Table 1.
Age- and sex-related prevalence and intensity of Schistosoma mansoni infection from one stool sample in 31,865 randomly selected children and adults along the coast of Lake Victoria in Mwanza region, Tanzania
| Age groups (years) | N | Schistosoma mansoni | ||
|---|---|---|---|---|
| Positives | Positives in % (95% CI)* | Intensity (epg) of positives GM (95% CI)† | ||
| Males | ||||
| 7–8 | 5,938 | 2,259 | 38.0 (36.8–39.2) | 113.2 (106.5–120.4) |
| 9–12 | 6,852 | 3,077 | 44.9 (43.7–46.1) | 115.8 (110.0–121.8) |
| 20–39 | 1,128 | 434 | 38.5 (35.8–41.2) | 72.1 (63.5–81.8) |
| 40–55 | 1,434 | 406 | 28.3 (25.9–30.7) | 70.0 (61.9–79.1) |
| Total | 15,352 | 6,176 | 40.2 (39.4–41.0) | 107.5 (103.6–111.4) |
| Females | ||||
| 7–8 | 6,420 | 2,393 | 37.3 (36.1–38.5) | 114.5 (107.9–121.4) |
| 9–12 | 7,730 | 3,191 | 41.3 (40.1–42.5) | 113.9 (108.4–119.6) |
| 20–39 | 1,313 | 321 | 24.4 (22.0–26.8) | 53.5 (46.7–61.4) |
| 40–55 | 1,050 | 195 | 18.6 (16.2–21.0) | 45.4 (38.7–53.4) |
| Total | 16,513 | 6,100 | 36.9 (36.1–37.7) | 106.5 (102.7–110.4) |
| Both sexes | ||||
| 7–8 | 12,358 | 4,652 | 37.6 (36.8–38.4) | 113.9 (109.1–118.8) |
| 9–12 | 14,582 | 6,268 | 43.0 (42.2–43.8) | 114.8 (110.8–118.9) |
| 20–39 | 2,441 | 755 | 30.9 (29.1–32.7) | 63.5 (57.8–69.7) |
| 40–55 | 2,484 | 601 | 24.2 (22.4–26.0) | 60.8 (55.1–67.2) |
| Total | 31,865 | 12,276 | 38.5 (37.9–39.1) | 107.0 (104.3–109.7) |
CI = confidence interval; epg = eggs per gram; GM = geometric mean.
Prevalence was similar between sexes in the 7–8 years group (P = 0.38), while males in the other three age groups had higher prevalence than females (P < 0.0005). For sexes combined, there were significant differences in prevalence by age group (P < 0.0005) with the following sequence: 9–12 > 7–8 > 20–39 > 40–55 years (χ2).
There was no sex difference among the schoolchildren (age group 7–8 and 9–12 years), but for adults (20–39 and 40–55 years), males had higher intensities than females (P = 0.002 and P < 0.0005, respectively). For sexes combined, there were no difference between the two groups of children and between the two adult groups, but intensity of the children was significantly higher (P < 0.0005) than that of the adults (one-way ANOVA).