Winning the war against ancient diseases

Poor people who live in remote, rural areas, urban slums and conflict zones are most at risk for these diseases, which generally flourish in places where unsafe water, inadequate hygiene and sanitation, and poor housing conditions are status quo. 

In 2007, a group of global partners convened by the WHO, agreed to tackle neglected tropical diseases together. A year later, the WHO published its Global Plan to Combat Neglected Tropical Diseases. Around the same time, the London Declaration on Neglected Tropical Diseases assembled partner organizations to try to help achieve these goals.

"That combination has been extremely powerful and constructive," said Dr. Julie Jacobson, an expert in the field and a representative of the American Society of Tropical Medicine & Hygiene. Looking at the data before and after the WHO published its first plan in 2008, global achievements in reducing neglected diseases went from "pretty stagnant" to "increasing, sequentially, every year, the number of people that have been reached and countries that have achieved their targets," said Jacobson.

"There's now nine countries that have been validated as eliminating lymphatic filariasis, on a national scale," said Jacobson, who added that the first country in Africa, Togo, was announced this week. Lymphatic filariasis, commonly called elephantiasis, is a mosquito-borne infection that causes abnormal enlargement of limbs and genitals.

The WHO also reports a total of 556 million people received preventive treatment for elephantiasis since the initiative began.

"You know we're not going to hit every 2020 target," said Jacobson. Still, she added, the substantial progress made by collaborative efforts across the globe is "very impressive."

In its roadmap, WHO recommends five interventions for controlling neglected tropical diseases.

The first two -- preventive chemotherapy and innovative disease management -- Engels refers to as "medical interventions," since both involve direct treatment for patients.

"There are some diseases where you can only treat early when the symptoms occur, like sleeping sickness, like Chagas disease, like leishmaniases," said Engels.

African trypanosomiasis or sleeping sickness, is a possibly fatal parasitic infection spread by tsetse flies. Chagas disease, which can progress from no symptoms to heart inflammation, is an infection transmitted by contaminated food, insects and a variety of other routes. Visceral leishmaniases attacks the internal organs, while cutaneous leishmaniases causes face ulcers, disfiguring scars and disability. Both these forms of leishmaniases are transmitted by female sandflies.

The aim of medical interventions, then, is to help people early "because sometimes when you're too late, you cannot change much anymore," said Engels.

"There's also a group of diseases that you can actually treat preventatively," said Engels, such as worm diseases. "The principle here is with a few worms you can live happily, it's only when you have too many that you start to get problems and you actually develop a disease," he explained.

"So for diseases like elephantiasis, Guinea worm disease, schistosomiasis, the intestinal worms and trachoma, you can regularly treat people with safe, single dose drugs and then they never actually build up a worm load that could cause them problems," said Engels.

Schistosomiasis is a larval worm infection transmitted by contact with infested water. Trachoma is a blinding infection spread by contact with discharge from the nose or eye.

Trachoma is the world's leading infectious cause of blindness and has been eliminated as a public health problem in Oman, Morocco and Mexico over the past 10 years, according to the new WHO report. At the same time, more than 185,000 trachoma patients have benefited from surgery.

Using medical interventions, then, "you can either treat whole communities, or you can treat specific groups like school-aged children through the schooling system, but if you keep on treating them, they never develop the symptoms anymore," said Engels.

"What has contributed enormously to that progress was the help we have received from the private sector," said Engels, noting that pharmaceutical companies donated medicines to the cause.

In addition to medical interventions, the WHO also recommends three "supportive interventions," said Engels: vector (carrier of disease) control, veterinary public health, and provision of water and sanitation.

All three are "fundamentally preventive" and "deal with the root causes of the neglected tropical diseases," said Engels. Not only do the poor lack appropriate housing in many cases, they often live in close proximity to their livestock and animals, they live in circumstances where mosquitoes, parasites and other disease-causing agents thrive, and they lack access to water and sanitation. A preventative intervention, then, might be improving a community's water system or building better houses.

"Here we're counting a lot on the new development framework," said Engels. The World Bank has developed a framework for infrastructure and social development. As Engels sees it, the neglected tropical diseases can be used "as a proxy for poverty," so if investments go "as a matter of priority to the poorest areas, then we can envisage that these diseases will be eliminated, or near eliminated, by 2030."

Engels' claims are not just wishful thinking, they are supported by hard numbers. In the Region of the Americas, for instance, only 12 reported deaths were attributable to rabies in 2015. Meanwhile, the WHO recorded well under 3,000 cases of sleeping sickness in 2015 -- a considerable decline from 37,000 new cases reported in 1999.

Jacobson worries about potential barriers to advancement. "Conflict areas are going to be the major bottlenecks within this (progress)," she said, though she still has "a lot of hope" for South Sudan. The country gained its independence from Sudan in 2011 and experienced two years of peace, which was then disrupted by internal conflict and civil war.

"They've been very successful in their Guinea worm eradication efforts," she explained. Based on this scaffold of achievement, there's an opportunity to build and accomplish more.

As Jacobson sees it, generating "the political will to move this forward and put resources and time into it" is key to the eradication of tropical diseases.

Though this may appear an unachievable or difficult goal, in fact, it's an easy "win" since the diseases are all treatable and preventable, she said. In fact, public health programs might bring a neglected disease under control, if only they understood they have a resource at their disposal -- donated drugs already exist for many of these diseases, says Jacobson. "I think if that were understood, more ministries of finance would be excited about it."

Looking ahead to the years beyond 2020, two challenges will likely remain, the WHO report indicates. One difficulty will be eliminating transmission of neglected tropical diseases, while a second problem will be delivering health services to those living with disease.

Engels worries about three illnesses in particular.

One of those diseases is Yaws, a chronic bacterial infection affecting mainly skin and bone. "We thought we would have been a lot further with Yaws," said Engels. "And that is basically because we don't have the medicines donated as we do with other diseases."

Another still-neglected disease is cutaneous leishmaniases, said Engels.

"There's been a lot of progress with visceral leishmaniases, which is a different disease, but which kills," said Engels. In 2015, for instance, elimination targets were achieved in 82% of India sub-districts, 97% of Bangladesh sub-districts, and 100% of Nepal.

"Cutaneous leishmaniases doesn't kill, but it disfigures," said Engels, noting the stigma and mental illness resulting from this disease. "So here we could do a lot more and the main problem here is also access to medicines -- access to affordable medicines," he said.

The third disease requiring more attention is Chagas, which has many transmission routes. "For the moment, we're only tackling two: through blood transfusion and vector transmission," said Engels, adding that it is necessary to address mother-to-child transmission and to develop medicines.

"There are still gaps," said Engels. "I hope in the next few years, we will be able to fill in those gaps."