Neglected tropical diseases: What are they and how can they be stopped?

Noma: New visibility could be a gamechanger

The fact that the exact causes of noma remain a mystery indicates just how neglected this disease is. Noma was finally added to the World Health Organization (WHO)’s official list of NTDs in 2023, and this higher visibility could be a gamechanger.

Due to limited research, difficulties reaching affected areas, and the fact that many people with noma are hidden away due to stigma, the true number of people impacted remains unknown. Studies on the prevalence of noma haven't been conducted in 25 years, and at the time indicated there were 140,000 new cases occurring each year.

The word noma comes from the Greek word for “devour”—because that is what noma does to the skin: It starts in the mouth where ulcers quickly develop and turn gangrenous, eating away at tissue. It is easily treatable with antibiotics if caught early, but when gangrene sets in, it is fatal for 90 percent of children. Survivors are left with severe facial disfigurement and often physical disabilities, such as difficulties speaking and eating due to the destruction the disease causes inside the mouth. The disfigurement caused by noma are so highly stigmatized that families often hide those affected away from society.

The campaign to add noma to WHO’s list of NTDs was led by Nigeria and backed by MSF, among others. We have supported the Nigerian Ministry of Health with a noma hospital in Sokoto for over a decade, providing treatment, reconstructive surgery, mental health support, and community outreach services. Now that this deadly disease has been added to the list of NTDs, we hope that there will be more investment in understanding, preventing, and treating noma. 

Schistosomiasis: A neglected form is affecting women and girls

Jonglei state in South Sudan, where MSF runs a hospital in the remote town of Old Fangak, has the highest documented burden of schistosomiasis in the country. MSF suspects that many girls and women suffer from an advanced form of the disease known as female genital schistosomiasis (FGS). 

Patients with FGS have a high parasite load within their reproductive and urinary system, causing debilitating inflammation, and sometimes even progression to fatal cancers. It is a highly neglected form of schistosomiasis, an already neglected disease.

Schistosomiasis is caused by a parasite that resides in snails from freshwater lakes and rivers, so people become infected through contact with infested water. Although schistosomiasis is one of the “big five” NTDs (schistosomiasis, elephantiasis, trachoma, river blindness, and intestinal worms) that receive most of the limited funding that is available, existing interventions are largely preventative. This means that girls and women who are already suffering with advanced disease and need treatment are often forgotten.

MSF is focusing on ensuring that women and girls are accurately diagnosed and provided with the best possible treatment. We are currently looking at ways to better identify and address the burden of the disease in humanitarian contexts, not only in South Sudan but also in other countries where the parasite is present.

Rabies: Gavi is expanding vaccine access for exposed people 

Rabies is one of the only vaccine-preventable NTDs, along with dengue and chikungunya. However, in many of the 150 countries where it is still a huge threat to human life, vaccine stocks are extremely limited and the cost of the vaccine is high.

Rabies is transmitted to humans through bites and scratches from infected mammals, most commonly dogs. If post-bite medical care is sought swiftly, it can be prevented. However, if the post-exposure vaccination is not received in time, the patient becomes infected with the virus. When clinical symptoms develop, it’s already too late—the disease is 100 percent fatal because there is no cure.

In wealthy countries with easy access to vaccines, dogs are among those vaccinated to keep the disease under control.

In 2024, Gavi launched an ambitious program to improve access to the rabies vaccine after animal bites. While this will not include vaccinations for dogs, countries can include rabies on the list of vaccines they request from Gavi for humans who are bitten. This means that ministries of health will finally be able to stock the vaccine in clinics and hospitals and quickly vaccinate anybody bitten by infected animals at no cost to patients. 

Sleeping sickness: Guinea is the latest country to eliminate the disease

Over the past 25 years, there has been a 97-percent reduction in the number of people suffering from sleeping sickness, leading to its elimination as a public health problem in Equatorial Guinea, Ivory Coast, Benin, Togo, Uganda, and Chad in 2024—and, today, in Guinea. This achievement is testament to what can happen when there is political will and funding, as well as when pharmaceutical companies invest in developing safer, more-effective treatments for NTDs. However, 1.5 million people are still at risk.

Sleeping sickness is caused by parasites transmitted from tsetse fly bites. In one form of the disease, it can progress to the acute stage—when the parasites attack the brain and spinal cord—within just a matter of weeks. This causes sleep disruption, convulsions, confusion, and eventually a coma. Without treatment, this form of sleeping sickness is fatal.

For many decades, the only cure for sleeping sickness was an arsenic derivative that killed 1 in 20 patients. In the 1970s, a new drug revolutionized the odds of survival. However, in the 1990s, the manufacturer of the drug, Sanofi-Aventis, wanted to discontinue production, which would have been a major step backward. Fortunately, pressure from WHO and MSF persuaded Sanofi-Aventis to prioritize sleeping sickness, donate the drug, and develop new, better, more patient-friendly treatments in collaboration with the Drugs for Neglected Diseases initiative (DNDi). This collaboration and continued investment have led to further advancements in medicine. Now, a simple and safe oral treatment is available.

Snakebite: WHO assessment could improve antivenoms 

Most snakebite victims have no access to antivenoms because they live too far from a health facility that could potentially have the antidote in stock—and even if they can reach a clinic, they would be unable to afford the high cost of the product.

Antivenoms are bespoke biological products intended for use in specific regions, so they are produced in small quantities. Their potency is often such that patients need to purchase many vials for effective treatment. Market regulation is very limited—it’s up to each country that uses antivenom to assess its efficacy against the venoms of local snakes. But when health systems are weak, even testing basic, regular medicines is difficult, so in practice many countries cannot conduct antivenom assessments.  

The good news is that in 2017, WHO launched an assessment of existing products by requesting samples from various manufacturers, and the results are being disclosed in real time. We hope this audit will put pressure on producers to improve their products. We also hope it will trigger more domestic and international financing to acquire more doses of quality antivenoms and distribute them free of charge to snakebite victims in need. 

New conflicts are jeopardizing much of the progress made against NTDs

When war breaks out, NTDs become even more neglected. Health systems that are already weak collapse, surveillance is disrupted, and even diseases that were once controlled can reemerge with a vengeance. Vigilance is vital.

In North Darfur, Sudan, MSF is on high alert. Although there have been no confirmed cases in our emergency response projects there yet, other regions in Sudan are known hotspots for the disease. We know from our long history in the country that the conditions of displacement and malnutrition are rife for an explosive outbreak of visceral leishmaniasis, so we are preparing our teams for the worst. When huge numbers of people with no previous exposure to the disease—and therefore no immunity—are displaced to areas where it is endemic, it can put them at huge risk. This is our fear for people in North Darfur and many other parts of Sudan where we are seeing mass displacement and the destruction of health care services.

Access constraints have been a hallmark of the conflict in Sudan, where supply trucks containing lifesaving medicines can be held up for months. As a result, we are pre-positioning stocks.

Diagnosing visceral leishmaniasis is complex: medical teams need the tools to diagnose cases early, and rapid testing will only be positive in some cases. In other cases, testing requires skilled staff to take tissue samples from internal organs. It also requires hospitals with functioning labs to run tests on blood and tissue samples. In North Darfur, all of these are in short supply. Additionally, health teams in North Darfur are less familiar with the disease because historically it has not been a hotspot compared to other parts of Sudan such as Gedaref state, where the majority of cases tend to occur. 

MSF has sent rapid tests and drugs to North Darfur, and have trained teams so we can help the Ministry of Health respond quickly if an outbreak occurs.   

Cuts to research and development put major breakthroughs at risk 

In the last few years, funding for research and development for NTDs has notably declined. If this continues as a downward trend, the final steps of major medical breakthroughs will be put at risk. Research is extremely time- and resource-consuming; many early innovations never “make the grade” in terms of efficacy and safety, so they have to be abandoned. Late-stage trials are expensive, and if there is no funding for them, new compounds to treat NTDs will have no chance of coming to market to save lives. 

Visceral leishmaniasis, dengue, and Chagas disease, for example, have new compounds that are ready for clinical trials, and a vaccine for schistosomiasis is also in the early stages of development. Snakebite is another NTD in which clinical trials could soon start. 

In 2019, the Wellcome Trust invested in a seven-year research and development project for snakebite, and additional funding is needed for the coming years. Although there are some exciting new products in the pipeline—most in the research community want a universal antidote—in order for this to be achieved, funding needs to be prioritized and sustained in the longer term, and the future of all of this progress is now hanging in the balance.

Diagnostic tests are vital, but in short supply 

Continued surveillance of NTDs is vital for keeping them under control—that’s why diagnostics are key. Many diagnostic tests are not always accurate, so investment is needed to improve them. Although some new diagnostics are being developed, they are for very niche markets, so it is difficult to persuade large companies to invest in them.

There is far less financial backing for diagnostic tests for NTDs. Many NTD medicines are produced by large drug companies like GSK who may wish to donate the drugs in exchange for a good reputation. The companies producing diagnostic tests are much smaller by comparison, and this is not an option for them. There is no global access mechanism for diagnostic tests for NTDs, so countries have to individually purchase their own.  

It is vital that diagnostics are also brought closer to communities. The ability to effectively diagnose these diseases early and initiate prompt treatment is essential for patients’ wellbeing and for preventing the spread of disease. This requires reliable, affordable, easy-to-use "point-of-care" rapid tests.

Major financing gaps persist 

NTDs face huge funding issues, and the “big five” get the majority of what little is available. For this reason, they can be addressed more rapidly by delivering blanket drug distributions to large numbers of people at once, and are therefore popular with donors.

Methods available for controlling the other 16 NTDs can be more complicated and expensive, and funding is much more limited. WHO has estimated that an additional $2 billion was needed to control NTDs from 2023-2025 alone, excluding the cost of the medicines.

International government donors could make a significant impact, but worryingly, they have been reducing funding rather than maintaining their commitments to these diseases of poverty.