Working group

Neglected tropical diseases

Short description

Currently, approximately one billion people worldwide are at risk of developing an inability to work or blindness, becoming maimed or dying due to neglected tropical diseases (NTD). NTDs include river blindness, dengue fever, sleeping sickness, snakebites and leprosy, only to name a few known examples of this diverse group of diseases. The poorest parts of the population, women and children in particular, are most severely affected.
In contrast to malaria, tuberculosis and AIDS, these diseases do not affect industrialised nations and travellers to these countries are also rarely at risk, which is why they are frequently neglected, also with regard to research funding. This, however, is due to change: A DZIF research consortium is taking these issues on in Africa and is developing new diagnostic tools for river blindness and other diseases that are caused by parasitic worms.

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Neglected tropical diseases are endemic in Africa and constitute “widespread diseases” so to say. “In the countries affected, they are often the chief causes of disease,” explains Prof Achim Hörauf of the University Hospital Bonn. He coordinates the DZIF consortium and develops new drugs against filarial worms, including corallopyronin A, an antibiotic that is effective against numerous bacteria and against members of the filarial worm group which cause river blindness.

From African sleeping sickness to trematode infections

The WHO has created a priority list of 20 neglected tropical diseases. These predominantly include worm infections in addition to infections with one-celled parasites, bacterial and viral pathogens. Known worm diseases include so-called river blindness and elephantiasis which causes the permanent swelling of limbs. An example of a bacterial infection is leprosy and viral infections include rabies and dengue fever. “At the DZIF, we will initially concentrate on worm diseases, and particularly on improving diagnostics,” explains Hörauf. “Being able to recognise these diseases early on can prevent enormous damage for the people affected.”

Four themes at four sites

DZIF scientists work in cooperation with African Partner Institutions and with two other institutions. They are initially conducting joint research and development projects in four different fields. In Bonn, they are developing improved biomarkers for the diagnosis of river blindness. In Hamburg, at the Bernhard Nocht Institute for Tropical Medicine, the focus in on developing more rapid diagnostics as well as on the epidemiology of bilharzia (schistosomiasis), a widespread worm infection with many secondary complications. At the Munich Partner Site, scientists will concentrate on helminths, which are parasitic worms that frequently occur as HIV coinfections. Tübingen will initially focus on diagnostics that can identify several parasitic infections occurring simultaneously. Coinfections with different parasites are a frequent problem in Africa which needs to be taken into consideration when developing vaccines and other procedures.

Patients with river blindness are recruited for a study.

© Achim Hörauf

Bonn: River blindness—risk of infection near Water

River blindness is caused by infections with filarial worms. The risk of infection with these worms is particularly high near rivers as blackflies, which transmit the disease, are naturally found in such environments. Over 30 million people are currently infected. “We urgently need rapid and reliable tests that indicate when treatment can be discontinued and when a risk of relapse exists,” explains Hörauf, who conducts research in search of new biomarkers with his team in Bonn. It is possible to palpate worm lesions under the skin, even though live worms no longer exist in the body. The aim is to use diagnostics based on urine samples which are easier to conduct and carry a lower risk than blood samples.

Hamburg: Bilharziamost widespread in Africa
Following malaria, bilharzia is the second most frequent parasitic tropical disease worldwide. The pathogen responsible for the disease is a trematode that feeds on human blood. The larvae develop in freshwater snails and the infection is contracted through contact with this freshwater. The worms can severely damage different organs. Currently, the most important control measure is to conduct mass treatment exercises with praziquantel, the only available drug. However, this drug may not be taken by pregnant women or by young children. “Conducting such broad-based treatment only makes sense in regions that have a high prevalence of the disease,” explains Dr Norbert Schwarz. Together with colleagues from the Bernhard Nocht Institute in Hamburg and from Madagascar, he intends to advance bilharzia diagnostics, especially rapid testing, so as to enable more targeted treatment of affected individuals.

Tübingen: A parasite rarely comes alone
Bilharzia is often accompanied by infections caused by other parasites. “In Africa, and Sub-Saharan Africa in particular, people frequently have coinfections with two or three other parasites,” explains Dr Carsten Köhler from the University Hospital Tübingen. Together with Dr Meral Esen and Dr Andrea Kreidenweiss at the DZIF, he now intends to develop a diagnosis scheme that is able to identify different pathogens. “For example, we showed that certain types of helminths, including schistosomes impair an infected person’s immune system in such a way that a malaria vaccine would become less effective,” explains Köhler. Being able to use blood samples to conduct as comprehensive an analysis as possible is critical to the development of interventions as well as to the successful prevention and treatment of affected patients.

Munich: Worm infections and HIV
Here, coinfections are also in the foreground. Scientists at the Medical Center of the University of Munich (LMU) research the interactions between certain worm infections and HIV infection. In a cohort study conducted in Tanzania, scientists discovered that infections with the Wuchereria bancrofti worm was associated with a two- or three-fold higher risk of contracting HIV. “In the newly created consortium, we intend to develop diagnosis systems that also produce reliable results for HIV patients,” explains Prof Michael Hölscher.
Research activities currently revolve around developing new diagnostic methods. However, in the future, DZIF scientists also intend to conduct research on drugs and vaccines, as is the case in other DZIF fields.

More on the topic:
By order of the BMBF, the Bernhard Nocht Institute for Tropical Medicine initiated a study aiming to analyse research involving neglected tropical diseases in Germany. DZIF scientists from the consortium were also involved in the study.

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