What are neglected tropical diseases – and what are we doing about them?

Twenty-one tropical diseases cause suffering to over one billion people globally. What’s more, all are treatable and preventable.

World Neglected Tropical Diseases Day, on 30 January, was created in 2020 to raise awareness of these diseases – and the actions needed to eradicate them.

Neglected tropical diseases (NTDs) are a group of diseases which, despite being treatable, continue to impact people living in the world’s poorest and most marginalized communities.

NTDs blind, disable and disfigure people, say the organizers of World NTD Day. They take away people’s health and their ability to earn a living or stay in school; they can also cause people to be ostracized by their families and communities.

The World Health Organization (WHO) says neglected tropical diseases are responsible for “devastating health, social and economic impacts” and are caused by bacteria, parasites and fungi, among a variety of pathogens.

Neglected tropical diseases include leprosy, rabies, trachoma, Guinea worm disease, Buruli ulcer, dengue and chikungunya, snakebite envenoming, foodborne trematodiases and yaws.

To date, 54 countries have eliminated at least one neglected tropical disease, according to the global advocacy organization, Uniting to Combat Neglected Tropical Diseases. This means 600 million people no longer need treatment.

In October 2024, the WHO confirmed that Viet Nam and India had joined Nepal, Myanmar and 18 other countries in eliminating trachoma, one of the leading causes of blindness. Affecting approximately 1.9 million people globally, it continues to pose a public health challenge in 39 countries.

In 2023, progress against neglected tropical diseases included the elimination of Human African trypanosomiasis (HAT) – or sleeping sickness – in Ghana. HAT is transmitted in the bites of tsetse flies and is generally fatal without treatment.

Bangladesh is the first country in the world to eliminate visceral leishmaniasis. Commonly known as kala-azar, this is a life-threatening disease with symptoms including fever, weight loss, spleen and liver enlargement. The country has also eliminated lymphatic filariasis, otherwise known as elephantiasis, which causes painful disfigurements as well as associated social stigma.

Other neglected tropical disease breakthroughs include the Maldives in the Indian Ocean achieving zero cases of child leprosy for five years. Leprosy is a chronic infectious disease that affects the skin, nerves, respiratory tract and eyes.

Since 1990, the prevalence of neglected tropical diseases per 100,000 people across 15 disease types has fallen from more than 40,000 cases to an estimated 12,375 cases in 2021, according to data from the Bill & Melinda Gates Foundation.

More than 300 organizations will be supporting Neglected Tropical Diseases Day in 2024, including governments, academia and the private sector.

Neglected tropical diseases were also sharply in focus at COP28 in December 2023, where the impact of the climate crisis on human health was a central theme.

And it's set to have a more prominent role in the upcoming COP29 this November, as a key driver for climate action. "We want to make sure everybody recognizes that health is the argument for more climate action," urged Dr Maria Neira, WHO’s Director of Environment, Climate Change and Health, in the WHO's latest joint webinar with the COP29 presidency on 23 October.

Partners at COP28, including hosts, the United Arab Emirates, and the Bill & Melinda Gates Foundation, pledged $777 million in funding to combat neglected tropical diseases. The funds will finance essential NTD programmes and treatments, support research and innovation, and strengthen front-line health systems and workforces, said the WHO.

The links between the climate crisis and health are explored in Quantifying the Impact of Climate Change on Human Health, a January 2024 World Economic Forum report.

“Climate change is having a profound impact on global health,” says Shyam Bishen, Head of the Centre for Health and Healthcare and a member of the Forum’s Executive Committee, in the foreword to the report.

“Whether it’s connected to the dwindling supply of freshwater because of droughts, the increase in infectious disease in the aftermath of flooding or the toxic air pollution accompanying raging wildfires.”

The report predicts 14.5 million climate-related deaths by 2050 and a “catastrophic rise” in public health conditions of concern, including non-communicable, infectious diseases and mental health illnesses.

For example, a potential rise in the mosquito population because of warmer temperatures could fuel an increase in diseases such as malaria, dengue and Zika. By 2050, an additional 500 million people could be exposed to diseases carried by insects.

The Forum calls for solutions such as early warning systems, innovative research and development and economic incentives to help make the world’s healthcare systems more resilient to the impacts of our changing climate.