Sensitive Test Developed for Sleeping Sickness

Proteins imitating typical parts of the sleeping sickness parasite can be used in more efficient diagnostic tests, without the need for culturing dangerous parasites.

In the regions where Trypanosoma brucei gambiense, the causative agent of sleeping sickness is found, medical workers for decades already use a rapid diagnostic test, to screen millions of people each year on the presence of antibodies in their blood.

A scientist at the Antwerp Institute of Tropical Medicine (Belgium) has developed a new and better test by trying to synthesize artificial targets. These 'mimotopes' mimic only a part of the original target protein, but still are sufficient to react with the patient's antibodies. The investigator produced mimotopes that are reliable and react with infected patients' serum. These mimotopes now can be the base for a new generation of rapid diagnostic tests for sleeping sickness.

In the original tests the antibodies are demonstrated by presenting them targets they will also recognize and attack on real trypanosomes such as the variable surface glycoprotein that cover the parasite as a mantle. When antibody and target react, the test is positive and is made visible by for instance a color change or a clotting. Today those targets are obtained from living parasites that are raised in laboratory animals, and are a constant danger for the laboratory technicians.

In an early stage, the disease is easy to treat, but once the brain is invaded, the treatment becomes more complex and physicians must use medicines with dangerous, even deadly, side effects. Therefore, it is important to detect the infection early. Patients become disoriented, their sleeping pattern disintegrates, and they get motor and mental problems. This inevitably leads to coma and death. According to the World Health Organization (WHO; Geneva, Switzerland) estimates, sleeping sickness claims 10,000 to 20,000 lives each year. In recent years, the number of cases has come down substantially, thanks to campaigns against the disease, so error margins that were acceptable in the old days, because the tests still saved so many lives, now become inadmissible.

Related Links:
Antwerp Institute of Tropical Medicine
World Health Organization