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UC San Diego Researchers Find Desert Plant May Help Treat Giardiasis

The creosote bush shown in the desert in Palm Springs, Calif., Jan. 26, 2002.

Credit: Associated Press

Above: The creosote bush shown in the desert in Palm Springs, Calif., Jan. 26, 2002.

A plant commonly found in the southwestern U.S. desert produces compounds that could be effective in treating an often-deadly diarrheal illness and an amoeba that causes a usually fatal form of encephalitis, according to researchers at UC San Diego.

In a study published in the journal PLOS Neglected Tropical Diseases, the scientists in the Skaggs School of Pharmacy and Pharmaceutical Sciences said the compounds produced by the creosote bush exhibited potent anti- parasitic activity. Researchers at the University of Colorado Anschutz Medical Campus assisted in the study.

Also known as greasewood, the creosote is a tough evergreen bush with small waxy leaves, yellow flowers and a turpentine-like scent. The researchers said Native Americans in both the U.S. and Mexico have long used the plant for a variety of ailments, including intestinal complaints.

Previous scientific studies have documented the plant's pharmacologically active compounds, including one with antiviral, antibacterial, anti-inflammatory and anti-cancer properties, according to UCSD. It's also a liver toxin at high doses.

"The significance and intrigue of our study is that it shows the value of prospecting for new medicines from plants traditionally used by indigenous people as medicine," said Anjan Debnath, an assistant adjunct pharmacy professor at UCSD.

Giardiasis, a diarrheal illness, is linked to about 846,000 deaths around the world each year. Infection usually occurs through ingestion of contaminated water or food. Though rarely lethal in the U.S., it's estimated there are more than 1 million cases of giardiasis in the country annually, the scientists said. According to the U.S. Centers for Disease Control and Prevention, the illness is common among campers and backpackers, and has been dubbed "Beaver Fever."

The study determined that six compounds from the plant are active against the pathogenic protozoa Giardia lamblia, which causes giardiasis, and Naegleria fowleri.

The latter is a water-borne amoeba that enters the brain through the nasal passage, causing a type of brain damage known as primary amoebic meningoencephalitis. Though relatively rare, PAM has a greater than 95 percent fatality rate, the scientists said. Called the "brain-eating amoeba," it can be found in soil and warm freshwater such as lakes, rivers, and hot springs.

The study was funded by the National Institutes of Health and the ALSAM Foundation of Salt Lake City.

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