Characteristics of the study population of school-age children
| Variables | n | % |
| Demographic and socioeconomic | ||
| Age, years | ||
| 6–9 | 1531/3960 | 38.7 |
| 10–13 | 1386/3960 | 35.0 |
| 14–16 | 1043/3960 | 26.3 |
| Sex | ||
| Male | 1905/3960 | 48.1 |
| Female | 2055/3960 | 51.9 |
| Family income | ||
| >US$150 | 732/3901 | 18.8 |
| ≤US$150 | 3169/3901 | 81.2 |
| Maternal education level | ||
| Complete secondary or higher | 309/3853 | 8.0 |
| Complete primary or incomplete secondary | 1330/3853 | 34.5 |
| Illiterate or incomplete primary | 2214/3853 | 57.5 |
| Household electric appliances | ||
| None | 700/3959 | 17.7 |
| 1–2 | 2164/3959 | 54.7 |
| 3–4 | 1095/3959 | 27.6 |
| Allergic symptoms | ||
| Asthma | ||
| Wheeze ever | 1249/3847 | 32.5 |
| Wheeze in past year | 406/3858 | 10.5 |
| Wheeze attacks in past year | ||
| 1–3 attacks | 311/3871 | 8.0 |
| 4–12 attacks | 69/3871 | 1.8 |
| ≥12 attacks | 27/3871 | 0.7 |
| Woken by wheeze in past year | 316/3346 | 9.4 |
| Wheeze limiting speech in past year | 146/3857 | 3.8 |
| Wheeze during or after exercise in past year | 224/3860 | 5.8 |
| Rhinitis | ||
| Rhinitis ever | 480/3907 | 12.3 |
| Rhinitis in past year without colds | 346/3907 | 8.9 |
| Rhinitis in past year with itchy eyes | 246/3895 | 6.3 |
| Eczema | ||
| Eczema ever | 330/3912 | 8.4 |
| Itchy rash affecting flexures in past year | 191/3912 | 4.9 |
| Woken at night by itchy rash in past year | 83/3881 | 2.1 |
| Skin prick reaction ≥3 mm | ||
| Any allergen | 477/3821 | 12.5 |
| House dust mite | 252/3821 | 6.6 |
| Mixed grass | 73/3821 | 1.9 |
| Cockroach | 167/3821 | 4.4 |
| Fungus | 18/3821 | 0.5 |
| Cat | 15/3821 | 0.4 |
| Dog | 67/3821 | 1.8 |
| Alternaria | 8/3692 | 0.2 |
| Geohelminth infections | ||
| Any helminth | 2851/3804 | 74.9 |
| Ascaris lumbricoides | 2013/3804 | 52.9 |
| Trichuris trichiura | 2178/3804 | 57.3 |
| Hookworm | 350/3804 | 9.2 |
| Strongyloides stercoralis | 16/3804 | 0.4 |