Schistosomiasis

Strategy

Control and preventive chemotherapy


The strategy for schistosomiasis control aims to prevent morbidity in later life through regular treatment with praziquantel, which is currently the only recommended drug for infection and disease caused by the species of schistosome infecting humans. Praziquantel has been used successfully over the past 30 years to control schistosomiasis in many countries. The recent increased support for the control of Neglected Tropical Diseases and increased access to praziquantel led to a significant increase in the number of people treated for schistosomiasis. In 2012 more than 35 million people, 83% of them in sub-Saharan Africa, were treated for schistosomiasis. Experience from China and Egypt shows that preventive chemotherapy, mass treatment without individual diagnosis, with high coverage can result on significant impacts on indices of infection and also reduced requirements for praziquantel. Treatment several times during childhood is likely to prevent disease in adulthood.

The consensus on neglected tropical diseases is that several of these diseases, including schistosomiasis can be controlled in a coordinated approach with treatment on a large scale with safe and effective drugs, and at regular intervals.

Preventive chemotherapy in human helminthiasis


This manual and its dose-poles provide health professionals and programmes managers with the latest recommendations. Ref: ISBN 92 4 154710 3

For the control strategy of schistosomiasis, see p.41.

Recommended intervention strategy for morbidity control


For morbidity control, mass treatment is targeted at high risk groups. The high risk group targeted and the frequency of treatment depends on the prevalence of infection. This is outlined in the "Manual on preventive chemotherapy” The aim is morbidity control: periodic treatment of at-risk populations will cure subtle morbidity and prevent infected individuals from developing severe, late-stage morbidity due to schistosomiasis. In children, lesions may be reversed following specific treatment.

Praziquantel is safe in pregnancy, and it is recommended that women, and adolescent girls of child-bearing age, should be included in public health interventions.

Target populations

  • School-age children.
  • Adults considered to be at risk, from special groups (pregnant and lactating women; groups with occupations involving contact with infested water, such as fishermen, farmers, irrigation workers, or women in their domestic tasks), to entire communities living in endemic areas.

Pre-school children


There is growing evidence that very young children become infected with schistosomiasis when taken to water contact sites by their care-givers and siblings. In some situations the prevalence of schistosomiasis infection in these young children is very high. Recent studies have shown that praziquantel, when made palatable for small children, is safe, well tolerated, and effective in the treatment of pre-school children. However inclusion of very young children in mass treatment campaigns could prove disruptive and unsafe as there is currently no appropriate paediatric formulation of praziquantel.

It is recommended that pre-school children should be treated for schistosomiasis within child-health services where their weight is monitored; they are immunized, dewormed and given micronutrient supplements.

Towards the elimination of schistosomiasis.

While still encouraging Member States to intensify schistosomiasis control efforts, as the burden of disease remains high, the 65th World Health Assembly noted that some countries have achieved the control of morbidity due to schistosomiasis, and could attempt to interrupt the transmission. The resolution WHA 65.21 adopted in May 2012 acknowledged that some countries interrupted schistosomiasis transmission, and that low-transmission countries should be encouraged to initiate interventions towards elimination. The resolution also requested the Organization to develop guidelines for implementation towards elimination, and to put in place a process to certify the interruption of transmission.

While chemotherapy with praziquantel is an important component of any schistosomiasis control programme, other operational components including provision of potable water and adequate sanitation, hygiene education, and snail control are essential to the control and elimination of schistosomiasis.

Access to drugs


Praziquantel is the recommended treatment for schistosomiasis at 40 mg/kg body weight. The cost of a single 600-mg tablet is about US$ 0.08 and an average treatment is estimated to be between US$ 0.20–0.30.

Praziquantel is now available free of charge to high-disease burden countries in sub-Saharan Africa, through a donation from Merck Serono to the World Health Organization. The donation of praziquantel is based on a successful review of the national plan for schistosomiasis control and a commitment of resources for implementation.

To be considered for this donation programme, please download and complete the form.

Additional praziquantel is available to selected countries with funding from the Department for International Development (DfID) and the USAID.

Latest news

25 Feb. 2011 | Geneva
Schistosomiasis: number of people treated worldwide in 2009. Weekly Epidemiological Record, 2011, 86:73–80

29 Jan. 2010 | Geneva
Please visit the new Schistosomiasis Control Initiative (SCI) website
www3.imperial.ac.uk/schisto

  • 05 Nov. 2009
    Elimination of schistosomiasis from low-transmission areas, Salvador, Bahia, Brazil, 18-19 August 2008

PCT Databank (SCH)