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Program: mass drug administration to control schistosomiasis

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In a nutshell

  • The Problem: Schistosomiasis infection can cause anemia (and other chronic conditions) and in serious cases, death. More information on schistosomiasis available here.
  • The Program: Mass administration of praziquantel (PZQ). (This program is often combined with administration of drugs targeting soil-transmitted helminths - more on the combination program here.)
  • Track record: There's strong evidence from repeated trials that praziquantel effectively reduces prevalence of schistosomiasis infection.
  • Cost-effectiveness: Estimates place this intervention among the most cost-effective.
  • Bottom line: This is a proven, inexpensive method for improving lives in the developing world.
Table of Contents

Basics of the program

What is the program? What problem does it target?

Schistosomiasis is a parasite infection that can cause chronic malnutrition, pain, anemia, and in some cases, death. It is further discussed here.

The World Health Organization recommends treatment with praziquantel at least three times during childhood to cure non-severe morbidity and prevent the development of severe symptoms later in life.1

What are the components required to implement this program - how does it work?

This program requires praziquantel and a means of administering the drug as efficiently as possible.

  • Drugs: Praziquantel is donated by Merck to high disease burdened areas and thus freely available.2
  • Distribution mechanism: The Disease Control Priorities Report states that schools provide a strong infrastructure for administration and that teachers can be trained to deliver drugs safely.3 In the absence of training, mobile teams can come in to implement drug administration, but this method can cost significantly more.4

Program track record

Micro evidence: Has this program been rigorously evaluated and shown to work?

A Cochrane review of 24 randomized and quasi-randomized controlled trials included 6,315 participants in interventions to treat urinary schistosomiasis. The review concluded that "praziquantel and metrifonate are effective treatments for urinary schistosomiasis and have few adverse events. Metrifonate requires multiple administrations and is therefore operationally less convenient in community-based control programmes."5

A Cochrane review of 13 randomized or pseudo-randomized trials treating intestinal schistosomiasis concluded that "oxamniquine and praziquantel both appear to be effective for treatment of S. mansoni, although lower doses of oxamniquine (less than 30 mg/kg) may not be as effective in some areas."6

Macro evidence: Has this program played a role in large-scale success stories?

We have identified no such success stories. More on the general idea of "macro evidence" here.

Recommendations and concerns

Do expert reviews of the comparative merits of interventions endorse this one?

See this page for sources consulted.

Experts endorse this intervention as part of the deworming intervention, which includes albendazole for soil-transmitted helminths (more on this combination program here).

  • The Copenhagen Consensus ranks deworming and other nutrition programs at school as its 6th most promising program.7
  • Jamison 2008 does not endorse this program8
  • The Disease Control Priorities report states, "Until new technologies become available, anthelmintic chemotherapy for school-age children remains the most practical and substantive means to control ... schistosome infections in the developing world."9

What versions of the intervention are best?

Three versions of this intervention are (1) population intervention, where everyone in a region is treated; (2) targeted intervention, where certain demographic subgroups are treated; and (3) selective intervention, where individuals selected by diagnosis or suspicion of infection are treated.10

Population deworming (treatment for all people in an area of high infection) is recommended by the World Health Organization as its first choice.11 However, treating school-aged children as a targeted population group is the version that has been most closely evaluated.12 It also may be the most cost-effective because school-aged children typically have the highest rate of helminth infection and reinfection, and schools offer an infrastructure for delivery.13

Cost-effectiveness

The Disease Control Priorities report estimates that this program costs $336-692 per disability-adjusted life-year (DALY) averted.14 (More on the DALY metric here.)

Note: In September 2011, we confirmed a number of errors in the estimates for the cost-effectiveness of deworming published in the Disease Control Priorities report. Based on those findings, we are currently rethinking our use of cost-effectiveness estimates, like the DCP2's, for which the full details of the calculations are not public. For more information, see our blog post on the topic.

Sources

  • 1.

    "Recommended intervention strategy and aim: Targeted distribution of praziquantel is the norm. Intervention frequency is determined by the prevalence of infection or of visible haematuria (for urinary schistosomiasis only) among school-age children. 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." WHO: Schistosomiasis Fact Sheet

  • 2.

    "Praziquantel is now available free of charge to high disease burden least developed countries (LDC), through a donation from Merck KGaA to the World Health Organization." WHO: Schistosomiasis Fact Sheet

  • 3.

    "Schools offer a readily available, extensive, and sustained infrastructure with a skilled workforce that is in close contact with the community. With support from the local health system, teachers can deliver the drugs safely. Teachers need only a few hours of training to understand the rationale for deworming and to learn how to give out the pills and keep a record of their distribution." DCP 2006, Pg 473

  • 4.

    "Integrating drug distribution through the school system rather than using mobile teams, along with a marked decline in the price of BZAs and PZQ, has resulted in a 10-fold reduction in delivery costs. However, those costs are artificially low because they do not include the external costs for the coordinating center responsible for supporting those approaches (Guyatt 2003)." DCP 2006, Pg 475

  • 5.

    Danso-Appiah 2008, Pg 2

  • 6.

    Saconato 1999, Pg 1

  • 7.

    Copenhagen Consensus 2008

  • 8.

    Jamison et al. 2008, Pg 51

  • 9.

    DCP 2006, page 480.

  • 10.

    "Drug treatment can be administered in the community using different strategies:

    • Universal treatment. The entire community is treated, irrespective of age, sex, infection status, and other characteristics.
    • Targeted treatment. Treatment targets population groups, which may be defined by age, sex, or other social characteristics, irrespective of the infectious status.
    • Selective treatment. Treatment targets individual-level application of anthelmintic drugs, which is selected on the basis of either diagnosis or a suspicion of current infection." DCP 2006, Pg 472
  • 11.

    "The recommended strategy for helminth control is a population-based approach, in which individuals in targeted communities are treated irrespective of their infection status (WHO 2002). This strategy is justified for several reasons, including the simplicity and safety of delivering treatment. Individual diagnosis is difficult and expensive and offers no safety benefit." DCP 2006, Pg 473

  • 12.

    "Several studies have evaluated the costs of school-based periodic deworming in several different settings, whereas comparable studies on other interventions are still lacking." DCP 2006, Pg 474

  • 13.

    "School-age children typically have the highest intensity of worm infection of any age group, and chronic infection negatively affects all aspects of children's health, nutrition, cognitive development, learning, and educational access and achievement (World Bank 2003). Regular deworming can cost-effectively reverse and prevent much of this morbidity. Furthermore, schools offer a readily available, extensive, and sustained infrastructure with a skilled workforce that is in close contact with the community. With support from the local health system, teachers can deliver the drugs safely. Teachers need only a few hours of training to understand the rationale for deworming and to learn how to give out the pills and keep a record of their distribution. School based deworming also has major externalities for untreated children and the whole community. By reducing transmission in the community of Ascaris and Trichuris infections, deworming substantially improves the health and school participation of both treated and untreated children, both in treatment schools and in neighboring schools (Bundy and others 1990; Miguel and Kremer 2003)." DCP 2006, Pg 473

  • 14.

    "The estimate of cost per DALY is higher for schistosomiasis relative to STH infections because of higher drug costs and lower disability weights. Depending on whether generics or original formulations are used, the cost per DALY averted ranges from US$3.36 to US$6.92. [sic; we have since learned that the decimal point was accidentally placed in the figure.] However, in combination, treatment with both albendazole and PZQ proves to be extremely cost effective, in the range of US$8 to US$19 per DALY averted." DCP 2006, Pg 476

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