On the World Day of Neglected Tropical Diseases: The biologist Sabine Specht on billions of people suffering, far-reaching consequences and the difficulties in developing drugs.
Ms. Specht, January 30th was the “World Day of Neglected Tropical Diseases”, which the WHO proclaimed for the first time in 2020. To what extent has the corona pandemic affected the perception of neglected tropical diseases? Are they even more neglected now – or has there been a rethink because even rich countries had to recognize how dangerous infectious diseases still are?
On the one hand, the pandemic has greatly increased awareness of the risk of infectious diseases. On the other hand, we unfortunately see that at the same time the attention paid to the neglected tropical diseases has decreased even more. Because unlike newly emerging diseases such as Sars, Mers or now Covid-19, they do not pose an acute, immediate threat to the entire world. They usually take a chronic course. They are ancient diseases that have been with us for centuries, if not millennia.
What types of diseases are included, are they all infectious diseases?
First, the term “neglected” does not mean that these diseases are rare. On the contrary: a lot of people suffer from it, more than 1.7 billion worldwide. But they find little international attention. Except for snake bites, which are also included, these are infectious diseases. Many are caused by parasites. These include worm infections in particular. Infections caused by bacteria and fungi have also been included in the list. This has expanded significantly in recent years.
What does this mean for the people affected individually and for the entire population in these regions?
The personal impairments are usually very strong, physical, but often also social. Some diseases, like sleeping sickness, are fatal if left untreated. In many cases, the infections massively weaken the sufferers. They can also disfigure a person. Lymphatic filariasis, for example, can lead to an extreme enlargement of the arms or legs. In the long term, these diseases drastically reduce the quality of life or lead to death, also indirectly, for example through hunger. People in low-income countries are particularly affected. The largest group are women and children, who then often go to school irregularly, if at all. When men fall ill, they are often no longer able to provide for their families. Often, these clinical pictures also cause stigmatization. Those affected are marginalized and cannot find a partner. All this has far-reaching and complex consequences. In this way, cycles of poverty are created or reinforced, which cost these countries billions of dollars and further weaken their economic power.
What conditions promote the transmission and outbreak of these diseases?
Poverty in these countries is an important factor. It usually goes hand in hand with poor hygienic conditions and a weak health system. But the climate also plays a major role, because many diseases are transmitted by vectors such as mosquitoes, which spread particularly well in warm temperatures.
Which areas are particularly at risk, is it more a problem in big cities or in rural areas?
The entire tropical belt is affected: Africa, Asia and South America – and there it is mainly the rural areas. The cities often do not have the right conditions for the animal carriers. In addition, people in rural areas are often particularly cut off from the health system. For example, the pharmaceutical industry has been providing the population with free antihelminthics (medicines against worm infections) for more than 20 years as part of so-called mass therapies. However, the medicines often do not reach the villages simply because of a lack of roads and a lack of human infrastructure and thus do not reach the people at all.
Are there enough therapies or is there also a deficit in research – possibly because it is not lucrative enough for the pharmaceutical industry?
Some medicines are already available, but the arsenal is in dire need of improvement. A prominent example is ivermectin, which is on everyone’s lips due to Covid. In the case of worm infections, this remedy is very effective at destroying the larvae in the body. However, you cannot attack adult worms with it. For this reason, ivermectin must be given regularly at least once a year for a period of up to 15 years. This is difficult to achieve in remote regions, and the pandemic has also led to further setbacks in this regard. Therefore, we absolutely need substances that also attack the adult worms. In the future we will need more targeted diagnostics and treatment to replace mass therapies. Our task as DNDi is to bring the pharmaceutical industry, academic partners and funders together to develop strategies and take concrete measures. There is a lot of catching up to do.
Why has this failed so far?
Funding is a major problem. Such drugs are very expensive to develop and deliver, and prioritized resources are limited. The neglected tropical diseases are often at the back of the list. Funding has barely increased in the past ten years and we fear it will decrease even more after the Covid pandemic. One of the main tasks of our organization is to get important partners on board from the start, including the pharmaceutical industry. In Germany, for example, we are trying to advance the development of new substances together with Bayer and the University of Bonn. This is funded, among other things, with federal funds.
How well do the people in the affected regions accept the offers?
Part of the story is that people don’t take therapy for a variety of reasons: because they’ve had bad experiences or because they’re afraid of side effects. Sometimes there are also reservations about accepting medicines from white people. That is why working with local partners and promoting personal responsibility in these countries is very important. When it comes to neglected tropical diseases, there are many problems at the same time.
Corona has shown that even rich countries can be severely affected by infectious diseases. Could neglected tropical diseases make it to more temperate latitudes and become a problem?
Climate change in particular could play a role here. So we have to keep an eye on the danger of diseases with mosquitoes as vectors. This includes, for example, dengue fever, which is transmitted by the tiger mosquito and is one of the neglected tropical diseases. We have also seen other infections taking place within Europe that have never been native here before. For example leishmaniasis or schistosomiasis. We should definitely keep an eye on how this develops.
Interview: Pamela Dörhöfer