. Fre- quency of soap use and urban living were found to be predictors of maternal helminth infection while avail- ability of piped water in the compound was indepen- dently associated with increased risk of infant helminth infection. The findings of this study provide some evidence for environmental and public health measures to counter STH infection; yet they must be interpreted in the light of certain limitations. We lacked the power to identify risks weakly associated with infant infection in this cohort. Moreover, information on potential confounders was based on mothers’ self-report, which may have led to information bias. Quantitative egg estimation to mea- sure the intensity of infections using Kato-Katz