Human African trypanosomiasis (HAT), also known as sleeping sickness, is a major killer disease of sub-Saharan Africa. It’s a parasitic infection, transmitted by tsetse flies. Parasites called trypanosomes eventually kill the patient unless a quick and aggressive treatment is administered. Now scientists at the University of Glasgow provided new insights into this deadly disease.
Human African trypanosomiasis, also known as African sleeping sickness, is transmitted by tsetse flies when they bite humans to consume a blood meal. Image credit: Wikimedia (CC BY-SA 3.0)
At the moment, HAT is characterized as having two stages: the early, stage 1, or haemo-lymphatic stage, which is when treatment is effective and relatively non-toxic, and the stage 2 when treatments are toxic and less effective. Diagnosis of the stage depends on a defined amount of white blood cells in the cerebrospinal fluid, but some physicians in different sub-Saharan African countries use different classification. Now researchers are questioning this classification of two stages.
Scientists used mouse models to improve their understanding of how the disease develops and found that a range of host genes controlling the development of central nervous system disease are activated much earlier than previously thought. Researchers say that these findings may help explain why neurological symptoms of HAT occur relatively early in the disease.
Tsetse fly from Burkina Faso. Image credit: International Atomic Energy Agency via Wikimedia, CC BY-SA 4.0
As mentioned above, the 2 stage classification is based on the number of white blood cells in the cerebrospinal fluid, but scientists now are saying that neurological symptoms occur much earlier than previously thought. In fact, neurological symptoms occur to patients who have no or few cells in the cerebrospinal fluid. The current classification would categorize these patients as early stage, even when the disease is actually quite advanced. Of course, this information could change the normal course of the treatment and could potentially save thousands if not millions of lives.
Professor Peter Kennedy, senior and corresponding author of the study, said: “Finding that host genes controlling the development of central nervous system disease are activated much earlier than previously after initial infection, calls into question the basis of dividing the disease into distinct early and late stages, and indicate that the disease development is complex and depends on a wide range of interacting factors.”
Human African trypanosomiasis is a deadly disease threatening the lives of millions of people in 36 sub-Saharan African countries. It is called “sleeping sickness”, because in the second stage of the disease there’s usually some sleeping problems, as well as confusion, numbness and poor coordination. It spreads through flies and is very difficult to control, but hopefully studies like this could help develop new treatments.
Source: University of Glasgow