Monitoring Schistosome Hybrids Under Under Praziquantel Pressure

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Brief Title

Monitoring Schistosome Hybrids Under Under Praziquantel Pressure

Official Title

Prevalence of Potential Schistosome Hybrids and Their Invasive Capacity Under Praziquantel Pressure in Northern Senegal

Brief Summary

      The overall objective of this project is to examine and quantify the potential existence and
      impact on Praziquantel (PZQ) efficacy, of naturally occurring S. haematobium and S. bovis
      hybrid populations in northern Senegal. Schistosome hybrids may present vigor compared to
      their pure parental forms and hence, may be less sensitive to PZQ. We hypothesise that PZQ
      repeated treatment selects the hybrid schistosome populations.

Detailed Description

      Human schistosomiasis is a Neglected Tropical Disease caused by schistosome helminth worms
      with impressive epidemiological statistics associated: 800 million people at risk in 78
      countries, > 230 million infected and > 200 000 deaths each year. The disease is highly
      endemic in sub-Saharan Africa where it persists despite mass drug administration with
      Praziquantel (PZQ). Some schistosomes are specific to humans and induce two main disease
      forms (either mesenteric or uro-genital) while others are associated with wild animals.
      However, hybridization can occur between different schistosome species. In northern Senegal,
      hybridization between schistosome species specific to humans and animals is now known to be
      frequent with the potential risk of zoonotic transmission.

      This study will propose an integrative approach by conducting parasitological and molecular
      analysis including, schistosome miracidia genotyping to show if PZQ repeated treatment
      affects the genomic composition (Frequencies of alleles) of hybrid populations.

      The objectives are:

        -  Determine the current prevalence of potential hybrid schistosome populations in their
           natural setting in Senegal

        -  Determine the sensitivity of hybrid schistosomes to praziquantel treatment in field

        -  Determine the molecular basis (at the genome level) of such phenotypic changes).

      The study is a longitudinal observation of a cohort of school children after repeated
      Praziquantel (40 mg/kg) treatment, a drug commonly used through Mass Drug Administration
      (MDA) to treat schistosomiasis.

      The cohort will be followed over a period of three years. Before the followup, a baseline
      urogenital schistosomiasis test will be performed on 1, 450 school-age children randomly
      selected in the five sites (290 in each site). All positive children will receive a single
      treatment (T1) of Praziquantel (PZQ) (40 mg/kg). Among those who test positive for S.
      haematobium eggs, only 50 in each site (five sites), who meet all the eligibility criteria
      will be invited to participate to the longitudinal follow-up. Four rounds of a single
      praziquantel (PZQ) treatment will be administered to positive individuals every 6 months. One
      round will consist of one treatment (T1 to T4) followed by a control treatment after one
      month (CT1 to CT4), hence, before the potential re-infecting schistosomes become adults and
      start egg-laying, which could bias the effectiveness of treatment evaluations. At each CT
      time, samples will be collected and S. haematobium eggs quantified (number of excreted
      eggs/10 mls of urine). Parasites (miracidia hatched from excreted eggs) will be recovered
      before each initial treatment (T1 to T4) and at CT1 to CT4 for subsequent genetic analysis to
      characterize hybrid schistosomes between S. haematobium and S. bovis.

Study Type


Primary Outcome

Change from baseline in prevalence and intensity of schistosome infection

Secondary Outcome

 Hybrids tolerance to praziquantel




Praziquantel 600 milligram


* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.

Recruitment Information

Recruitment Status


Estimated Enrollment


Start Date

August 11, 2020

Completion Date

December 31, 2022

Primary Completion Date

July 31, 2021

Eligibility Criteria

        Inclusion Criteria:

          -  Children between the initiation courses (CI) and elementary course second year (CE2)

          -  Absence of declared chronic pathologies that could impact the follow-up

          -  Be positive for S. haematobium infection during the selection period (excreting eggs)

          -  Residing in the study area during the 3 years of the follow-up

        Exclusion Criteria:

          -  Absence of written informed consent or expressed refusal from the child

          -  Enrolled in another on going study, which implicates the administration of PZQ or
             tests another product.




5 Years - 10 Years

Accepts Healthy Volunteers

Accepts Healthy Volunteers


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Location Countries


Location Countries


Administrative Informations



Organization ID


Responsible Party


Study Sponsor

Institut de Recherche pour le Developpement

Study Sponsor

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Verification Date

September 2020