Accuracy of the WHO praziquantel dose pole for large-scale community treatment of urogenital schistosomiasis in northern Mozambique: Is it time for an update?

Pedro H Gazzinelli-Guimaraes,Herminio O Aurelio,Carl H Campbell,Neerav Dhanani,Alan Fenwick,Anna E Phillips,Josefo Ferro,Rassul Nala,Charles H King,Song Liang

doi:10.1371/journal.pntd.0006957

Abstract

BackgroundA pioneering strategy developed by the World Health Organization (WHO) for the control of schistosomiasis was the concept of a height-based dose pole to determine praziquantel (PZQ) dosing in large-scale treatment campaigns. However, some recent studies have shown variable accuracy for the dose pole in terms of predicting correct mg/Kg dosing, particularly for treatment of adults. According to the WHO, 91 million adults in 52 countries are targeted to be treated by 2020.Methods/Principal findingsThe present study aimed to test the accuracy of the dose pole in determining PZQ dosage by comparing the number of tablets determined by the dose pole with the number of tablets determined according to total body weight. The analysis included height-for-weight data from 9,827 school-aged children (SAC) and adults from 42 villages in the province of Cabo Delgado in Mozambique. The results revealed that of the 7,596 SAC, 91.8% has received an appropriate dose (30-60mg/Kg), 6% received an insufficient dose (<30mg/Kg) and 2% an excessive dose (> 60mg/Kg). On the other hand, 13.7% out of 2,231 adults were treated inaccurately with 13.5% receiving an insufficient dose and 0.2% an excessive dose. When the percentage of insufficient dosing was disaggregated by gender, the frequency of adult females who were underdosed reached 18.3% versus 10.8% of adult males. Of note, Adult females aged 21–55 years were found to have an underdose frequency of 21.3%, compared to 11.8% of adult males in the same age range. The performance of a proposed modified dose pole was compared using the same dataset of adult Mozambicans. The results showed that the modified dose pole reduced the underdose frequency among adults from 13.5% to 10.4%, and subsequently increased the percentage of optimal dosing from 33.7% to 45.3%.ConclusionsOur findings highlight the need to update the WHO-dose pole to avoid administration of insufficient PZQ doses to adults and therefore minimize the potential emergence of PZQ-resistant strains.Trial registrationInternational Standard Randomized Controlled Trial registry under ISRTC number 14117624

Highlights

Human schistosomiasis is an acute and chronic neglected tropical disease (NTD) caused by six species of parasitic blood flukes of genus Schistosoma: S. guineensis, S. haematobium, S. intercalatum, S. japonicum, S. mansoni and S. mekongi
When the percentage of insufficient dosing was disaggregated by gender, the frequency of adult females who were underdosed reached 18.3% versus 10.8% of adult males
Our findings highlight the need to update the World Health Organization (WHO)-dose pole to avoid administration of insufficient PZQ doses to adults and minimize the potential emergence of PZQresistant strains

Summary

Introduction

Human schistosomiasis is an acute and chronic neglected tropical disease (NTD) caused by six species of parasitic blood flukes of genus Schistosoma: S. guineensis, S. haematobium, S. intercalatum, S. japonicum, S. mansoni and S. mekongi. Together, they affect about 250 million people worldwide, with more than 779 million people are at risk of infection [1, 2]. For almost 20 years, schistosomiasis control has been based on large-scale, repeated, preventive chemotherapy treatment with praziquantel (PZQ), with an optimal dose of 40-60mg/ Kg bodyweight. A pioneering strategy developed by the World Health Organization (WHO) for the control of schistosomiasis was the concept of a height-based dose pole to determine praziquantel (PZQ) dosing in large-scale treatment campaigns. According to the WHO, 91 million adults in 52 countries are targeted to be treated by 2020

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