Trypanosomes, which cause sleeping sickness, can suddenly disappear from the blood of the infected, but only in order to return again after a while and inflict a fatal blow. Only now it became clear where she was hiding during such periods.
Tropical sleeping sickness is caused by the simplest trypanosomes, which can be transmitted to humans through the bite of tsetse flies. Covering entire African villages, it can suddenly disappear without a trace and just as unexpectedly return, hitting many people almost simultaneously. Until now, it was not possible to understand where it disappears and from where it again affects people, whose analyzes did not reveal any traces of trypanosomes. It turned out that all this time the disease was hiding literally under the noses of doctors and scientists, leaving the bloodstream and persisting as a skin disease. This is described in an article published by eLife magazine.
Researchers from Europe and Congo, led by Annette MacLeod from the University of Glasgow, note that after the remarkable successes that were achieved in the fight against trypasonomiasis in the middle of the twentieth century, their incidence dropped to 7-10 thousand cases a year, almost always fatal. Given the fact that more than 65 million people live in the risk zone, this is very small, but doctors could not get rid of these last thousands.
The work used archival case histories and biopsies of people who were treated in Congo clinics in the first half of the 1990s. In some skin preparations, McLeod and her colleagues found the presence of trypanosomes, although they were not noticed during treatment and such patients did not show any characteristic symptoms. In experiments on mice, it was shown that parasites can colonize the skin and, moreover, spread by flies "from skin to skin." Strictly speaking, such a mechanism of spread has not been shown in humans, but the authors are confident that the skin is an "underestimated reservoir" of trypanosomal infections.
It is in the skin, apparently, that the infection is hidden in those periods when it suddenly ceases to be detected and manifest itself as vivid symptoms, because doctors still test only blood samples for the presence of trypanosomes. Now, having found the enemy's secret lair, doctors can launch the ultimate offensive against the deadly sleeping sickness.
Sergey Vasiliev