Researchers have determined genetic blueprints for the parasites that cause three deadly insect-borne diseases: African sleeping sickness, leishmaniasis and Chagas disease.

The research, funded in part by the National Institute of Allergy and Infectious Diseases ( NIAID ), part of the National Institutes of Health, is published in the journal Science.

Knowing the full genetic make-up of the three parasites--Trypanosoma brucei, Trypanosoma cruzi and Leishmania major--could lead to better ways to treat or prevent the diseases they cause.

All three diseases are spread by insects.

T. brucei, which causes sleeping sickness, is spread by the tsetse fly and is found in sub-Saharan Africa. The World Health Organization estimates there may be as many as 500,000 cases of sleeping sickness each year. If left untreated, sleeping sickness is fatal.

Various forms of leishmaniasis are spread by the sandfly and are endemic in 88 countries on five continents. Visceral leishmaniasis, also known as kala azar, is the most severe form of the disease and causes high fever, a swollen spleen and severe weight loss before killing its victims. Cutaneous leishmaniasis, also known as "Baghdad boil," produces numerous skin ulcers that can leave sufferers permanently scarred.

T. cruzi causes Chagas disease and is spread through the infected feces of an insect sometimes called the "kissing bug" for its habit of biting near a person's mouth. Found throughout Central and South America, Chagas disease is particularly prevalent among the poor and claims 50,000 lives each year.

“One of the biggest surprises to come out of the genome sequencing projects is that these parasites--despite major differences in how they are spread and how they cause disease--nevertheless have a core of 6,200 genes in common," says Martin John Rogers, of NIAID's Parasitology and International Programs Branch. At a genetic level, the similarities among these parasites outweigh their differences. The shared genes give scientists a vastly expanded array of targets for development of new drugs that conceivably could work against all three parasites, explains Rogers. Conversely, he adds, analyzing the relatively smaller ways in which the organisms diverge genetically could help researchers design vaccines, drugs and improved diagnostics targeted to each of the three parasites.

Source: National Institute of Allergy and Infectious Diseases / NIH, 2005


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