Scientists of the Antwerp Institute of Tropical Medicine (ITG) opened a new front against the cause of sleeping sickness. This parasite is transmitted between humans by tsetse flies. The researchers learned a bacterium living in those flies how to produce antibodies against the parasite. Application in the field is still a long way of, but the technique shows quite some promise.
Sleeping sickness is caused by trypanosomes, parasites being transmitted by the bite of a tsetse fly.
The World Health Organization estimates the yearly death toll at between 10 000 and 20 000 people. On top of that, the parasite also infects cattle, causing considerable economic loss. Many small African farmers depend on their cattle.
Without treatment, an infection is irrevocably fatal. Unfortunately, many poor people present at the hospital only in a late stadium. At that time the Trypanosoma parasites have lodged themselves in the brain, behind the notorious blood-brain barrier that keeps most drugs out. Arsenic compounds can pass the barrier and kill the parasite, but they also kill five per cent of the patients. New drugs are not in the pipeline.
Besides the parasite, one may also attack its vector, the tsetse fly. But insecticides may be detrimental to the environment, certainly in the long run. Therefore scientists look for alternative strategies. For instance genetically modified insects that are incapable of being infected by the parasite, or do not transmit it. But germline transformation of tsetse flies is unfeasible. To do so, one must be able to handle the eggs, but tsetse flies do not lay eggs, they directly bring forth a larva.
Therefore, the Antwerp researchers took another road. Tsetse flies harbour, as is the case with many insects, resident bacteria. One of them, Sodalis glossinidius (literally: companion of the tsetse fly) exclusively lives in tsetse flies. And it can be cultivated in the lab.