Control and Elimination of Human Schistosomiasis

Publication Date: February 14, 2022
Last Updated: March 14, 2022

Summary of Recommendations

In endemic communities with prevalence of Schistosoma spp. infection ≥ 10%, WHO recommends annual preventive chemotherapy with a single dose of praziquantel at ≥ 75% treatment coverage in all age groups from 2 years old, including adults, pregnant women after the first trimester and lactating women, to control schistosomiasis morbidity and advance towards eliminating the disease as a public health problem. (S, M)
Implementation considerations:
  • Prevalence of infection is defined as the percentage of individuals of all agesin a population targeted for treatment who are infected with any species ofSchistosoma. The strategy of preventive chemotherapy does not differ bySchistosoma species.
  • The prevalence threshold of 10% is based on estimation by parasitologicalmicroscopy, using duplicate Kato–Katz smears from one stool sample for intestinalschistosomiasis, predominantly S. mansoni and S. japonicum, and single 10 mLurine filtration for urogenital schistosomiasis due to S. haematobium.
  • The point-of-care circulating cathodic antigen test can be used to determineprevalence of S. mansoni; 30% prevalence by this test is to be consideredequivalent to 10% prevalence by the Kato–Katz technique.
  • Routine monitoring for effective coverage and evaluation of the impact of theintervention (using repeat population-based surveys conducted after five roundsof preventive chemotherapy, or more frequently with a mid-term evaluation afterthree rounds) should be integral parts of preventive chemotherapy programmes,to help inform the decision on changing the strategy and continuing or stoppingthe programme.
  • Expanded preventive chemotherapy programmes pose a greater theoretical riskto the development of drug resistance. Evidence of the potential emergence ofreduced praziquantel efficacy in response to increased drug use is rarely reported;thus, continued vigilance to monitor drug efficacy over time through efficacysurveys is imperative to detect any emergence of drug resistance.
  • Routine monitoring for safety of the intervention should also be an integral part ofpreventive chemotherapy programmes.
  • Preventive chemotherapy in preschool-aged children (pre-SAC) is appropriatefor those aged ≥ 2 years. Younger children, aged < 2 years, may be consideredfor treatment on an individual clinical basis. The medication for children aged <2 years should be an oral disintegrating tablet formulation (under development)that is easily administered, disintegrates in the mouth and, ideally, has a sweettaste and smell; if paediatric formulations are not available, praziquantel crushedin soft food may be used for individual case treatment only.
  • Available evidence does not differentiate approaches to infection with thedifferent species of Schistosoma.
  • The 10% prevalence threshold for intervention will expand eligibility for preventivechemotherapy programmes and necessitate a larger global supply of praziquantelthan that currently available via donation schemes (estimated at 300 milliontablets annually at the time of publication of this guideline).
  • Community mapping of the epidemiology of schistosomiasis can reduce the needfor praziquantel, as treatment can be better targeted to communities and at-riskregions.
  • Ensuring high coverage is essential for preventive chemotherapy and may requireincentivization of local community drug distributors.
  • Public health awareness campaigns are necessary to ensure high coverage inpreventive chemotherapy programmes and to address concerns about adverseevents from medication.



Control and Elimination of Human Schistosomiasis

Authoring Organization