Implementation considerations ƒ Prevalence of infection is defined as the percentage of individuals of all ages in a population targeted for treatment who are infected with any species of Schistosoma. The strategy of preventive chemotherapy does not differ by Schistosoma species. ƒ The prevalence threshold of 10% is based on estimation by parasitological microscopy, using duplicate Kato–Katz smears from one stool sample for intestinal schistosomiasis, predominantly S. mansoni and S. japonicum, and single 10 mL urine filtration for urogenital schistosomiasis due to S. haematobium. ƒ The point-of-care circulating cathodic antigen test can be used to determine prevalence of S. mansoni; 30% prevalence by this test is to be considered equivalent to 10% prevalence by the Kato–Katz technique. ƒ Routine monitoring for effective coverage and evaluation of the impact of the intervention (using repeat population-based surveys conducted after five rounds of preventive chemotherapy, or more frequently with a mid-term evaluation after three rounds) should be integral parts of preventive chemotherapy programmes, to help inform the decision on changing the strategy and continuing or stopping the programme. ƒ Expanded preventive chemotherapy programmes pose a greater theoretical risk to the development of drug resistance. Evidence of the potential emergence of reduced praziquantel efficacy in response to increased drug use is rarely reported; thus, continued vigilance to monitor drug efficacy over time through efficacy surveys is imperative to detect any emergence of drug resistance. ƒ Routine monitoring for safety of the intervention should also be an integral part of preventive chemotherapy programmes. ƒ Preventive chemotherapy in preschool-aged children (pre-SAC) is appropriate for those aged ≥ 2 years. Younger children, aged < 2 years, may be considered for 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 sweet taste and smell; if paediatric formulations are not available, praziquantel crushed in soft food may be used for individual case treatment only. ƒ Available evidence does not differentiate approaches to infection with the different species of Schistosoma. ƒ The 10% prevalence threshold for intervention will expand eligibility for preventive chemotherapy programmes and necessitate a larger global supply of praziquantel than that currently available via donation schemes (estimated at 300 million tablets annually at the time of publication of this guideline). ƒ Community mapping of the epidemiology of schistosomiasis can reduce the need for praziquantel, as treatment can be better targeted to communities and at-risk regions. ƒ Ensuring high coverage is essential for preventive chemotherapy and may require incentivization of local community drug distributors. ƒ Public health awareness campaigns are necessary to ensure high coverage in preventive chemotherapy programmes and to address concerns about adverse events from medication.