Table 3. Univariable and multivariable analysis of factors associated with intensity of hookworm infection.
| EPG (N = 1012)* | Univariable | Multivariable | |||
|---|---|---|---|---|---|
| Arithmetic mean (SD) | IIR (95%CI) | p | mIIR (95%CI) | p | |
| Individual factors | |||||
| Age | |||||
| PSAC (1–4 years) | 538.8 (847.7) | 1 | <0.001 | 1 | <0.001 |
| SAC (5–14 years) | 389.7 (746.3) | 7.4 (3.6, 15.5) | 9.2 (4.3, 19.7) | ||
| Adult (15+ years) | 661.1 (1562.3) | 525.2 (259.3, 1063.8) | 332.5 (166.4, 664.5) | ||
| Sex† | |||||
| Male | 664.7 (1682.5) | 1 | 0.017 | ||
| Female | 608.4 (1316.6) | 1.5 (1.1, 2.0) | |||
| Lived there most of past 6 months | |||||
| Yes | 530.0 (978.0) | 1 | 0.058 | ||
| No | 634.6 (1496.4) | 0.2 (0.0, 1.1) | |||
| Slept there the previous night | |||||
| Yes | 480.6 (742.9) | 1 | 0.213 | ||
| No | 637.1 (1504.9) | 0.5 (0.1, 1.5) | |||
| Wearing shoes during survey‡ | |||||
| No | 638.9 (1509.1) | 1 | 0.304 | ||
| Yes | 618.9 (1473.6) | 0.8 (0.5, 1.2) | |||
| Dewormed in last 12 months‡ | |||||
| No | 636.8 (1503.3) | 1 | <0.001 | 1 | <0.001 |
| Yes | 536.4 (1352.1) | 0.0 (0.0, 0.0) | 0.1 (0.1, 0.2) | ||
| Household factors | |||||
| Population density§ | |||||
| <50 | 593.5 (792.2) | 1 | 0.015 | ||
| 50–249 | 659.2 (1632.9) | 1.0 (0.5, 2.3) | |||
| 250–999 | 610.9 (1336.7) | 0.8 (0.3, 1.9) | |||
| > = 1000 | 219.8 (213.8) | 0.2 (0.1, 0.7) | |||
| Family size | |||||
| < = 4 members | 652.9 (1374.5) | 1 | <0.001 | ||
| > = 5 members | 610.1 (1633.5) | 0.4 (0.3, 0.6) | |||
| Farming household¶ | |||||
| No | 722.4 (1691.4) | 1 | 0.483 | ||
| Yes | 534.1 (1210.2) | 1.1 (0.8, 1.6) | |||
| Livestock possession | |||||
| No | 627.6 (1214.9) | 1 | 0.178 | ||
| Yes | 639.0 (1682.0) | 1.3 (0.9, 1.7) | |||
| Highest education level of any female family member# | |||||
| No education | 718.6 (1682.3) | 1 | <0.001 | ||
| Some primary | 460.0 (962.4) | 0.5 (0.3, 0.9) | |||
| Some middle | 652.6 (1361.2) | 0.4 (0.2, 0.6) | |||
| Some secondary | 624.9 (1736.1) | 0.2 (0.1, 0.4) | |||
| Some higher secondary / college | 475.2 (1012.7) | 0.1 (0.1, 0.2) | |||
| Highest education level of household head** | |||||
| No education | 670.8 (1563.8) | 1 | <0.001 | 1 | <0.001 |
| Some primary | 777.1 (1897.2) | 0.5 (0.3, 0.8) | 0.6 (0.4, 1.0) | ||
| Some middle | 592.3 (1132.1) | 0.4 (0.2, 0.6) | 0.5 (0.3, 0.8) | ||
| Some secondary | 385.5 (1111.8) | 0.2 (0.1, 0.3) | 0.4 (0.2, 0.6) | ||
| Some higher secondary / college | 640.4 (1150.9) | 0.1 (0.1, 0.2) | 0.2 (0.1, 0.5) | ||
| Household floor‡‡ | |||||
| Natural materials | 669.1 (1588.3) | 1 | 0.013 | ||
| Manmade materials | 624.6 (1468.0) | 0.5 (0.3, 0.9) | |||
| SES (1 = Low, 5 = High) | |||||
| 1 | 764.0 (1786.7) | 1 | <0.001 | 1 | <0.001 |
| 2 | 618.6 (1555.6) | 0.5 (0.3, 0.9) | 0.5 (0.3, 0.8) | ||
| 3 | 651.7 (1327.8) | 0.4 (0.2, 0.7) | 0.5 (0.3, 0.9) | ||
| 4 | 346.2 (672.9) | 0.2 (0.1, 0.3) | 0.3 (0.1, 0.5) | ||
| 5 | 593.1 (1272.9) | 0.1 (0.1, 0.2) | 0.2 (0.1, 0.4) | ||
| Water source‡‡ | |||||
| Unimproved facilities | 805.2 (2128.6) | 1 | 0.877 | ||
| Improved facilities | 611.8 (1390.5) | 1.1 (0.4, 2.6) | |||
| Sanitation facilities§§ | |||||
| Unimproved facilities | 655.0 (1564.5) | 1 | <0.001 | 1 | 0.016 |
| Improved facilities | 543.6 (1138.5) | 0.4 (0.3, 0.6) | 0.6 (0.4, 0.9) | ||
| Handwashing facility¶¶ | |||||
| No | 683.2 (1633.7) | 1 | <0.001 | ||
| Yes | 465.7 (858.6) | 0.3 (0.2, 0.5) | |||
| Environmental factors | |||||
| Mean normalised difference vegetation index (NDVI)§ | |||||
| First tertile | 511.8 (1069.3) | 1 | 0.018 | 1 | <0.001 |
| Second tertile | 553.4 (1392.1) | 1.8 (1.2, 2.9) | 2.4 (1.5, 3.8) | ||
| Third tertile | 779.6 (1776.3) | 1.8 (1.1, 2.9) | 2.4 (1.4, 3.9) | ||
| Mean of middle infrared (MIR)§ | |||||
| First tertile | 786.0 (1878.8) | 1 | 0.515 | ||
| Second tertile | 574.5 (1190.3) | 0.8 (0.5, 1.4) | |||
| Third tertile | 461.8 (1042.0) | 0.7 (0.4, 1.3) | |||
| Elevation (N = 6,083)§ | |||||
| First tertile | 476.4 (941.3) | 1 | <0.001 | 1 | <0.001 |
| Second tertile | 458.2 (1193.4) | 0.9 (0.4, 1.8) | 1.0 (0.5, 2.0) | ||
| Third tertile | 740.5 (1715.8) | 8.1 (3.4, 19.3) | 14.1 (6.5, 30.7) | ||
| Sand fraction (N = 6,083)§ | |||||
| First tertile | 610.1 (1433.8) | 1 | 0.348 | ||
| Second tertile | 639.9 (1575.4) | 1.0 (0.7, 1.6) | |||
| Third tertile | 647.3 (1502.0) | 1.5 (0.8, 2.6) | |||
| Soil acidity (pH KCL)§ | |||||
| First tertile | 680.7 (1679.0) | 1 | 0.169 | ||
| Second tertile | 576.6 (1300.1) | 0.6 (0.4, 1.1) | |||
| Third tertile | 557.2 (1062.5) | 0.6 (0.3, 1.2) | |||
*EPG is presented for the infected individuals only, but the negative binomial models include all individuals regardless of infection status
† 1 missing value
‡ 118 missing values
§ 6 missing values
¶ 264 missing values
# 58 missing values and data not included in the multivariable model as education of the head of the household was included
** 46 missing values
†† 11 missing values
¶¶529 missing values, not included in the multivariable model due to high number of missing values
Natural flooring refers to earth, dung, palm or bamboo and stone
Man-made flooring includes wood, brick, vinyl or asphalt strips, tiles, cement, carpet and polished stone like marble or granite
Improved water source refers to limited and basic facilities, Unimproved refers to surface water and unimproved facilities
Improved sanitation refers to limited and basic facilities, Unimproved refers to open defaecation and unimproved facilities
Acronyms: EPG—egg per gram, IIR–Infection intensity ratio, mIIR–multivariable IIR, 95% CI—95% confidence interval