Sounding an alarm in a recent commentary in The Lancet, four British and American doctors say that shortages of the drug for schistosomiasis, a parasitic disease as widespread as malaria, have reached the proportions of a humanitarian crisis in Africa.
Schistosomiasis has proved difficult to control for centuries; today, it kills about 300,000 people and afflicts more than 200 million yearly with chronic and severe anemia, abdominal pain, diarrhea, infertility and bladder cancer. It stunts children’s growth, affects their memory and IQ, and keeps them out of school. In women, schistosomiasis can cause genital sores that increase vulnerability to HIV and AIDS. Especially prevalent in sub-Saharan Africa, by some estimates, nearly 800 million people are at risk of infection.
“Schistosomiasis is a far more important disease than we ever realized,” said Peter Hotez, one author of the commentary and the chairman of the department of microbiology, immunology, and tropical medicine at The George Washington University. “The failure of the global community to provide access to this essential medicine is impeding sustainable development in Africa.”
The drug praziquantel is the only commercially available treatment for the disease. It is manufactured in Mexico by Merck KGaA of Darmstadt, Germany, and it is made generically. One to three tablets of praziquantel per person per year would dramatically improve the health of millions, Hotez said, but it is too expensive for many African health ministries. The tablets cost 8 cents apiece.
In 2007, as part of a World Health Organization initiative, Merck KGaA pledged to donate 200 million tablets of praziquantel to Africa over the next 10 years, a donation valued by the company at $80 million. The company also said it was prepared to sell additional praziquantel at cost by scaling up production to 100 million tablets per year. Yet, in the Aug. 14 issue of The Lancet, Hotez and his co-authors — Dirk Engels and Lorenzo Savioli of the World Health Organization and Alan Fenwick of the Imperial College London — estimate that 1 billion tablets are needed to treat 400 million people annually or every other year. Typically, Hotez said, an entire village must get the drug because doctors do not have time to find out who is infected.
What’s needed is 10 to 20 times what is being donated now, he and his colleagues said. Without further donations from Merck, they said, $100 million will be needed every year to purchase praziquantel.
“We are failing to provide praziquantel, costing just a few cents per tablet, and yet when given once yearly to children, this drug could avert a level of morbidity in Africa that exceeds that of malaria or other disease scourges,” the doctors said. “… The international community must rise to the challenge of filling in the gap. …”
In a statement e-mailed to Miller-McCune, Merck KGaA said it would need outside funding and the assurance of a constant and continuous demand for praziquantel in order to ramp up its production of the drug. The company said it was working with the World Health Organization to identify funding sources and sort out the complex logistics of distributing larger amounts of the drug to the parts of the world where it is most needed.
“Merck would like to help more African schoolchildren but there is a limit to our donation ability,” the company said. “… Expanding production capacity could not happen overnight. It would certainly need one or two years.”
Merck KGaA posted a 16 percent increase in total revenues for the second quarter of this year, compared to the second quarter of 2009, for a record $2.8 billion. (The company is not affiliated with the U.S. drugmaker Merck & Co. Merck KGaA is known as EMD Chemicals in the United States and Canada.)
Schistosomiasis traveled with the slave trade to the Caribbean and Brazil, and is prevalent there as well as in Africa. It is transmitted by freshwater snails that shed the larvae of parasitic worms, which in turn can penetrate human skin. Praziquantel is not a paneacea – it does not kill immature worms and does not prevent recurrence of infection. Hotez is developing a vaccine against schistosomiasis at the Washington, D.C.-based Sabin Vaccine Institute, a nonprofit organization that he heads, but the work is still in the early stages.
As reported earlier this year in Miller-McCune, Hotez and Fenwick have been critical of the international community’s priorities in funding AIDS, tuberculosis and malaria treatment in Africa while neglecting a host of tropical diseases that exclusively afflict the poor. U.S. support for global AIDS relief amounts to nearly $7 billion yearly. At the same time, Hotez said, treatment and prevention of such diseases as leprosy, hookworm, sleeping sickness and schistosomiasis could be delivered for less than a dollar per person per year, including up to 24 cents for praziquantel.
“Who will step up to donate it?” he asked. “Somebody’s got to step up.”
In 2001, the World Health Assembly passed a resolution aimed at schistosomiasis, setting a goal of treating at least 75 percent of all school-aged children at risk of the disease by this year. But only 10 percent of children at risk get the drug today, Hotez and his colleagues said. At the same time, they said, the private sector is donating unlimited supplies of drugs for other diseases. For example, the New Jersey-based Merck & Co. has pledged to eliminate river blindness, and GlaxoSmithKline has pledged to eliminate elephantiasis.
The U.S., through the Agency for International Development, is providing $65 million for the control of neglected tropical diseases this year. President Barack Obama has requested $155 million for 2011, but, given budget constraints, the final allocation may be closer to $100 million.
In an Aug. 31 editorial for the Public Library of Science, Hotez noted that these dollars pale in comparison to U.S. support for AIDS, but, he said, they will go a long way. Hotez called on Germany, Italy and other rich European nations to do their part as well. Germany, the country where Bayer Schering Pharma AG and Merck KGaA developed praziquantel in the 1970s, “has failed to find a mechanism by which to establish an urgently needed public-private partnership in order to fully donate this desperately needed drug for Africa,” Hotez said.
China, India, Russia, Brazil and Indonesia, some of the world’s fastest-growing economies, should take responsibility, too, Hotez said, and so should wealthy Middle Eastern nations such as Saudi Arabia, Oman, Kuwait and Quatar.
By some estimates, Hotez said, Chinese investments in Africa are growing by 50 percent annually, as China exploits the continent’s oil and natural gas reserves. China, which has made enormous progress in reducing schistosomiasis within its own borders, should transfer its know-how to Africa, Hotez said.
“There is now a moral and ethical imperative for China to take the lead…,” he said. “Given the billions of dollars China invests annually in Africa, it certainly can afford a comparatively modest investment in neglected tropical disease control, one that is at least equivalent to the USAID commitment.”