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Table 2 Relative (to baseline) changes in the force of infection (FOI) and their 95 % confidence intervals estimated at the point of monitoring (one or two years) after each round of preventive chemotherapy with praziquantel for Schistosoma mansoni areas

From: Estimation of changes in the force of infection for intestinal and urogenital schistosomiasis in countries with schistosomiasis control initiative-assisted programmes

Country

BL Infection Intensity Category

Number in cohort (n)

BL infection Intensity (epg)

BL FOI (wppy)

FY1 ζ1

FY2 ζ2

FY3 ζ3

Mali

High/Medium

215

452.75

16.35

0.97 [0.45, 1.92]

0.60 [0.41, 0.97]a

NA

Mali

Low

937

23.55

5.45

0.68 [0.45, 0.92]a

0.18 [0.09, 0.41]a

NA

Tanzania

High/Medium

290

400.38

18.26

3.61 [1.23, 5.04]b

2.03 [0.75, 3.22]

Tanzania

Low

769

11.06

0.44

2.41 [1.23, 3.77]b

0.35 [0.15,0.78]a

Uganda

High

262

766.04

30.00

0.78 [0.46, 1.50]

0.37 [0.22, 0.63]a

0.37 [0.19, 0.86]a

Uganda

Medium

235

231.69

10.02

1.04 [0.49, 2.00]

0.34 [0.13, 0.74]a

0.46 [0.17, 1.06]

Uganda

Low

600

33.54

1.69

0.24 [0, 0.61]a

0.32 [0.06, 0.64]a

0.20 [0.04, 0.43]a

Zambia

Medium

83

326.8

14.80

1.28 [0.52, 3.43]

NA

NA

Zambia

Low

1362

9.13

0.35

1.26 [0.89, 2.01]

NA

NA

  1. FOI: force of infection expressed as the mean number of adult female parasites acquired per person per year; epg: eggs per gram of faeces; wppy: worm pairs per person per year; BL: baseline; FY1: follow-up year 1; FY2: follow-up year 2; FY3: follow-up year 3; ζ1, ζ2, ζ3: the relative change in the FOI at FY1, FY2, FY3 respectively, expressed as a proportion of that at baseline; asignificant decreases in FOI from baseline; bsignificant increases in FOI from baseline: NA: not available. In Tanzania there was no treatment or survey at FY2 so the data collected at FY3 comprise an average across the previous two years