Sleeping sickness detectable even before the first symptoms

Researchers have developed a system for the early detection of the pathogen in the blood

Trypanosoma pathogen seen through the light microscope. Here: in the blood of a patient. © CDC / Public domain
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Scientists have developed a method with which the pathogens of sleeping sickness can be detected quickly and inexpensively in the blood before the onset of the disease. This was important, according to the Darmstadt researchers, because the first symptoms were that patients were often difficult to treat and in many cases would die from the disease or the strong side effects of the drugs. However, if one has a means of early detection of transmitted by the tsetse fly parasite, many people in the African tropics and their likewise infected livestock can be helped.

So far, African sleeping sickness is a widespread infectious disease, especially south of the Sahara; 60 million people are infected every day but only 4 million are medically monitored. According to American researchers, the virus will continue to spread as a result of global warming, which could extend the problem to an additional 40 to 77 million people.

Blame is a parasite of the genus Trypanosoma, die in the infected without medical treatment in any case. The first signs of illness are headache and fever, followed by weeks or months of confusion, coordination difficulties and sleep disturbances. Therapy at such an advanced stage is difficult because the parasites have already penetrated into the central nervous system where they cause irreversible damage. In addition, from this point on only highly toxic drugs such as arsenic compounds are available. Because of the serious side effects, the treatment must be done in the hospital and often costs the patient even life.

Neglected diseases - uninteresting for the pharmaceutical industry?

The infection, also known as African trypanosomiasis, is one of the "neglected diseases" according to WHO (World Health Organization). These are infectious diseases that cause thousands of deaths a year, especially in particularly poor parts of the world. However, the pharmaceutical companies based in the industrial nations do not see any financial potential in their treatment. In order to nevertheless ensure a control of the expanding infectious disease, the researchers of the Technical University of Darmstadt looked for a more cost-effective method of diagnosis. Ulrich Göringer and his colleagues have for the first time combined two existing systems: the potentiometer and the so-called aptamers alias Spiegelmere.

The measuring device (potentiometer) can detect a contained substance or larger components on the basis of voltage changes in a liquid to be measured - in this case the blood. However, the components must carry an electrical charge or be ionic. This property is possessed by the aptamers, which in addition can specifically bind to a component of the fluid under investigation - here a protein of the pathogen. Their electric charge depends on whether a molecule is bound to it or not. If the aptamers detect trypanosomes in the blood of a patient, their charge changes and the potentiometer can detect this as a change in voltage, thus providing information about a possible infection. This is possible because the aptamer, a molecule made up of DNA or RNA strands, fits like a key to a lock and thus binds only those components that are to be detected. display

Structure of an aptamer for the detection of pathogens of sleeping sickness TU Darmstadt

With only a few drops of blood

"We can now find out with just a few drops of blood, even before the outbreak of the disease, whether a person is infected or not, " reports G ringer. The system is also applicable to other diseases. All that is necessary is to determine the correct - that is to say constant regions of a pathogen - and to synthetically develop a suitable spiegelmer. "The measuring method is very simple", says the Darmstadt researcher, "no biochemical preparation is necessary". Instead, you can simply sprinkle the measuring solution with the aptamers on paper or plastic and thus offer it as a test strip. For example, it would be possible to combine different specific aptamers to offer detection systems that deliver results simultaneously and quickly for multiple diseases.

Since the $ 5 system is too cheap even before it enters mass production and thus has too little economic potential, the interest of the pharmaceutical industry is limited. Nevertheless, the Darmstädter are optimistic to get an industrial partner for the large-scale production: "In two to three years, we want to make mass production possible, which should make the process even cheaper", predicts G ringer. If the system is produced as a test strip or as a measuring chip, the price can drop to two dollars, the researchers agree. This would also be in line with the WHO's reasonable cost for controlling a neglected disease.

(TU Darmstadt, 13.12.2012 - KBE)