Treatment of intestinal schistosomiasis in Ugandan preschool children: best diagnosis, treatment efficacy and side-effects, and an extended praziquantel dosing pole

Schematic map of Uganda, with its major water bodies (in grey). Inset are a map of Africa (top left: Uganda is highlighted) as well as detailed maps of the study areas in Lake Albert (top right) and Victoria (bottom right), depicting the prevalence of intestinal schistosomiasis in both mothers (nM) and children (nC) from different villages. The area of the dark sector in the pie chart is proportional to the prevalence of positives for egg-patent infection. Refer to Table 1 for prevalence values and CI₉₅.

Charts detailing the different prevalence levels of intestinal schistosomiasis, assessed by different diagnostic methodologies, in preschool children (≤6 year olds) and their mothers, from villages on the shores of Lakes Albert (top) and Victoria (bottom), Uganda. CI₉₅ around the prevalence are indicated in dashed lines.

Creating and applying the newly developed extended dose pole for the rapid administration of praziquantel to preschool children (≤six year olds). A Distribution of height and weight measurements from Uganda (‘genesis’ population n=1046, ‘same villages’ population n=1047, ‘different villages’ population n=1210) and Zanzibar (n=470). A polynomial model was fitted to indicate the correlation between height and weight data from the ‘genesis’ population and then used to predict bodyweight of each subject from height. B The distribution of PZQ dosages that would have been given to Ugandan and Zanzibari children if height had been used to predict weight. Vertical dotted lines mark the upper and lower ranges of dosage given in practise if the target dosage is 20, 40 or 60mg/kg.²⁸ C and D Box-and-whisker plots of theoretical dosages given to the different sexes and ages, respectively, using as test populations those from Uganda (‘different villages’ population) and Zanzibar (total n=1680). Shading depicts prevalence of intestinal schistosomiasis at each age according to total diagnostic evidence from the two targeted surveys (see Figure 1), (total population: 18 children were under one, 46 were one, 67 were two, 81 were three, 69 were four, 36 were five and 17 were six years of age). The horizontal bar in the middle shows the median theoretical dosage; both boxes show the interquartile range (25^th to 75^th percentile); the vertical dashed lines show the minimum and maximum values, or, the presence of outliers (the circles), show 1.5 times the interquartile range (roughly two times the standard deviation); the notches at the ‘waist’ give an impression of CI₉₅ around the medians, where boxes whose notches do not overlap have significantly different medians (P<0·05).⁴⁹

Pictorial representation of the current WHO dose pole for administration of PZQ tablets (at 600mg each) (left) and the proposed dose pole (right) with two new height thresholds added to allow for treatment of preschool children (≤six year olds): 60–84cm for one-half and 84–99cm for three-quarters PZQ table.¹⁹ The illustrated child needs three-quarters of one tablet. Additionally, the WHO pole's single tablet lower limit has been amended from 94cm to 99cm.