Neglected tropical diseases.
These are the diseases of neglected people—the poor, the powerless, the women and fishermen and shantytown dwellers the world over.
These are the unpronounceable diseases—schistosomiasis, leishmaniasis, dracunculosis, onchocerciasis, lymphatic filariasis, dengue, and chagas and more.
These are the diseases that scientists don’t study, that funders don’t fund. These are the diseases that afflict 1.3 billion people each year.
Luckily, these neglected tropical diseases are not as deeply neglected as they have been previously. In 2000 NTDs were not even on the global health agenda. But then the Global Fund was established to combat HIV, tuberculosis and malaria, and the awareness grew that we needed funds for the other tropical diseases, too. The first “neglected tropical disease” meeting was held in Berlin in 2003, and by 2007 the WHO met to create the Global Plan to Combat Neglected Tropical Diseases, 2008-2015. Awareness, funding and public/private partnerships continue to grow.
From July 8-10 2011 the International Society for Infectious Diseases held its first ever conference devoted to Neglected Tropical Diseases. 370 researchers, policy makers, health ministers, funders and interested others from 62 countries met in Cambridge, Massachusetts, to share approaches to combating the tropical diseases.
There is hope and ambition for eradication. Drancunculosis, better known as guinea worm, is on its way to becoming only the second disease, after smallpox, eradicated from this earth. It is a striking infection where worms caught through drinking infected water grow over 12-14 months in the blood vessels then begin to escape the body, frequently burrowing through the legs. They come out through ulcers, and are wrapped around sticks as they slowly emerge. “It doesn’t kill,” said Dr. Gautam Biswas, director of the WHO’s guinea worm eradication program, “but it creates a lot of trouble for the individual, family and society.”
In the 1980s, the disease existed in 20 countries. Today it is only reported in four countries worldwide. Strong partnerships between the Carter Center, UNICEF, DFID and the Gates Foundation, along with support from health ministries and local health workers and volunteers, dropped the number of cases from 1 million in 1989, to 755 in 2010. Most of those cases (98%) are in Sudan, where difficult governance led to difficult disease control. The handful reported in Mali, Ethiopia and Chad in 2010 were mostly exported from Sudan, but continued surveillance is needed to prevent a resurgence.
Other diseases are much further from eradication. Schistosomiasis is a waterborne parasitic disease that affects the poorest of the poor, who catch the worms from skin contact with infected water. It is far from the only disease to devastate poor populations with poor access to safe water or clean latrines or basic health education for behavioral change, yet it is the most prevalent. The “silent scourge of development” infects 200 million people worldwide, killing an estimated 282,000 people each year. Co-infection increases HIV transmission three to four fold. The quality adjusted life years lost to the disease are estimated to be higher than malaria. It is treatable with praziquantel, a single drug in a single dose, whose cost has fallen from $1 a pill in 1988 to 7 cents a pill in 2008. But only 8.3% of the world’s infected population has been treated in the last few years.
The world needs integrated programs of neglected disease control, overseen by national health ministries that distribute anti-worm medications free to the population. Each locality may create a specific de-worming schedule, similar to an immunization schedule, based on the endemic diseases, seasonal variations in transmission, and school calendars. Children would be protected from developing the stigmatizing, debilitating effects of the tropical diseases to which they are exposed.
Drug companies are donating drugs for worldwide distribution. “These are not poor quality drugs for poor people,” said Lorenzo Savioli, head of the WHO NTD group, “but good drugs for good people.” Merck donates ivermectin for onchocerciasis (river blindness) control. Pfizer donates azithromycin for trachoma. GlaxoSmithKline donates albendazole for soil-transmitted worm infections. Merck-Serono in Germany will donate 200 million tablets of praziquantel to treat schistosomiasis, and Easai, a Japanese drug company, will start manufacturing the drug DEC to treat lymphatic filariasis, preventing the gross swelling of the testicles or the limbs that result from blockage of the lymphatic drainage system. In total, these interventions cost about a billion dollars, to save and improve a billion lives.
Though there is the danger that the worms will develop resistance to the single drugs available to treat them, in the same way that viruses and bacteria have developed anti-viral and antibiotic resistance, the worms’ life cycles are much longer, so we hopefully have years before resistance develops over many generations. Still, warns Princeton vaccine expert Dr. Adel Mahmoud, “We have neglected the science of the neglected tropical diseases.” The development of new drugs, diagnostic tests, and potential vaccines remains important.
Only 0.6% of the worlds’ total overseas development assistance are put towards the neglected tropical diseases, despite them afflicting 1/6 of the world’s population.
Happily, USAID gave $100 million in 2006, and an additional $450 million over five years for the neglected tropical diseases. Even as we face increasing deficits at home, we must continue to sustain our commitment to a healthier, more stable world.
“We have a moral imperative to eliminate these diseases,” said Mirta Roses Periago, Director of the Pan American Health Organization, “to free the world from unacceptable disability, pain and death.”