Schistosoma mansoni worms, the cause of schistosomiasis, which plagues more than 200 million across the globe.

Five years after the launch of an international effort to combat the burden of tropical diseases, global health leaders say enormous progress has been made toward freeing some of the planet’s poorest people from some of nature’s most gruesome and debilitating threats.

The effort to ease the burden of neglected tropical diseases has been led by the World Health Organization and a host of other institutions and nonprofits, notably the Bill and Melinda Gates Foundation. They have worked with pharmaceutical companies to arrange large-scale drug donations — 1.5 billion treatment courses in 2015 alone — and cultivated political support for action in affected countries.

On Tuesday, backers of the initiative are gathering in Geneva to mark five years since the signing of the London Declaration on Neglected Tropical Diseases, a commitment to try to rid the world of scourges like Guinea worm — in which people become infected with worms that bore their way out of the body — and lymphatic filariasis, or elephantiasis, a condition in which limbs become hugely and irreversibly swollen after tiny worms — transmitted via mosquito bites — invade the lymphatic system.

advertisement

Neglected diseases have historically been overlooked by the scientific community and pharmaceutical industry, but advocates believe they are beginning to turn that tide. At the same time, they fear that the effort could be undermined by waning support for global health funding in Washington and elsewhere.

“We’re not big enough to do this without the incredible generosity of the big governments that are far bigger than us,” Bill Gates, who argued that the programs are money well spent, told STAT in an interview. “Under any framework, whether it’s humanitarian or strategic, maintaining these investments makes sense.’’

advertisement

Gates, who met last month with President Trump, said he made a point of telling the president how effective money spent on neglected tropical diseases can be.

“We’ve made really amazing progress. Guinea worm, we’re pretty close [to eradication],” he added, noting a couple of setbacks, including the civil war in South Sudan, have kept the long-standing campaign — led by former President Jimmy Carter’s Atlanta-based Carter Foundation — from completing the job of stopping transmission of Guinea worm.

“Give us a couple of years and hopefully those things will get straightened out. President Carter deserves to celebrate the end of Guinea worm,” Gates said.

When the bid to eradicate Guinea worm kicked off in 1986, it is estimated that 3.5 million people in 21 African and Asian countries were infected with the excruciatingly painful worms, which are acquired by drinking contaminated water. Last year there were 25 cases in three countries; this year so far, only one country — Chad — has reported three cases.

The effort to launch a coordinated assault on neglected tropical diseases dates back about a dozen years. Professor David Molyneux, a tropical diseases expert at the Liverpool School of Tropical Medicine, said he and some others in the field — at the WHO and in academia — decided to brand a number of little-known but horrible conditions “neglected tropical diseases” in order to raise their profile and to emphasize that in at least some cases they could be prevented at relatively low cost.

“The problem lay in the fact that many of these diseases had unpronounceable names, didn’t affect people in Western societies, [and] couldn’t be transmitted in the West,” Molyneux said.

They were right. Names like onchocerciasis, schistosomiasis, soil-transmitted helminths, and human African trypanosomiasis (sleeping sickness) don’t exactly roll off the tongue. These diseases haven’t earned the level of awareness that results in little pink or yellow lapel pins worn on specified days to honor the struggle against them. But they plague huge numbers of people around the globe.

“Here you are with diseases that are affecting a billion-plus people, with perfectly adequate solutions available at very low cost and known to be capable of working. So we said: ‘Why can’t you do this?’” Molyneux said.

In the years since, there’s been increased funding from the US and the UK. On Sunday, the British government announced it will spend 360 million pounds ($462 million) on neglected tropical diseases over the next five years; 205 million pounds ($263 million) of that is newly committed funding.

In January 2012, when the London Declaration was signed, partners committed themselves to working to control, eliminate, or eradicate 10 neglected tropical diseases for which there currently are effective drugs or other measures, such a water filters to prevent transmission of Guinea worm.

Drug companies have come on board in a big way, donating billions of doses of drugs.

“During 2015, nearly 1 billion people — the highest number ever — received protection through preventive chemotherapy for at least one of these diseases,” Director-General Margaret Chan noted in the forward of a WHO report that is being released Wednesday in Geneva.

The drug ivermectin — which won its co-discoverers the 2015 Nobel Prize for Medicine — has been donated to prevent onchocerciasis or river blindness. Chan wrote that an estimated 270 million treatment courses of the drug are donated annually.

Ellen Agler is the CEO of The END Fund, a nongovernmental agency that works to eliminate or control five neglected tropical diseases: intestinal worms, schistosomiasis, lymphatic filariasis, trachoma, and river blindness.

Agler said she was in the process of interviewing for her job when the London declaration was signed. In the years since, she’s seen enormous advances, not least of which is a massive scaling up of the number of people being treated.

“There are hundreds of millions more people getting treated now than five years ago. That’s remarkable,” Agler said.

In 2012, few of the governments in the affected countries had plans to address neglected tropical diseases; they didn’t necessarily know where the diseases were spreading or have logistics in place to get free drugs to the people who needed them. But increasingly countries have become involved in the work and are setting their own priorities, Agler said.

Another huge step forward has occurred in disease mapping. “If you don’t have maps of what is the prevalence and where you need to treat, you obviously don’t even know where to begin. So that has increased radically,” she said.

Newsletters Sign up for Daily Recap A roundup of STAT's top stories of the day. Please enter a valid email address. Privacy Policy Leave this field empty if you're human:

There have been setbacks along the way. But there have also been unexpected gains. It was recently found that adding a third medication to the two-drug regime used to treat lymphatic filariasis can speed up the treatment, reducing what now takes as many as 10 years down to a year or two.

“We’ve had a few positive surprises like this triple drug therapy that looks like it will be effective for lymphatic filariasis,” Gates said. “That if you go a couple of years with reasonable quality, you can get rid of it.”

Agler said this has been an invigorating time to work in this field. “They’ve been around for thousands of years, these diseases. You read about them in the Bible. Egyptian pharaohs had these diseases,” she said. “And it’s just remarkable to think that we are at that point in history where we can really turn the tide on something that’s been plaguing humanity forever.”

Though continued success, Gates and others warned, rests on continued American financial assistance.

“We have no idea what Congress and the new president will actually commit. … And if the commitment falls, then the number of people who are going to be treated with three drugs is going to fall proportionately,” said Molyneux.

“For relatively small amounts of money compared to what we’ve spent on HIV and malaria, we’ve made huge progress,” he said. “I hope that progress can continue.”