The sleeping sickness parasite kills nearly 66,000 people annually and silently infects almost 450,000 more, mostly in sub-Saharan Africa. Current drug treatments are wanting because they work best in the disease's initial stages, when diagnosis is often difficult. New research published online this week by the Proceedings of the National Academy of Sciences may help identify alternate pharmaceutical strategies. The study results suggest that the parasite contains algae genes, and thus could succumb to drugs based on herbicides.

Fred R. Opperdoes of the Christian de Duve Institute of Cellular Pathology in Belgium and his colleagues analyzed the genomes of two types of trypanosomatids, the group of bugs behind sleeping sickness, Chagas' disease and leishmaniasis. The team found that the genomes of Trypanosoma brucei (see image) and Leishmania mexicana contain 16 genes closely related to genes found in plants. The corresponding plant genes contribute to photosynthesis. Trypanosomatids lack the ability to photosynthesis but the scientists did detect proteins produced by these genes in the microbes' glycosomes, which help them extract energy from food. The researchers thus posit that a small algal organism used to live inside trypanosomatids, and was eliminated by evolution save for some of its genes.

The findings could point to new ways to combat parasitic diseases, the authors conclude, because the effects of a variety of agricultural herbicides on trypanosomes and leishmaniasis can easily be tested.