The epidemic of unusual seizures that causes many children in eastern Africa to behave like zombies has been linked to a parasitic worm secreting neurotoxins in the intestines, according to an article published in the journal Science Translational Medicine.
“Our discovery also indicates that suppressing the immune system can help not only carriers of the nodding syndrome, but also epileptics and people suffering from brain disorders. Another plus is that we have proven that eliminating black flies and parasites will forever solve the problem of the spread of this disease in Africa,”said Avindra Nath, head of the National Institute of Nervous System Diseases and Strokes in Bethesda, USA.
In the mid-60s of the last century, a mysterious disease began to spread across East Africa, affecting mainly children. Infected people began to periodically fall into a state of "zombies", losing contact with the outside world and constantly nodding. For this reason, scientists have called the disease "nodding syndrome." Its development leads to brain atrophy in adults and developmental delays in children. According to the latest WHO estimates, several thousand people in Sudan and Tanzania are suffering from the syndrome today.
For a long time, scientists did not know the causes of this strange disease - neither viruses nor bacteria were found in the blood samples of its victims. Scientists have recently discovered that nodding syndrome can be caused by certain substances in water or food, as well as the nematode worms Onchocerca volvulus. The problem is that this worm lives in the intestines and does not enter the brain - this called into question its ability to manipulate the nervous system.
Nat and his colleagues, having collected and studied blood samples from dozens of Ugandans who have suffered from the disease for several years, have proven that the worm really knows how to do this. All of them were carriers of eggs and adults of Onchocerca volvulus, and their blood contained proteins that are usually absent in the body of healthy people.
After analyzing their composition, American molecular biologists were surprised to find that the body of worms and humans contained the same protein - leiomodine-1. It is one of the key signaling molecules in brain cells that governs the growth of individual nerve endings and connections between nerve cells.
It turned out that the structure of this protein in worms and humans is very similar, which is why the human immune system did not respond to the penetration of its molecules into the bloodstream, and the immune barrier between the brain and the rest of the body freely passed them into the nervous system.
Then the following happens: when the immune system begins to fight the parasite, it produces antibodies to its proteins. Since leiomodine and nematode protein are similar to each other, the immune system begins to attack those cells that produce it - that is, not only the worm, but also the brain cells. There is an acute reaction to the leiomodine-1 molecules in the brain fluids, which the immune system tries to suppress with the help of antibodies. As a result of an acute inflammatory reaction, a large number of nerve cells die, causing something similar to an epileptic seizure.
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The discovery, scientists believe, will help doctors find a cure for the nodding syndrome and help African children already suffering from the disease avoid further developmental delays.
