WHO | Launch of new guideline for the control and elimination of human schistosomiasis

The World Health Organization (WHO) launched a new guideline that provides evidence-based recommendations to countries in their efforts to achieve control and elimination of schistosomiasis as a public health problem, and to move towards interruption of transmission.

The new guideline highlights six recommendations that will help countries to implement national schistosomiasis control and elimination programmes and support efforts to verify the
interruption of transmission. The specific objectives are to provide guidance on:

• ƒ prevalence thresholds, target age groups and frequency of preventive chemotherapy for schistosomiasis;
• ƒ establishment of water, sanitation and hygiene (WASH) and snail control activities to support control and elimination of schistosomiasis;
• ƒ use of diagnostic tests in humans in low transmission areas and for moving to, and evaluating the interruption of transmission of schistosomiasis;
• ƒ tools for the assessment of Schistosoma spp. infection in snail hosts; and
• ƒ diagnostic tests for the assessment of schistosomiasis infection in animal reservoirs of infection

The six recommendations are:

• Recommendation 1: 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. Strong recommendation. Certainty of evidence: moderate

• Recommendation 2: In endemic communities with prevalence of Schistosoma spp. infection < 10%,  WHO suggests one of two approaches based on programmatic objectives and resources: (i) where there has been a programme of regular preventive chemotherapy, to continue the intervention at the same or reduced frequency towards interruption of transmission; or (ii) where there has not been a programme of regular preventive chemotherapy, to use a clinical approach of test-and-treat, instead of preventive chemotherapy targeting a population. Conditional recommendation. Certainty of evidence: very low

• Recommendation 3: In endemic communities with prevalence of Schistosoma spp. infection ≥ 10% that demonstrate lack of an appropriate response to annual preventive chemotherapy, despite adequate treatment coverage (≥ 75%), WHO suggests consideration of biannual (twice yearly) instead of annual preventive chemotherapy. Conditional recommendation. Certainty of evidence: very low.

• Recommendation 4: WHO recommends that health facilities provide access to treatment with praziquantel to control morbidity due to schistosomiasis in all infected individuals regardless of age, including infected pregnant excluding the first trimester, lactating women and pre-SAC aged < 2 years. The decision to administer treatment in children under 2 years of age should be based on testing and clinical judgement. Strong recommendation. Certainty of evidence: moderate.

• Recommendation 5: WHO recommends WASH interventions, environmental interventions (waterengineering and focal snail control with molluscicides) and behavioural change interventions as essential measures to help reduce transmission of Schistosoma spp. in endemic areas. Strong recommendation. Certainty of evidence: low.

• Recommendation 6: In communities approaching the interruption of transmission (defined as having no autochthonous human cases reported for 5 consecutive years), WHO suggests a verification framework that consists of:
  1. Testing for Schistosoma infection in humans with a diagnostic that has high sensitivity and specificity. This may require the use of a two-step diagnostic process starting with a high sensitivity test confirmed with a second, high specificity test.
  2. Testing for Schistosoma infection in snails with a diagnostic that has high sensitivity and specificity. This may require the use of a two-step diagnostic process starting with a high sensitivity test confirmed with a second, high specificity test.
  3. Testing for Schistosoma infection in non-human mammalian hosts, as applicable, with a diagnostic that has high sensitivity and specificity. This may require the use of a two-step diagnostic process starting with a high sensitivity test confirmed with a second, high specificity test. Conditional recommendation. Certainty of evidence: low

Download the guideline

This guideline is based on the best evidence available in 2021. For many questions that the guideline set out to answer, the evidence base was limited. Evidence is in any event subject to change. The guideline will therefore be updated accordingly as new evidence emerges.