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Neglected tropical diseases: The campaign trail

10 Jan, 2012

In recent years, a new phrase – ‘neglected tropical diseases’ – has been used to describe a group of infections that cause enormous suffering among the world’s poorest people. The phrase was first used by a group of scientists whose aim was to increase both awareness of these diseases and the global resources available for tackling them.

In the second of our series, Michael Regnier speaks to some of the researchers who are now leading advocates for neglected tropical diseases.

Since the first research paper to use and define the term ‘neglected tropical diseases’ (NTDs) was published in 2005, the phrase has become a standard part of global health vocabulary. It describes diseases that have long been endemic in low- and middle-income countries but currently lack the necessary tools or resources to control them fully. For example, the original list of 13 NTDs included several for which effective drugs were available but various challenges prevented the drugs getting to all the people who needed them.

Professor Alan Fenwick, now Director of the Schistosomiasis Control Initiative (SCI) at Imperial College London, worked in Egypt for 15 years. In that time, the prevalence of schistosomiasis fell from 20 per cent to less than 5 per cent. He knew it was possible to reduce the burden of schistosomiasis until it was no longer a public health issue; his problem was in finding support to apply this knowledge in other countries.

“Many organisations are interested in supporting research,” says Fenwick, “but this left schistosomiasis and others in limbo: most of the research had been done. We had the tools which, if implemented properly, could help some 200 million people in sub-Saharan Africa.”

In 2002, he approached the Bill & Melinda Gates Foundation for funding to develop a vaccine for schistosomiasis. The Foundation’s focus at that time was on vaccines but schistosomiasis was not considered a priority. Fenwick agrees it was probably the right decision but he did not take no for an answer. He asked if they would consider another option: buying and distributing praziquantel, an effective schistosomiasis drug treatment, in countries where the disease was endemic.

A pair of Schistosoma haematobium blood worms

A pair of Schistosoma haematobium blood worms

“They agreed to allow me to test the proof of principle: ‘Will these countries implement control if given access to drugs and funding?’” Fenwick was awarded $30 million to work with African countries to introduce national programmes to control schistosomiasis. The first treatment began in Uganda in 2003 and after one year, the intensity of schistosome infection had fallen by 70 per cent. The SCI quickly expanded to cover six countries and by 2012, it had supported or is currently working in 12 African countries.

The SCI approach is effective not only because the drugs are donated or provided at low cost, but also because they can be given orally in a single dose every six or twelve months. NTDs tend to cluster in rural areas, where any one person can be infected with several NTDs at the same time. Another benefit, therefore, is that they can include another drug called albendazole to treat the same people for parasitic worms as well as schistosomiasis through one integrated programme.

Activist researchers

Integration has been made possible in part through initiatives such as the Global Network for NTDs, founded in 2005 by a group of researchers, including Fenwick, who had an interest in global policy efforts to combine mass drug administration programmes in order to increase efficiencies as they scaled up. Other founders of the Global Network included Professor Peter Hotez, President of the Sabin Vaccine Institute, Professor David Molyneux, a lymphatic filariasis researcher at the Liverpool School of Tropical Medicine, Dr Lorenzo Savioli of the World Health Organization, Dr Jeff Sachs at the Earth Institute, Dr Kathy Spahn of Helen Keller International and Dr Jacob Kumaresan, then at the International Trachoma Initiative.

Professor Peter Hotez

Professor Peter Hotez

Hotez’s research is on vaccines for human hookworm infections and other parasitic worms. He also heads a non-profit product development partnership, linked with the Sabin Vaccine Institute, that is leading global efforts to develop vaccines for hookworm, as well as schistosomiasis and Chagas’ disease.

As with many NTDs, parasitic worms are not lethal in themselves but infections can last for decades, impairing children’s growth, development and physical fitness and causing severe anaemia during pregnancy, which leads to low birth weight and increases the risk of death for mothers and children.

“The most common neglected tropical diseases have high morbidity and low mortality,” explains Hotez. “They are causes of poverty through their effects on children, pregnant women and workers. From descriptions in ancient texts, we know these diseases have been around forever. They are the opposite of emerging diseases.”

We are more scared of emerging diseases, he suggests, but NTDs do more harm overall. Giving them a collective name was a fundamental step in the campaign to gain greater traction by considering them as a set of interrelated problems rather than discrete diseases.

“The phrase was part of a drive to think about these diseases in a fresh light,” says Hotez. In particular, it was a response to the effects of the United Nations Millennium Development Goals, which launched in 2000. The Millennium Development Goals were the UN’s blueprint for concerted actions to meet the needs of the world’s poorest people. Goal 6 acknowledged the deleterious effect of long-term poor health on economic development, calling for efforts to “combat HIV/AIDS, malaria and other diseases”. Detailed targets included stopping the spread of AIDS, achieving universal access to treatment for AIDS, increasing efforts to prevent and treat malaria, accelerating progress in tuberculosis and beginning to reverse the incidence of “other major diseases”.

“It led to a lot going on in HIV, tuberculosis and malaria,” Hotez says, “but those of us working on ‘other diseases’ felt we were on the outside looking in. We were driven to think afresh, to ‘rebrand’ these conditions.”

Grouping NTDs together has succeeded in drawing attention to the huge problem they present, and the need for sustained action. Hotez highlights some achievements made since 2005: major initiatives from the US Agency for International Development and the UK Department for International Development; a new Department of Control of Neglected Tropical Diseases at the World Health Organization (WHO); and PLoS NTDs, a journal that launched in 2007 with Hotez as Editor-in-Chief.

The journal was in some ways responsible for the expanding definition of NTDs. Over and above the original list of 13, PLoS NTDs sparked interest from researchers working on other diseases as well: “We started getting papers from researchers claiming neglected status,” recalls Hotez. “Everyone’s disease area was ‘the most neglected’, so we decided to open the tent to everything.”

The WHO’s official list of NTDs currently has 17 diseases; while endorsing the WHO list, the PLoS NTDs website identifies more than twice as many. “We might even consider malaria vivax to be an NTD,” adds Hotez, referring to a form of malaria less deadly than the better known, and more researched, malaria falciparum.

Broader benefits

The Wellcome Trust has consistently funded research on tropical diseases and currently spends a significant proportion of its funding on global health research. Such research brings benefits beyond tackling debilitating and deadly diseases. As Professor David Dunne, a Wellcome Trust-funded schistosomiasis researcher based at the University of Cambridge, explains, basic research on NTDs helps the wider international scientific community.

Professor David Dunne

Professor David Dunne

“It’s not just about combating intractable, long-neglected diseases,” he says. “It’s also about research into the ecological and physiological relationships between humans and chronic, endemic infectious diseases in their natural environments. This can bring unique insights into our basic biology and the biology of disease that would be a major benefit to us all.

“In the developed world, we try to understand the immune mechanisms of ‘Western diseases’ like allergy without thinking about why we have evolved to have these immune mechanisms: what are they for? Rural Africa represents a more natural environment where these allergic mechanisms help protect against parasitic infections. And as we learn more about the genomics of parasitic worms, we start to see links: worm antigens are very similar to allergens, for example, which should inform research on both fronts.”

Dunne has always worked in long-term partnerships with African scientists and believes it is crucial to strengthen African scientific capacity. “You can’t really understand the relationships that evolved naturally between people and parasites by having a few ex-pats and scientific tourists like me visit Africa,” he says. “We need an internationally competitive, indigenous scientific community in Africa to get that depth. African science has a major contribution to make in cutting-edge basic science as well as in public health.”

Work on NTDs has already contributed to improved national surveillance and monitoring systems and strengthened local operational research and laboratory services. Furthermore, thanks to programmes like the SCI, there is now a network of more than 162 000 community-based drug distributors in sub-Saharan Africa who provide mass treatment for schistosomiasis and worm infections. This in turn has strengthened general health services by enabling additional interventions, such as vitamin A distribution, childhood vaccinations and antimalarial bednets.

Future philanthropy

Although capacity is increasing in research and healthcare systems in low- and middle-income countries, ongoing control and elimination of NTDs will continue to require significant support from high-income countries and international agencies. This is far from guaranteed in the current international economic climate. The recent G-FINDER report, which detailed global funding for research and development (R&D) in ‘neglected diseases’ (NTDs plus the big three of HIV/AIDS, malaria and tuberculosis), showed that the overall level of funding fell in 2010.

“There is too much reliance on the US and UK,” says Hotez. “In terms of R&D, there are some very nice commitments from the Dutch and German governments in product development partnerships but I also want to see some of the emerging markets getting involved.

“Gates and Wellcome are stalwarts in terms of foundations but we need new partners to increase the pot and bring new perspectives. Where are the newest billionaires from the emerging market economies such as India, China and Brazil?” he asks. “Where’s the philanthropy?”

Professor Alan Fenwick, Director of the Schistosomiasis Control Initiative

Professor Alan Fenwick

Alan Fenwick is also looking for more widespread philanthropy – while the SCI currently has funding from 18 separate grants, he is always looking to raise funds to continue and extend their work. He is happy to admit that he is no longer a research scientist but a passionate advocate for NTDs and the work of the SCI.

How does he feel that it has been left largely to scientists to get programmes such as the SCI off the ground? “I’ve never even thought about it,” he says. “It’s invigorating. I passionately believe in treating schistosomiasis. More than 100 million people have been treated with at least one treatment but we’re still growing, continuing treatments and scaling up. If we stop treating, I fear that within five years it will come back again. We will need donations from bilateral country aid or from the public – remember that every £1 allows us to treat three children.”

Ultimately, says Fenwick, it will be impossible to achieve any of the Millennium Development Goals without tackling NTDs. “How can you break the poverty cycle?” he asks. “How can you achieve primary education for all if the kids are full of worms? If they have no energy so that even if they go to school they fall asleep? Anaemia in pregnant women is the most common cause of birth complications. How can you improve maternal and child survival unless you control NTDs?”

It’s a persuasive argument and one that Fenwick, Hotez and others will continue to make to anyone who will listen. “I think as scientists we are taught not to be advocates,” says Hotez. “That’s something I’m trying to correct.”

This is one of a series of blog posts accompanying a Wellcome News feature on neglected tropical diseases. Next week: a look at the Wellcome Trust’s long history of funding research into tropical diseases.

Related resources:

Molyneux DH, Hotez PJ, & Fenwick A (2005). “Rapid-impact interventions”: how a policy of integrated control for Africa’s neglected tropical diseases could benefit the poor. PLoS medicine, 2 (11) PMID: 16212468

Hotez PJ, Fenwick A, Savioli L, & Molyneux DH (2009). Rescuing the bottom billion through control of neglected tropical diseases. Lancet, 373 (9674), 1570-5 PMID: 19410718

Hotez PJ, & Pecoul B (2010). “Manifesto” for advancing the control and elimination of neglected tropical diseases. PLoS neglected tropical diseases, 4 (5) PMID: 20520793

Bailey P (2011). Out of Africa: what is an allergen? Wellcome Trust website – More on David Dunne’s research.

The Wellcome Trust website has a number of scientific animations showing the life cycles of many parasites, bacteria and viruses that cause diseases including some NTDs. Eg:
Intestinal worms

Image credits: Wellcome Images/CDC (main image); Schistosomiasis Control Initiative (Alan Fenwick); Agapito Sanchez, Baylor College of Medicine (Peter Hotez)

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