This past summer three international groups published the DNA sequences of the parasites that cause Chagas' disease, African sleeping sickness and leishmaniasis. These deadly ailments, transmitted by bloodsucking insects such as the "kissing bug" and the tsetse fly, take an enormous toll on tropical and subtropical populations--not only do they kill 125,000 people every year, but they can also compromise blood banks and disfigure patients so badly that they are ostracized from society. Although treatments derived from the work are still several years away, the sequencing of the genomes of the three parasites--Trypanosoma cruzi, T. brucei and Leishmania major--represents new hope in the battle against the diseases.

No vaccine exists against these parasites, collectively called the Tritryps, and current medicines are toxic, difficult to administer and not always successful, according to the World Health Organization. Based on arsenic and antimony, those therapies in widest use date back to the 1940s. Some newer treatments exist but have limited efficacy. "They are neglected parasites that afflict deeply impoverished people," says Najib El-Sayed, a parasitologist at the Institute for Genomic Research in Rockville, Md., who is the lead author of the paper on T. cruzi and the principal investigator of the T. brucei project.

This article was originally published with the title Parsing Parasites.

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