Table 3. Predictors of intensity of hookworm infection amongst preschool-age children, school-age children, and adults in Namwera, Mangochi district, Malawi in 2018.
| Characteristic | Mean hookworm EPG (SD)1 | Univariable analysis2 | Multivariable analysis2,3 | ||
|---|---|---|---|---|---|
| IRR (95% CI) | P value | Multivariable IRR (95% CI) | P value | ||
| Individual factors | |||||
| Sex: | |||||
| Male | 32 (345) | 1 | - | - | - |
| Female | 38 (518) | 1.04 (0.62–1.76) | 0.87 | - | - |
| Age group: | |||||
| <1 year | 16 (548) | 1 | - | 1 | - |
| 1–4 years | 14 (180) | 11.21 (4.35–28.90) | - | 21.56 (8.64–53.82) | - |
| 5–14 years | 54 (512) | 148.53 (60.23–366.29) | <0.001 | 25.40 (12.66–50.98) | <0.001 |
| Currently in education: | |||||
| No | 50 (561) | 1 | - | 1 | - |
| Yes | 10 (152) | 0.12 (0.06–0.21) | <0.001 | 0.23 (0.11–0.50) | <0.001 |
| Dewormed within past 12 months: | |||||
| No | 48 (513) | 1 | - | 1 | - |
| Yes | 23 (411) | 0.27 (0.15–0.46) | <0.001 | 0.60 (0.35–1.02) | 0.006 |
| Household factors | |||||
| Access to sanitation: | |||||
| Open defecation | 30 (197) | 1 | - | - | - |
| Unimproved | 11 (73) | 0.71 (0.08–6.60) | - | - | - |
| Limited | 56 (769) | 1.13 (0.17–7.55) | - | - | - |
| Basic | 32 (354) | 0.67 (0.10–4.29) | 0.44 | - | - |
| Sanitation facility is shared: | |||||
| No | 31 (343) | 1 | - | - | - |
| Yes | 54 (751) | 1.58 (0.85–2.94) | 0.15 | - | - |
| Access to handwashing facility: | |||||
| No facility | 39 (379) | 1 | - | - | - |
| Limited | 33 (468) | 0.79 (0.42–1.48) | - | - | - |
| Basic | 51 (720) | 0.41 (0.10–1.59) | 0.42 | - | - |
| Household flooring: | |||||
| Natural materials | 38 (456) | 1 | - | - | - |
| Man-made materials | 26 (484) | 0.50 (0.24–1.03) | 0.06 | - | - |
| Socio-economic status: | |||||
| Poorest (Q1) | 72 (782) | 1 | - | 1 | - |
| Q2 | 30 (245) | 0.47 (0.22–1.02) | - | 0.37 (0.18–0.79) | - |
| Q3 | 33 (432) | 0.51 (0.22–1.18) | - | 0.69 (0.32–1.52) | - |
| Q4 | 37 (432) | 0.57 (0.25–1.27) | - | 0.62 (0.29–1.34) | - |
| Least poor (Q5) | 10 (77) | 0.19 (0.08–0.45) | 0.005 | 0.29 (0.13–0.65) | 0.013 |
| Source of household income: | |||||
| Ganyu4 only | 50 (604) | 1.07 (0.39–2.96) | - | - | - |
| Farming | 33 (329) | 1.15 (0.41–3.20) | - | - | - |
| Other informal | 27 (329) | 0.42 (0.14–1.26) | - | - | - |
| Formal | 27 (461) | 0.19 (0.03–1.20) | 0.02 | - | - |
| Highest education level of any adult household member: | |||||
| No education | 45 (416) | 1 | - | 1 | - |
| Primary incomplete | 34 (467) | 0.48 (0.26–0.87) | - | 0.74 (0.42–1.30) | - |
| Primary complete or higher | 29 (507) | 0.26 (0.11–0.60) | 0.005 | 0.46 (0.21–0.97) | 0.12 |
| Household size: | |||||
| # household members | - | 0.83 (0.74–0.92) | 0.001 | - | - |
| Environmental factors | |||||
| Aridity: | |||||
| Semi-arid | 20 (300) | 1 | - | - | - |
| Dry sub-humid | 45 (534) | 2.52 (1.09–5.82) | 0.03 | - | - |
| Elevation: | |||||
| Mean, SD | - | 1.007 (1.001–1.011) | 0.014 | - | - |
| Sand fraction: | |||||
| Mean, SD | - | 0.91 (0.86–0.97) | 0.002 | 0.91 (0.85–0.96) | 0.001 |
| Population density within 1km | |||||
| <50 | 7 (54) | 1 | - | - | - |
| 50–249 | 41 (456) | 7.22 (1.47–35.38) | - | - | - |
| >249 | 33 (475) | 4.44 (0.90–21.98) | 0.03 | - | - |
16102 observations with Kato-katz result included. All variables have complete data, with the exception of age group (n = 6098), dewormed within past 12 months (n = 5939), access to handwashing facility (n = 5929), household flooring (n = 6095), source of household income (n = 5654) and highest education level of any adult household member (n = 6072).
2Mixed effects negative binomial regression of egg counts, with quantity of stool assessed per sample included as an offset, accounting for clustering at the household, village and cluster level. Reference category is indicated by a value of [1].
35885 observations included in fully adjusted mixed effects negative binomial regression model.
4Casual off-own-farm labour (e.g. weeding or ridging).
Acronyms: CI = Confidence interval, EPG = Eggs per gram, IRR = Incidence rate ratio, SD = Standard deviation.