Closing the praziquantel treatment gap: new steps in epidemiological monitoring and control of schistosomiasis in African infants and preschool-aged children

Abstract

SUMMARYWhere very young children come into contact with water containing schistosome cercariae, infections occur and schistosomiasis can be found. In high transmission environments, where mothers daily bathe their children with environmentally drawn water, many infants and preschool-aged children have schistosomiasis. This ‘new’ burden, inclusive of co-infections with Schistosoma haematobium and Schistosoma mansoni, is being formally explored as infected children are not presently targeted to receive praziquantel (PZQ) within current preventive chemotherapy campaigns. Thus an important PZQ treatment gap exists whereby infected children might wait up to 4–5 years before receiving first treatment in school. International treatment guidelines, set within national treatment platforms, are presently being modified to provide earlier access to medication(s). Although detailed pharmacokinetic studies are needed, to facilitate pragmatic dosing in the field, an extended ‘dose pole’ has been devised and epidemiological monitoring has shown that administration of PZQ (40 mg/kg), in either crushed tablet or liquid suspension, is both safe and effective in this younger age-class; drug efficacy, however, against S. mansoni appears to diminish after repeated rounds of treatment. Thus use of PZQ should be combined with appropriate health education/water hygiene improvements for both child and mother to bring forth a more enduring solution.

Schistosomiasis Sustained Control Program in Ethnic Groups Around Ninefescha (Eastern Senegal)

“…Cases of reinfection were also observed in the study carried out by Stothard in Uganda, who found that even a 6-month period after two praziquantel administrations had little impact in decreasing prevalence. 16 Moreover, a slight increase in S. mansoni prevalence was observed between 2014 and 2015. A possible explanation is that the backwaters are the main source of water used by mothers to bathe their children, which is how they get infested in the first place.…”

“…12 Our results are also in line with several studies showing that children under 2 years of age have active infection with this helminth. [16][17][18][19] Because of the efforts of the WHO authorities in Senegal, the medical regional authorities accepted to treat children under 6 years of age but only on an individual basis and under PNLB supervision in 2014. The study pointed out that these children were very difficult to treat and get reinfected very rapidly.…”

Epidemiology of Schistosomiasis in Two High-Risk Communities of South Côte d'Ivoire with Particular Emphasis on Pre-School–Aged Children

“…The lack of pharmacological data and an appropriate formulation of praziquantel for pre-schoolers are important reasons why this age group is largely excluded from preventive chemotherapy. 25,26 However, pre-school-aged children might be particularly vulnerable to the negative consequences of an early-life infection with Schistosoma, because they would not get treatment until entering school. 27 Additionally, adolescents and adults are given far less attention than the school-aged population when it comes to schistosomiasis control.…”

“…18 Previous studies have highlighted such early Schistosoma infection in areas of high endemicity. 25,28,33,34 The negative health impact of such early infections has been emphasized. 31,32,35,36 Our observation of CCA detected in the urine of a child as young as 3 months in the absence of S. mansoni eggs in fecal samples is in line with recent observations from a study in Uganda using different approaches for detecting Schistosoma infections in pre-school-aged children.…”

Urinary schistosomiasis

“…In the clinic setting, children are treated with two doses of 20 mg/kg PZQ at intervals ranging from 1 day to 4 weeks. Although pharmacokinetic studies are lacking, a suspension formulation or crushed tablets have been successfully used in the treatment of younger children [37,38]. Side effects may include nausea, emesis, diarrhea, dizziness, headache and pyrexia, but these are less likely to occur with the two-daily dosing regimen than with the single-dose treatment [38].…”