Sixty million people in 36 countries of sub-Saharan Africa are threatened daily by a deadly parasitic disease known as African sleeping sickness.
African sleeping sickness is caused by trypanosomes which are protozoan parasites. It is transmitted to humans through the bite of the tsetse fly of the genus Glossina.
There are two forms, each caused by a different parasite :
- Trypanosoma brucei gambiense, which causes a chronic infection lasting years and affecting countries of western and central Africa;
- Trypanosoma brucei rhodesiense , which causes acute illness lasting several weeks in countries of eastern and southern Africa.
When a person becomes infected, the trypanosome multiples in the blood and lymph glands, crossing the blood-brain barrier to invade the central nervous system where it provokes major neurological disorders. Infection by trypanosomes causes neurological alterations which are often irreversible even after successful treatment. Psychomotor and neurological retardation even among cured children is frequent. Without treatment, the disease is invariably fatal.
Sleeping sickness is a daily threat to more than 60 million men, women and children in 36 countries of sub-Saharan Africa, 22 of which are among the least developed countries in the world. However, only 3 to 4 million of these people are under surveillance and the 45 000 cases reported in 1999 do not reflect the reality of the situation, but simply show the absence of case detection. The estimated number of people thought to have the disease is between 300 000 and 500 000.
Detection of people infected with sleeping sickness and subsequent patient care require well trained staff, resources, drugs and well-equipped health centres. Furthermore, without systematic screening of exposed populations and without treatment, the majority of sick people will die without ever having been diagnosed.
In the February issue (Volume 17, Issue 3) of the journal Molecular Cell, scientists in the Marine Biological Laboratory's (MBL's) Josephine Bay Paul Center for Comparative Molecular Biology and Evolution report their discovery of a protein called JBP2, which will help them test their hypothesis that a uniquely modified DNA base called base J is a key component of the trypanosome's mechanism for evading the immune system. If the hypothesis is correct, it will bring scientists closer to developing a more effective drug for treating African sleeping sickness.