Public Release: 

A little blue and purple helps body fend off deadly parasites

Dyes may help Latin American countries affordably treat Chagas disease epidemic, could bolster blood transfusion safety worldwide

University of California - Irvine

Irvine, Calif., Oct. 15, 2002 -- Chagas disease, a parasitic disease that is nearly epidemic from Mexico to Tierra del Fuego, may have met its match in a simple solution of dyes, a UC Irvine study has found.

The study, which used purple and blue dyes commonly found in laboratories, may provide an affordable, effective treatment for the disease, which currently infects about 17 million people in 21 Latin American countries. It may also provide an effective way to remove harmful organisms from blood. The study was presented recently at the annual meeting of the Argentina Association of Hematology and Immuno-hematology in Buenos Aires.

Dr. Jose Ocariz, associate professor of pathology and director of UCI Medical Center's Blood Bank and Donor Services, and his colleagues found that the two dyes -- crystal violet and methylene blue -- eliminated measurable concentrations of Trypanosoma cruzi, the parasite that causes Chagas disease, in human blood samples.

"The two dyes appeared to wipe out any measurable concentration in the laboratory of T. cruzi from the blood samples," Ocariz said. "This means the dyes could prove a low-tech way to eliminate most of the parasites, allowing the body's immune system to fight the disease successfully. The dyes also removed from blood a number of disease-causing organisms, including viruses and bacteria."

Brazilian physician Carlos Chagas discovered the disease in 1909. It is considered a disease of poverty because the parasite is transmitted by a bug found in substandard housing and thatched roofs, according to the World Health Organization. The WHO estimates that nearly 100 million people in South America live in conditions that put them at risk for the disease.

It also can be transmitted by transfusions of contaminated blood. In some countries, the rate of T. cruzi contamination in blood banks often ranges higher than similar rates for the viruses that cause AIDS and hepatitis.

While Chagas may be endemic to South and Central America, the problem of contaminated blood is of worldwide concern. Reports have surfaced of infections with AIDS, hepatitis, West Nile encephalitis and other diseases from tainted transfusions, causing a number of repeated blood shortages and a worldwide attempt to find new ways to ensure clean, transfused blood. Many resolutions are either very expensive or result in new but occasionally lethal complications for transfusion recipients. Some dyes such as methylene blue are used alone to treat the disease, but require the use of ultraviolet radiation, which has been associated with increased rates of certain cancers. Ocariz' combination treatment did not require the use of radiation. As an added measure of safety, the dyes can be removed by an inexpensive filter before transfusion to patients.

Ocariz and his colleagues found that when human blood samples spiked with T. cruzi were treated with these dyes no measurable amount of T. cruzi remained in the blood samples. However, when the researchers injected the treated blood into mice that lacked a functioning immune system, some of the mice died, though not as quickly as those receiving untreated blood.

The researchers think that a minute amount of T. cruzi may remain in the treated blood, but that a healthy immune system may be able to combat the remaining parasites.

"The immune-suppressed mice showed us that the body's immune system must still play a role in the elimination against Chagas disease," Ocariz said. "Now, we hope to measure how well the dyes work in concert with a healthy immune system."

The researchers are continuing to look at how well dyes can eliminate parasites, bacteria and other organisms from blood, as well as other simple and cost-effective methods that will add an extra layer of safety. Ocariz's colleagues included Dr. Edward Shanbrom, a private researcher who is a pioneer in the use of products to clean transfused blood; Gerald Manning, chair of molecular biology and biochemistry; and John Owens, research associate at the College of Medicine.


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