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Fighting schistosomiasis with praziquantel

Over 200 million people in Africa suffer from the widespread tropical worm disease schistosomiasis. It is estimated that more than 200,000 die each year as a result of this chronic parasitic condition, which makes it the most common tropical disease in Africa after malaria. Schistosomiasis is widespread primarily in the tropical and subtropical areas of sub-Saharan Africa. In these regions, a vast majority of the population has no access to clean water and sanitary installations.

The disease is caused by flatworms and is spread through stagnant water. People become infected by the worm larvae in the water, while bathing, fishing, playing, washing their clothes, or working agricultural land. These larvae penetrate human skin and enter the blood vessels, where they grow into adult worms. The female's eggs infest inner organs such as the intestines, bladder, spleen, or liver, and often cause severe inflammation. Symptoms include severe abdominal pain, diarrhea, and bloody urine or stool. The infection rate is especially high among children, and the chronic symptoms that result are particularly serious. Schistosomiasis stunts growth, causes learning disabilities and leads to anemia.

28 million

28 million children have been treated to date within the scope of our Praziquantel Donation Program to combat schistosomiasis.

Merck KGaA, Darmstadt, Germany has been supporting the World Health Organization (WHO ) since 2007 in the fight against schistosomiasis in Africa. Our efforts are thus in line with the United Nations Millennium Development Goals. In addition, they are part of the initiative to fight neglected tropical diseases that was launched by the Bill & Melinda Gates Foundation in early 2012. Merck KGaA, Darmstadt, Germany donates tablets containing the active ingredient praziquantel to WHO, which then distributes these mainly to African school children. Since the start of our Praziquantel Donation Program, over 100 million tablets have been donated. A total of more than 28 million children have been treated. In 2012 alone, Merck KGaA, Darmstadt, Germany supplied WHO with over 27 million praziquantel tablets. In 2012, an estimated seven million children were treated for schistosomiasis (final figures will be available mid-2013).

Praziquantel is the only active ingredient with which all forms of schistosomiasis can be treated. In addition, praziquantel is well-tolerated. WHO has therefore included it on its Model List of Essential Medicines. Merck KGaA, Darmstadt, Germany developed praziquantel in the 1970s as part of a research collaboration. Our plant in Mexico produces the tablets under the brand name Cesol 600®; we organize and finance the transport to Africa, and WHO coordinates local distribution.

Program expansion

Originally, our program was scheduled to end in 2017. However, Merck KGaA, Darmstadt, Germany decided at the end of 2011 to continue its efforts indefinitely. The goal, agreed upon in conjunction with WHO, is to eliminate the worm disease in Africa. To this end, Merck KGaA, Darmstadt, Germany intends to increase the number of tablets donated in the medium term, raising the total to 250 million annually. This will allow around 100 million children to be treated each year.

This planned donation has a value of approximately US$ 23 million per year; in 2012, Merck KGaA, Darmstadt, Germany invested US$ 2.85 million (2011: US$ 2.3 million) in the donation program. These figures include the logistics costs to ship the tablets from the production site in Mexico to Africa, but not the costs for the awareness program or the research into a pediatric formulation.

Educating people

In addition to the tablet donation, Merck KGaA, Darmstadt, Germany is also supporting an awareness program at schools in Africa; it uses comic booklets  and posters  to explain the causes of schistosomiasis, teaching pupils how to prevent the disease. In 2011, a pilot project was launched at schools in Senegal and Malawi; through 1,100 brochures and 130 posters, the project reached around 1,100 school children. WHO is currently adapting the materials based on the experience gained from the pilot regions. In 2013, the program is being launched in Senegal with 750,000 brochures and in Malawi with 250,000 brochures.

Optimizing the formulation

As part of the donation program expansion, Merck KGaA, Darmstadt, Germany is also working to optimize the formulation of the drug. For instance, pharmaceutical experts are currently developing a fruity coating intended to make it easier for children to take the tablets.


Within the scope of a public-private partnership (PPP) , Merck KGaA, Darmstadt, Germany is researching a formulation of praziquantel for small children. Praziquantel tablets in their current form are suitable for adults and children over the age of six; for children younger than six, it is currently not possible to properly treat the disease. We believe that a pediatric formulation of praziquantel will be a significant step toward eliminating schistosomiasis in Africa. The partners of this public-private partnership, which was founded in July 2012, include Merck KGaA, Darmstadt, Germany, TI Pharma , Astellas Pharma Inc., and the Swiss Tropical and Public Health Institute (“Swiss TPH ”) in Basel.

Managing and monitoring

Our Praziquantel Donation Program (MPDP) is being conducted in partnership with WHO, with Merck KGaA, Darmstadt, Germany and WHO each contributing their particular expertise. Merck KGaA, Darmstadt, Germany produces the tablets and handles the costs for transporting the tablets to Africa. WHO manages, monitors, and documents the local distribution of the Praziquantel tablets and works with local authorities to implement the treatment at schools. WHO supplies the local data on morbidity rates and treatment frequency in the countries in which our Praziquantel Donation Program has been rolled out. The data for each country can be found in the WHO PCT databank . A steering committee consisting of representatives from WHO and Merck KGaA, Darmstadt, Germany convenes several times a year in order to review the program's progress and decide on its future course. The last meeting was held in Kenya in November 2012.


As part of a Bertelsmann Foundation project on corporate social engagement, we collaborated on the development of the "IOOI" method  (Input, Output, Outcome, Impact), a way of gauging and assessing social engagement. We have applied this method to our donation program to combat schistosomiasis, which allows us to evaluate the progress of the project.

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Praziquantel: Evaluation









Measuring instruments


1% infection rate = Schistosomiasis has been eliminated as a public health issue.

Scientific studies conducted by WHO


Infection rate

In 2013, WHO is conducting scientific studies in select countries; reviewing the scope of treatment via the WHO PCT online databank.


Number of school children who received praziquantel in one year.

Medical experts and teachers document the treatment of school children. WHO consolidates these data into reports on the distribution of the tablets in the individual countries.


Number of tablets supplied by Merck KGaA, Darmstadt, Germany to the individual countries.

A logistics partner delivers the tablets to Africa and reports on their distribution.

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Goals: Praziquantel











Strategic goal



Status in 2011 and 2012


Eliminate the worm disease schistosomiasis in Africa

Provide tablets containing praziquantel free of charge to treat school children in Africa


More than 100 million tablets were donated from the beginning of the project to the end of 2012. More than 28 million children were treated in total (figure not yet final; figures for 2012 will not be finalized until July 2013). In 2011 and 2012, over seven million children were treated.

2011: 25 million tablets provided to nine countries in Africa

2012: 27 million tablets provided to eight countries in Africa


Run an awareness program to explain the causes of schistosomiasis and potential preventive measures.

End of 2013

Until mid-2012, instructional materials were tested in Senegal and Malawi as part of a pilot project. In 2013, the awareness program will be initiated in both countries, taking into account experience from the pilot projects.


Incrementally increase the number of tablets donated annually by a factor of ten, up to 250 million

End of 2016

Currently searching for additional API suppliers.


Research a new formulation of praziquantel for children under 6 years old


In July 2012, a public-private partnership (PPP) was founded.
Milestone: Preclinical development is to be completed by 2014; clinical development is scheduled to start in 2014.


Optimize the praziquantel formulation

End of 2014

Development of a film coating to make the tablets easier for patients to swallow and to make them even more resistant to long transport times.

Legend: Achieved In progress Not achieved New goal


Publication of Merck KGaA, Darmstadt, Germany.

In the United States and Canada the subsidiaries of Merck KGaA, Darmstadt, Germany operate under the umbrella brand EMD.


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