Researchers from the United States and the United Kingdom have found that a group of parasites responsible for several devastating diseases -- including malaria -- share a metabolic pathway essential for survival in many plants, fungi and bacteria but not found in mammals. This finding provides many new targets for anti-parasitic medications, including the possibility of medicines related to currently available herbicides.

In the June 25 issue of the journal Nature, the researchers demonstrate that the herbicide glyphosate (Roundup), which interferes with the sixth of the initial seven enzymes in the plant-like pathway, inhibits in the test tube the growth of the parasites that cause malaria, toxoplasmosis and crytosporidiosis.

They also show that adding the herbicide to sub-therapeutic doses of a common anti-microbial medication can protect mice from otherwise fatal infections with Toxoplasma gondii. Similar tests against related parasites are planned.

"We urgently need new and better medicines to treat these extremely common diseases caused by parasites," said team leader Rima McLeod, M.D., the Jules and Doris Stein Research to Prevent Blindness Professor of Ophthalmology and Visual Sciences at the University of Chicago. Some of these diseases are untreatable at present because no known medicines inhibit them and others are caused by parasites that have developed resistance to available medicine. "These studies provide new, rational targets for development of novel treatments as well as several well-studied compounds that can interfere with this pathway."

The parasites that rely on this chemical cascade are members of the phylum Apicomplexa, which includes many important human and animal pathogens, such as: