NTDs: Why these neglected tropical diseases affect us too

The abbreviation NTD stands for “Neglected Tropical Disease”. This refers to tropical diseases that medicine and politics pay little attention to. You can read here why this is and how NTDs are also spreading beyond tropical countries.

Neglected tropical diseases is a collective term for various clinical pictures. The WHO currently counts a total of 20 diseases as NTDs – but other sources give different figures. The diseases in question are caused by a wide variety of vectors, including not only viruses and bacteria, but also parasites, fungi and toxins.

According to the WHO, more than a billion people worldwide are affected by neglected tropical diseases. According to the German Network for Neglected Tropical Diseases (DNTDs), they are 1.7 billion people in a total of 149 countries.

The Big Five of Neglected Tropical Diseases

Not all neglected tropical diseases are equally widespread. Five diseases are responsible for more than 90 percent of all diseases. These are considered the “Big Five” or the “Great Five”. The following NTDs belong to the Big Five:

• Lymphatic filariasis: A disease that causes severe physical disfigurement and disability. It is also responsible for the clinical picture of elephantiasis.
• onchocerciasis: Better known as river blindness. This disease is transmitted by the black fly and causes blindness.
• trachoma: If left untreated, trachoma can also cause blindness. Bacteria are carriers here.
• schistosomiasis: Bilharziasis is a worm disease that can damage the intestines, but also other organs. It impairs the development of children and the physical performance of adults.
• geohelminths: This disease is also an infestation of worms in the intestinal area. Intestinal worms can cause anemia. For this reason, they are particularly dangerous for women who are giving birth, because anemia can lead to complications during childbirth.

Where do Neglected Tropical Diseases occur?

Despite their individual differences, all NTDs have two key things in common:

1. They mainly appear in tropical countries up, especially in Asia and Africa. The NTD expert Achim Hörauf limits the distribution area even more specifically: It is therefore between the northern and southern tropics, each beginning with the 23rd degree of latitude. This equatorial area has a warm and humid climate that favors transmission.
2. suffer the most poorer countries or poorer ones population groups of neglected tropical diseases. According to the WHO, the vast majority of those affected belong to poor communities (“impoverished communities”). These are regions that have little access to clean water, sanitation or effective health care. Under these circumstances, diseases can spread particularly easily.

It is also these two factors that contribute significantly to the neglect of NTDs. The diseases are neglected on several levels.

Neglected Tropical Diseases: Why Neglected?

Although they occur frequently and widely in the affected areas, neglected tropical diseases are hardly in the public eye – neither as a political, social, nor as a medical issue. This neglect takes various forms. Achim Hörauf differentiates between three main levels:

• NTDs are neglected in the public eye because they mainly in the Global South occur and primarily affect poor sections of the population. In richer countries, the social and medical interest in them is therefore low. The poor population also does not have a strong public presence and cannot effectively draw attention to the problem.
• In contrast to “more well-known” tropical diseases such as malaria, NTDs are neglected by research. They are responsible for fighting outbreaks and developing medicines less funding to disposal.
• The public and research neglect is related to a third point: Most NTDs ask only a danger for travelers during longer stays The diseases therefore very rarely affect tourists, business travelers or military personnel from rich countries. This is one of the reasons why they receive less attention than tropical diseases, which pose a health risk to foreigners even if they stay only for a short time.

So the fundamental problem is that the countries that would have the best opportunities to research and combat NTDs have little interest in raising the necessary funds. However, neglected tropical diseases are not completely ignored. In recent years there have been two major developments in the fight against NTDs: the London Declaration and the WHO roadmap.

What is the world doing about NTDs?

Outbreaks of neglected tropical diseases are closely related to poor sanitation and health conditions. A key goal in combating them must therefore be to improve these circumstances and strengthen local health systems.

A first step in this direction was the London Declaration (“London Declaration on Neglected Tropical Diseases”), which the WHO formulated in 2012. The goals set out in the declaration should be achieved by 2020. These goals primarily included eradicating or significantly reducing various NTDs and making medicines available to others. Financial and technical support on the ground should also be improved through more efficient international cooperation.

The result gives hope: By 2020, 42 countries had actually managed to successfully eliminate one or more NTDs. However, the approach taken by the companies and organizations involved is often criticized for focusing too much on individual diseases. Interactions or overlaps between different NTDs, which definitely play a role in practice, were not sufficiently taken into account. So you have missed opportunities to fight the spread of diseases even more effectively.

Following the London Declaration, the WHO presented a comprehensive roadmap for further combating neglected tropical diseases in 2021. This time, the envisaged targets are to be achieved by 2030. The Deutsches Ärzteblatt summarizes the key points of the roadmap as follows:

• By 2030, the number of people affected by NTDs is to be reduced by 90 percent.
• At least two NTDs are expected to be completely eradicated by 2030.
• At least one NTD is said to be completely eliminated in 100 countries.
• The number of years of life lost due to illness is to be reduced by a total of 75 percent. The concept of years of life lost through illness is also known by the abbreviation DALY (Disability-Adjusted Life Years). This factor can be used to determine the quality of life in a country or a specific region. It is calculated as the sum of the years of life lost through death or reduced through illness in the total population.

Neglected Tropical Diseases and Climate Change

Although neglected tropical diseases are essentially limited to the Global South, these boundaries are gradually shifting. It’s mainly her fault climate crisis.

Achim Hörauf points out that global warming generally favors the spread of tropical diseases. At least in southern European countries, imported diseases could survive longer and be transmitted better due to the rising temperatures. This is especially true for mosquito-borne diseases, which are spreading further north due to climate change. Cases of dengue fever, for example, which is also one of the neglected tropical diseases, have repeatedly become known in Europe in recent years. Other tropical diseases are also spreading to European countries: the worm disease billharzia, for example, which is one of the “Big Five” of NTDs, can now be detected in Corsica.

This clearly shows that neglected tropical diseases are no longer just a local problem far away from our comfort zone. They are also increasingly becoming a global problem. For this reason alone, research will not be able to afford to continue to neglect them in the long term.

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