ADVOCATING CONTROL OF SCHISTOSOMIASIS IN AFRICAN CHILDREN (≤ 6 YEAR OLDS): DEVELOPMENT OF A ‘DOSE POLE’ FOR THE ADMINISTRATION OF PRAZIQUANTEL

Sousa-Figueiredo J.C.1, Pleasant J.2, Kabatereine N.3, Rollinson D.1, Stothard J.R.1

1 Department of Zoology, Natural History Museum, London, United Kingdom; 2Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK

3 Vector Control Division, Ministry of Health, PO Box 1661, Kampala, Uganda

Provide further evidence of occurrence of intestinal schistosomiasis in preschool-aged children and modify the current WHO ‘dose pole’ to facilitate their inclusion in current control initiatives

OBJECTIVE

References: •Strandgaard H et al (2007). Field testing of the WHO dose pole for administration of praziquantel in the treatment of opisthorchiasis in Lao PDR. Trans Royal Soc of Trop Med and Hyg, 101, 1120-1123

•Kabatereine et al. (2006) Epidemiology and geography of Schistosoma mansoni in Uganda: implications for planning control. Trop Med and Intern Health, 9, 372-80•Hall A et al (1999). Alternatives to bodyweight for estimating the dose of praziquantel needed to treat schistosomiasis. Trans Royal Soc of Trop Med and Hyg, 93, 653-658

•Stothard JR and Gabrielli A-F (2007). Schistosomiasis in African infants and pre-school children: to treat or not to treat? Trends in Parasiitology, 23, 83-86

Acknowledgements: Ugandan MoH, Vector Control Division; Zanzibar MoHSW and The Health Foundation, UK.

We strongly advocate the inclusion of preschool-aged children in current and future schistosomiasis control campaigns in Uganda given the proven substantial infection risk to younger children, the established pharmacological safety of praziquantel, and now the improvement of the WHO ‘dose pole’.

CONCLUDING REMARK

PRESENT HEALTH INEQUITY

Preschool-aged children (≤ 6 years) have long been overlooked by preventative chemotherapy campaigns aiming to control schistosomiasis. To eliminate the present health inequity, and to facilitate the administration of the drug of choice, praziquantel (PZQ), the current ‘dose pole’ must be improved to accommodate this younger age-class.

DATA FOR DEVELOPMENT OF THE ‘DOSE POLE’

Data on height from 1144 preschool-aged children living along the coast of Lake Albert (Uganda) were used to predict bodyweight and dosage of PZQ, as well as, estimate height thresholds for PZQ tablet administration. This provisional ‘dose pole’ was then hypothetically tested on 470 children from Zanzibar, Tanzania, to validate the pole’s applicability in another endemic sub-Saharan Africa population (Graphs 1 & 2).

PZQ dose Uganda (n=1144)

Zanzibar (n=470)

Dose administered (mg / kg)

Minimum 21.5 25.6

Maximum 90.5 67.1

Average 40.7 40.7

No. (%) of individuals receiving dose

<30 mg/kg 12 (1.1%) 5 (1.1%)

≥ 30 & <40 mg/kg 554 (48.4%) 153 (32.5%)

≥40 & ≤60 mg/kg 564 (49.3%) 306 (65.1%)

>60 mg/kg 14 (1.2%) 6 (1.3%)

UGANDAN PRESCHOOLERS AND RISK OF BILHARZIA

A sub-set of 109 preschoolers was investigated for disease prevalence and mothers were interviewed on behalf of their children on a variety of putative risk factors.

Classical example of young child’s exposure to contaminated water

Prevalence of infection in Ugandan school-aged children could be mirrored by their younger

counterparts (Fig. from Kabatereine et al, 2004)

Graph 1 – The relationship between bodyweight of preschool-aged children from Uganda and Zanzibar and height. The equation for the line of best fit is shown and r, correlation coefficient

Table 1 – Performance of the updated WHO dose pole in estimating dosages of PZQ in preschool-aged children

Graph 2 – The distribution of PZQ dosage that would have been given to the children in Uganda and Zanzibar if weight had been predicted from height. Vertical dotted lines mark the upper and lower ranges of dosage given in practise if the target dosage is 20, 40 or 60 mg/kg

• Preschool-aged children participated in high risk activities: 70.3% go into the water with their mothers and 91.7% are bathed using water from the lake

• overall prevalence of infection of 45.9% (36.3–55.7%)• >95% of individuals would have received a proven

efficacious and safe praziquantel dose (30 - 60 mg/kg) in Uganda and Zanzibar (Table 1)

KEY FINDINGS