Table 1. Description of the two cohorts at enrollment (T0).
| Cohort 1* | Cohort 2† | |
| Year of enrollment (T0) | 2000 | 2007 |
| S. japonicum infection prevalence in cohort villages at enrollment‡ | 46.9 | 10.6 |
| Mean infection intensity in EPG in cohort villages at enrollment (SE)‡ | 46.0 (4.7) | 2.6 (0.6) |
| % Female | 51.9 | 57.3 |
| Mean age at enrollment (SE) | 31.3 (0.7) | 45.6 (0.7) |
| % of adults reporting farming as their occupation | 92.9 | 98.7 |
| % of adults that have at least a middle school education | 39.3 | 22.0 |
| Mean water contact hours by month (% reporting any water contact)** | ||
| April | 28.4 (79.7) | – |
| May | 5.4 (80.9) | 44.8 (82.2) |
| June | 7.7 (82.3) | 11.4 (72.5) |
| July | 4.8 (83.5) | 4.6 (59.0) |
| August | 4.9 (83.0) | 3.8 (53.0) |
| September | 5.4 (78.5) | 18.6 (57.7) |
| October | 2.9 (69.3) | 2.1 (40.5) |
| Mean water contact hours by activity (% reporting any water contact) | ||
| Washing vegetables or laundry | 5.7 (23.6) | 11.6 (60.3) |
| Irrigation ditch operation or maintenance | 1.9 (54.7) | 7.7 (40.5) |
| Fishing | 0.4 (3.1) | 0.4 (4.0) |
| Washing hands or feet | 11.6 (63.0) | 3.7 (87.0) |
| Harvesting rice | 1.6 (4.2) | 16.6 (43.0) |
| Planting rice | 32.2 (70.3) | 42.3 (66.5) |
| Swimming or playing | 5.0 (16.5) | 0.2 (9.5) |
| Washing agricultural tools | 1.1 (29.0) | 2.8 (72.3) |
Cohort 1 is composed of 424 residents from 10 villages in Xichang County, Sichuan, China where schistosomiasis was endemic, monitored from 2000 to 2006.
Cohort 2 is composed of 400 residents from 27 villages in two counties in Sichuan, China where schistosomiasis reemerged following reduction of S. japonicum infection prevalence below 1%, monitored from 2007 to 2010.
Prevalence and infection intensity estimates include all participants in village-wide infection surveys conducted at cohort enrollment: 1,801 individuals in 10 villages in cohort 1, 1,608 individuals in 27 villages in cohort 2.
Participants were asked about water contact behaviors from the start of the rice planting season. In Xichang County (from which cohort 1 participants were drawn) rice planting begins in April, whereas in the two reemerging counties (from which cohort 2 participants were drawn) rice planting begins in May.